Quantum memory device

Abstract

A quantum memory device includes a waveguide, a memory cell, and a control circuit. The waveguide is arranged to spatially limit a photon path therein; the memory cell includes a micro-ring resonator, a frequency adjuster, and a quantum memory material portion, where a first portion of the micro-ring resonator is parallel to a portion of the waveguide, the frequency adjuster being arranged to adjust an effective refractive index in or around a second portion of the micro-ring resonator to adjust a photon resonance frequency in the micro-ring resonator, the quantum memory material part comprises a quantum memory material which has a ground state and an excited state in which photons are stored, and is positioned in or on the third part of the micro-ring resonator; the control circuit is arranged to adjust a photon resonance wavelength in the micro-ring resonator to match a predetermined wavelength in a first step of the capture photon operation and to generate a plurality of capture photons in the micro-ring resonator.

Description

Technical Field

[0001] The embodiments of the utility model relate to a solid-state quantum memory device, and more particularly to a device that can be operated at room temperature and is suitable for quantum communication applications. Background Art

[0002] Quantum information storage and communication has the potential to achieve faster and more secure communications. However, existing quantum storage structures usually require low temperatures and complex system support settings such as vacuum environments. Utility Model Content

[0003] The purpose of the present invention is to provide a quantum memory device to solve at least one of the above problems.

[0004] The quantum memory device provided by an embodiment of the utility model comprises: a waveguide, which is configured to spatially confine a photon path therein; a memory unit, which comprises a microring resonator, a frequency adjuster, and a quantum memory material portion, wherein a first portion of the microring resonator is parallel to a portion of the waveguide, wherein the frequency adjuster is configured to adjust an effective refractive index in or around a second portion of the microring resonator to adjust a photon resonance frequency in the microring resonator, and wherein the quantum memory material portion comprises a quantum memory material having a ground state and an excited state in which photons are stored, and is located in or on a third portion of the microring resonator; and a control circuit, which is configured to adjust a photon resonance wavelength in the microring resonator to match a predetermined wavelength during a first step of a photon capture operation, and generate a plurality of captured photons in the microring resonator, and the predetermined wavelength is a wavelength of the captured photons.

[0005] A quantum memory device provided by an embodiment of the utility model comprises a first die and a second die assembled by bonding, wherein the first die comprises: a waveguide configured to spatially confine a photon path therein; a microring resonator comprising a first portion parallel to a portion of the waveguide; a frequency adjuster configured to adjust the effective refractive index in or around the second portion of the microring resonator to adjust the photon resonance frequency in the microring resonator; and a quantum memory material portion comprising a quantum memory material having a ground state and an excited state storing photons therein and located in or on a third portion of the microring resonator; and wherein the second die comprises a control circuit configured to adjust the photon resonance wavelength in the microring resonator to match a predetermined wavelength during a first step of a photon capture operation and generate captured photons in the microring resonator.

[0006] A quantum memory device provided by an embodiment of the utility model comprises a waveguide, which is configured to spatially confine a photon path therein; a memory unit, which comprises a microring resonator, a frequency adjuster, and a quantum memory material portion, wherein the microring resonator comprises a first portion parallel to a portion of the waveguide, wherein the frequency adjuster is configured to adjust an effective refractive index in or around a second portion of the microring resonator to adjust a photon resonance frequency in the microring resonator, and wherein the quantum memory material portion comprises a quantum memory material having a ground state and an excited state storing photons therein, and being located in or on a third portion of the microring resonator; a control circuit, which is configured to adjust a photon resonance wavelength in the microring resonator during a first step of a photon capture operation; and a magnetic field generator, which is configured to generate a magnetic field in the third portion of the microring resonator and the quantum memory material portion during a second step of the photon capture operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figures 1A to 1C This is a manufacturing process for forming a first bare chip in an embodiment of the present invention.

[0008] Figure 2A and Figure 2B This is a manufacturing process for forming a second bare chip in one embodiment of the present invention.

[0009] Figure 3 It is a vertical cross-sectional view of a joint assembly in one embodiment of the utility model.

[0010] Figure 4A For the embodiment Figure 3 A magnified view of region M in which Figure 3 The first die in the bonding assembly is a first arrangement.

[0011] Figure 4B for Figure 4A A plan view of a first arrangement of a first die.

[0012] Figure 4C for Figure 4A A plan view of a first other embodiment of a first arrangement of a first die.

[0013] Figure 4D for Figure 4A A plan view of a second other embodiment of a first arrangement of a first die.

[0014] Figure 5 for Figure 3 A plan view of the quantum memory array in the first die is shown.

[0015] Fig. 6A For the embodiment Figure 3 A magnified view of region M in which Figure 3The first die in the bonding assembly is a second arrangement.

[0016] Figure 6B for Fig. 6A A plan view of a first arrangement of a first die.

[0017] Fig. 7A For the embodiment Figure 3 A magnified view of region M in which Figure 3 The first die in the bonding assembly is a third arrangement.

[0018] Figure 7B for Fig. 7A A plan view of a first arrangement of a first die.

[0019] Fig. 8A For the embodiment Figure 3 A magnified view of region M in which Figure 3 The first die in the bonding assembly is a fourth arrangement.

[0020] Figure 8B for Fig. 8A A plan view of a first arrangement of a first die.

[0021] Fig. 9 1 is a top view of various configurations of a microring resonator according to an embodiment of the present invention.

[0022] Fig.10 1 is a vertical cross-sectional view of various configurations of a microring resonator in an embodiment of the present invention.

[0023] Fig.11A It is a vertical cross-sectional view of a first arrangement of a quantum memory material portion in an embodiment of the present invention.

[0024] Fig. 11B It is a vertical cross-sectional view of a second configuration of a quantum memory material portion in an embodiment of the present invention.

[0025] Fig. 11C and Fig.11D It is a vertical cross-sectional view of a third arrangement of the sequence for manufacturing a quantum memory material portion in one embodiment of the present invention.

[0026] Fig.12 This is a first flow chart of the process steps used to manufacture a quantum memory device in one embodiment of the present invention.

[0027] Fig.13 This is a second flow chart of the process step sequence used to manufacture a quantum memory device in one embodiment of the present invention.

[0028] Fig.14FIG. 3 is a third flow chart of the process steps for manufacturing a quantum memory device in one embodiment of the present invention.

[0029] Fig.15 This is a fourth flow chart of a sequence of process steps used to operate a quantum memory device in one embodiment of the present invention.

[0030] Fig.16 FIG. 5 is a fifth flow chart of a sequence of process steps for operating a quantum memory device in one embodiment of the present invention.

[0031] Fig.17 This is a sixth flow chart of the process step sequence used to manufacture a quantum memory device in one embodiment of the present invention.

[0032] Fig.18 This is a seventh flow chart of the process step sequence used to manufacture a quantum memory device in one embodiment of the present invention.

[0033] Fig.19 FIG. 8 is an eighth flow chart of a sequence of process steps for manufacturing a quantum memory device in one embodiment of the present invention.

[0034] The reference numerals are as follows:

[0035] B: Magnetic field

[0036] hd1: first horizontal direction

[0037] hd2: second horizontal direction

[0038] M: Area

[0039] 9: Carrier substrate

[0040] 10: Quantum Memory Unit

[0041] 18A: Access line

[0042] 18W1: First word line

[0043] 18W2: Second character line

[0044] 20: Waveguide

[0045] 20N: Silicon Nitride Waveguide

[0046] 20S: Semiconductor waveguide

[0047] 22: Additional waveguide

[0048] 30: Frequency Regulator

[0049] 40: Microring Resonator

[0050] 40A: Part 1

[0051] 40B: Part 2

[0052] 40C: Part 3

[0053] 44,62: Insulation layer

[0054] 45:Interface dielectric material layer

[0055] 46: Graphene electrode

[0056] 47: Heating element

[0057] 48: Contact structure

[0058] 60: Quantum memory materials

[0059] 60': injection layer

[0060] 70:Metal Structure

[0061] 100: First Bare Chip

[0062] 101: Quantum Memory Array

[0063] 130: first dielectric material layer

[0064] 180: First metal interconnect structure

[0065] 198: first metal bonding pad

[0066] 200: Second bare chip

[0067] 201:Semiconductor substrate

[0068] 202: Source region

[0069] 205: Gate

[0070] 208: Drain region

[0071] 210: Field Effect Transistor

[0072] 230: second dielectric material layer

[0073] 240: Control circuit

[0074] 250: Frequency regulator control circuit

[0075] 251: Electrical bias circuit

[0076] 252: Temperature Controller

[0077] 270: Current switching circuit

[0078] 280: Second metal interconnect structure

[0079] 298: second metal bonding pad

[0080] 300: The third die

[0081] 420: Lightly doped semiconductor material part

[0082] 421: first doped semiconductor portion

[0083] 422: Second doped semiconductor portion

[0084] 424: Silicon nitride ring

[0085] 481: First contact structure

[0086] 482: Second contact structure

[0087] 1210,1220,1230,1310,1320,1330,1340,1410,1420,1430,1510,1520,1530,1540,1610,1620,1630,1640,1710,1720,1730,1810,1820,1910,1920,1930: Steps DETAILED DESCRIPTION

[0088] The following detailed description may be accompanied by the accompanying drawings to facilitate understanding of various aspects of the present invention. It is worth noting that the various structures are only for illustrative purposes and are not drawn to scale, as is common in the industry. In fact, the dimensions of the various structures may be increased or decreased arbitrarily for the sake of clarity.

[0089] The following content provides different embodiments or examples that can implement different structures of the present invention. The following specific components and arrangement embodiments are used to simplify the content of the present invention and are not intended to limit the present invention. For example, the description of forming a first component on a second component includes an embodiment in which the two are in direct contact, or an embodiment in which the two are separated by other additional components but not in direct contact. In addition, multiple examples of the present invention may repeatedly use the same number for simplicity, but the elements with the same number in multiple embodiments and / or settings do not necessarily have the same corresponding relationship.

[0090] In addition, spatially relative terms such as "below", "beneath", "lower", "above", "above", or similar terms can be used to simplify the description of the relative relationship between one element and another element in the diagram. Spatially relative terms can be extended to elements used in other directions, and are not limited to the direction shown in the diagram. The elements can also be rotated 90 degrees or other angles, so directional terms are only used to illustrate the direction in the diagram. Units with the same number may refer to the same unit, such as having the same material composition and the same thickness range, unless otherwise specified. The "configured for" function or operation described herein, or the element or system "configured to" provide or perform a function or operation, refers to providing an element or system with hardware and applicable software to implement this function or this operation described in the embodiment of the utility model as known in the art, and the details of this hardware or this software do not need to be explicitly described here.

[0091] The present invention provides a solid-state quantum memory device that can operate at room temperature and is suitable for quantum communication applications. The quantum memory device of the present invention includes a microring resonator, a frequency adjuster, a quantum memory material portion, and a magnetic field generator. The frequency adjuster may include a doped semiconductor material or a two-dimensional conductive material, and the magnetic field generator includes a metal structure configured to pass a current.

[0092] To store quantum information, the microring resonator couples a quantum signal in the form of a photon transmitted into the waveguide with a resonant photon state in the microring resonator, thereby capturing the incident photon in the microring resonator. A frequency adjuster can adjust the resonant frequency of the microring resonator, which adjusts the resonant frequency (and therefore the resonant wavelength) of the photon that can be stored in the microring resonator. The captured photon is then stored in the quantum memory material in the form of a quantum excitation with an energy state higher than the ground state. A magnetic field generator is used to increase the coupling between the energy level of the captured photon and the quantum transition from the ground state to the excited state. The magnetic field can be turned off to decouple the quantum transition from the resonant photon energy in the microring resonator.

[0093] To obtain quantum information, a magnetic field can be applied to the quantum memory material to recreate the coupling between the quantum transition from the ground state to the excited state and the resonant photon state in the microring resonator. As the excited state in the quantum memory material decays to the ground state, photons can be generated in the microring resonator. The frequency adjuster recreates the coupling between the photon energy state in the microring resonator and the photon energy state in the waveguide and releases the photon from the waveguide.

[0094] A two-dimensional array of quantum memory arrays is provided. In this embodiment, a one-dimensional array of waveguides can serve as bit lines. Word lines can be connected to frequency adjusters of individual columns in the two-dimensional array of quantum memory cells. Access lines are parallel to the word lines and can be used to control current through a column of metal structures, and the metal structures can generate a magnetic field in a column of quantum memory material portions.

[0095] In one embodiment of the utility model, a two-dimensional quantum memory array may be formed in a first die, and the first die may be a photonic die without semiconductor devices. Generally speaking, the first die may be a photonic integrated die. The second die may be a semiconductor die containing a control circuit, and the control circuit may include a field effect transistor. The second die may be bonded to the first die via metal-to-metal bonding, control collapse chip connection bonding, or chip connection bonding. Therefore, the bonded assembly may include a two-dimensional quantum memory array on one side and may include a control circuit on the other side. The second die may be any semiconductor die, such as an integrated chip system die.

[0096] Figures 1A to 1C This is a manufacturing process used to form the first die 100 in one embodiment of the present invention.

[0097] like Figure 1A As shown, a two-dimensional array of first dies 100 may be formed on a carrier substrate 9. The carrier substrate 9 may include any substrate that can be removed later. For example, the carrier substrate 9 may include a semiconductor substrate, an insulating substrate, or a conductive substrate. The first dies 100 may each include a quantum memory array 101, which contains a two-dimensional array of quantum memory cells 10. The structure of each quantum memory cell 10 and its formation process will be described in detail below with other drawings of the embodiments of the present invention. For example, a first dielectric material layer 130 may be formed on the carrier substrate 9, and the quantum memory array 101 may be formed in a set of first dielectric material layers 130. A first metal interconnect structure 180 may be formed in the first dielectric material layer 130. A first set of first metal interconnect structures 180 may be formed as a component of the quantum memory array 101, and a second set of first metal interconnect structures 180 may be used to provide metal wiring used by the quantum memory array 101. A first metal bonding pad 198 may be formed on the topmost layer of the first dielectric material layer 130. The first metal bonding pad 198 may be configured for metal-to-metal bonding, controlled collapse chip connection bonding, or micro-bump bonding (also referred to as chip connection bonding).

[0098] like Figure 1B As shown, the carrier substrate can be removed. For example, the carrier substrate 9 can be removed by cutting away the first dielectric material layer 130 and the structure buried therein. The carrier substrate 9 can also be removed by backside grinding, grinding, anisotropic etching process and / or isotropic etching process.

[0099] like Figure 1C As shown, the two-dimensional array of first dies 100 can be cut along cutting channels to provide a plurality of first dies 100. The first dies can each include a respective quantum memory array 101, a first metal interconnect structure 180, and a first metal bonding pad 198 buried in the first dielectric material layer 130.

[0100] Figure 2A and Figure 2B This is a manufacturing process used to form the second die 200 in one embodiment of the present invention.

[0101] like Figure 2A As shown, a two-dimensional array of second dies 200 can be formed on a semiconductor substrate 201. The second dies 200 can each include a control circuit 240, which is configured to control the operation of the quantum memory array 101 in the first die 100. The control circuit 240 can include a field effect transistor, such as a complementary metal oxide semiconductor field effect transistor. The control circuit 240 can each include a frequency adjuster control circuit and a circuit switch circuit, which will be described in detail below. In addition, the second dies 200 can each include a second dielectric material layer 230 to bury the second metal interconnect structure 280. The first set of second metal interconnect structures 280 can be used to provide electrical interconnects between the field effect transistors of the control circuit 240, and the second set of second metal interconnect structures 280 can be used to provide electrical interconnects between the control circuit 240 and the respective sets of second metal bonding pads 298, and the second metal bonding pads 298 are located at the topmost layer of the second dielectric material layer 230. The pattern of the set of second metal bonding pads 298 may be micro-mirrored with the pattern of the first metal bonding pads 198 in the first die 100. The second metal bonding pads 298 may be configured for metal-to-metal bonding, controlled collapse chip connection bonding, or micro-bump bonding (also referred to as chip connection bonding).

[0102] like Figure 2B As shown, the two-dimensional array of second dies 200 can be cut along the cutting channels to provide a plurality of second dies 200. In general, each of the second dies 200 includes a control circuit 240, a second metal interconnect structure 280, and a second metal bonding pad 298 buried in the second dielectric material layer 230. The control circuit 240 includes a semiconductor device such as a field effect transistor, and is configured to provide a control signal used by the quantum memory array 101 in the first die 100.

[0103] like Figure 3As shown, the first die 100 can be bonded to the second die 200. Generally speaking, the first die 100 can be a photonic die, which includes a waveguide for directing the transmission path of photons. In addition, the first die 100 includes the quantum memory array 101 of the embodiment of the present invention. The second die 200 includes a semiconductor die, which includes a semiconductor device such as a field effect transistor. The second die 200 includes a control circuit for controlling the operation of the quantum memory unit 10 in the quantum memory array 101. The control signal can be transmitted across the first die 100 and the second die 200 via a conductive path containing a pair of first metal bonding pads 198 and second metal bonding pads 298 that are bonded individually. Although the embodiment of the present invention adopts metal-to-metal bonding to bond the second metal bonding pad 298 to the first metal bonding pad 198, and provides a conductive path extending across the first die 100 and the second die 200 for illustration, the conductive path implemented in the embodiment may also include a bonding structure containing a solder ball. Additional dies such as a third die 300 may be attached to the second die 200 as appropriate. The third die 300 may include a semiconductor die containing at least one field effect transistor therein. The third die 300 may include a logic die, a memory die, a passive device die, or any other type of semiconductor die. The third die 300 may include a third metal bonding pad 398 to bond to a set of second metal bonding pads 298 in the second die.

[0104] like Figure 4A and Figure 4B The first arrangement of regions shown includes the quantum memory cell 10 in the first die 100 and a portion of the control circuit 240 in the second die 200 , with the control circuit 240 being electrically connected to the quantum memory cell 10 . Figure 4A For the embodiment Figure 3 A magnified view of region M in which Figure 3 The first die 100 in the bonded assembly is in a first configuration. Figure 4B for Figure 4A FIG. 1 is a plan view of a first configuration of the first die 100 in which the first metal interconnect structure 180 and surrounding components are omitted for clarity of the drawing.

[0105] In general, the quantum memory cells 10 each include a microring resonator 40. A microring resonator is a waveguide that can be topologically homeomorphic to a torus and can be sized to provide at least one resonant frequency and a corresponding resonant wavelength. A closed loop of the microring resonator can capture photons having a resonant wavelength. The captured photons can be transported around the circumference of the generally annular structure of the microring resonator and semi-permanently trapped in the microring resonator until the photons interact with energy states in the surrounding material or the material of the microring resonator.

[0106] The material included in the microring resonator 40 of the embodiment of the utility model may have a high refractive index. In some embodiments, the composition of the microring resonator 40 may be a semiconductor material such as silicon. In some embodiments, the composition of the microring resonator 40 may be silicon nitride. The confined photons in the microring resonator 40 may be a resonant mode, which is characterized by the wave function having photon constructive interference when transmitted around the microring resonator 40. In general, the resonance condition of the microring resonator 40 is as follows: nC=mλ, where n is the refractive index of the microring resonator 40, C is the effective average circumference of the microring resonator 40, λ is the resonant wavelength, and m is a non-negative integer. For the basic resonant mode, m is equal to 1.

[0107] The above formula can be used with the wavelength λ (measured in a vacuum) of the photons used to operate the quantum memory cell 10 to determine the effective average circumference of the microring resonator 40. The wavelength λ can be 1550 nm (using semiconductor materials such as indium phosphide or gallium arsenide), 1330 nm (using semiconductor materials such as indium gallium arsenide phosphide), 852 nm (D2 line of cesium), 795 nm (D1 line of rubidium), 780 nm (D2 line of rubidium), or the like.

[0108] In an embodiment where the wavelength λ is 1330 nm and the microring resonator 40 comprises silicon (refractive index 3.5), if a base node is used to store photons (i.e., m=1), the average circumference of the microring resonator 40 may be about 380 nm. In an embodiment where the top view shape of the microring resonator 40 is a ring, the effective radius of the microring resonator may be about 60.4 nm. In an embodiment where the wavelength λ is 1330 nm and the microring resonator 40 comprises silicon nitride (refractive index 2.0), if a base node is used to store photons (i.e., m=1), the average circumference of the microring resonator 40 may be about 6650 nm. In an embodiment where the top view shape of the microring resonator 40 is a ring, the effective radius of the microring resonator may be about 106 nm.

[0109] A waveguide 20 is provided for each microring resonator. The waveguide 20 is configured to spatially confine a photon path therein. The width and height of the waveguide 20 may be selected to confine photons of wavelength λ (i.e., the resonant wavelength of the microring resonator 40) in the waveguide 20 as the photons propagate along the length of the waveguide 20. Generally, in embodiments where the waveguide comprises silicon nitride, the width and length of the waveguide 20 may be 300 nm to 600 nm, such as 400 nm to 500 nm. In embodiments where the waveguide 20 comprises silicon, the width and length of the waveguide 20 may be 200 nm to 500 nm, such as 300 nm to 400 nm. In one embodiment, the waveguide 20 may comprise the same material as the microring resonator 40. In one embodiment, the waveguide 20 is composed of a semiconductor material such as silicon. In this embodiment, the waveguide 20 may be a semiconductor waveguide 20S.

[0110] The microring resonator 40 includes an arcuate first portion 40A that is generally parallel to a portion of the waveguide 20 to provide optical coupling between the waveguide 20 and the microring resonator. In embodiments where the waveguide 20 is composed of silicon nitride, the average gap between the first portion 40A and the waveguide 20 may be about 50 nm to 100 nm. In embodiments where the waveguide 20 is composed of silicon, the average gap between the first portion 40A and the waveguide 20 may be about 100 nm to 200 nm.

[0111] The quantum memory cells 10 each include a frequency adjuster 30 formed on a microring resonator 40. Generally speaking, the frequency adjuster 30 is configured to adjust the effective refractive index in or around the second portion of the microring resonator 40 to adjust the photon resonance frequency (also referred to as the resonance frequency) in the microring resonator 40. The frequency adjuster 30 may change the charge distribution in or around the second portion 40B of the microring resonator 40 to adjust the effective refractive index in or around the second portion 40B of the microring resonator 40. The frequency adjuster 30 may be formed as a component of the microring resonator 40, or may be formed as an additional component of the microring resonator 40.

[0112] exist Figure 4A and Figure 4B In the first configuration shown, the frequency adjuster 30 may be formed by forming a first doped semiconductor portion 421 in a first portion of the second portion 40B of the microring resonator 40, and forming a second doped semiconductor portion 422 in a second portion of the second portion 40B of the microring resonator 40. The first doped semiconductor portion 421 has a doping of a first conductivity type, and the second doped semiconductor portion 422 has a doping of a second conductivity type, and the second conductivity type is opposite to the first conductivity type. In one embodiment, the first doped semiconductor portion 421 and the second doped semiconductor portion 422 are in direct contact with each other. In one embodiment, a vertically extending pn junction is formed between the first doped semiconductor portion 421 and the second doped semiconductor portion 422.

[0113] The first doped semiconductor portion 421 and the second doped semiconductor portion 422 may be formed by providing a microring resonator 40 (which includes an intrinsic or lightly doped semiconductor material) and performing a two-mask ion implantation process to implant p-type dopants and n-type dopants, respectively. The first doped semiconductor portion 421 may include a first conductive type dopant with a first atomic concentration of 5.0 x 10 19 / cm 3 Up to 2.0x 10 21 / cm 3 The second doped semiconductor portion 422 may include a second conductive type dopant having a second atomic concentration of 5.0×10 19 / cm 3 Up to 2.0x 1021 / cm 3 Higher or lower dopant atomic concentrations may also be used for the first doped semiconductor portion 421 and / or the second doped semiconductor portion 422. The portion of the microring resonator 40 other than the second portion 40B may include an intrinsic or lightly doped semiconductor material portion 420 containing a dopant atomic concentration less than 1.0×10 18 / cm 3 , less than 1.0x 10 17 / cm 3 and / or less than 1.0x 10 16 / cm 3 .

[0114] In one embodiment, a bias voltage may be applied across the first doped semiconductor portion 421 and the second doped semiconductor portion 422 (i.e., across the pn junction), and the charge carrier distribution in the second portion 40B of the microring resonator 40 may be changed (which may be induced by the applied bias voltage) to adjust the effective refractive index in the second portion 40B of the microring resonator 40. In one embodiment, the frequency adjuster 30 includes a pn junction between the first doped semiconductor portion 421 and the second doped semiconductor portion 422, and the bias voltage may adjust the width of the depletion region across the pn junction. Generally speaking, the % shift of the resonant frequency caused by adjusting the effective refractive index in the second portion 40B of the microring resonator 40 may be 0.5% to 5%, such as 1% to 3%, but smaller or larger % may also be used.

[0115] Although the embodiment of the present invention uses the pn junction between the first doped semiconductor portion 421 and the second doped semiconductor portion 422 for description, wherein the pn junction is formed in the middle between the innermost periphery of the microring resonator 40 and the outermost periphery of the microring resonator 40 along the vertical direction, the pn junction of the embodiment can be formed into different geometric shapes. In addition, although the embodiment of the present invention uses the microring resonator 40 with a stepped vertical cross-sectional profile for description, the microring resonator 40 implemented in the embodiment can have different vertical cross-sectional profiles.

[0116] The quantum memory cells 10 each include a quantum memory material portion 60 containing a quantum memory material. The quantum memory material has a ground state and an excited state in which photons are stored. Generally, the quantum memory material portion 60 may be formed in or on the third portion 40C of the microring resonator 40. The first portion 40A, the second portion 40B, and the third portion 40C may be separated from each other in azimuth angles.

[0117] The "quantum memory material" described herein can maintain a quantum excited state to store and retain quantum information for a period of time, and the energy level of the quantum excited state is higher than the energy level of the ground state. The quantum memory material can also be regarded as a quantum state capture material, a quantum state maintenance material, a photon capture material, a photon memory material, or the like. Exemplary quantum memory materials include crystalline materials doped with rare earth ions, semiconductor quantum dots, hexagonal boron nitride, or the like. In one embodiment, the quantum memory material includes and / or consists essentially of the following materials: hexagonal boron nitride containing nitrogen vacancies. In one embodiment, the quantum memory material includes and / or consists essentially of the following materials: molybdenum diselenide, tungsten diselenide, or aluminum nitride.

[0118] In one embodiment, the quantum memory material may be a two-dimensional material having a greater conductivity in the plane than out of the plane. In one embodiment, the ratio of the in-plane conductivity to the out-of-plane conductivity may be greater than 3, 10, and / or 30. The thickness of the quantum memory material portion 60 may be 0.3 nm to 2 nm, such as 0.6 nm to 1.5 nm, although lesser or greater thicknesses may be used. In one embodiment, the quantum memory material portion 60 includes a quantum memory material film having a thickness less than 20%, 10%, 5%, and / or 2% of the largest lateral dimension of the film.

[0119] The quantum memory cells 10 each include a metal structure 70 configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 when a current passes through the metal structure 70. The metal structure 70 is formed on or near the third portion 40C of the microring resonator 40. Generally, the metal structure 70 includes one of a coil structure, an antenna structure, and a transmission line structure. Figure 4A and Figure 4B In the example shown, the metal structure 70 comprises a coil structure.

[0120] like Figure 4C In a first further embodiment of the first arrangement shown, the metal structure 70 comprises a transmission line.

[0121] like Figure 4D In a second further embodiment of the first arrangement shown, the metal structure 70 comprises an antenna structure.

[0122] like 4A to 4DAs shown, the quantum memory cells 10 may each include a microring resonator 40, a frequency adjuster 30, a quantum memory material portion 60, and a metal structure 70. The quantum memory cells 10 are each formed in a first dielectric material layer 130, and are thus buried in the first dielectric material layer 130. A plurality of first metal interconnect structures 180 are formed in the first dielectric material layer 130. In addition, a first metal bonding pad 198 may be formed in the topmost first dielectric material layer 130. An additional waveguide 22 may be formed below the quantum memory cell 10.

[0123] The control signal used by the frequency adjuster 30 may be provided by word lines (18W1, 18W2), which may be a set of first metal interconnect structures. In one embodiment, the word lines (18W1, 18W2) may include a first word line 18W1 connected to a first doped semiconductor portion 421, such as via a first contact structure 481 such as a first metal-semiconductor alloy portion (i.e., a metal silicide portion); and a second word line 18W2 connected to a second doped semiconductor portion 422, such as via a second contact structure 482 such as a second metal-semiconductor alloy portion. The first contact structure 481 and the second contact structure 482 may be collectively referred to as a contact structure 48. The word lines (18W1, 18W2) may each be electrically connected to a respective first metal bonding pad 198 via a respective set of first metal interconnect structures 180.

[0124] The current flowing through the metal structure 70 can generate a magnetic field B in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60, and the current can pass through the access line 18A, which is a set of first metal interconnect structures 180. Both ends of the access line 18A can be electrically connected to a pair of first metal bonding pads 198 through respective sets of first metal interconnect structures 180.

[0125] In one embodiment of the present invention, the control circuit 240 in the second die 200 can provide a control signal for the control operation of the quantum memory unit 10. In other words, the control circuit 240 is formed in the second die 200, and the second die 200 is bonded to the first die 100. The control circuit 240 includes a semiconductor device and is configured to generate captured photons in the microring resonator 40 from incident photons in the waveguide 20. Specifically, the control circuit 240 is configured to adjust the photon resonance wavelength (i.e., adjust the resonance frequency) in the microring resonator 40 during the first step of the photon capture operation to match the predetermined wavelength (which is the photon wavelength of the photons in the waveguide 20) and generate the captured photons in the microring resonator 40.

[0126] In one embodiment, the control circuit 240 includes a frequency adjuster control circuit 250 that controls the photon resonance wavelength (and therefore the resonance frequency) of the frequency adjuster 30. In embodiments where a bias voltage is applied to affect the effective refractive index of the second portion 40B or a cladding material surrounding the second portion 40B, the frequency adjuster control circuit 250 may include an electrical bias circuit 251 configured to apply a bias voltage to the frequency adjuster 30. In embodiments where the frequency adjuster 30 includes a first doped semiconductor portion 421 and a second doped semiconductor portion 422, the frequency adjuster control circuit 250 may include an electrical bias circuit 251 configured to apply a bias voltage across the first doped semiconductor portion 421 and the second doped semiconductor portion 422.

[0127] In one embodiment of the present invention, the control circuit 240 is configured to induce at least one electronic state in the quantum memory material portion 60 to convert (i.e., convert state) to a respective high energy state (the difference from the respective electronic state is the energy E of the captured photon) to convert the energy of the captured photon in the microring resonator 40 to the quantum memory material portion 60. The energy E of the captured photon can be expressed as hν, where h is the Plank constant and ν is the photon frequency. The energy E of the captured photon can also be expressed as E=hc / l, where c is the speed of light in a vacuum and l is the wavelength of light in a vacuum. In general, the control circuit 240 applies a magnetic field to the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 to induce quantum coupling between the captured photon and the state conversion. In one embodiment, the control circuit 240 is configured to induce a state conversion (i.e., quantum conversion) from a ground state to an excited state in the quantum memory material.

[0128] In one embodiment, the components of the control circuit 240 configured to induce a state transition in the quantum memory material may include a current switching circuit 270. The current switching circuit 270 may include at least one field effect transistor 210 configured to switch a current flowing through the metal structure 70. The second die 200 may be bonded to the first die 100 to electrically connect the current switching circuit 270 to the metal structure 70. The conductive path between the current switching circuit 270 and the metal structure 70 may include a set of first metal interconnect structures 180 including the access line 18A, a set of first metal bonding pads 198, a set of second metal bonding pads 298, and a set of second metal interconnect structures 280. In general, the quantum memory cell 10 includes a microring resonator 40 and is formed in a first dielectric material layer 130 in the first die 100. The current switching circuit 270 is formed in the second die 200, and the second die 200 is different from the first die 100. The method includes bonding the second die 200 to the first die 100.

[0129] The second die 200 may be any type of semiconductor die such as an integrated system-on-chip die, a CPU, a graphics processor, a memory die, or the like. The frequency adjuster control circuit 250 and the current switch circuit 270 may each include a respective set of field effect transistors 210. The field effect transistors 210 may each include a respective gate 205, a respective gate dielectric layer, a respective source region 202, and a respective drain region 208. In general, the second die 200 each includes a control circuit 240, a second metal interconnect structure 280, and a second metal bonding pad 298 buried in the second dielectric material layer 230.

[0130] In one embodiment of the present invention, a quantum memory device includes: a waveguide 20 configured to spatially confine a photon path therein; a quantum memory unit 10 including a microring resonator 40, a frequency adjuster 30, and a quantum memory material portion 60, wherein the microring resonator 40 includes a first portion 40A parallel to a portion of the waveguide 20, wherein the frequency adjuster 30 is configured to adjust an effective refractive index in or around a second portion 40B of the microring resonator 40 to adjust a photon resonance frequency in the microring resonator 40, and wherein the quantum memory material portion 60 includes a quantum memory material having a ground state and an excited state storing photons therein and located in or on a third portion 40C of the microring resonator 40. In one embodiment, the microring resonator 40 is embedded in a first dielectric material layer 130 in a first die 100.

[0131] In one embodiment, a control circuit 240 may be provided, which includes a frequency adjuster control circuit 250. The control circuit 240 may be configured to generate captured photons in the microring resonator 40 from incident photons in the waveguide 20 and induce a state transition from a ground state to an excited state in the quantum memory material. The control circuit 240 (specifically, the frequency adjuster control circuit 250) may be configured to adjust the photon resonance wavelength in the microring resonator 40 to match a predetermined wavelength (such as the photon wavelength of the photons in the waveguide 20) during the first step of the photon capture operation and generate captured photons in the microring resonator 40.

[0132] In one embodiment, the control circuit 240 may apply a magnetic field to the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 during the second step of the photon capture operation to induce quantum coupling between the captured photons and the state transition. In one embodiment, a magnetic field generator (70, 270) may be provided, which is configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60. The magnetic field generator (70, 270) may be used to increase the quantum absorption of photons captured by the quantum memory material.

[0133] In one embodiment, the magnetic field generator (70, 270) includes a metal structure 70 located on or near the third portion 40C of the microring resonator 40; and a current switching circuit 270, which includes at least one field effect transistor 210 configured to switch the current flowing through the metal structure 70. The current switching circuit 270 can be a component of the control circuit 240. In one embodiment, the control circuit 240 (specifically the current switching circuit 270) can be configured to use the magnetic field generator (70, 270) to generate a magnetic field during the second step of the photon capture operation to increase the absorption of the captured photons by the quantum memory material. Therefore, the incident photon energy transmitted through the waveguide 20 can be captured as excitation energy in the excited state in the quantum memory material portion 60.

[0134] Generally speaking, the quantum memory material portion 60 can maintain an excited state for at least 1 microsecond, typically several microseconds to more than 10 microseconds, without significant decay of the excited state. In the photon release operation, as photons are generated in the waveguide 20, the energy stored in the quantum memory material portion 60 is released, and the process steps used to capture photons in the waveguide 20 are reversed.

[0135] In one embodiment, the control circuit 240 is configured to generate a magnetic field using a magnetic field generator (70, 270) during the first step of the photon release operation to increase the quantum coupling between the energy stored in the quantum memory material and the resonant photon state in the microring resonator 40. The magnetic field can enhance the coupling between the state transition from the excited state to the ground state in the quantum memory material portion 60 and the photons generated in the microring resonator 40. As the excited state in the quantum memory material portion 60 transitions to the ground state, photons can be generated in the microring resonator.

[0136] In addition, the control circuit 240 (specifically the frequency adjuster control circuit 250) can be configured to adjust the photon resonance wavelength in the microring resonator 40 during the second step of the photon release operation to match a predetermined wavelength (such as the photon wavelength of the photons in the waveguide 20) and generate photons in the waveguide 20.

[0137] The magnetic field generator (70, 270) includes a metal structure 70 located on or near the third portion 40C of the microring resonator 40 and configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 once a current passes through the metal structure 70. The metal structure 70 includes one of a coil structure, an antenna structure, and a transmission line structure. The microring resonator 40 is embedded in the first dielectric material layer 130 in the first die 100, and the current switching circuit 270 is located in the second die 200 bonded to the first die 100.

[0138] The frequency of the magnetic field applied to the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 may be 1 GHz to 60 GHz, such as 3 GHz to 30 GHz, but higher frequencies may also be used. In one embodiment, the current switching circuit 270 and the metal structure 70 may be configured to make the temporal and spatial average of the magnetic field in the volume of the third portion 40C of the microring resonator 40 be 0.1 T to 5.0 T. The temporal and spatial averages described herein refer to the average of the magnetic field formed by generating the spatial average of the magnetic field calculated over the entire volume of the quantum memory material portion 60 for each time point when the magnetic field is turned on, and then averaging the spatial average of the magnetic field (as a function of time) during the time interval when the magnetic field is turned on. In general, the magnetic field may be substantially perpendicular to the direction of high conductivity in the quantum memory material. In one embodiment, the magnetic field (70, 270) is configured to generate a magnetic field such that the perpendicular component of the average magnetic field in the volume of the film having the magnetic field is at least 90% of the average magnetic field in the volume of the film.

[0139] In one embodiment, the frequency adjuster 30 includes a first doped semiconductor portion 421 implemented as a first portion of the second portion 40B of the microring resonator 40 and having a first conductive type of doping; and a second doped semiconductor portion 422 implemented as a second portion of the second portion 40B of the microring resonator 40 and having a second conductive type of doping, and the second conductive type is opposite to the first conductive type. For example, an electrical bias circuit 251 can be formed in the second die 200. The electrical bias circuit 251 is configured to apply a bias voltage across the first doped semiconductor portion 421 and the second doped semiconductor portion 422.

[0140] In one embodiment, the first doped semiconductor portion 421 and the second doped semiconductor portion 422 are in direct contact with each other. In one embodiment, a vertically extending pn junction exists between the first doped semiconductor portion 421 and the second doped semiconductor portion 422. In this embodiment, a bias voltage may be applied across the first doped semiconductor portion 421 and the second doped semiconductor portion 422 to adjust the photon resonance frequency.

[0141] Generally speaking, 4A to 4D The operation method of the quantum memory device shown may be to transmit a photon having a photon wavelength through the waveguide 20; adjust the photon resonance wavelength in the microring resonator 40 to optically couple the microring resonator 40 to the photon in the waveguide 20 and generate a trapped photon in the microring resonator 40; and adjust the photon resonance wavelength in the microring resonator 40 to match the photon wavelength to generate a trapped photon in the microring resonator 40; and convert the energy in the trapped photon into the quantum memory material portion 60 in the form of a quantum excitation from a ground state to an excited state. In one embodiment, the energy in the trapped photon may be converted into the quantum memory material portion 60 in the form of a quantum excitation from a ground state to an excited state.

[0142] In one embodiment of the present invention, the energy of the trapped photons in the microring resonator can be converted to the quantum memory material portion 60 through quantum coupling between the trapped photons and the quantum excitation caused by applying a magnetic field to the third portion 40C of the microring resonator 40 and the quantum memory material portion 60. Specifically, through the transition from the ground state to the excited state in the quantum memory material, the quantum memory material can be induced to absorb the trapped photons, thereby storing data bits in the quantum memory material portion 60. In one embodiment, the quantum memory unit 10 includes a magnetic field generator (70, 270) configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60. In this embodiment, a magnetic field can be generated in the quantum memory material portion 60 and the third portion 40C of the microring resonator 40 to induce the transition from the ground state to the excited state in the quantum memory material.

[0143] In one embodiment, the quantum memory device includes a metal structure 70 located on or near the third portion 40C of the microring resonator 40. A current can be passed through the metal structure 70 to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60. The quantum memory device may include a current switching circuit 270, which includes at least one field effect transistor 210. The current switching circuit 270 can be used to switch the current flowing through the metal structure 70 to turn on the magnetic field when the current passes through the metal structure 70, and turn off the magnetic field when the current does not pass through the metal structure 70.

[0144] During the photon release operation, a transition from a ground state to an excited state in the quantum memory material can be induced to generate confined photons in the microring resonator 40. Optical coupling between the confined photons and the waveguide 20 can be induced to induce generation of a photon beam in the waveguide 20.

[0145] Figure 5 for Figure 3 A plan view of a quantum memory array 101 in a first die 100 is shown. Figure 5 correspond Figure 4B , and shows the internal connections between word lines (18W1, 18W2) and various portions of access line 18A.

[0146] Generally speaking, Figure 3 , 4A to 4D and Figure 5The quantum memory device shown may be provided by forming a one-dimensional array of waveguides 20 extending laterally along a first horizontal direction hd1; forming a two-dimensional array of quantum memory cells 10, wherein each of the quantum memory cells 10 includes a microring resonator 40, a frequency adjuster 30, and a quantum memory material portion 60; and forming word lines (18W1, 18W2) to electrically connect to the frequency adjusters 30 of respective columns. The microring resonator 40 in each quantum memory cell 10 includes a first portion 40A parallel to and optically coupled to a respective waveguide 20 in the one-dimensional array of waveguides 20. The frequency adjuster 30 in each quantum memory cell 10 is configured to adjust an effective refractive index in or around a second portion 40B of the microring resonator 40 to adjust a photon resonance frequency in the microring resonator 40. The quantum memory material portion 60 includes a quantum memory material having a ground state and an excited state storing photons therein, and is formed in or on a third portion 40C of the microring resonator 40. The word lines ( 18W1 , 18W2 ) are configured to apply electrical signals to adjust the photonic resonance frequencies in the microring resonators 40 of the respective columns.

[0147] In one embodiment, each quantum memory cell 10 includes a metal structure 70 configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 in the respective quantum memory cell 10 once a current passes through the metal structure 70. In one embodiment, an access line 18A may be formed to electrically connect the access line to the metal structure 70 of the respective column. As described above, each metal structure 70 includes one of a coil structure, an antenna structure, and a transmission line structure. For example, a current switching circuit 270 may be formed in the second die 200. The current switching circuit 270 includes at least one field effect transistor 210 configured to switch current. The second die 200 may be bonded to the first die 100 to electrically connect each access line 18A to a respective current switching circuit 270. Similarly, the second die 200 may be bonded to the first die 100 to connect each word line (18W1, 18W2) to a respective frequency adjuster control circuit 250. The word lines ( 18W1 , 18W2 ) and the access line 18A may extend laterally along a second horizontal direction hd2 , and the second horizontal direction hd2 may or may not be perpendicular to the first horizontal direction hd1 .

[0148] In one embodiment, the access line 18A may be electrically connected to the metal structures 70 of the respective columns. The metal structures 70 may be each configured to generate a magnetic field in the quantum memory material portion 60 of the respective quantum memory cell 10. The access line 18A is electrically connected to a respective current switching circuit 270 including at least one field effect transistor 210, and the field effect transistor 210 is configured to switch the current flowing through the metal structures 70 of the respective columns. Therefore, once the selected access line 18A is activated, a magnetic field may be generated in the quantum memory material portion 60 of the selected column.

[0149] In general, a one-dimensional array of waveguides 20, a two-dimensional array of quantum memory cells 10, and word lines (18W1, 18W2) are formed in a first die 100. A control circuit 240 may be formed in a second die 200, and the control circuit 240 is configured to control the operation of the word lines (18W1, 18W2). The control circuit 240 includes a field effect transistor 210. The second die 200 may be bonded to the first die 100 to provide electrical connections between the control circuit 240 and the word lines (18W1, 18W2).

[0150] In one embodiment, Figure 3 , 4A to 4D and Figure 5The method for manufacturing the quantum memory device shown may be to form a first die 100, wherein the first die 100 includes a one-dimensional array of waveguides 20 extending laterally along a first horizontal direction hd1; a two-dimensional array of quantum memory cells 10; and word lines (18W1, 18W2), wherein the quantum memory cells 10 each include a microring resonator 40, a frequency adjuster 30, and a quantum memory material portion 60, wherein the microring resonator 40 includes a first portion 40A parallel to and optically coupled to a respective waveguide 20 in the one-dimensional array of waveguides 20, wherein the frequency adjuster 30 is configured to adjust the effective refractive index in or around a second portion 40B of the microring resonator 40 to adjust the photon resonance frequency in the microring resonator 40, and wherein the quantum memory material portion 60 includes a quantum memory material having a ground state and storing photons at The excited state is formed in or on the third portion 40C of the microring resonator 40, and the formation method thereof can be introduced into or on the third portion 40C of the microring resonator 40 by introducing at least one material used to form the quantum memory material portion 60, and wherein the word lines (18W1, 18W2) are electrically connected to the frequency adjusters 30 of the respective columns, wherein the word lines (18W1, 18W2) are configured to apply an electrical signal to adjust the photon resonance frequency in the microring resonators 40 of the respective columns; forming a second die 200, which includes a control circuit 240 configured to control the operation of the word lines (18W1, 18W2), and the control circuit 240 includes a field effect transistor 210; and bonding the second die 200 to the first die 100 to provide an electrical connection between the control circuit 240 and the word lines (18W1, 18W2).

[0151] Generally speaking, Figure 3 , 4A to 4D and Figure 5 The operation method of the quantum memory device shown may be to transmit a photon having a photon wavelength through a waveguide 20, and the waveguide 20 is optically coupled to a selected quantum memory cell 10 in a two-dimensional array of quantum memory cells 10; adjust the photon resonance wavelength in a microring resonator 40 of the selected quantum memory cell 10 to match the photon wavelength to generate a trapped photon in the microring resonator 40 of the selected quantum memory cell 10; and convert the energy in the trapped photon into a quantum memory material portion 60 of the selected quantum memory cell 10 in the form of quantum excitation.

[0152] In one embodiment, each of the quantum memory cells 10 includes a metal structure 70 configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 in the respective quantum memory cell 10 once a current passes through the metal structure 70. In this embodiment, a magnetic field may be applied to the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 of the selected quantum memory cell 10 to induce quantum coupling between the trapped photons and the quantum excitations in the quantum memory material portion 60 of the selected quantum memory cell 10.

[0153] In one embodiment, the three-dimensional quantum memory device includes an access line 18A electrically connected to the metal structure 70 of each column and electrically connected to a current switch circuit 270 including at least one field effect transistor 210. In this embodiment, the current switch circuit 270 connected to the access line can be turned on to generate a magnetic field, and the access line is connected to the metal structure 70 in the selected quantum memory cell 10.

[0154] Fig. 6A and Figure 6B is a second configuration of a quantum memory device, which can be derived from Figure 3 , 4A to 4D and Figure 5 The first configuration of the quantum memory device shown, for example, adjusts the frequency adjuster 30 in each quantum memory unit 10 . Fig. 6A For the embodiment Figure 3 A magnified view of region M in which Figure 3 The first die 100 in the bonded assembly is in a second configuration. Figure 6B for Fig. 6A FIG. 1 is a plan view of a first arrangement of a first die 100 .

[0155] In a second configuration, the frequency adjuster 30 includes an insulating layer 44 sandwiched between a first doped semiconductor portion 421 and a second doped semiconductor portion 422. The first doped semiconductor portion 421 and the second doped semiconductor portion 422 are separated from each other by the insulating layer 44. The insulating layer 44 includes a dielectric material such as silicon oxide or a dielectric metal oxide, and its thickness may be 1 nm to 6 nm, such as 2 nm to 4 nm, but lesser or greater thicknesses may also be used. In one embodiment, the second doped semiconductor portion 422 is completely above a horizontal plane containing the topmost surface of the first doped semiconductor portion 421. In one embodiment, the microring resonator 40 may include a pair of intrinsic or lightly doped semiconductor material portions 420, which are located outside the volume of the second portion 40B. The pair of intrinsic or lightly doped semiconductor material portions 420 may be vertically separated from each other by the insulating layer 44.

[0156] In the second configuration, the frequency adjuster 30 includes a first doped semiconductor portion 421 implemented as a first portion of the second portion 40B of the microring resonator 40 and having a first conductivity type of doping; and a second doped semiconductor portion 422 implemented as a second portion of the second portion 40B of the microring resonator 40 and having a second conductivity type of doping. The second conductivity type is opposite to the first conductivity type. An electrical bias circuit 251 may be provided in the second die 200, and the electrical bias circuit 251 is configured to apply a bias voltage across the first doped semiconductor portion 421 and the second doped semiconductor portion 422.

[0157] The operating principle of the quantum memory device in the second setting may be similar to the operating principle of the quantum memory device in the first setting. In the second setting, a bias voltage may be applied across the first doped semiconductor portion 421 and the second doped semiconductor portion 422 to adjust the photon resonance frequency of the microring resonator 40. Specifically, the bias voltage changes the charge carrier distribution in the second portion 40B of the microring resonator 40 to adjust the effective refractive index in the second portion 40B of the microring resonator 40. Except for the frequency adjustment mechanism, the operation of the second setting of the quantum memory device may be the same as the operation of the quantum memory device of the first setting described above.

[0158] Fig. 7A and Figure 7B A third configuration of a quantum memory device can be derived from Figure 3 , 4A The first configuration of the quantum memory device shown in 4D and 5 includes, for example, using silicon nitride waveguide 20N instead of silicon waveguide 20S, using silicon nitride used in microring resonator 40 instead of silicon, and using frequency adjuster 30 (which uses a two-dimensional cladding material that can change the refractive index once a bias voltage is applied in each quantum memory unit 10). Fig. 7A for Figure 3 A magnified view of region M in which Figure 3 The first die 100 in the bonded assembly is in a third configuration. Figure 7B for Fig. 7A FIG. 1 is a plan view of a first arrangement of a first die 100 .

[0159] All of the microring resonators 40 in the third arrangement may include silicon nitride. As such, the microring resonators 40 in the third arrangement may include an annular silicon nitride ring 424, which may have an annular shape, an elongated annular shape, or an annular shape having one or more corner regions (i.e., regions having a smaller curvature than other regions in a top view). The lateral dimensions and height of the silicon nitride waveguide 20N and the annular silicon nitride ring 424 may be larger than the lateral dimensions and height of the silicon waveguide 20S and the microring resonator 40 in the first and second arrangements because the refractive index of silicon nitride is lower than the refractive index of the semiconductor material.

[0160] In one embodiment, the frequency adjuster 30 may include a graphene electrode 46 formed on, on the side of, or below the second portion of the microring resonator 40. The graphene electrode 46 may directly contact the upper surface, sidewall and / or lower surface of the microring resonator. The interface dielectric material layer 45 may be sandwiched between the microring resonator and the graphene electrode 46 instead. The thickness of the graphene electrode 46 may be 0.6nm to 3nm, such as 1nm to 2nm, but a smaller or larger thickness may also be used. In general, the graphene electrode 46 is preferably a thin graphene layer, which can maximize the refractive index change in the graphene electrode 46 once a bias voltage is applied. The bias voltage can be applied by the electrical bias circuit 251 of the frequency adjuster. The bias voltage can be a DC bias voltage, which can be 0.5V to 10V, such as 1V to 3V. The electrical bias circuit 251 is configured to apply a bias voltage to the graphene electrode 46 that can be formed in the second bare chip 200.

[0161] It should be noted that the graphene electrode 46 is directly on or in close proximity to the outer surface of the microring resonator 40. As such, the wavelength of photons in the microring resonator 40 may have a spatial overlap with the volume of the graphene electrode 46, and thus a change in the refractive index of the graphene electrode 46 may cause a change in the resonant frequency of the microring resonator 40. The graphene electrode 46 may thus serve as a cladding material for the microring resonator 40, and a change in the refractive index in the graphene electrode 46 may cause a change in the effective refractive index of the microring resonator 40 with respect to the resonant frequency of the microring resonator 40. Applying a bias voltage to the graphene electrode 46 may change the spatial distribution of charge in the graphene electrode 46, and thus change the refractive index of the graphene electrode 46.

[0162] The operating principle of the quantum memory device in the third setting can be similar to the operating principle of the quantum memory device in the first setting. In the third setting, a bias voltage can be applied across the graphene electrode 46 and the second portion 40B of the microring resonator 40 to adjust the photon resonance frequency. Specifically, the charge distribution change in the graphene electrode 46 can modulate the effective refractive index around the second portion 40B of the microring resonator 40. In addition to the frequency adjustment mechanism, the second setting of the quantum memory device operates in the same manner as the quantum memory device of the first setting described above.

[0163] Fig. 8A and Figure 8B A fourth configuration of a quantum memory device can be derived from Figure 3 , 4A to 4D and Figure 5 The first setup of the quantum memory device shown is derived from Figure 3 , Figure 5 , Fig. 6A and Figure 6B The second setting shown, or derived from Figure 3 , Figure 5 , Fig. 7A and Figure 7B The third arrangement shown, for example, employs a frequency adjuster 30 that is temperature controlled (ie, heat is applied) to induce a change in the refractive index of the second portion 40B of the microring resonator 40 . Fig. 8A For the embodiment Figure 3 A magnified view of region M in which Figure 3 The first die 100 in the bonded assembly is in a second configuration. Figure 8B for Fig. 8A FIG. 1 is a plan view of a first arrangement of a first die 100 .

[0164] In a fourth configuration, the frequency adjuster 30 includes a heating element 47 formed on the second portion 40B of the microring resonator 40. The heating element 47 may include a thin metal layer or a conductive metal nitride layer, including a conductive metal nitride such as titanium nitride, tantalum nitride, tungsten nitride, or an aluminum-rich aluminum nitride alloy. The thickness of the heating element 47 may be 5 nm to 50 nm, such as 10 nm to 25 nm, but lesser or greater thicknesses may also be used. The heating element 47 may be formed directly on the upper surface, sidewalls, and lower surface of the microring resonator 40. The interface dielectric material layer 45 may instead be sandwiched between the microring resonator and the heating element 47.

[0165] The frequency regulator control circuit 250 may include a temperature controller 252 configured to control the heat output of the heating element 47. The temperature controller 252 may be formed in the second die 200. Once the second die 200 is bonded to the first die 100, the temperature controller 252 may be electrically connected to the heating element 47. The temperature controller 252 may include at least one field effect transistor 210.

[0166] The operating principle of the quantum memory device in the fourth configuration may be similar to the operating principle of the quantum memory device in the first configuration. In the fourth configuration, the temperature of the second portion 40B of the microring resonator 40 may be changed to adjust the effective refractive index of the second portion 40B of the microring resonator 40. Specifically, applying heat from the heating element 47 to the second portion 40B of the microring resonator 40 may adjust the photon resonance frequency. Except for the frequency adjustment mechanism, the second configuration of the quantum memory device may be operated in the same manner as the quantum memory device of the first configuration described above.

[0167] Fig. 91 is a top view of various configurations of the microring resonator 40 in the embodiment of the present invention. The general shape of the microring resonator 40 is annular (i.e., a torus), and can be circular, elongated, or have at least one corner (having a smaller radius of curvature than the surrounding area in the top view). The effective circumference of the microring resonator 40 can be expressed as nC=ml, where in the effective refractive index of the microring resonator 40, C is the effective circumference of the microring resonator 40, m is a non-negative integer (usually 1), and l is the photon resonance wavelength (i.e., the wavelength of the captured photon measured in a vacuum).

[0168] Fig.10 1 is a top view of various configurations of the microring resonator 40 in an embodiment of the present invention. The vertical cross-sectional shape of the microring resonator 40 can adopt a variety of shapes. The various shapes can include a rectangle, a rounded rectangle, a trapezoid, a multi-layered mesa structure, or the like. The lateral dimensions and heights of the various vertical cross-sectional shapes of the microring resonator 40 can be determined to optimize the lateral and vertical confinement of photons therein, and can be the same as the lateral dimensions and heights of the waveguide 20 of the same shape. In the example, the lateral dimensions and heights of the various vertical cross-sectional shapes of the microring resonator 40 are typically 200nm to 600nm, and can be adjusted according to the wavelength of the captured photons and the refractive index of the material of the microring resonator 40.

[0169] Fig.11A This is the first configuration of the quantum memory material portion 60 in one embodiment of the present invention. In one embodiment, the method for forming the quantum memory material portion 60 may be to directly deposit a quantum memory material film on the material of the microring resonator 40. For example, an etching mask layer and an etching process may be used to pattern the quantum memory material portion 60. The etching process may be selective to the material of the microring resonator 40, that is, the material of the microring resonator 40 is not etched and collateral damage to the microring resonator 40 may be minimized.

[0170] Fig. 11B This is a second configuration of the quantum memory material portion 60 in one embodiment of the present invention. In one embodiment, an insulating layer 62 such as an interface insulating layer can be directly formed on the material of the microring resonator 40. The insulating layer 62 includes an insulating material such as silicon oxide, silicon nitride, or a dielectric metal oxide, and its thickness can be 1 nm to 20 nm, such as 2 nm to 10 nm, but a smaller or larger thickness can also be used. The method of forming the quantum memory material portion 60 can be to deposit a quantum memory material film on the insulating layer 62.

[0171] Fig. 11C and Fig.11D It is a vertical cross-sectional view of a third arrangement of the quantum memory material portion 60 in an embodiment of the present invention.

[0172] like Fig. 11CAs shown, an implantation layer 60' may be formed in the upper portion of the third portion 40C of the microring resonator 40, and the formation method may be to implant atoms of at least one element, which includes the atomic element that subsequently forms the quantum memory material portion 60. For example, if the quantum memory material portion 60 includes hexagonal boron nitride with nitrogen vacancies, the atoms of the at least one element in the embodiment where the microring resonator 40 includes silicon nitride may include boron atoms; or the atoms of the at least one element in the embodiment where the microring resonator 40 includes silicon may include boron atoms and nitrogen atoms. In the embodiment where boron and nitrogen atoms are implanted, the dosage ratio of the boron atoms to the nitrogen atoms may be selected to ensure that a suitable nitrogen vacancy level is provided after the annealing process. In another example, if the quantum memory material portion 60 includes molybdenum diselenide, tungsten diselenide, or aluminum nitride, the implanted species may include molybdenum, tungsten, aluminum, selenium and / or nitrogen depending on the final material composition of the quantum memory material portion 60.

[0173] like Fig.11D As shown, a thermal annealing process may be performed to induce crystallization of the implanted atoms in the implanted layer 60'. The thermal annealing process may transform the atoms of at least one element in the implanted layer 60' into a two-dimensional material. In one embodiment, more than 80% of the atomic bonds may be located in a two-dimensional plane (e.g., a plane parallel to the nearest surface of the microring resonator 40).

[0174] like FIG. 11A to FIG. 11D As shown, the method of forming the quantum memory material portion 60 can be to introduce at least one material used to form the quantum memory material portion 60 into or on the third portion 40C of the microring resonator 40. The quantum memory material has a ground state and an excited state in which photons are stored. In one embodiment, the quantum memory material includes hexagonal boron nitride containing nitrogen vacancies. In one embodiment, the quantum memory material includes molybdenum diselenide, tungsten diselenide, or aluminum nitride. In one embodiment, the quantum memory material portion 60 includes a quantum memory material film having a thickness less than 20%, 10%, 5% and / or 2% of the maximum lateral dimension of the film.

[0175] like FIG. 1A to FIG. 11DAs shown, various embodiments of the present invention provide a quantum memory device, which includes a waveguide 20 configured to spatially confine a photon path therein; a quantum memory unit 10, which includes a microring resonator 40, a frequency adjuster 30, and a quantum memory material portion 60, wherein the microring resonator 40 includes a first portion 40A parallel to a portion of the waveguide 20, wherein the frequency adjuster 30 is configured to adjust the effective refractive index in or around a second portion 40B of the microring resonator 40 to adjust the photon resonance frequency in the microring resonator 40, and wherein the quantum memory material portion 60 includes a quantum memory material having a ground state and an excited state storing photons therein and located in or on a third portion 40C of the microring resonator 40; and a magnetic field generator (70, 270) configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60.

[0176] In one embodiment, the magnetic field generator (70, 270) includes a metal structure 70 located on or near the third portion 40C of the microring resonator 40, and the current switching circuit 270 includes at least one field effect transistor 210 configured to switch the current through the metal structure 70. In one embodiment, the microring resonator 40 is embedded in the first dielectric material layer 130 in the first die 100, and the current switching circuit 270 is located in the second die 200 bonded to the first die 100. In one embodiment, the first die 100 includes a first metal interconnect structure 180 and a first metal bonding pad 198 embedded in the first dielectric material layer 130, and the second die 200 includes a second metal interconnect structure 280 and a second metal bonding pad 298 embedded in the second dielectric material layer 230, and the second metal bonding pad 298 is bonded to the first metal bonding pad 198. In one embodiment, the metal structure 70 includes one of a coil structure, an antenna structure, and a transmission line structure.

[0177] In one embodiment, the quantum memory material portion 60 includes a quantum memory material film having a thickness less than 20% of the largest lateral dimension of the film; and a magnetic field generator (70, 270) configured to generate a magnetic field such that an average perpendicular magnetic field component in the volume of the film is at least 90% of an average magnetic field in the volume of the film.

[0178] In one embodiment, the quantum memory device includes a control circuit 240 configured to adjust the photon resonance wavelength in the microring resonator 40 to match a predetermined wavelength (which is the photon wavelength of the photons in the waveguide 20) during the first step of the photon capture operation and generate captured photons in the microring resonator 40. In one embodiment, the control circuit 240 is configured to use a magnetic field generator (70, 270) to generate a magnetic field during the second step of the photon capture operation to increase quantum absorption of the captured photons by the quantum memory material.

[0179] Another embodiment of the present invention provides a quantum memory device, which includes: a waveguide 20, which is configured to spatially confine a photon path therein; a quantum memory unit 10, which includes a microring resonator 40, a frequency adjuster 30, and a quantum memory material portion 60, wherein the microring resonator 40 includes a first portion 40A parallel to a portion of the waveguide 20, wherein the frequency adjuster 30 is configured to adjust the effective refractive index in or around a second portion 40B of the microring resonator 40 to adjust the photon resonance frequency in the microring resonator 40, and wherein the quantum memory material portion 60 includes a quantum memory material having a ground state and an excited state storing photons therein and is located in or on a third portion 40C of the microring resonator 40; and a metal structure 70, which is located on or near the third portion 40C of the microring resonator 40 and is configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and in the quantum memory material portion 60 when a current passes through the metal structure 70.

[0180] In one embodiment, the quantum memory device includes a current switching circuit 270 including at least one field effect transistor 210 configured to switch current flowing through the metal structure 70. In one embodiment, the current switching circuit 270 and the metal structure 70 are configured so that the temporal and spatial average magnetic field in the volume of the third portion 40C of the microring resonator 40 is 0.1T to 5.0T.

[0181] In one embodiment, the microring resonator 40 is embedded in the first dielectric material layer 130 in the first die 100, and the power switch circuit 270 is located in the second die 200 bonded to the first die 100. In one embodiment, the first die 100 includes a first metal interconnect structure 180 and a first metal bonding pad 198 embedded in the first dielectric material layer 130; the second die 200 includes a second metal interconnect structure 280 and a second metal bonding pad 298 embedded in the second dielectric material layer 230; and the second metal bonding pad 298 is bonded to the first metal bonding pad 198. In one embodiment, the metal structure 70 includes one of a coil structure, an antenna structure, and a transmission line structure.

[0182] In another embodiment of the present invention, a quantum memory device includes a first die 100 and a second die 200. The first die 100 includes a waveguide 20 configured to spatially confine a photon path therein; a microring resonator 40 including a first portion 40A parallel to a portion of the waveguide 20; a frequency adjuster 30 configured to adjust an effective refractive index in or near a second portion 40B of the microring resonator 40 to adjust a photon resonance frequency in the microring resonator 40; a quantum memory material portion 60 including a quantum memory material having a ground state and an excited state storing photons therein and located in or on a third portion 40C of the microring resonator 40; and a metal structure 70 located on or near the third portion 40C of the microring resonator 40 and configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and in the quantum memory material portion 60 once a current passes through the metal structure 70. The second die 200 includes a current switching circuit 270 including at least one field effect transistor 210 configured to switch current flowing through the metal structure 70 .

[0183] In one embodiment, the first die 100 includes a first dielectric material layer 130 to bury the metal structure 70, the first metal interconnect structure 180, and the first metal bonding pad 198; the second die 200 includes a second dielectric material layer 230 to bury the second metal interconnect structure 280 and the second metal bonding pad 298; and the second metal bonding pad 298 is bonded to the first metal bonding pad 198. In one embodiment, the metal structure 70 includes one of a coil structure, an antenna structure, and a transmission line structure.

[0184] In one embodiment, the second die 200 includes a control circuit 240 configured to adjust the photon resonance wavelength in the microring resonator 40 to match the predetermined wavelength (the photon wavelength of the photons in the waveguide 20) during the first step of the photon capture operation, and generate captured photons in the microring resonator 40. In one embodiment, the control circuit 240 is configured to generate a magnetic field using a magnetic field generator (70, 270) during the second step of the photon capture operation to increase the quantum absorption of the photons captured by the quantum memory material. In one embodiment, the control circuit 240 is configured to generate a magnetic field using a magnetic field generator (70, 270) during the first step of the photon release step to increase the quantum coupling between the energy stored in the quantum memory material and the resonant photon state in the microring resonator 40.

[0185] Another embodiment of the present invention provides a quantum memory device, which includes: a waveguide 20, which is configured to spatially confine a photon path therein; a quantum memory unit 10, which includes a microring resonator 40, a frequency adjuster 30, and a quantum memory material portion 60, wherein the microring resonator 40 includes a first portion 40A parallel to a portion of the waveguide 20, wherein the frequency adjuster 30 is configured to adjust the effective refractive index in or around a second portion 40B of the microring resonator 40 to adjust the photon resonance frequency in the microring resonator 40, and wherein the quantum memory material portion 60 includes a quantum memory material having a ground state and an excited state storing photons therein, and is located in or on a third portion 40C of the microring resonator 40; and a control circuit 240, which is configured to generate a captured photon in the microring resonator 40 from an incident photon in the waveguide 20, and induce a state transition from a ground state to an excited state in the quantum memory material.

[0186] In one embodiment, the control circuit 240 is configured to apply a magnetic field to the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 to induce quantum coupling between the captured photons and the state transition. In one embodiment, the quantum memory device includes a metal structure 70 located on or near the third portion 40C of the microring resonator 40 and configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 once a current passes through the metal structure. In one embodiment, the quantum memory device includes a current switching circuit 270, which includes at least one field effect transistor 210. The field effect transistor 210 is configured to switch the current flowing through the metal structure 70. In one embodiment, the microring resonator 40 is embedded in the first dielectric material layer 130 in the first die 100, and the current switching circuit 270 is located in the second die 200 bonded to the first die 100.

[0187] In one embodiment, the frequency adjuster 30 includes a first doped semiconductor portion 421, which is implemented as a first portion of the second portion 40B of the microring resonator 40 and has a first conductivity type of doping; and a second doped semiconductor portion 422, which is implemented as a second portion of the second portion 40B of the microring resonator 40 and has a second conductivity type of doping, and the second conductivity type is opposite to the first conductivity type. The quantum memory device may also include an electrical bias circuit 251, which is configured to apply a bias voltage across the first doped semiconductor portion 421 and the second doped semiconductor portion 422.

[0188] In one embodiment, the first doped semiconductor portion 421 and the second doped semiconductor portion 422 are in direct contact with each other. In one embodiment, the frequency adjuster 30 further includes an insulating layer 44 interposed between the first doped semiconductor portion 421 and the second doped semiconductor portion 422. In one embodiment, a vertically extending pn junction exists between the first doped semiconductor portion 421 and the second doped semiconductor portion 422. In one embodiment, the second doped semiconductor portion 422 is completely higher than a horizontal plane containing the topmost surface of the first doped semiconductor portion 421.

[0189] In one embodiment, the frequency adjuster 30 includes a graphene electrode 46 located on, on the side of, or below the second portion 40B of the microring resonator 40; and an electrical bias circuit 251 configured to apply a bias voltage to the graphene electrode 46. In one embodiment, the microring resonator 40 includes silicon nitride.

[0190] In one embodiment, the frequency adjuster 30 includes a heating element 47 located on the second portion 40B of the microring resonator 40. The quantum memory device includes a temperature controller 252 configured to control the heat output of the heating element 47.

[0191] In another embodiment of the present invention, a quantum memory device is provided, which includes: a one-dimensional array of waveguides 20 extending laterally along a first horizontal direction hd1; a two-dimensional array of quantum memory cells 10, wherein each quantum memory cell 10 includes a microring resonator 40, a frequency adjuster 30, and a quantum memory material portion 60, wherein the microring resonator 40 includes a first portion 40A parallel to and optically coupled to a respective waveguide 20 in the one-dimensional array of waveguides 20, wherein the frequency adjuster 30 is configured to adjust an effective refractive index in or around a second portion 40B of the microring resonator 40 to adjust a photon resonance frequency in the microring resonator 40, and wherein the quantum memory material portion 60 includes a quantum memory material having a ground state and an excited state storing photons therein, and is located in or on a third portion 40C of the microring resonator 40; and word lines (18W1, 18W2) electrically connected to the frequency adjusters 30 of respective columns and configured to apply an electrical signal to adjust the photon resonance frequency in the microring resonators 40 of respective columns.

[0192] In one embodiment, the quantum memory cell 10 includes a metal structure 70 configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 in the respective quantum memory cell 10 once a current passes through the metal structure 70. In one embodiment, the quantum memory device includes an access line 18A electrically connected to the metal structure 70 of the respective column and electrically connected to the respective current switching circuit 270 including at least one field effect transistor 210. The field effect transistor 210 is configured to switch the current flowing through the metal structure 70 of the respective column. In one embodiment, the metal structures 70 each include one of a coil structure, an antenna structure, and a transmission line structure.

[0193] Fig.12 This is a first flow chart of the process steps used to manufacture a quantum memory device in one embodiment of the present invention.

[0194] As in step 1210, Figures 1A to 1C ,and FIG. 4A to FIG. 10 As shown, a combination of a waveguide 20 and a microring resonator 40 may be formed. The waveguide 20 is configured to spatially confine a photon path therein, and the microring resonator 40 includes a first portion 40A parallel to a portion of the waveguide 20.

[0195] As in step 1220, Figures 1A to 1C ,and FIG. 4A to FIG. 8B As shown, the frequency adjuster 30 may be formed on the microring resonator 40. The frequency adjuster 30 is configured to adjust the effective refractive index in or around the second portion 40B of the microring resonator 40 to adjust the photon resonance frequency in the microring resonator 40.

[0196] As in step 1230, Figures 1A to 1C , FIG. 4A to FIG. 8B ,and FIG. 11A to FIG. 11D As shown, a quantum memory material portion 60 including a quantum memory material having a ground state and an excited state storing photons therein may be formed in or on the third portion 40C of the microring resonator 40 .

[0197] In one embodiment, the manufacturing method further includes forming a control circuit 240 configured to adjust the photon resonance wavelength in the microring resonator 40 to match the predetermined wavelength (the photon wavelength of the photons in the waveguide 20) during the first step of the photon capture operation. In one embodiment, the manufacturing method further includes forming a magnetic field generator (70, 270) configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60.

[0198] Fig.13 This is a second flow chart of the process step sequence used to manufacture a quantum memory device in one embodiment of the present invention.

[0199] As in step 1310, Figures 1A to 1C ,and FIG. 4A to FIG. 10 As shown, a combination of a waveguide 20 and a microring resonator 40 may be formed. The waveguide 20 is configured to spatially confine a photon path therein, and the microring resonator 40 includes a first portion 40A parallel to a portion of the waveguide 20.

[0200] As in step 1320, Figures 1A to 1C ,and FIG. 4A to FIG. 8B As shown, the frequency adjuster 30 may be formed on the microring resonator 40. The frequency adjuster 30 is configured to adjust the effective refractive index in or around the second portion 40B of the microring resonator 40 to adjust the photon resonance frequency in the microring resonator 40.

[0201] As in step 1330, Figures 1A to 1C , FIG. 4A to FIG. 8B ,and FIG. 11A to FIG. 11D As shown, a quantum memory material portion 60 including a quantum memory material having a ground state and an excited state storing photons therein may be formed in or on the third portion 40C of the microring resonator 40 .

[0202] As in step 1340, Figure 2A , Figure 2B and Figure 3 ,and FIG. 4A to FIG. 8B As shown, a control circuit 240 may be formed that is configured to generate trapped photons in the microring resonator 40 from incident photons in the waveguide 20 and induce a state transition from a ground state to an excited state in the quantum memory material.

[0203] In one embodiment, the control circuit 240 is configured to apply a magnetic field to the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 to induce quantum coupling between the captured photons and the state transition. In one embodiment, the manufacturing method further includes forming a metal structure 70 on the third portion 40C of the microring resonator 40, wherein the metal structure 70 is configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 once a current passes through the metal structure 70. In one embodiment, the manufacturing method further includes forming a current switching circuit 270, which includes at least one field effect transistor 210 configured to switch the current flowing through the metal structure 70; and electrically connecting the current switching circuit 270 to the metal structure 70. In one embodiment, the microring resonator 40 is formed in the first dielectric material layer 130 in the first die 100, and the current switching circuit 270 is formed in the second die 200, and the second die 200 is different from the first die 100. The manufacturing method may include bonding the second die 200 to the first die 100 .

[0204] In one embodiment, the method for forming the frequency adjuster 30 is to form a first doped semiconductor portion 421 in a first portion of the second portion 40B of the microring resonator 40, wherein the first doped semiconductor portion 421 has a doping of a first conductivity type; to form a second doped semiconductor portion 422 in a second portion of the second portion 40B of the microring resonator 40, wherein the second doped semiconductor portion 422 has a doping of a second conductivity type, and the second conductivity type is opposite to the first conductivity type; and to form an electrical bias circuit 251, which is configured to apply a bias voltage across the first doped semiconductor portion 421 and the second doped semiconductor portion 422. In one embodiment, the first doped semiconductor portion 421 and the second doped semiconductor portion 422 are in direct contact with each other. In one embodiment, the manufacturing method further includes forming an insulating layer 44, wherein the first doped semiconductor portion 421 and the second doped semiconductor portion 422 are separated from each other by the insulating layer 44. In one embodiment, a vertically extending pn junction is formed between the first doped semiconductor portion 421 and the second doped semiconductor portion 422. In one embodiment, the second doped semiconductor portion 422 is completely above a horizontal plane containing the topmost surface of the first doped semiconductor portion 421 .

[0205] In one embodiment, the frequency adjuster 30 is formed by forming a graphene electrode 46 on, on the side of, or under the second portion 40B of the microring resonator 40; and forming an electrical bias circuit 251 configured to apply a bias voltage to the graphene electrode 46. In one embodiment, the microring resonator 40 includes silicon nitride.

[0206] In one embodiment, the frequency adjuster 30 includes a heating element 47 formed on the second portion 40B of the microring resonator 40 ; and the manufacturing method includes forming a temperature controller 252 configured to control the heat output of the heating element 47 .

[0207] Fig.14 FIG. 3 is a third flow chart of the process steps for manufacturing a quantum memory device in one embodiment of the present invention.

[0208] As in step 1410, Figures 1A to 1C ,and FIG. 4A to FIG. 8B As shown, a one-dimensional array of waveguides 20 is formed, which extend laterally along a first horizontal direction hd1.

[0209] As in step 1420, Figures 1A to 1C ,and 4A to 11DAs shown, a two-dimensional array of quantum memory cells 10 is formed. The quantum memory cells 10 each include a microring resonator 40, a frequency adjuster 30, and a quantum memory material portion 60, wherein the microring resonator 40 includes a first portion 40A that is parallel to and optically coupled to an individual waveguide 20 in the one-dimensional array of waveguides 20. The frequency adjuster 30 is configured to adjust the effective refractive index in or around the second portion 40B of the microring resonator 40 to adjust the photon resonance frequency in the microring resonator 40. The quantum memory material portion 60 includes a quantum memory material having a ground state and an excited state in which photons are stored and formed in or on a third portion 40C of the microring resonator 40.

[0210] As in step 1430, Figures 1A to 1C ,and FIG. 4A to FIG. 8B As shown, word lines (18W1, 18W2) can be formed, which can be electrically connected to the frequency adjusters 30 of the respective columns. The word lines (18W1, 18W2) can be configured to apply electrical signals to adjust the photon resonance frequency in the microring resonators 40 of the respective columns.

[0211] In one embodiment, the quantum memory cell 10 includes a metal structure 70 configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 in the respective quantum memory cell 10 when a current passes through the metal structure 70. In one embodiment, the manufacturing method further includes forming an access line 18A, wherein the access line 18A is electrically connected to the metal structure 70 of the respective column; forming a current switching circuit 270, each of which includes at least one field effect transistor 210 configured to switch current; and electrically connecting each access line 18A to the respective current switching circuit 270.

[0212] In one embodiment, a one-dimensional array of waveguides 20, a two-dimensional array of quantum memory cells 10, and word lines (18W1, 18W2) are formed in a first die 100. The manufacturing method further includes forming a control circuit 240 configured to control the operation of the word lines (18W1, 18W2) in a second die 200, and the control circuit 240 includes a field effect transistor 210. The manufacturing method may include bonding the second die 200 to the first die 100 to provide an electrical connection between the control circuit 240 and the word lines (18W1, 18W2).

[0213] In another embodiment of the present invention, a method for operating a quantum memory device is provided. The quantum memory device includes: a waveguide 20 configured to spatially confine a photon path therein; and a quantum memory unit 10, which includes a microring resonator 40, a frequency adjuster 30, and a quantum memory material portion 60, wherein the microring resonator 40 includes a first portion 40A parallel to a portion of the waveguide 20, wherein the frequency adjuster 30 is configured to adjust the effective refractive index in or around a second portion 40B of the microring resonator 40 to adjust the photon resonance frequency in the microring resonator 40, and wherein the quantum memory material portion 60 includes a quantum memory material having a ground state and an excited state storing photons therein and is located in or on a third portion 40C of the microring resonator 40. The operation method includes: transmitting a photon having a photon wavelength through the waveguide 20; adjusting the photon resonance wavelength in the microring resonator 40 to optically couple the microring resonator 40 to the photons in the waveguide 20 to generate trapped photons in the microring resonator 40; and inducing a transition from a ground state to an excited state in the quantum memory material to convert energy in the trapped photons to the quantum memory material, thereby storing data bits in the quantum memory material portion 60.

[0214] In one embodiment, the operating method further includes inducing a transition from an excited state to a ground state in the quantum memory material to generate confined photons in the microring resonator 40; and inducing optical coupling between the confined photons and the waveguide 20 to induce a photon beam in the waveguide 20. In one embodiment, the quantum memory unit 10 includes a magnetic field generator (70, 270) configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60; and generating a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 to induce a transition from a ground state to an excited state in the quantum memory material.

[0215] Fig.15 This is a fourth flow chart of a sequence of process steps used to operate a quantum memory device in one embodiment of the present invention.

[0216] As shown in step 1510 and FIG. 1A to FIG. 11DAs shown, a quantum memory device is provided, which includes a waveguide 20 configured to spatially confine a photon path therein; and a quantum memory unit 10, which includes a microring resonator 40, a frequency adjuster 30, and a quantum memory material portion 60, wherein the microring resonator 40 includes a first portion 40A parallel to a portion of the waveguide 20, wherein the frequency adjuster 30 is configured to adjust the effective refractive index in or around a second portion 40B of the microring resonator 40 to adjust the photon resonance frequency in the microring resonator 40, and wherein the quantum memory material portion 60 includes a quantum memory material having a ground state and an excited state storing photons therein, and is located in or on a third portion 40C of the microring resonator 40.

[0217] As in step 1520 and FIG. 4A to FIG. 8B As shown, photons having a photonic wavelength may be transmitted through waveguide 20.

[0218] As in step 1530 and FIG. 4A to FIG. 8B As shown, the photon resonance wavelength in the microring resonator 40 can be adjusted to match the photon wavelength, thereby generating trapped photons in the microring resonator 40 .

[0219] As in step 1540 and FIG. 4A to FIG. 8B As shown, the energy in the captured photons is converted into the quantum memory material portion 60 in the form of quantum excitation from a ground state to an excited state.

[0220] In one embodiment, a magnetic field may be applied to the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 to convert energy in the trapped photons to the quantum memory material portion 60 via quantum coupling between the trapped photons and the quantum excitations. In one embodiment, the quantum memory device includes a metal structure 70 located on or around the third portion 40C of the microring resonator 40, and the operating method includes passing a current through the metal structure 70 to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60.

[0221] In one embodiment, the quantum memory device includes a current switch circuit 270 including at least one field effect transistor 210; and the operation method includes using the current switch circuit 270 to switch the current flowing through the metal structure 70, so that the magnetic field is turned on when the current flows through the metal structure 70, and the magnetic field is turned off when the current does not flow through the metal structure 70. In one embodiment, the microring resonator 40 is embedded in the first dielectric material layer 130 in the first die 100, and the current switch circuit 270 is located in the second die 200 bonded to the first die 100. In one embodiment, the metal structure 70 includes one of a coil structure, an antenna structure, and a transmission line structure.

[0222] In one embodiment, the frequency adjuster 30 includes a first doped semiconductor portion 421, such as a first portion of the second portion 40B of the microring resonator 40, having a doping of a first conductivity type; and a second doped semiconductor portion 422, such as a second portion of the second portion 40B of the microring resonator 40, having a doping of a second conductivity type, and the second conductivity type is opposite to the first conductivity type. A bias voltage can be applied across the first doped semiconductor portion 421 and the second doped semiconductor portion 422 to adjust the photon resonance frequency. In one embodiment, the bias voltage changes the charge carrier distribution in the second portion 40B of the microring resonator 40 to adjust the effective refractive index in the second portion 40B of the microring resonator 40. In one embodiment, the frequency adjuster 30 includes a pn junction between the first doped semiconductor portion 421 and the second doped semiconductor portion 422, and the bias voltage adjusts the depletion region width across the pn junction. In one embodiment, the frequency adjuster 30 also includes an insulating layer 44 sandwiched between the first doped semiconductor portion 421 and the second doped semiconductor portion 422.

[0223] In one embodiment, the frequency adjuster 30 includes a graphene electrode 46 located on, on both sides of, or below the second portion of the microring resonator 40, and a bias voltage can be applied across the graphene electrode 46 and the second portion 40B of the microring resonator 40 to adjust the photon resonance frequency, wherein the charge distribution in the graphene electrode 46 changes to adjust the effective refractive index around the second portion 40B of the microring resonator 40. In one embodiment, the microring resonator 40 includes silicon nitride.

[0224] In one embodiment, the frequency adjuster 30 includes a heating element 47 located on the second portion 40B of the microring resonator 40 , and the operating method includes changing the temperature of the second portion 40B of the microring resonator 40 to adjust the effective refractive index of the second portion 40B of the microring resonator 40 .

[0225] Fig.16 This is a fifth flow chart of the sequence of process steps used to operate a quantum memory device in an embodiment of the present invention.

[0226] As shown in step 1610 and FIG. 1A to FIG. 11DAs shown, a quantum memory device is provided, which includes a one-dimensional array of waveguides 20 extending laterally along a first horizontal direction hd1; a two-dimensional array of quantum memory cells 10, wherein the quantum memory cells 10 include microring resonators 40, frequency adjusters 30, and quantum memory material portions 60, wherein the microring resonator 40 includes a first portion 40A parallel to and optically coupled to individual waveguides 20 in the one-dimensional array of waveguides 20, wherein the frequency adjuster 30 is configured to adjust the photon resonance frequency in the microring resonator 40, and wherein the quantum memory material portion 60 includes a quantum memory material having a ground state and an excited state storing photons therein, and is located in or on a third portion 40C of the microring resonator 40; and word lines (18W1, 18W2) electrically connected to the frequency adjusters 30 of individual columns.

[0227] As in step 1620 and FIG. 4A to FIG. 8B As shown, a photon having a photon wavelength may be transmitted through a waveguide 20 which is optically coupled to a selected quantum memory cell 10 in the two-dimensional array of quantum memory cells 10 .

[0228] As shown in step 1630 and FIG. 4A to FIG. 8B As shown, the photon resonance wavelength in the microring resonator 40 of the selected quantum memory unit 10 can be adjusted to match the photon wavelength to generate captured photons in the microring resonator 40 of the selected quantum memory unit 10 .

[0229] As in step 1640 and FIG. 4A to FIG. 8B As shown, the energy in the captured photon may be transferred into the quantum memory material portion 60 of the selected quantum memory cell 10 in the form of a quantum excitation.

[0230] In one embodiment, each of the quantum memory cells 10 includes a metal structure configured to generate a magnetic field in the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 in the individual quantum memory cell 10 once a current passes through the metal structure; and the operating method includes applying a magnetic field to the third portion 40C of the microring resonator 40 and the quantum memory material portion 60 of the selected quantum memory cell 10 to induce quantum coupling between the captured photon and the quantum excitation in the quantum memory material portion 60 of the selected quantum memory cell 10. In one embodiment, the three-dimensional quantum memory device includes an access line 18A electrically connected to the metal structure 70 of the individual column and electrically connected to the individual current switch circuit 270 including at least one field effect transistor 210; and the operating method includes turning on the current switch circuit 270 connected to the access line to generate a magnetic field, and the access line is connected to the metal structure 70 in the selected quantum memory cell 10.

[0231] In one embodiment, a two-dimensional quantum memory array is provided on a first die 100; a quantum memory device including a control circuit 240 is located in a second die 200 and configured to control the operation of the two-dimensional array of quantum memory cells 10 and word lines (18W1, 18W2); and the second die 200 is bonded to the first die 100.

[0232] Fig.17 This is a sixth flow chart of the process step sequence used to manufacture a quantum memory device in one embodiment of the present invention.

[0233] As in step 1710, Figures 1A to 1C , and Figure FIG. 4A to FIG. 10 As shown, a combination of a waveguide 20 and a microring resonator 40 may be formed. The waveguide 20 is configured to spatially confine a photon path therein, and wherein the microring resonator 40 includes a first portion 40A parallel to a portion of the waveguide 20 .

[0234] As in step 1720, Figures 1A to 1C ,and FIG. 4A to FIG. 8B As shown, the frequency adjuster 30 may be formed on the microring resonator 40. The frequency adjuster 30 is configured to adjust the effective refractive index in or around the second portion 40B of the microring resonator 40 to adjust the photon resonance frequency in the microring resonator 40.

[0235] As in step 1730, Figures 1A to 1C , FIG. 4A to FIG. 8B ,and FIG. 11A to FIG. 11D As shown, a quantum memory material portion 60 may be formed, wherein the quantum memory material includes a ground state and an excited state in which photons are stored. The method for forming the quantum memory material portion 60 may be to introduce at least one material used to form the quantum memory material portion 60 into or onto the third portion 40C of the microring resonator 40.

[0236] In one embodiment, the quantum memory material comprises hexagonal boron nitride containing nitrogen vacancies. In one embodiment, the quantum memory material comprises molybdenum diselenide, tungsten diselenide, or aluminum nitride. In one embodiment, the quantum memory material portion 60 comprises a quantum memory material film having a thickness less than 20% of the maximum lateral dimension of the film.

[0237] In one embodiment, the quantum memory material portion 60 is formed by implanting atoms of at least one element and then performing a thermal annealing process to transform the atoms of at least one element into a two-dimensional material in which more than 80% of the atomic bonds are in a two-dimensional plane. In one embodiment, the at least one element includes boron and nitrogen, and the quantum memory material includes hexagonal boron nitride.

[0238] In one embodiment, the quantum memory material portion 60 is formed by directly depositing a quantum memory material film on the material of the microring resonator 40. In one embodiment, the quantum memory material portion 60 is formed by depositing a quantum memory material film on an insulating layer, and the insulating layer is directly formed on the material of the microring resonator 40.

[0239] In one embodiment, the manufacturing method further comprises forming a magnetic field generator (70, 270) configured to generate a magnetic field such that the average magnetic field perpendicular component in the volume of the quantum memory material portion 60 is at least 90% of the average magnetic field in the volume of the quantum memory material portion 60. In one embodiment, the magnetic field generator (70, 270) comprises a metal structure 70 formed in a first dielectric material layer 130 in which the microring resonator 40 is embedded; and a current switching circuit 270 comprising at least one field effect transistor 210 configured to switch current flowing through the metal structure 70. In one embodiment, the waveguide 20, the microring resonator 40, the metal structure 70, and the first dielectric material layer 130 are formed in a first die 100, and the manufacturing method comprises forming a first metal bonding pad 198 in the first die 100; the current switching circuit 270 is formed in a second die 200 including a second metal bonding pad 298, and the manufacturing method comprises bonding the second metal bonding pad 298 to the first metal bonding pad 198.

[0240] In one embodiment, the manufacturing method includes forming a control circuit 240 configured to generate trapped photons in the microring resonator 40 from incident photons in the waveguide 20 and induce a state transition from a ground state to an excited state in the quantum memory material. In one embodiment, the waveguide 20 and the microring resonator 40 are formed in a first die 100, and the manufacturing method includes forming a first metal bonding pad 198 in the first die 100. The control circuit 240 is formed in a second die 200 containing a second metal bonding pad 298, and the manufacturing method includes bonding the second metal bonding pad 298 to the first metal bonding pad 198.

[0241] Fig.18 Flow chart of the process steps used to manufacture a quantum memory device in an embodiment of the present invention.

[0242] As in step 1810, Figures 1A to 1C ,and FIG. 4A to FIG. 10 As shown, a one-dimensional array of waveguides 20 is formed, which extend laterally along a first horizontal direction hd1.

[0243] As in step 1820, Figures 1A to 1C ,and 4A to 11DAs shown, a two-dimensional array of quantum memory cells 10 can be formed. The quantum memory cells 10 each include a microring resonator 40, a frequency adjuster 30, and a quantum memory material portion 60, wherein a first portion 40A of the microring resonator 40 is parallel to and optically coupled to a respective waveguide 20 in the one-dimensional array of waveguides 20. The frequency adjuster 30 is configured to adjust the effective refractive index in or around a second portion 40B of the microring resonator 40 to adjust the photon resonance frequency in the microring resonator 40. The quantum memory material portion 60 includes a quantum memory material having a ground state and an excited state in which photons are stored. At least one material used to form the quantum memory material portion 60 is introduced into or onto a third portion 40C of the microring resonator 40 to form the quantum memory material portion 60 in or onto the third portion of the microring resonator 40.

[0244] In one embodiment, the quantum memory material portion 60 is formed by implanting atoms of at least one element and then performing a thermal annealing process, which transforms the atoms of at least one element into a two-dimensional material, wherein more than 80% of the atomic bonds are in a two-dimensional plane. In one embodiment, the quantum memory material portion 60 is formed by directly depositing a quantum memory material film on the material of the microring resonator 40. In one embodiment, the quantum memory material portion 60 is formed by depositing a quantum memory material film on an insulating layer, and the insulating layer is directly formed on the material of the microring resonator 40.

[0245] In one embodiment, the manufacturing method further includes forming word lines (18W1, 18W2) electrically connected to the frequency adjuster 30 of the respective column, wherein the word lines (18W1, 18W2) are configured to apply an electrical signal to adjust the photon resonance frequency in the microring resonator 40 of the respective column. In one embodiment, the manufacturing method further includes forming access lines 18A, wherein the access lines 18A are electrically connected to the metal structures 70 of the respective column, wherein the metal structures 70 are each configured to generate a magnetic field in the quantum memory material portion 60 of the respective quantum memory cell 10; forming circuit switch circuits 270, each of which includes at least one field effect transistor 210, and the field effect transistor 210 is configured to switch current; and electrically connecting each access line 18A to a respective circuit switch circuit 270.

[0246] Fig.19 This is an eighth flow chart of the process step sequence used to manufacture a quantum memory device in an embodiment of the present invention.

[0247] As in step 1910, Figures 1A to 1C ,and 4A to 11DAs shown, a first die 100 may be formed. The first die 100 includes a one-dimensional array of waveguides 20 extending laterally along a first horizontal direction hd1, a two-dimensional array of quantum memory cells 10, and word lines (18W1, 18W2), wherein each quantum memory cell 10 includes a microring resonator 40, a frequency adjuster 30, and a quantum memory material portion 60. The microring resonator 40 includes a first portion 40A that is parallel to and optically coupled to a respective waveguide 20 in the one-dimensional array of waveguides 20. The frequency adjuster 30 is configured to adjust the effective refractive index in or around the second portion of the microring resonator 40 to adjust the photon resonance frequency in the microring resonator 40. The quantum memory material portion 60 includes a quantum memory material having a ground state and an excited state storing photons therein, and is formed in or on a third portion 40C of the microring resonator 40. The method of forming the quantum memory material portion 60 may be to introduce at least one material used to form the quantum memory material portion 60 into or on the third portion 40C of the microring resonator 40. The word lines ( 18W1 , 18W2 ) are electrically connected to the frequency adjusters 30 of the respective columns, wherein the word lines ( 18W1 , 18W2 ) are configured to apply electrical signals to adjust the photon resonance frequency in the microring resonators 40 of the respective columns.

[0248] As in step 1920, Figure 2A and Figure 2B ,and FIG. 4A to FIG. 8B As shown, a second die 200 may be formed, which includes a control circuit 240 configured to control the operation of the word lines ( 18W1 , 18W2 ). The control circuit 240 includes a field effect transistor 210 .

[0249] As in step 1930 and Figures 3 to 8B As shown, the second die 200 may be bonded to the first die 100 to provide electrical connections between the control circuit 240 and the word lines ( 18W1 , 18W2 ).

[0250] Various embodiments of the present invention can be used to provide a solid-state quantum memory device that can capture and release photons to serve as a memory device for storing data when operating a photon device. The solid-state quantum memory device of the present invention embodiment does not use a cryogenic environment or a vacuum environment, and can be integrated into a semiconductor package to be integrated with a semiconductor device.

[0251] The quantum memory device provided by an embodiment of the utility model comprises: a waveguide, which is configured to spatially confine a photon path therein; a memory unit, which comprises a microring resonator, a frequency adjuster, and a quantum memory material portion, wherein a first portion of the microring resonator is parallel to a portion of the waveguide, wherein the frequency adjuster is configured to adjust an effective refractive index in or around a second portion of the microring resonator to adjust a photon resonance frequency in the microring resonator, and wherein the quantum memory material portion comprises a quantum memory material having a ground state and an excited state in which photons are stored, and is located in or on a third portion of the microring resonator; and a control circuit, which is configured to adjust a photon resonance wavelength in the microring resonator to match a predetermined wavelength during a first step of a photon capture operation, and generate a plurality of captured photons in the microring resonator, and the predetermined wavelength is a wavelength of the captured photons.

[0252] In one embodiment, the quantum memory device further comprises a magnetic field generator configured to generate a magnetic field in the third portion of the microring resonator and the quantum memory material portion.

[0253] In one embodiment, the control circuit is configured to generate a magnetic field during the second step of the light trapping step to increase quantum absorption of photons trapped by the quantum memory material.

[0254] In one embodiment, the microring resonator is embedded in a plurality of first dielectric material layers in a first die; and the magnetic field generator includes a metal structure embedded in the first dielectric material layer, and a current switching circuit, wherein at least one field effect transistor included in the current switching circuit is configured to switch current flowing through the metal structure.

[0255] In one embodiment, the first die includes a plurality of first metal bonding pads; and the current switching circuit is located in the second die, and the second die includes a plurality of second metal bonding pads bonded to the first metal bonding pads.

[0256] In one embodiment, the metal structure is electrically connected to the current switching circuit via a group of multiple first metal interconnect structures buried in a first dielectric material layer, a group of first metal bonding pads, a group of second metal bonding pads, and a group of multiple second metal interconnect structures buried in multiple second dielectric material layers in a second die.

[0257] In one embodiment, the microring resonator is embedded in a first dielectric material layer in a first die; and the current switching circuit is located in a second die, and the second die includes a plurality of second metal bonding pads bonded to a plurality of first metal bonding pads of the first die.

[0258] In one embodiment, the quantum memory material portion is directly located on the surface of the third portion of the microring resonator.

[0259] In one embodiment, the quantum memory material is partially embedded in the third portion of the microring resonator.

[0260] In one embodiment, the quantum memory material portion contacts the dielectric spacer layer on the surface of the third portion of the microring resonator.

[0261] In one embodiment, the frequency adjuster includes a first doped semiconductor portion implemented as a first portion of a second portion of a microring resonator and having a first conductivity type of doping, and a second doped semiconductor portion implemented as a second portion of the microring resonator and having a second conductivity type of doping, and the second conductivity type is opposite to the first conductivity type; and the quantum memory device includes an electrical bias circuit configured to apply a bias voltage across the first doped semiconductor portion and the second doped semiconductor portion.

[0262] In one embodiment, the frequency adjuster includes: a graphene electrode located on, on the side of, or below the second portion of the microring resonator; and an electrical bias circuit configured to apply a bias voltage to the graphene electrode.

[0263] In one embodiment, the frequency adjuster includes a heating element located on the second portion of the microring resonator; and the quantum memory device includes a temperature controller configured to control a heat output of the heater element.

[0264] In one embodiment, a quantum memory device includes a two-dimensional memory array including a memory cell and an additional plurality of memory cells; the two-dimensional memory array includes a plurality of waveguides extending laterally along a first horizontal direction, and the waveguides include waveguides; and the two-dimensional memory array includes a plurality of word lines connected to respective frequency adjusters of respective memory arrays in the two-dimensional memory array and extending laterally along a second horizontal direction.

[0265] A quantum memory device provided by an embodiment of the utility model comprises a first die and a second die assembled by bonding, wherein the first die comprises: a waveguide configured to spatially confine a photon path therein; a microring resonator comprising a first portion parallel to a portion of the waveguide; a frequency adjuster configured to adjust the effective refractive index in or around the second portion of the microring resonator to adjust the photon resonance frequency in the microring resonator; and a quantum memory material portion comprising a quantum memory material having a ground state and an excited state storing photons therein and located in or on a third portion of the microring resonator; and wherein the second die comprises a control circuit configured to adjust the photon resonance wavelength in the microring resonator to match a predetermined wavelength during a first step of a photon capture operation and generate captured photons in the microring resonator.

[0266] In one embodiment, the first die includes multiple first dielectric material layers to bury multiple first metal interconnect structures and multiple first metal bonding pads; and the second die includes multiple second dielectric material layers to bury multiple second metal interconnect structures and multiple second metal bonding pads, and the second metal bonding pads are bonded to the first metal bonding pads.

[0267] In one embodiment, the quantum memory device further comprises a magnetic field generator configured to generate a magnetic field in the third portion of the microring resonator and the quantum memory material portion, wherein the magnetic field generator comprises a metal structure buried in the first dielectric material layer in the first die; and a current switching circuit located in the second die and comprising at least one field effect transistor, and the at least one field effect transistor is configured to switch a current through the metal structure.

[0268] A quantum memory device provided by an embodiment of the utility model comprises a waveguide, which is configured to spatially confine a photon path therein; a memory unit, which comprises a microring resonator, a frequency adjuster, and a quantum memory material portion, wherein the microring resonator comprises a first portion parallel to a portion of the waveguide, wherein the frequency adjuster is configured to adjust an effective refractive index in or around a second portion of the microring resonator to adjust a photon resonance frequency in the microring resonator, and wherein the quantum memory material portion comprises a quantum memory material having a ground state and an excited state storing photons therein, and being located in or on a third portion of the microring resonator; a control circuit, which is configured to adjust a photon resonance wavelength in the microring resonator during a first step of a photon capture operation; and a magnetic field generator, which is configured to generate a magnetic field in the third portion of the microring resonator and the quantum memory material portion during a second step of the photon capture operation.

[0269] In one embodiment, the magnetic field generator includes a metal structure located on or near the third portion of the microring resonator; and a current switching circuit including at least one field effect transistor configured to switch current flowing through the metal structure.

[0270] In one embodiment, the microring resonator is embedded in a first dielectric material layer in a first die; and the current switching circuit is located in a second die bonded to the first die.

[0271] The structures of several embodiments summarized above are helpful for those skilled in the art to understand the embodiments of the utility model. The term "comprising" of each embodiment inherently discloses additional embodiments, wherein the term "comprising" is replaced by "consisting essentially of..." or "consisting of..." unless otherwise explicitly stated. Whenever two or more elements in the same or different paragraphs are listed as alternatives, the Markush group of the two or more element lists is also implied.

[0272] Whenever the auxiliary verb "may" is used in an embodiment of the present invention to describe the formation or processing steps of an element, an embodiment in which the processing steps of this element are not performed is also explicitly envisioned, as long as the final device or equipment can provide equivalent results. In this way, the auxiliary verb "may" in forming an element or performing a processing step should be interpreted as "may" or "may or may not", as long as omitting the formation of this element or this processing step can provide the same result or an equivalent result, and equivalent results include slightly better results and slightly worse results. Those skilled in the art should understand that the present invention can be used as a basis to design and change other processes and structures to achieve the same purpose and / or the same advantages of the above-mentioned embodiments. Those skilled in the art should also understand that these equivalent substitutions do not depart from the spirit and scope of the present invention, and can be changed, replaced, or modified without departing from the spirit and scope of the present invention.

Claims

1. A quantum memory device, characterized in that: include: a waveguide configured to spatially confine the photon path therein; A memory cell comprising a microring resonator, a frequency adjuster, and a quantum memory material portion, wherein a first portion of the microring resonator is parallel to a portion of the waveguide, wherein the frequency adjuster is configured to adjust an effective refractive index in or around a second portion of the microring resonator to adjust a photon resonance frequency in the microring resonator, and wherein the quantum memory material portion comprises a quantum memory material having a ground state and an excited state storing photons therein and is located in or on a third portion of the microring resonator; and A control circuit is configured to adjust the photon resonance wavelength in the microring resonator to match a predetermined wavelength and generate a plurality of captured photons in the microring resonator during the first step of the photon capture operation, wherein the predetermined wavelength is the wavelength of the plurality of captured photons.

2. The quantum memory device according to claim 1, characterized in that A magnetic field generator is also included to generate a magnetic field in the third portion of the microring resonator and the quantum memory material portion.

3. The quantum memory device according to claim 2, characterized in that The control circuit is configured to generate a magnetic field during a second step of the light trapping step to increase quantum absorption of photons trapped by the quantum memory material.

4. The quantum memory device according to claim 2, characterized in that The microring resonator is embedded in a plurality of first dielectric material layers in a first die; and The magnetic field generator includes a metal structure buried in a plurality of the first dielectric material layers, and a current switching circuit, wherein at least one field effect transistor included in the current switching circuit is configured to switch the current flowing through the metal structure.

5. The quantum memory device according to claim 4, characterized in that The first die includes a plurality of first metal bonding pads; and The current switch circuit is located in a second die, and the second die includes a plurality of second metal bonding pads bonded to the plurality of first metal bonding pads.

6. The quantum memory device according to claim 5, characterized in that The metal structure is electrically connected to the current switching circuit via a group of multiple first metal interconnect structures buried in the first dielectric material layer, a group of multiple first metal bonding pads, a group of multiple second metal bonding pads, and a group of multiple second metal interconnect structures buried in multiple second dielectric material layers in the second bare chip.

7. A quantum memory device, characterized in that: include: A bonding assembly of a first die and a second die, The first bare chip includes: a waveguide configured to spatially confine the photon path therein; a microring resonator including a first portion parallel to a portion of the waveguide; a frequency adjuster configured to adjust the effective refractive index in or around a second portion of the microring resonator to adjust the photon resonance frequency in the microring resonator; and a quantum memory material portion, comprising a quantum memory material having a ground state and an excited state storing photons therein, and located in or on a third portion of the microring resonator; and The second die includes a control circuit, which is configured to adjust the photon resonance wavelength in the microring resonator to match a predetermined wavelength and generate captured photons in the microring resonator during the first step of the photon capture operation.

8. The quantum memory device according to claim 7, characterized in that The first die includes a plurality of first dielectric material layers to embed a plurality of first metal interconnect structures and a plurality of first metal bonding pads; and The second die includes a plurality of second dielectric material layers for embedding a plurality of second metal interconnect structures and a plurality of second metal bonding pads, and the plurality of second metal bonding pads are bonded to the plurality of first metal bonding pads.

9. A quantum memory device, characterized in that: include: a waveguide configured to spatially confine the photon path therein; A memory cell comprising a microring resonator, a frequency adjuster, and a quantum memory material portion, wherein the microring resonator comprises a first portion parallel to a portion of the waveguide, wherein the frequency adjuster is configured to adjust an effective refractive index in or around a second portion of the microring resonator to adjust a photon resonance frequency in the microring resonator, and wherein the quantum memory material portion comprises a quantum memory material having a ground state and an excited state storing photons therein and located in or on a third portion of the microring resonator; a control circuit configured to adjust a photon resonance wavelength in the microring resonator during a first step of a photon capture operation; and A magnetic field generator is configured to generate a magnetic field in the third portion of the microring resonator and the quantum memory material portion during the second step of the photon capture operation.

10. The quantum memory device according to claim 9, characterized in that The magnetic field generator includes a metal structure located on or near the third portion of the microring resonator; and a current switching circuit including at least one field effect transistor configured to switch current flowing through the metal structure.

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