Quantum memory device and quantum memory method based on optical resonator

Abstract

This invention provides a quantum storage device and a quantum storage method based on an optical resonant cavity. The quantum storage device includes: a light generation module that emits pump light and an optical signal; an electrical pulse generation module that generates an electrical pulse signal corresponding to the optical signal according to a preset storage method; the storage module includes a rare-earth-doped crystal, wherein a first reflective film on a first surface and a second reflective film on a second surface of the rare-earth-doped crystal constitute an optical resonant cavity, with the first and second surfaces forming a preset angle to change the resonant frequency of the optical resonant cavity; an optical waveguide array disposed inside a third surface of the rare-earth-doped crystal; an electrical waveguide array disposed on the third surface and electrically connected to the electrical pulse generation module, and changing the absorption band structure of rare-earth ions through the electrical pulse signal; the optical signal is coupled into the optical resonant cavity through the optical waveguide array, interacts with rare-earth ions within the optical resonant cavity, and excites the population of rare-earth ions to the upper optical energy level to store the optical signal.

Description

Technical Field

[0001] This invention relates to the technical field of quantum storage, and more specifically, to a quantum storage device and quantum storage method based on an optical resonant cavity. Background Technology

[0002] In the field of optical quantum communication, photons experience varying degrees of loss during transmission in free space or optical fibers, making it difficult to achieve ultra-long-distance quantum communication. To achieve quantum communication over distances exceeding 100 kilometers, quantum repeaters are one feasible solution, and quantum memories are one of the core components of quantum repeaters.

[0003] The storage efficiency of quantum memories directly affects the information transmission rate of quantum communication networks. Currently, optical signals are stored by being directly incident into rare-earth-doped crystals and absorbed by rare-earth ions. During the signal retrieval process, the generated photon echo, i.e., the read signal, is repeatedly absorbed by the rare-earth-doped crystal, resulting in a theoretical upper limit of storage efficiency of 54%. Summary of the Invention

[0004] To address at least one of the technical problems in the prior art, embodiments of the present invention provide a quantum storage device and a quantum storage method based on an optical resonant cavity, which can improve the efficiency of quantum storage.

[0005] This invention provides a quantum storage device based on an optical resonant cavity, comprising: a light generating module configured to emit pump light and an optical signal; an electrical pulse generating module configured to generate an electrical pulse signal corresponding to the optical signal according to a preset storage method; and a storage module comprising: a rare-earth-doped crystal, wherein the storage module is configured to form an optical absorption band on the rare-earth-doped crystal using the pump light according to the preset storage method, and to store the optical signal according to the optical absorption band; a first reflective film is disposed on a first surface of the rare-earth-doped crystal, and a second reflective film is disposed on a second surface of the rare-earth-doped crystal; the first reflective film and the second reflective film constitute an optical resonant cavity, wherein the second surface is configured to be aligned with the pump light... A plane extends perpendicular to the direction of the emitted optical signal, with the first surface and the second surface forming a predetermined angle to change the resonant frequency of the optical resonant cavity; an optical waveguide array is disposed inside the third surface of the rare-earth-doped crystal; and an electrical waveguide array is disposed on the third surface and electrically connected to the electrical pulse generation module. The electrical waveguide array modulates the rare-earth ions in the rare-earth-doped crystal through the electrical pulse signal to change the absorption band structure of the rare-earth ions. The optical signal is coupled into the optical resonant cavity through the optical waveguide array and interacts with the rare-earth ions in the optical resonant cavity, thereby exciting the population of the rare-earth ions to the upper optical level and storing the optical signal.

[0006] Optionally, the length difference between the optical waveguide at the longest distance between the first surface and the second surface and the optical waveguide at the shortest distance between the first surface and the second surface is greater than the operating wavelength of the rare earth-doped crystal.

[0007] Optionally, the transmittance of the first reflective film is the sum of the effective absorption depth of the rare-earth-doped crystal and the transmission loss of the optical signal in the optical waveguide array, so as to achieve impedance matching between the optical signal and the optical resonant cavity.

[0008] Optionally, when the preset storage method is an electrically controlled atomic frequency comb, the optical absorption band is an absorption band of a frequency comb structure, and the electrical pulse signal is a pulsed electric field signal; when the preset storage method is a spin wave atomic frequency comb, the optical absorption band is an absorption band of a frequency comb structure, and the electrical pulse signal is a radio frequency magnetic field signal; when the preset storage method is a noiseless photon echo, the optical absorption band is an isolated absorption band, and the electrical pulse signal is a radio frequency magnetic field signal.

[0009] Optionally, the above-mentioned electrical waveguide array includes: a plurality of electrical waveguides, which are respectively arranged adjacent to each optical waveguide in the above-mentioned optical waveguide array, so as to apply the above-mentioned electrical pulse signal to the above-mentioned rare earth ions located in the above-mentioned optical waveguides.

[0010] Optionally, the light generating module includes: a laser configured to emit a laser; a first modulator configured to modulate the laser to obtain the pump light; and a second modulator configured to modulate the laser to obtain the optical signal.

[0011] Optionally, the quantum storage device further includes a beam shaper disposed between the light generation module and the storage module, wherein the beam shaper is configured to change the polarization direction of the pump light and the optical signal.

[0012] Optionally, the quantum storage device further includes a temperature control module configured to provide a low-temperature operating environment for the storage module, so that the rare earth ions remain in a coherent state.

[0013] Optionally, the quantum storage device further includes: a first directional moving stage configured to drive the storage module to move in the height direction, such that the pump light and the optical signal are coupled into the optical waveguide array; and a second directional moving stage disposed on the first directional moving stage, the second directional moving stage being configured to drive the storage module to move in a direction perpendicular to the height direction and parallel to the second surface, such that the pump light and the optical signal are coupled into optical waveguides in the optical waveguide array that satisfy their respective impedance matching.

[0014] According to another aspect of the inventive concept of the present invention, a quantum storage method based on an optical resonant cavity is also provided, applied to the aforementioned quantum storage device. The quantum storage method includes: generating pump light using a light generation module; forming an optical absorption band on an optical waveguide array of a rare-earth-doped crystal using the pump light; generating an optical signal using the light generation module; and storing the optical signal in the optical resonant cavity of the storage module based on the optical absorption band.

[0015] According to an embodiment of the present invention, a quantum storage device and quantum storage method based on an optical resonant cavity are disclosed. A light generation module emits pump light and an optical signal, and an electrical pulse generation module generates an electrical pulse signal corresponding to the optical signal according to a preset storage method. The storage module includes a rare-earth-doped crystal, an optical waveguide array, and an electrical waveguide array. The storage module is configured to form an optical absorption band on the rare-earth-doped crystal using the pump light according to the preset storage method, and to store the optical signal based on the optical absorption band. A first reflective film is disposed on a first surface of the rare-earth-doped crystal, and a second reflective film is disposed on a second surface of the rare-earth-doped crystal. The first and second reflective films constitute an optical resonant cavity. The second surface is configured to extend along a plane perpendicular to the direction of emission of the pump light and the optical signal. The first and second surfaces form a preset angle. By reducing the length of the optical absorption band, the effective absorption depth of the optical absorption band is reduced, and the resonant frequency of the optical resonant cavity is changed, thereby improving the efficiency of quantum storage. An optical waveguide array is disposed inside the third surface of the rare-earth-doped crystal, and an electrical waveguide array is disposed on the third surface and electrically connected to an electrical pulse generation module. The electrical waveguide array modulates the rare-earth ions in the rare-earth-doped crystal through electrical pulse signals to change the absorption band structure of the rare-earth ions. Coupled with the optical signal into the optical resonant cavity via the optical waveguide array, the optical signal is confined within the optical waveguide array and interacts with the rare-earth ions within the optical resonant cavity. This excites the population of the rare-earth ions to the upper optical energy level, thereby storing the optical signal and reducing the storage efficiency loss caused by spatial mode mismatch in the optical resonant cavity. Attached Figure Description

[0016] Figure 1 This is a block diagram of a quantum storage device based on an optical resonant cavity according to an embodiment of the present invention;

[0017] Figure 2 This is a perspective view of a rare-earth-doped crystal according to an embodiment of the present invention;

[0018] Figure 3 This is a flowchart of a quantum storage method based on an optical resonant cavity according to an embodiment of the present invention;

[0019] Figure 4 This is a storage time sequence diagram according to an embodiment of the present invention, in the case of a preset storage method of atomic frequency comb.

[0020] In the accompanying drawings, the meanings of the reference numerals are as follows:

[0021] 1. Laser;

[0022] 2. First modulator;

[0023] 3. Second modulator;

[0024] 4. Beam shaper;

[0025] 5. Rare earth doped crystals;

[0026] 51. First reflective film;

[0027] 52. Second reflective film;

[0028] 6. Optical waveguide array;

[0029] 7. Temperature control module;

[0030] 8. First direction moving station;

[0031] 9. Second direction moving station. Detailed Implementation

[0032] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0034] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0035] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0036] Currently, optical signals are directly incident into rare-earth-doped crystals and absorbed by rare-earth ions, thus achieving optical signal storage. For example, when using the atomic frequency comb storage protocol, an atomic frequency comb photon echo, i.e., the signal being read, is generated during the signal reading process. Due to phase matching, the atomic frequency comb photon echo propagates in the same direction as the optical signal. Since the atomic frequency comb photon echo is repeatedly absorbed by the rare-earth-doped crystal, the theoretical upper limit of storage efficiency is 54%.

[0037] To improve the efficiency of quantum storage, according to one aspect of the invention, a light-generating module emits pump light and an optical signal, and an electrical pulse-generating module generates an electrical pulse signal corresponding to the optical signal according to a preset storage method. The storage module includes a rare-earth-doped crystal, an optical waveguide array, and an electrical waveguide array. The storage module is configured to form an optical absorption band on the rare-earth-doped crystal using the pump light according to the preset storage method, and to store the optical signal based on the optical absorption band. A first reflective film is disposed on a first surface of the rare-earth-doped crystal, and a second reflective film is disposed on a second surface of the rare-earth-doped crystal. The first and second reflective films constitute an optical resonant cavity. The second surface is configured to extend along a plane perpendicular to the direction of emission of the pump light and the optical signal. The first and second surfaces form a preset angle. By reducing the length of the optical absorption band, the effective absorption depth of the optical absorption band is reduced, and the resonant frequency of the optical resonant cavity is changed, thereby improving the efficiency of quantum storage. An optical waveguide array is disposed inside the third surface of the rare-earth-doped crystal, and an electrical waveguide array is disposed on the third surface and electrically connected to an electrical pulse generation module. The electrical waveguide array modulates the rare-earth ions in the rare-earth-doped crystal through electrical pulse signals to change the absorption band structure of the rare-earth ions. Coupled with the optical signal into the optical resonant cavity via the optical waveguide array, the optical signal is confined within the optical waveguide array and interacts with the rare-earth ions within the optical resonant cavity. This excites the population of the rare-earth ions to the upper optical energy level, thereby storing the optical signal and reducing the storage efficiency loss caused by spatial mode mismatch in the optical resonant cavity.

[0038] Figure 1 This is a block diagram of a quantum storage device based on an optical resonant cavity according to an embodiment of the present invention. Figure 2 This is a perspective view of a rare earth-doped crystal 5 according to an embodiment of the present invention.

[0039] An embodiment of the present invention provides a quantum storage device based on an optical resonant cavity, such as... Figure 1 and Figure 2As shown, the system includes a light generation module, an electrical pulse generation module, and a storage module. The light generation module is configured to emit pump light and an optical signal. The electrical pulse generation module is configured to generate an electrical pulse signal corresponding to the optical signal according to a preset storage method. The storage module includes a rare-earth-doped crystal 5, an optical waveguide array 6, and an electrical waveguide array. The storage module is configured to form an optical absorption band on the rare-earth-doped crystal 5 using pump light according to a preset storage method, and store the optical signal according to the optical absorption band. A first reflective film 51 is disposed on the first surface of the rare-earth-doped crystal 5, and a second reflective film 52 is disposed on the second surface of the rare-earth-doped crystal 5. The first reflective film 51 and the second reflective film 52 constitute an optical resonant cavity. The second surface is configured to extend along a plane perpendicular to the direction of emission of the pump light and the optical signal, and the first surface and the second surface form a preset angle to change the resonant frequency of the optical resonant cavity. The optical waveguide array 6 is disposed inside the third surface of the rare-earth-doped crystal 5. An electrical waveguide array is disposed on the third surface and electrically connected to the electrical pulse generation module. The electrical waveguide array modulates the rare earth ions in the rare earth-doped crystal 5 through electrical pulse signals to change the absorption band structure of the rare earth ions. Meanwhile, the optical signal is coupled into the optical resonant cavity through the optical waveguide array 6 and interacts with the rare earth ions within the optical resonant cavity, exciting the population of the rare earth ions to the upper optical energy level, thereby storing the optical signal.

[0040] According to embodiments of the present invention, such as Figure 2 The diagram shows only four optical waveguides in the optical waveguide array 6, but the actual number is much greater than four. The optical waveguide array 6 is inscribed 5 μm below the third surface of the rare-earth-doped crystal 5, ensuring the uniformity of the first reflective film 51 deposited on the first surface of the rare-earth-doped crystal 5 and the second reflective film 52 deposited on the second surface of the rare-earth-doped crystal 5.

[0041] According to an embodiment of the present invention, the rare earth ions doped in the rare earth-doped crystal 5 need to have suitable optical and spin transition energy level structures, including Er 3+ Yb 3+ Eu 3+ Tm 3+ For example, trivalent europium ions (Eu) are preferred. 3+ ,That 7 F0- 5 The wavelength corresponding to the D0 transition frequency is 580nm.

[0042] According to an embodiment of the present invention, the rare earth-doped crystal 5 is purified using an isotope at a concentration of 0.07%. 151 Eu 3+ Doped yttrium silicate crystals, such as Figure 2As shown, the length of side AC is 4.9 mm, the width of side AB is 5 mm, and the height (AE) of rare-earth-doped crystal 5 is 4 mm. The angle between the first and second surfaces is approximately 10 arcseconds. The first surface is the front surface of rare-earth-doped crystal 5, which is the light incident surface, i.e., the plane containing side CD. The second surface is the rear surface of rare-earth-doped crystal 5, which is the plane containing side AB. By changing the cavity length of the optical resonant cavity, the resonant frequency of the optical resonant cavity is changed. The first reflective film 51 deposited on the first surface is a partial reflective film with a reflectivity R1 of 60%. The second reflective film 52 deposited on the second surface is a total reflective film with a reflectivity R2 of 99.4%. Using femtosecond laser processing, at a distance from the third surface (the upper surface of rare-earth-doped crystal 5), Figure 2 In the plane ABCD, at intervals of 7μm to 30μm, a pair of 23μm high and 23μm spaced grooves are machined every 100μm (the center-to-center spacing of each optical waveguide) along the direction of side length AC, totaling 50 pairs to form an optical waveguide array 6. The waveguide cavity constructed in this way has a cavity linewidth of approximately 2GHz, and is purified with an isotope concentration of 0.07%. 151 Eu 3+ The doped yttrium silicate crystal has a non-uniform broadening of approximately 1.3 GHz, which is covered by the cavity linewidth.

[0043] According to an embodiment of the present invention, the light generation module emits pump light and an optical signal, and the electrical pulse generation module generates an electrical pulse signal corresponding to the optical signal according to a preset storage method. The storage module includes a rare-earth-doped crystal 5, an optical waveguide array 6, and an electrical waveguide array. The storage module is configured to form an optical absorption band on the rare-earth-doped crystal 5 using pump light according to the preset storage method, thereby changing the population distribution of the ground state energy level of rare-earth ions (the distribution of the number of electrons occupying each energy level in the rare-earth ions when the population distribution of the ground state energy level is the lowest energy state), and storing the optical signal according to the optical absorption band. A first reflective film 51 is provided on the first surface of the rare-earth-doped crystal 5, and a second reflective film 52 is provided on the second surface of the rare-earth-doped crystal 5. The first reflective film 51 and the second reflective film 52 constitute an optical resonant cavity. The second surface is configured to extend along a plane perpendicular to the direction of emission of the pump light and the optical signal. The first surface and the second surface form a preset angle. By reducing the length of the optical absorption band, the effective absorption depth of the optical absorption band is reduced, the resonant frequency of the optical resonant cavity is changed, and the efficiency of quantum storage is improved. An optical waveguide array 6 is disposed inside the third surface of the rare-earth-doped crystal 5. An electrical waveguide array is disposed on the third surface and electrically connected to the electrical pulse generation module. The electrical waveguide array modulates the rare-earth ions in the rare-earth-doped crystal through electrical pulse signals to change the absorption band structure of the rare-earth ions. By coupling the optical signal into the optical resonant cavity through the optical waveguide array 6 with almost no increase in the transmission loss caused by the optical waveguide, the optical signal can be confined within the waveguide range and interact with the rare-earth ions within the optical resonant cavity. This causes the optical signal to resonate with the rare-earth ion ensemble, exciting the population of the rare-earth ion ensemble to the upper optical energy level, thereby storing the optical signal and reducing or eliminating the storage efficiency loss caused by spatial mode mismatch in the optical resonant cavity.

[0044] According to an embodiment of the present invention, the length difference between the optical waveguide at the longest distance between the first and second surfaces and the optical waveguide at the shortest distance between the first and second surfaces is greater than the operating wavelength of the rare-earth-doped crystal, which can be expressed by the following formula (1):

[0045] 2nΔL>λ(1;

[0046] Where n represents the refractive index of the rare earth-doped crystal 5, ΔL represents the length difference between the optical waveguide at the longest distance between the first and second surfaces and the optical waveguide at the shortest distance between the first and second surfaces, and λ represents the operating wavelength of the rare earth-doped crystal 5.

[0047] According to an embodiment of the present invention, at any frequency, a certain optical waveguide in the optical waveguide array 6 can be found whose length satisfies the cavity resonance condition of the following formula (2):

[0048] 2nL=kλ(2;

[0049] Where L represents the length of a single optical waveguide, and k is any integer.

[0050] According to an embodiment of the present invention, the transmittance of the first reflective film 51 needs to satisfy the following formula (3) to achieve impedance matching between the optical signal and the optical resonant cavity, which is expressed as:

[0051] 1-R1=e -2d (3);

[0052] Wherein, R1 represents the transmittance of the first reflective film 51, and d represents the single-pass optical depth. The single-pass optical depth represents the optical depth of light propagating from the first surface to the second surface. The single-pass optical depth includes the effective absorption depth of the rare earth doped crystal 5 and the transmission loss of the optical signal in the optical waveguide array 6.

[0053] According to embodiments of the present invention, the preset storage method should support high-fidelity, on-demand, and integrable quantum bit storage. Examples include electrically controlled atomic frequency combing, spin-wave atomic frequency combing, and noiseless photon echoing.

[0054] According to embodiments of the present invention, in the case of an electrically controlled atomic frequency comb with a preset storage mode, the optical absorption band is the absorption band of a frequency comb structure, and the electrical pulse signal is a pulsed electric field signal. In the case of an atomic frequency comb with a preset storage mode of spin wave, the optical absorption band is the absorption band of a frequency comb structure, and the electrical pulse signal is a radio frequency magnetic field signal. In the case of a noise-free photon echo with a preset storage mode, the optical absorption band is an isolated absorption band, and the electrical pulse signal is a radio frequency magnetic field signal.

[0055] According to an embodiment of the present invention, in a rare-earth-doped crystal system, the atomic frequency comb (AFC) protocol has high multi-mode bandwidth capability and high storage fidelity, and the quantum storage process is realized by preparing periodic frequency absorption bands.

[0056] According to an embodiment of the present invention, when the preset storage method is atomic frequency comb, the effective absorption depth of the optical absorption band is significantly reduced due to the shortened length of the optical absorption band. The optical signal is coupled into the optical resonant cavity through the optical waveguide array 6, confining the optical mode within the optical waveguide and reducing efficiency loss caused by spatial mode mismatch. The resulting atomic frequency comb photon echo propagates in a reverse propagation mode, theoretically achieving an efficiency limit of 100%. Especially when rare-earth ions have weak absorption of the optical signal, the optical resonant cavity, constructed through the first reflective film 51 and the second reflective film 52, avoids losses caused by the optical signal passing through various medium interfaces. The quantum storage device of the present invention is a resonant cavity-enhanced quantum storage device. By utilizing the impedance matching between the optical signal and the optical resonant cavity, the storage module can completely absorb and store the optical signal even at a low effective absorption depth, thus improving the efficiency of quantum storage.

[0057] According to an embodiment of the present invention, the electrical waveguide array includes a plurality of electrical waveguides, which are respectively arranged adjacent to each optical waveguide in the optical waveguide array 6, so as to apply an electrical pulse signal to rare earth ions located in the optical waveguide.

[0058] According to an embodiment of the present invention, each electrical waveguide may be composed of two parallel metal conduction bands, fabricated on the third surface of a rare-earth-doped crystal 5 by ultraviolet lithography and electron beam evaporation. The two parallel metal conduction bands are respectively disposed on both sides of each optical waveguide to apply an electrical pulse signal to the rare-earth ions located in the optical waveguide. The electrical pulse signal is a local electric field signal capable of covering a single optical waveguide. Multiple electrical waveguides modulate the rare-earth ions in the rare-earth-doped crystal 5 through electrical pulse signals, thereby changing the absorption band structure of the rare-earth ions.

[0059] According to an embodiment of the present invention, the light generating module includes a laser 1, a first modulator 2, and a second modulator 3. The laser 1 is configured to emit a laser beam. The first modulator 2 is configured to modulate the laser beam to obtain pump light. The second modulator 3 is configured to modulate the laser beam to obtain an optical signal.

[0060] According to an embodiment of the present invention, laser 1 is configured to emit a laser beam with a beam width of less than 10 kHz.

[0061] According to an embodiment of the present invention, the first modulator 2 can be an acousto-optic modulator with a center frequency of 200MHz. The second modulator 3 can be an acousto-optic modulator with a center frequency of 200MHz.

[0062] According to an embodiment of the present invention, the first modulator 2 can modulate multiple pump lights required for a specific optical absorption band according to the laser, and output the pump light pulse sequence (the pump light pulse sequence includes a first pump pulse 21, a second pump pulse 22 and a third pump pulse 23, which are described in detail below) to the storage module in sequence. The second modulator 3 can modulate the optical signal to be stored according to the laser and output the optical signal to the waveguide cavity-based storage module.

[0063] According to an embodiment of the present invention, the quantum storage device further includes a beam shaper 4. The beam shaper 4 is disposed between the light generation module and the storage module, and the beam shaper 4 is configured to change the polarization direction of the pump light and the optical signal.

[0064] According to an embodiment of the present invention, the beam shaper 4 includes a half-wave plate and a polarization beam splitter crystal. The half-wave plate and the polarization beam splitter crystal can adjust the polarization direction of the pump light and optical signal emitted by the light generation module to H-polarization.

[0065] According to an embodiment of the present invention, the rare earth-doped crystal 5 is purified using an isotope at a concentration of 0.07%. 151 Eu 3+ In the case of doped yttrium silicate crystals, optical waveguide array 6 only confines the H polarization state, while 151 Eu 3+ Ions exhibit the strongest H-polarization absorption when the pump light and optical signal are incident along the direction extending AC, further improving the efficiency of quantum storage.

[0066] According to an embodiment of the present invention, the quantum storage device further includes a temperature control module 7, which is configured to provide a low-temperature operating environment for the storage module, so that rare earth ions remain in a coherent state.

[0067] According to embodiments of the present invention, the low-temperature operating environment is below 5K, for example, approximately 3K. This low-temperature operating environment enables rare-earth ions to exhibit longer quantum coherence lifetimes for optical and spin transitions.

[0068] According to an embodiment of the present invention, the quantum storage device further includes a first-direction moving stage 8 and a second-direction moving stage 9. The first-direction moving stage 8 is configured to drive the storage module to move in the height direction, such that the pump light and the optical signal are coupled into the optical waveguide array 6. The second-direction moving stage 9 is disposed on the first-direction moving stage 8, and the second-direction moving stage 9 is configured to drive the storage module to move in a direction perpendicular to the height direction and parallel to the second surface, such that the pump light and the optical signal are coupled into the optical waveguides in the optical waveguide array 6 that satisfy their respective impedance matching.

[0069] According to embodiments of the present invention, such as Figure 2As shown, the second directional moving stage 9 is configured to drive the storage module to move in a direction perpendicular to the height direction and parallel to the second surface, that is, to move in the direction extending along the side length AB. The total displacement of the second directional moving stage 9 is greater than the total width of the optical waveguide array.

[0070] According to an embodiment of the present invention, the first direction moving stage 8 and the second direction moving stage 9 can be made of copper, which has good thermal conductivity in low-temperature working environments.

[0071] The quantum storage device provided by the embodiments of the present invention does not require consideration of matching of the spatial mode of the optical field, avoids the loss caused by the optical signal passing through various medium interfaces, and can be connected to optical fibers. It has advantages such as large-scale integration, high efficiency and ease of implementation.

[0072] According to an embodiment of the present invention, before quantum storage, the light generation module emits continuous light, and the storage module is driven to move by the first direction moving stage 8 and the second direction moving stage 9, so that the pump light and optical signal emitted by the light generation module are coupled into the optical waveguide array 6 and satisfy the resonance of their respective rare earth ion transition frequencies.

[0073] According to an embodiment of the present invention, when performing quantum storage, the preset storage method uses the effective absorption depth as an adjustable parameter to achieve impedance matching conditions. When the preset storage method is an atomic frequency comb, the effective absorption depth can be adjusted by changing the fineness of the comb manufacturing.

[0074] Figure 3 This is a flowchart of a quantum storage method based on an optical resonant cavity according to an embodiment of the present invention. Figure 4 This is a storage time sequence diagram according to an embodiment of the present invention, in the case of a preset storage method of atomic frequency comb.

[0075] According to embodiments of the present invention, such as Figure 3 As shown, a quantum storage method based on an optical resonant cavity is provided, which is applied to the aforementioned quantum storage device based on an optical resonant cavity. The quantum storage method based on an optical resonant cavity includes the following steps S1 to S3.

[0076] Step S1: Use the light generation module to generate pump light.

[0077] Step S2: Use pump light to form an optical absorption band on the optical waveguide array 6 of the rare earth doped crystal 5.

[0078] According to an embodiment of the present invention, when the preset storage method is an atomic frequency comb, such as Figure 4As shown, the light generation module generates a first pump pulse 21 for hole burning and a second pump pulse 22 for increasing the accumulated population. The first pump pulse 21 and the second pump pulse 22 initialize the optical absorption band on the rare-earth-doped crystal 5. Spectral hole burning refers to using a light pulse with a certain frequency bandwidth that resonates with the rare-earth ions in the rare-earth-doped crystal 5 to cause the population of the rare-earth ions in that frequency range to transition from the ground state to an excited state. After a lifetime much longer than the excited state energy level, the population in the excited state energy level will spontaneously radiate, returning to multiple different ground state energy levels caused by nuclear spin hyperfine splitting according to the transition branching ratio. After repeatedly (e.g., hundreds of times) injecting this light pulse, the population of rare-earth ions in that frequency range will be cleared, forming a "hole." After "hole burning," within a time much shorter than the lifetime of the ground state hyperfine energy level, the incident light pulse at that frequency will completely pass through the crystal and will not be absorbed. Both the first pump pulse 21 for generating the hole and the second pump pulse 22 for accumulating the population utilize the spectral hole-burning process. The difference lies in that the first pump pulse 21 generates the hole by burning the frequency bandwidth of the photons used during storage, while the second pump pulse 22 burns the hole at other frequency positions calculated from the energy level structure, thereby accumulating the population within the frequency bandwidth of the photons used during storage to form an optical absorption band.

[0079] According to an embodiment of the present invention, the light generation module regenerates the third pump pulse 23 for comb formation, forming an atomic frequency comb on the rare earth doped crystal 5.

[0080] Step S3: Generate an optical signal using the light generation module, and store the optical signal in the optical resonant cavity of the storage module based on the optical absorption band.

[0081] According to an embodiment of the present invention, based on the optical absorption band, the optical signal 24 to be stored generated by the light generation module is stored in the optical resonant cavity of the storage module, and the optical signal in the optical resonant cavity is read after a preset time to obtain the stored optical signal 25.

[0082] According to an embodiment of the present invention, the quantum storage method based on an optical resonant cavity may further include step 4.

[0083] Step S4: Using the electrical pulse generation module and the optical generation module, generate electrical pulse signals and optical pulse signals corresponding to the optical signals respectively according to the preset storage method.

[0084] According to an embodiment of the present invention, step 4 can be omitted when the preset storage method is an atomic frequency comb. When the preset storage method is an electrically controlled atomic frequency comb or a spin wave atomic frequency comb, the quantum storage method based on an optical resonant cavity may include step 4.

[0085] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of the invention is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. A quantum storage device based on an optical resonant cavity, characterized in that, include: The light generation module is configured to emit pump light and optical signals; An electrical pulse generation module is configured to generate an electrical pulse signal corresponding to the optical signal according to a preset storage method. Storage module, including: A rare-earth-doped crystal, wherein the storage module is configured to form an optical absorption band on the rare-earth-doped crystal using the pump light according to the preset storage method, and to store the optical signal according to the optical absorption band. A first reflective film is disposed on a first surface of the rare-earth-doped crystal, the first reflective film being a partial reflective film, and a second reflective film is disposed on a second surface of the rare-earth-doped crystal, the second reflective film being a total reflective film. The first reflective film and the second reflective film constitute an optical resonant cavity. The second surface is configured to extend along a plane perpendicular to the direction of emission of the pump light and the optical signal. The first surface and the second surface form a preset angle to change the resonant frequency of the optical resonant cavity. An optical waveguide array is inscribed beneath the third surface of the rare-earth-doped crystal; and An electrical waveguide array is disposed on the third surface and electrically connected to the electrical pulse generation module. The electrical waveguide array modulates the rare earth ions of the rare earth doped crystal through the electrical pulse signal to change the absorption band structure of the rare earth ions. The transmittance of the first reflective film is the sum of the effective absorption depth of the rare-earth-doped crystal and the transmission loss of the optical signal in the optical waveguide array, so as to achieve impedance matching between the optical signal and the optical resonant cavity. The optical signal is coupled into the optical resonant cavity through the optical waveguide array and resonates with the rare earth ion ensemble in the optical resonant cavity, thereby exciting the population of the rare earth ions to the optical upper energy level and storing the optical signal.

2. The quantum storage device according to claim 1, characterized in that, The length difference between the optical waveguide at the longest distance between the first surface and the second surface and the optical waveguide at the shortest distance between the first surface and the second surface is greater than the operating wavelength of the rare earth-doped crystal.

3. The quantum storage device according to claim 1, characterized in that, When the preset storage method is an electrically controlled atomic frequency comb, the optical absorption band is the absorption band of the frequency comb structure, and the electrical pulse signal is a pulsed electric field signal; In the case where the preset storage method is the atomic frequency comb method of spin wave, the optical absorption band is the absorption band of the frequency comb structure, and the electrical pulse signal is a radio frequency magnetic field signal; When the preset storage method is noiseless photon echo mode, the optical absorption band is an isolated absorption band, and the electrical pulse signal is a radio frequency magnetic field signal.

4. The quantum storage device according to claim 2, characterized in that, The electrical waveguide array includes: Multiple electrical waveguides are respectively arranged adjacent to each optical waveguide in the optical waveguide array to apply the electrical pulse signal to the rare earth ions located in the optical waveguides.

5. The quantum storage device according to claim 1, characterized in that, The light generation module includes: A laser is configured to emit laser light. A first modulator is configured to modulate the laser to obtain the pump light; A second modulator is configured to modulate the laser to obtain the optical signal.

6. The quantum storage device according to claim 5, characterized in that, Also includes: A beam shaper is disposed between the light generation module and the storage module, and the beam shaper is configured to change the polarization direction of the pump light and the optical signal.

7. The quantum storage device according to any one of claims 1-6, characterized in that, Also includes: A first-direction moving stage is configured to drive the storage module to move in the height direction, such that the pump light and the optical signal are coupled into the optical waveguide array; A second directional moving stage is disposed on the first directional moving stage. The second directional moving stage is configured to drive the storage module to move in a direction perpendicular to the height direction and parallel to the second surface, such that the pump light and the optical signal are respectively coupled into the optical waveguide array and satisfy their respective impedance matching.

8. A quantum storage method based on an optical resonant cavity, characterized in that, Applied to any one of claims 1-7, the quantum storage method comprises: Pump light is generated using a light generation module; The pump light is used to form an optical absorption band on an optical waveguide array of rare-earth-doped crystals; An optical signal is generated using the light generation module, and the optical signal is stored in the optical resonant cavity of the storage module based on the optical absorption band.

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