Quantum storage device and quantum storage method based on optical resonant cavity

Abstract

The invention provides a quantum storage device and a quantum storage method based on an optical resonant cavity. The quantum storage device comprises a light generation module which emits pump light and a light signal; the electric pulse generation module generates an electric pulse signal corresponding to the optical signal according to a preset storage mode; the storage module comprises a rare earth doped crystal, a first reflecting film on a first surface of the storage module and a second reflecting film on a second surface of the rare earth doped crystal form an optical resonant cavity, and a preset included angle is formed between the first surface and the second surface so as to change the resonant frequency of the optical resonant cavity; the optical waveguide array is arranged in the third surface of the rare earth doped crystal; the electrical waveguide array is arranged on the third surface and is electrically connected with the electrical pulse generation module, and the absorption band structure of the rare earth ions is changed through electrical pulse signals; an 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, so that the population of the rare earth ions is excited to an optical upper energy level, and the optical signal is stored.

Description

Technical Field

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

[0002] In the field of optical quantum communication, it is difficult to achieve ultra-long distance quantum communication because photons will produce different degrees of loss when transmitted in free space or optical fiber. In order to achieve quantum communication over 100 kilometers, quantum relay is one of the feasible solutions, and quantum memory is one of the core components of quantum repeaters.

[0003] The storage efficiency of quantum memory directly affects the information transmission rate of quantum communication networks. At present, optical signals are directly incident into rare earth-doped crystals and absorbed by rare earth ions, thereby realizing the storage of optical signals. In the process of reading the stored signal, the photon echo generated, that is, 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 solve at least one of the technical problems in the prior art, an embodiment of the present invention provides a quantum storage device and a quantum storage method based on an optical resonant cavity, which can improve the efficiency of quantum storage.

[0005] The present 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; 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 store the optical signal according to the optical absorption band, a first reflection film is arranged on a first surface of the rare earth doped crystal, a second reflection film is arranged on a second surface of the rare earth doped crystal, the first reflection film and the second reflection film constitute an optical resonant cavity, wherein the second surface is configured to be along the direction parallel to the pump light. The first surface extends along a plane perpendicular to the direction in which the optical signal is emitted, and the first surface and the second surface form a preset angle to change the resonance frequency of the optical resonant cavity; an optical waveguide array is arranged inside the third surface of the rare-earth-doped crystal; and an electrical waveguide array is arranged on the third surface and electrically connected to the electrical pulse generating module, and the electrical waveguide array regulates 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; wherein 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, so that the population of the rare earth ions is excited to the optical energy level, thereby storing the optical signal.

[0006] Optionally, a length difference between the optical waveguide at a location where the distance between the first surface and the second surface is the longest and the optical waveguide at a location where the distance between the first surface and the second surface is the shortest is greater than an 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 above-mentioned preset storage mode is an electrically controlled atomic frequency comb mode, the above-mentioned optical absorption band is an absorption band of a frequency comb structure, and the above-mentioned electrical pulse signal is a pulsed electric field signal; when the above-mentioned preset storage mode is a spin wave atomic frequency comb mode, the above-mentioned optical absorption band is an absorption band of a frequency comb structure, and the above-mentioned electrical pulse signal is a radio frequency magnetic field signal; when the above-mentioned preset storage mode is a noise-free photon echo mode, the above-mentioned optical absorption band is an absorption band of an isolated structure, and the above-mentioned electrical pulse signal is a radio frequency magnetic field signal.

[0009] Optionally, the electrical waveguide array comprises: a plurality of electrical waveguides, each disposed adjacent to each optical waveguide in the optical waveguide array, so as to apply the electrical pulse signal to the rare earth ions in the optical waveguide.

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

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

[0012] Optionally, the quantum storage device further comprises: a temperature control module configured to provide a low-temperature working environment for the storage module so that the rare earth ions maintain a coherent state.

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

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

[0015] According to an embodiment of the present invention, a quantum storage device and a quantum storage method based on an optical resonant cavity are provided. The light generating module emits pump light and an optical signal, the 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, and the storage module is configured to form an optical absorption band on the rare earth doped crystal using pump light according to a preset storage method, and store the optical signal according to the optical absorption band. A first reflective film is provided on the first surface of the rare earth doped crystal, and a second reflective film is provided on the second surface of the rare earth doped crystal. 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 in which the pump light and the optical signal are emitted. 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, and the resonance frequency of the optical resonant cavity is changed, the efficiency of quantum storage is improved. The optical waveguide array is arranged inside the third surface of the rare earth doped crystal, the electrical waveguide array is arranged on the third surface and is electrically connected to the electrical pulse generating module, and the electrical waveguide array regulates the rare earth ions of the rare earth doped crystal through electrical pulse signals 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, so that the optical signal can be bound in the optical waveguide array and interact with the rare earth ions in the optical resonant cavity, so that the population of the rare earth ions is excited to the optical energy level, thereby storing the optical signal and reducing the loss of storage efficiency caused by the spatial mode mismatch of the optical resonant cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 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 is a three-dimensional diagram of a rare earth-doped crystal according to an embodiment of the present invention;

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

[0019] Figure 4 It is a storage time series diagram according to an embodiment of the present invention when the preset storage mode is an atomic frequency comb.

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

[0021] 1. Laser;

[0022] 2. A first modulator;

[0023] 3. Second modulator;

[0024] 4. Beam shaper;

[0025] 5. Rare earth doped crystals;

[0026] 51. A first reflective film;

[0027] 52. A second reflective film;

[0028] 6. Optical waveguide array;

[0029] 7. Temperature control module;

[0030] 8. First direction moving platform;

[0031] 9. Second direction mobile platform. DETAILED DESCRIPTION

[0032] Below, 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 present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0033] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

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

[0035] In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0036] At present, light signals are directly incident into rare earth doped crystals and absorbed by rare earth ions, thus realizing the storage of light signals. For example, when using the atomic frequency comb storage protocol, the atomic frequency comb photon echo will be generated during the storage signal reading process, that is, the read signal. Due to phase matching, the atomic frequency comb photon echo is a co-propagation mode, and the propagation direction is the same as the light signal direction. At this time, the atomic frequency comb photon echo is repeatedly absorbed by the rare earth doped crystal, resulting in a theoretical upper limit of storage efficiency of 54%.

[0037] In order to improve the efficiency of quantum storage, according to the inventive concept of one aspect of the present invention, the optical generation module emits pump light and optical signal, 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, an optical waveguide array and an electrical waveguide array, and the storage module is configured to form an optical absorption band on the rare earth doped crystal using pump light according to the preset storage method, and store the optical signal according to the optical absorption band. A first reflection film is provided on the first surface of the rare earth doped crystal, and a second reflection film is provided on the second surface of the rare earth doped crystal. The first reflection film and the second reflection film constitute an optical resonant cavity, and the second surface is configured to extend along a plane perpendicular to the direction in which the pump light and the optical signal are emitted, and the first surface and the second surface form a preset angle, and by reducing the length of the optical absorption band, reducing the effective absorption depth of the optical absorption band, and changing the resonance frequency of the optical resonant cavity, the efficiency of quantum storage is improved. The optical waveguide array is arranged inside the third surface of the rare earth doped crystal, the electrical waveguide array is arranged on the third surface and is electrically connected to the electrical pulse generating module, and the electrical waveguide array regulates the rare earth ions of the rare earth doped crystal through electrical pulse signals 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, so that the optical signal can be bound in the optical waveguide array and interact with the rare earth ions in the optical resonant cavity, so that the population of the rare earth ions is excited to the optical energy level, thereby storing the optical signal and reducing the loss of storage efficiency caused by the spatial mode mismatch of the optical resonant cavity.

[0038] Figure 1 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 is a stereoscopic view of a rare earth-doped crystal 5 according to an embodiment of the present invention.

[0039] According to an embodiment of the present invention, a quantum storage device based on an optical resonant cavity is provided, such as Figure 1 and Figure 2As shown, it includes a light generating module, an electric pulse generating module and a storage module. The light generating module is configured to emit pump light and an optical signal. The electric pulse generating 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 reflection film 51 is provided on the first surface of the rare earth doped crystal 5, and a second reflection film 52 is provided on the second surface of the rare earth doped crystal 5. The first reflection film 51 and the second reflection film 52 constitute an optical resonant cavity. Among them, the second surface is configured to extend along a plane perpendicular to the direction in which the pump light and the optical signal are emitted, 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 arranged inside the third surface of the rare earth doped crystal 5. The electrical waveguide array is arranged on the third surface and is electrically connected to the electrical pulse generating module. The electrical waveguide array regulates the rare earth ions of the rare earth doped crystal 5 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 6, and interacts with the rare earth ions in the optical resonant cavity, so that the population of the rare earth ions is excited to the optical energy level, thereby storing the optical signal.

[0040] According to an embodiment of the present invention, Figure 2 Only four optical waveguides in the optical waveguide array 6 are shown, and the actual number is much more than four. The optical waveguide array 6 is engraved below 5 μm from the third surface of the rare earth doped crystal 5, which ensures the uniformity of coating the first reflective film 51 on the first surface of the rare earth doped crystal 5 and the second reflective film 52 on the second surface of the rare earth doped crystal 5.

[0041] According to the 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 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 by isotope with a concentration of 0.07%. 151 Eu 3+ Doped yttrium silicate crystals, such as Figure 2As shown, the length of the side AC is 4.9 mm, the width of the side AB is 5 mm, and the height (AE) of the rare earth doped crystal 5 is 4 mm. The angle between the first surface and the second surface is about 10 arc seconds. The first surface is the front end surface of the rare earth doped crystal 5, and the first surface is the light incident end surface, that is, the plane where the side CD is located. The second surface is the rear end surface of the rare earth doped crystal 5, and the second surface is the plane where the side AB is located. By changing the cavity length of the optical resonant cavity, the resonance frequency of the optical resonant cavity is changed. The first reflection film 51 coated on the first surface is a partial reflection film, and the reflectivity R1 of the first reflection film 51 is 60%. The second reflection film 52 coated on the second surface is a total reflection film, and the reflectivity R2 of the second reflection film 52 is 99.4%. By using femtosecond laser processing, at a distance from the third surface (the upper surface of the rare earth doped crystal 5, Figure 2 A pair of notches with a height of 23 μm and a spacing of 23 μm are processed every 100 μm (the center spacing of each optical waveguide) along the direction of the side length AC, and a total of 50 pairs form an optical waveguide array 6. The waveguide cavity thus constructed has a cavity line width of about 2 GHz, and the concentration of 0.07% isotope purification 151 Eu 3+ For doped yttrium silicate crystals, the inhomogeneous broadening is about 1.3 GHz, which is covered by the cavity linewidth.

[0043] According to an embodiment of the present invention, the optical generation module emits pump light and optical signal, the electrical pulse generation module generates an electrical pulse signal corresponding to the optical signal according to a preset storage mode, the storage module includes a rare earth doped crystal 5, an optical waveguide array 6 and an electrical waveguide array, and 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 mode, change the distribution of the ground state energy level population of the rare earth ions (the distribution of the number of electrons occupied at each energy level in the rare earth ions when the ground state energy level population distribution is the lowest energy state), and store the optical signal according to the optical absorption band. A first reflection film 51 is provided on the first surface of the rare earth doped crystal 5, and a second reflection film 52 is provided on the second surface of the rare earth doped crystal 5. The first reflection film 51 and the second reflection film 52 constitute an optical resonant cavity, and the second surface is configured to extend along a plane perpendicular to the direction in which the pump light and the optical signal are emitted, and the first surface and the second surface form a preset angle, and by reducing the length of the optical absorption band, the effective absorption depth of the optical absorption band is reduced, and the resonance frequency of the optical resonant cavity is changed, thereby improving the efficiency of quantum storage. The optical waveguide array 6 is arranged inside the third surface of the rare earth doped crystal 5, and the electrical waveguide array is arranged on the third surface and is electrically connected to the electrical pulse generating module. The electrical waveguide array regulates 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. In the case of almost no increase in the loss caused by the optical waveguide transmission, the optical signal is coupled into the optical resonant cavity through the optical waveguide array 6, so that the optical signal can be bound within the waveguide range, and interact with the rare earth ions in the optical resonant cavity, so that the optical signal resonates with the rare earth ion ensemble, and the population of the rare earth ion ensemble is excited to the optical energy level, thereby storing the optical signal, reducing or eliminating the loss of storage efficiency caused by the spatial mode mismatch of the optical resonant cavity.

[0044] According to an embodiment of the present invention, the difference in length 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, which can be expressed by the following formula (1):

[0045] 2nΔL>λ(1);

[0046] Wherein, 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 surface and the second surface and the optical waveguide at the shortest distance between the first surface and the second surface, 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, it is possible to find an optical waveguide in the optical waveguide array 6 whose length satisfies the cavity resonance condition of the following formula (2):

[0048] 2nL=kλ(2);

[0049] Wherein, L represents the length of a single optical waveguide, and k is an arbitrary 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. Formula (3) is expressed as:

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

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

[0053] According to an embodiment of the present invention, the preset storage method should support high-fidelity, on-demand, and integrable quantum bit storage, such as electrically controlled atomic frequency comb method, spin wave atomic frequency comb method, and noise-free photon echo method.

[0054] According to an embodiment of the present invention, when the preset storage mode is an electrically controlled atomic frequency comb mode, the optical absorption band is the absorption band of the frequency comb structure, and the electrical pulse signal is a pulsed electric field signal. When the preset storage mode is a spin wave atomic frequency comb mode, 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 mode is a noiseless photon echo mode, the optical absorption band is the absorption band of the isolated structure, 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, an atomic frequency comb (AFC) protocol has a high multi-mode large bandwidth capability and a high storage fidelity, and a quantum storage process is realized by preparing a periodic frequency absorption band.

[0056] According to the embodiment of the present invention, when the preset storage mode is the atomic frequency comb mode, the effective absorption depth of the optical absorption band is greatly reduced due to the reduction of the length of the optical absorption band, and the optical signal is coupled into the optical resonant cavity through the optical waveguide array 6, so that the optical mode is bound in the optical waveguide, reducing the efficiency loss caused by the spatial mode mismatch. At this time, the propagation direction of the atomic frequency comb photon echo generated is the reverse propagation mode, and the theoretical efficiency limit can reach 100%. Especially in the case where the rare earth ions have weak absorption of the optical signal, the optical resonant cavity is formed by the first reflective film 51 and the second reflective film 52, avoiding the loss 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, which uses the impedance matching of the optical signal and the optical resonant cavity. When the effective absorption depth is low, the storage module can completely absorb the optical signal for storage, thereby 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 disposed adjacent to each optical waveguide in the optical waveguide array 6 to apply electrical pulse signals to the rare earth ions in the optical waveguides.

[0058] According to an embodiment of the present invention, each electrical waveguide can be composed of two parallel metal conduction bands, which are prepared on the third surface of the rare earth doped crystal 5 by ultraviolet lithography and electron beam evaporation, and the two parallel metal conduction bands are respectively arranged on both sides of each optical waveguide to apply an electrical pulse signal to the rare earth ions located in the optical waveguide, and the electrical pulse signal is a local electric field signal that can cover a single optical waveguide. Multiple electrical waveguides regulate the rare earth ions of 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 optical generating module includes a laser 1, a first modulator 2 and a second modulator 3. The laser 1 is configured to emit laser light. The first modulator 2 is configured to modulate the laser light to obtain pump light. The second modulator 3 is configured to modulate the laser light to obtain an optical signal.

[0060] According to an embodiment of the present invention, the laser 1 is configured as a laser having an output beam width of 10 kHz or less.

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

[0062] According to an embodiment of the present invention, the first modulator 2 can modulate a plurality of 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, and the first pump pulse 21, the second pump pulse 22 and the third pump pulse 23 are all described in detail below) to the storage module in sequence, and the second modulator 3 can modulate the optical signal to be stored according to the laser, and output the optical signal to the storage module based on the waveguide cavity.

[0063] According to an embodiment of the present invention, the quantum storage device further comprises a beam shaper 4. The beam shaper 4 is disposed between the light generating module and the storage module, and is configured to change the polarization directions 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 the optical signal emitted by the optical generating module to H polarization.

[0065] According to an embodiment of the present invention, the rare earth doped crystal 5 is purified by using an isotope with a concentration of 0.07%. 151 Eu 3+ In the case of the doped yttrium silicate crystal, the optical waveguide array 6 only binds the H polarization state, while 151 Eu 3+ When the pump light and the optical signal are incident along the direction extending along the side length AC, the ions absorb H polarization most strongly, further improving the efficiency of quantum storage.

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

[0067] According to an embodiment of the present invention, the low-temperature working environment is below 5 K, for example, approximately 3 K. The low-temperature working environment can make the optical transition and spin transition of the rare earth ions have a longer quantum coherence lifetime.

[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 so 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 so that the pump light and the optical signal are respectively coupled into the optical waveguides in the optical waveguide array 6 that satisfy respective impedance matching.

[0069] According to an embodiment of the present invention, Figure 2As shown, 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, that is, to move in a direction extending along the side length AB, and the total displacement of the second direction moving stage 9 is greater than the total width of the optical waveguide array.

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

[0071] The quantum storage device provided according to the embodiment of the present invention does not need to consider the matching of the spatial mode of the light field, avoids the loss of the light signal caused by passing through various medium interfaces, and can be connected to the optical fiber. It has the advantages of large-scale integration, high efficiency and easy implementation.

[0072] According to an embodiment of the present invention, before performing quantum storage, the light generating module emits continuous light, and the first direction moving stage 8 and the second direction moving stage 9 are used to drive the storage module to move, so that the pump light and the optical signal emitted by the light generating module are coupled into the optical waveguides in the optical waveguide array 6 that meet the resonance with the transition frequency of the rare earth ions.

[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.

[0074] Figure 3 is a flow chart of a quantum storage method based on an optical resonant cavity according to an embodiment of the present invention. Figure 4 It is a storage time series diagram according to an embodiment of the present invention when the preset storage mode is an atomic frequency comb.

[0075] According to an embodiment of the present invention, Figure 3 As shown, a quantum storage method based on an optical resonant cavity is provided, which is applied to the above-mentioned 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: Generate pump light using a light generating module.

[0077] Step S2: forming an optical absorption band on the optical waveguide array 6 of the rare-earth doped crystal 5 by using pump light.

[0078] According to an embodiment of the present invention, when the preset storage mode is an atomic frequency comb, such as Figure 4As shown, the optical generation module generates a first pump pulse 21 for hole burning and a second pump pulse 22 for stacking 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 the use of a light pulse with a certain frequency bandwidth that resonates with the rare earth ions in the rare earth doped crystal 5 to transition the population of the ground state energy level of the rare earth ions in the frequency range from the ground state to the excited state. After a lifetime much longer than the excited state energy level, the population of the excited state energy level will spontaneously radiate and return to multiple different ground state energy levels brought by nuclear spin hyperfine splitting according to the transition branching ratio. After repeatedly injecting the light pulse for many times (for example, hundreds of times), the population of the rare earth ions in the frequency range will be emptied, forming a "hole burning". After the "hole burning", within a time much shorter than the lifetime of the ground state hyperfine energy level, the incident light pulse of this frequency will completely pass through the crystal and will not be absorbed. The first pump pulse 21 for generating hole burning and the second pump pulse 22 for stacking population both apply the spectral hole burning process. The difference is that the first pump pulse 21 for generating hole burning burns holes in the frequency bandwidth of photons used for storage, and the second pump pulse 22 for stacking population burns holes in other frequency positions calculated from the energy level structure, thereby stacking population within the frequency bandwidth of photons used for storage to form an optical absorption band.

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

[0080] Step S3: Generate an optical signal using the optical 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 generating 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 generating module and the optical generating module to respectively generate an electrical pulse signal and an optical pulse signal corresponding to the optical signal according to a preset storage method.

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

[0085] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination. The scope of the present invention is defined by the attached claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A quantum storage device based on an optical resonant cavity, characterized in that: include: 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 mode; 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 mode, and store the optical signal according to the optical absorption band, a first reflection film is arranged on a first surface of the rare earth doped crystal, a second reflection film is arranged on a second surface of the rare earth doped crystal, the first reflection film and the second reflection film constitute an optical resonant cavity, wherein the second surface is configured to extend along a plane perpendicular to the direction in which the pump light and the optical signal are emitted, and 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, disposed inside the third surface of the rare-earth-doped crystal; and An electrical waveguide array is disposed on the third surface and is electrically connected to the electrical pulse generating module, wherein the electrical waveguide array regulates 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 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, so that the population of the rare earth ions is excited to an optical energy level, thereby storing the optical signal.

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

3. The quantum storage device according to claim 1, characterized in that 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.

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

5. The quantum storage device according to claim 2, characterized in that The electrical waveguide array comprises: A plurality of electrical waveguides are respectively disposed adjacent to each optical waveguide in the optical waveguide array to apply the electrical pulse signal to the rare earth ions in the optical waveguide.

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

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

8. The quantum storage device according to any one of claims 1 to 7, characterized in that: Also includes: The temperature control module is configured to provide a low-temperature working environment for the storage module so that the rare earth ions maintain a coherent state.

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

10. A quantum storage method based on an optical resonant cavity, characterized in that: Applied to the quantum storage device according to any one of claims 1 to 9, the quantum storage method comprises: generating pump light using a light generating module; Using the pump light to form an optical absorption band on an optical waveguide array of a rare earth-doped crystal; The optical generation module is used to generate an optical signal, and based on the optical absorption band, the optical signal is stored in an optical resonant cavity of a storage module.

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