Solid-state quantum storage device based on optical fiber microcavity

Abstract

The invention provides a solid-state quantum storage device based on an optical fiber microcavity, and relates to the technical field of quantum information. The device is characterized in that a light generation unit generates pump light, reference light and signal light; the rare earth ion doped crystal film is arranged in the optical fiber microcavity and stores signal light; the pump light generates a specific absorption band corresponding to the parameters of the pump light on the rare earth ion doped crystal film according to an atomic frequency comb scheme so as to adjust the storage time of the signal light; the adjusting system applies stress to the rare earth ion doped crystal thin film, changes the light absorption frequency based on the piezoelectric spectroscopy effect, enables the center frequency of the light absorption frequency to be consistent with the frequency of the signal light, adjusts the cavity length of the optical fiber microcavity to be the cavity length corresponding to the frequency of the reference light according to the frequency of the reference light, and enables the cavity length of the optical fiber microcavity to be locked. Resonance of signal light in the optical fiber microcavity is achieved, and the influence of vibration on the cavity length of the optical fiber microcavity is isolated. According to the invention, high-efficiency quantum storage of signal light with different frequencies is realized.

Description

Technical Field

[0001] The present invention relates to the field of quantum information technology, and more particularly, to a solid-state quantum storage device based on an optical fiber microcavity. Background Art

[0002] The quantum no-cloning theorem provides a fundamental guarantee for the security of quantum communication. However, this principle also limits the quantum signal from being directly amplified like a classical signal. During optical fiber transmission, photons will experience exponential attenuation loss as the distance increases, which greatly hinders the possibility of directly achieving long-distance quantum communication of more than one hundred kilometers through an optical fiber channel. To overcome this problem, three solutions based on quantum memories are proposed: optical fiber quantum repeaters, mobile quantum memories, and spaceborne free-space quantum communication. The implementation of these solutions all relies on the support of high-performance quantum memories.

[0003] Among many physical systems, rare-earth ion-doped crystals have been widely used in the field of quantum information technology because they exhibit excellent coherence times and energy-level lifetimes at liquid helium temperatures. The broadband characteristics of these crystals provide favorable conditions for multi-mode multiplexing, which is of great significance for improving the communication rate and accelerating the practical process of quantum networks. In addition, as solid-state systems, a major advantage of rare-earth ion-doped crystals is that they can be conveniently processed and integrated using existing mature technologies.

[0004] However, the vast majority of rare-earth ion-doped crystals usually exhibit low optical transition intensities, which means that their ability to absorb photons is relatively weak, resulting in low storage efficiency. Summary of the Invention

[0005] In view of this, the present invention provides a solid-state quantum storage device based on an optical fiber microcavity.

[0006] One aspect of the present invention provides a solid-state quantum storage device based on an optical fiber microcavity, comprising: an optical generation unit and a microcavity storage unit; the optical generation unit is used to generate pump light, reference light and signal light, and transmit the pump light, the reference light and the signal light to the microcavity storage unit; wherein, the signal light carries qubit information to be stored; the microcavity storage unit is used to realize the quantum storage of signal light with different frequencies; the microcavity storage unit includes an optical fiber microcavity, a rare-earth ion-doped crystal film and an adjustment system; the rare-earth ion-doped crystal film is arranged inside the optical fiber microcavity; the rare-earth ion-doped crystal film is used to store the signal light; the pump light generates a specific absorption band corresponding to the parameters of the pump light on the rare-earth ion-doped crystal film according to the atomic frequency comb scheme to adjust the storage time of the signal light; the adjustment system is used to apply stress to the rare-earth ion-doped crystal film, change the light absorption frequency of the rare-earth ion-doped crystal film based on the piezoreflectance spectroscopy effect, and make the central frequency of the light absorption frequency consistent with the frequency of the signal light, and is also used to adjust the cavity length of the optical fiber microcavity to a cavity length corresponding to the frequency of the reference light according to the frequency of the reference light, lock the cavity length of the optical fiber microcavity, so as to realize the resonance of the signal light in the optical fiber microcavity and isolate the influence of vibration on the cavity length of the optical fiber microcavity.

[0007] According to an embodiment of the present invention, the optical fiber microcavity includes an optical fiber concave mirror and a plane mirror; the optical fiber concave mirror and the plane mirror form an open Fabry-Perot cavity.

[0008] According to an embodiment of the present invention, the rare-earth ion-doped crystal film includes an inner surface and an outer surface; the inner surface is the surface facing the optical fiber concave mirror; the outer surface is the surface opposite to the inner surface; the plane mirror is obtained by coating an optical high-reflection film on the outer surface of the rare-earth ion-doped crystal film.

[0009] According to an embodiment of the present invention, the adjustment system includes a cavity length locking system and a spring shock absorption platform; the cavity length locking system is used to adjust the cavity length of the optical fiber microcavity to a cavity length corresponding to the frequency of the reference light according to the frequency of the reference light, lock the cavity length of the optical fiber microcavity, isolate the influence of vibration on the cavity length of the optical fiber microcavity in an active manner, and realize the resonance of the signal light in the optical fiber microcavity; the spring shock absorption platform is used to isolate the influence of vibration on the cavity length of the optical fiber microcavity in a passive manner.

[0010] According to an embodiment of the present invention, the above-mentioned adjustment system further includes a thin film stress adjustment device; the above-mentioned thin film stress adjustment device is arranged on the outer surface or the inner surface of the above-mentioned rare earth ion doped crystal thin film; the above-mentioned thin film stress adjustment device is used to apply stress to the above-mentioned rare earth ion doped crystal thin film, and based on the piezophotoluminescence effect, change the light absorption frequency of the above-mentioned rare earth ion doped crystal thin film, and make the central frequency of the above-mentioned light absorption frequency consistent with the frequency of the above-mentioned signal light.

[0011] According to an embodiment of the present invention, the above-mentioned device further includes a detection unit; the above-mentioned detection unit is used to receive the stored signal light output from the above-mentioned microcavity storage unit, count the cumulative number of the above-mentioned stored signal light within a period of time, and extract the qubit information in the above-mentioned stored signal light.

[0012] According to an embodiment of the present invention, the above-mentioned light generation unit includes a first laser, a second laser, an acousto-optic modulator, a signal light source, and a feedback optimization system; the above-mentioned first laser is used to generate the above-mentioned reference light; the above-mentioned second laser is used to generate the initial laser; the above-mentioned signal light source is used to generate signal light; the above-mentioned acousto-optic modulator is used to modulate the above-mentioned initial laser to obtain the above-mentioned pump light; the above-mentioned feedback optimization system is used to adjust the parameters of the above-mentioned pump light based on the cumulative number of the above-mentioned stored signal light determined by the above-mentioned detection unit within the above-mentioned period of time and based on the principle of atomic frequency comb dephasing.

[0013] According to an embodiment of the present invention, the above-mentioned detection unit includes a chopping device, a filtering device, a projective measurement device, and a single photon counting and time correlation device; the above-mentioned chopping device is used to remove the above-mentioned pump light from the optical signal output from the above-mentioned microcavity storage unit to obtain a detection optical signal; the above-mentioned filtering device is used to filter out the reference light in the above-mentioned detection optical signal to obtain the above-mentioned stored signal light; the above-mentioned projective measurement device is used to extract the qubit information in the above-mentioned stored signal light; the above-mentioned single photon counting and time correlation device is used to perform single photon detection on the signal light after extracting the qubit information and count the cumulative number of the signal light after extracting the qubit information within the above-mentioned period of time.

[0014] According to an embodiment of the present invention, the cavity length of the above-mentioned fiber microcavity is set in the range of 0.1 micrometer to 900 micrometers to increase the cavity resonance linewidth; by increasing the cavity resonance linewidth, the storage bandwidth of the above-mentioned solid-state quantum storage device based on the fiber microcavity is improved to achieve time multi-mode multiplexing.

[0015] According to an embodiment of the present invention, the thickness of the above-mentioned rare earth ion doped crystal thin film is set in the range of 0.1 micrometer to 900 micrometers, so that the stress is evenly distributed on the above-mentioned rare earth ion doped crystal thin film under the action of the above-mentioned thin film stress adjustment device.

[0016] According to an embodiment of the present invention, pump light is used to generate a specific absorption band corresponding to the parameters of the pump light on a rare-earth ion-doped crystal thin film according to the atomic frequency comb scheme, and the storage time of the signal light is adjusted; stress is applied to the rare-earth ion-doped crystal thin film by an adjustment system, and based on the piezoreflectance spectroscopy effect, the light absorption frequency of the rare-earth ion-doped crystal thin film is changed, and the central frequency of the light absorption frequency is made consistent with the frequency of the signal light, thereby improving the absorption efficiency of the signal light in the specific absorption band; according to the frequency of the reference light, the cavity length of the fiber microcavity is adjusted to a cavity length corresponding to the frequency of the reference light, so that the cavity length of the fiber microcavity is locked, to achieve resonance of the signal light in the fiber microcavity and isolate the influence of vibration on the cavity length of the fiber microcavity, thereby making the energy transfer efficiency of the signal light reach a relatively high state and further improving the absorption efficiency of the signal light in the specific absorption band; since the signal light carries quantum bit information to be stored, by improving the absorption efficiency of the signal light in the specific absorption band, the efficiency of quantum storage is improved. Description of the Drawings

[0017] Through the following description of the embodiments of the present invention with reference to the drawings, the above and other objects, features and advantages of the present invention will become clearer. In the drawings:

[0018] Figure 1 The structural block diagram of a solid-state quantum storage device based on a fiber microcavity according to an embodiment of the present invention is shown.

[0019] Figure 2 The structural block diagram of a solid-state quantum storage device based on a fiber microcavity according to another embodiment of the present invention is shown.

[0020] Figure 3 The schematic diagram of the component connection of a solid-state quantum storage device based on a fiber microcavity according to another embodiment of the present invention is shown.

[0021] Figure 4 The timing schematic diagram of the storage process of a solid-state quantum storage device based on a fiber microcavity according to another embodiment of the present invention is shown. Detailed Embodiments

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, it should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In the following detailed description, for the sake of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, obviously, one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0023] The terms used herein are merely for describing specific embodiments and are not intended to limit the present invention. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0024] 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 should be interpreted to have a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0025] In the case of using expressions such as "at least one of A, B, and C, etc.", generally, it should be interpreted according to the meaning commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include, but not be limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0026] In the embodiments of the present invention, in aspects such as the collection, update, analysis, processing, use, transmission, provision, disclosure, storage, etc. of the involved data (for example, including but not limited to user personal information), they all comply with the provisions of relevant laws and regulations, are used for legal purposes, and do not violate public order and good customs. In particular, necessary measures are taken for user personal information to prevent illegal access to user personal information data and to maintain the security of user personal information and network security.

[0027] In the embodiments of the present invention, the authorization or consent of the user is obtained before obtaining or collecting user personal information.

[0028] Most rare-earth-ion-doped crystals usually exhibit low optical transition intensities, which means that their ability to absorb photons is relatively weak, resulting in low storage efficiency. For most practical applications of quantum networks, high-efficiency quantum storage is crucial. To solve this problem, researchers have proposed using an impedance-matched Fabry–Perot cavity to enhance the interaction between light and matter. By implementing the cavity-enhanced atomic frequency comb scheme, a storage efficiency of 100% can be theoretically achieved.

[0029] The currently commonly used scheme is the combination of a Fabry–Perot cavity with a length above millimeter level and a bulk rare-earth-ion-doped crystal. However, these designs have many deficiencies: on the one hand, the large cavity length will limit the resonance linewidth of the cavity, and thus limit the bandwidth of the memory; on the other hand, long cavities are usually accompanied by large insertion losses and poor stability, which further limits the efficiency of the memory. In addition, the design of large cavities also does not meet the actual application requirements of miniaturization and integration.

[0030] An embodiment of the present invention provides a solid-state quantum storage device based on an optical fiber microcavity.

[0031] Figure 1 The structural block diagram of a solid-state quantum storage device based on an optical fiber microcavity according to an embodiment of the present invention is shown.

[0032] As Figure 1 shown, the solid-state quantum storage device based on an optical fiber microcavity includes: an optical generation unit 11 and a microcavity storage unit 12; the optical generation unit 11 is configured to generate pump light, reference light, and signal light, and transmit the pump light, reference light, and signal light to the microcavity storage unit 12; wherein, the signal light carries quantum bit information to be stored; the microcavity storage unit 12 is configured to implement quantum storage of signal lights with different frequencies; the microcavity storage unit 12 includes an optical fiber microcavity 121, a rare-earth ion-doped crystal thin film 122, and an adjustment system 123; the rare-earth ion-doped crystal thin film 122 is disposed inside the optical fiber microcavity 121; the rare-earth ion-doped crystal thin film 122 is configured to store the signal light; the pump light generates a specific absorption band corresponding to the parameters of the pump light on the rare-earth ion-doped crystal thin film 122 according to the atomic frequency comb scheme, and adjusts the storage time of the signal light; the adjustment system 123 is configured to apply stress to the rare-earth ion-doped crystal thin film 122, change the light absorption frequency of the rare-earth ion-doped crystal thin film 122 based on the piezoreflectance spectroscopy effect, and make the central frequency of the light absorption frequency consistent with the frequency of the signal light, and is further configured to adjust the cavity length of the optical fiber microcavity 121 to a cavity length corresponding to the frequency of the reference light according to the frequency of the reference light, lock the cavity length of the optical fiber microcavity 121, so as to implement resonance of the signal light in the optical fiber microcavity 121 and isolate the influence of vibration on the cavity length of the optical fiber microcavity 121.

[0033] In Figure 1 it, the object of action indicated by the dashed arrow means that the adjustment system 123 has an adjustment effect on the optical fiber microcavity 121 and the rare-earth ion-doped crystal thin film 122. For example, the dashed arrow between the adjustment system 123 and the rare-earth ion-doped crystal thin film 122 indicates that the adjustment system 123 applies stress to the rare-earth ion-doped crystal thin film 122, and the dashed arrow between the adjustment system 123 and the optical fiber microcavity 121 indicates that the adjustment system 123 adjusts the cavity length of the optical fiber microcavity 121 and isolates the influence of vibration on the cavity length of the optical fiber microcavity 121.

[0034] According to an embodiment of the present invention, the microcavity storage unit prepares a specific absorption band of a rare-earth ion-doped crystal thin film through pump light according to a specified cavity-enhanced optical quantum storage scheme, adjusts and locks the cavity length of the fiber microcavity by using reference light, changes the optical absorption frequency of the rare-earth ion-doped crystal thin film based on the piezospectroscopy effect, and realizes high-efficiency quantum storage of signal light and tunable-frequency quantum storage. Among them, the specified cavity-enhanced optical quantum storage scheme is preferably the cavity-enhanced atomic frequency comb scheme. The signal light is a single-photon pulse.

[0035] According to an embodiment of the present invention, the adjustment system includes a cavity length locking system and a spring shock-absorbing platform; the cavity length locking system is used to adjust the cavity length of the fiber microcavity to a cavity length corresponding to the frequency of the reference light according to the frequency of the reference light, lock the cavity length of the fiber microcavity, and is used to actively isolate the influence of vibration on the cavity length of the fiber microcavity and realize resonance of the signal light in the fiber microcavity; the spring shock-absorbing platform is used to passively isolate the influence of vibration on the cavity length of the fiber microcavity, and the spring shock-absorbing platform can adaptively adjust the influence of vibration on the cavity length of the fiber microcavity by using the physical properties of the spring.

[0036] According to an embodiment of the present invention, the adjustment system further includes a thin film stress adjustment device; the thin film stress adjustment device is arranged on the outer surface or the inner surface of the rare-earth ion-doped crystal thin film; the thin film stress adjustment device is used to apply stress to the rare-earth ion-doped crystal thin film, change the optical absorption frequency of the rare-earth ion-doped crystal thin film based on the piezospectroscopy effect, and make the central frequency of the optical absorption frequency consistent with the frequency of the signal light.

[0037] The rare-earth ion-doped crystal thin film absorbs the signal light according to the specific absorption band prepared by the pump light and releases the signal light after a specified time. The spring shock-absorbing platform is used to isolate the influence of vibration on the cavity length of the fiber microcavity. The thin film stress adjustment device changes the optical absorption frequency of the rare-earth ion-doped crystal thin film by adjusting the stress applied to the rare-earth ion-doped crystal thin film based on the piezospectroscopy effect. A channel for the light path to pass through is arranged on the thin film stress adjustment device, and the light path can be the light path of the reference light, the pump light, and / or the signal light. The light paths of the reference light, the pump light, and / or the signal light pass through the thin film stress adjustment device. For example, the thin film stress adjustment device is provided with corresponding through holes for the light path. The spring shock-absorbing platform and the cavity length locking system respectively stabilize the cavity length of the open fiber microcavity in passive and active ways. Among them, the spring shock-absorbing platform is preferably a beryllium copper spring, and its spring stiffness still remains good at low temperatures. Among them, the specified time is determined by the specific absorption band prepared by the pump light.

[0038] According to an embodiment of the present invention, pump light generates a specific absorption band corresponding to the parameters of the pump light on a rare-earth ion-doped crystal thin film according to the atomic frequency comb scheme, and adjusts the storage time of the signal light; a stress is applied to the rare-earth ion-doped crystal thin film by an adjustment system, and based on the piezoreflectance spectroscopy effect, the light absorption frequency of the rare-earth ion-doped crystal thin film is changed, and the central frequency of the light absorption frequency is made consistent with the frequency of the signal light, thereby improving the absorption efficiency of the signal light in the specific absorption band; according to the frequency of the reference light, the cavity length of the fiber microcavity is adjusted to a cavity length corresponding to the frequency of the reference light, so that the cavity length of the fiber microcavity is locked, so as to realize the resonance of the signal light in the fiber microcavity and isolate the influence of vibration on the cavity length of the fiber microcavity, thereby enabling the energy transfer efficiency of the signal light to reach a relatively high state, and further improving the absorption efficiency of the signal light in the specific absorption band; since the signal light carries the qubit information to be stored, by improving the absorption efficiency of the signal light in the specific absorption band, the efficiency of quantum storage is improved, and a quantum storage function with high efficiency, multi-mode, easy integration and tunable frequency is realized, which can be widely applied to fields such as quantum communication and quantum computing.

[0039] According to an embodiment of the present invention, the fiber microcavity includes a fiber concave mirror and a plane mirror; the fiber concave mirror and the plane mirror form an open Fabry - Perot cavity, which is used to realize the function of adjustable cavity length and realize high-efficiency quantum storage of signal light based on the principle of cavity-enhanced light-matter interaction.

[0040] According to an embodiment of the present invention, the fiber microcavity is an open Fabry - Perot cavity composed of a microscopic fiber concave mirror and a macroscopic plane mirror, which is used to enhance the interaction between the signal light and the rare-earth ion-doped crystal thin film.

[0041] According to an embodiment of the present invention, the rare-earth ion-doped crystal thin film includes an inner surface and an outer surface; the inner surface is the side facing the fiber concave mirror; the outer surface is the side opposite to the inner surface; the plane mirror is obtained by coating an optical high-reflection film on the outer surface of the rare-earth ion-doped crystal thin film, which is used to further improve the quantum storage efficiency of the signal light based on the principle of reducing the loss in the cavity. Specifically, the plane mirror of the fiber microcavity can be formed by coating a distributed Bragg reflector-type high-reflection film on the side of the rare-earth ion-doped crystal thin film away from the fiber concave mirror. The fiber concave mirror is obtained by using a carbon dioxide laser etching technique to make a fiber concave on the fiber end face, and then using an ion beam sputtering coating technique to coat an optical high-reflection film on the fiber concave.

[0042] According to an embodiment of the present invention, by coating an optical high-reflection film on the outer surface of the rare-earth ion-doped crystal thin film, the insertion loss of the rare-earth ion-doped crystal thin film can be reduced, which is beneficial to realizing high-efficiency quantum storage of the signal light.

[0043] According to an embodiment of the present invention, a multimode optical fiber with a diameter of 125 μm can be used for the optical fiber, and the concave surface of the optical fiber can be prepared by carbon dioxide laser ablation. The radius of curvature of the prepared concave surface of the optical fiber is 800 μm, and the effective cavity mirror diameter is 45 μm. Both the plane mirror and the concave mirror of the optical fiber are coated with an anti-reflection film of the distributed Bragg reflector type, and the reflectivity to 606 nm is 99% for both, and the reflectivity to 580 nm is different. Among them, the reflectivity of the plane mirror to 580 nm is 96.5%, and the reflectivity of the concave mirror of the optical fiber to 580 nm is 99.9%. The finesse of the optical fiber microcavity cavity is 180.

[0044] According to an embodiment of the present invention, the cavity length of the optical fiber microcavity is in the order of hundreds of micrometers or shorter. For example, the range of the cavity length of the optical fiber microcavity is set to 0.1 micrometer to 900 micrometers, so as to achieve a larger cavity resonance linewidth, and further improve the storage bandwidth of the solid-state quantum storage device based on the optical fiber microcavity, and realize time multimode multiplexing. Due to the large cavity resonance linewidth, using time-division multiplexing technology, time multimode storage can be supported; the volume of the optical fiber microcavity is one ten-thousandth cubic millimeter or smaller, which can support integrated applications. For the concave mirror of the optical fiber microcavity, using the optical fiber array technology, the rare-earth ion-doped crystal film is divided into multiple small storage units according to the optical fiber array, and an integrated quantum memory can be realized. The thickness of the rare-earth ion-doped crystal film is in the order of hundreds of micrometers or thinner. For example, the range of the thickness of the rare-earth ion-doped crystal film is set to 0.1 micrometer to 900 micrometers, to achieve the stress uniformity and broadband adjustment characteristics of the light absorption frequency of the rare-earth ion-doped crystal film under the action of the thin film stress adjustment device, generating high pressure under low stress, and through the thin film stress adjustment device, its light absorption frequency can be widely regulated. Under the action of the thin film stress adjustment device, the frequency adjustment range of the rare-earth ion-doped crystal film exceeds the inhomogeneous broadening of the rare-earth ion-doped crystal itself.

[0045] For example, when the cavity length of the optical fiber microcavity is 300 μm and the resonance linewidth of the cavity is 3 GHz, time multimode storage is realized using time-division multiplexing technology. The volume of the optical fiber microcavity is 4×10 -5 mm 3 。

[0046] According to an embodiment of the present invention, the cavity length locking system includes a cavity length adjustment device, a photodetector, a servo feedback device, and a broadband amplifier; the photodetector is used to detect the reflected light signal of the reference light coupled into the optical fiber microcavity and input the reflected light signal as an error signal into the servo feedback device; the servo feedback device is used to output an adjustment signal according to the error signal and send the adjustment signal to the broadband amplifier; the broadband amplifier is used to amplify the adjustment signal and send the amplified adjustment signal to the cavity length adjustment device; the cavity length adjustment device is fixedly connected to the pigtail of the optical fiber end face; the cavity length adjustment device is used to adjust the distance between the optical fiber end face and the plane mirror according to the amplified adjustment signal.

[0047] According to an embodiment of the present invention, the cavity length locking system adjusts and locks the cavity length of the fiber microcavity according to the reference light by using a specified active feedback technique. In order to make the signal light resonate in the fiber microcavity, it is necessary to adjust the cavity length of the fiber microcavity. Therefore, the reference light is incident first, and by adjusting the cavity length of the fiber microcavity, the signal light resonates in the fiber microcavity, and the cavity length of the fiber microcavity at this time is locked. On this basis, when the frequency of the signal light changes, by changing the frequency of the reference light, the adaptive adjustment of the cavity length of the fiber microcavity is realized, so as to realize the resonance of signal lights of different frequencies in the fiber microcavity. Further, the high-efficiency quantum storage of signal lights of different frequencies is realized. The rare-earth ion-doped crystal thin film changes its absorption frequency of the signal light through the film stress adjustment device, and the fiber microcavity changes its resonance frequency of the signal light through the cavity length locking system, jointly realizing the high-efficiency quantum storage of signal lights of different frequencies. Among them, the specified active feedback technique is preferably the Pound-Drever-Hall locking technique, and the side-of-fringe locking technique can also be used.

[0048] According to an embodiment of the present invention, the cavity length adjustment device is preferably a stacked shear piezoelectric ceramic, and the fiber tail part of the fiber concave mirror in the fiber microcavity is fixed to the cavity length adjustment device with glue. In the side-of-fringe locking technique, the reference light detected by the photodetector is coupled into the reflected light signal of the fiber microcavity and input to the servo feedback device as an error signal. The output signal after being processed by the servo feedback device is amplified by a broadband amplifier and then output to the cavity length adjustment device.

[0049] According to an embodiment of the present invention, the film stress adjustment device is preferably a shear piezoelectric ceramic with a hole in the center. The side of the rare-earth ion-doped crystal thin film coated with the high-reflection film is fixed to the film stress adjustment device with glue. The film stress adjustment device can adjust the shear stress applied to the rare-earth ion-doped crystal thin film by applying different voltages. According to the principle of the piezospectroscopic effect, a stress of 10 N can generate an optical absorption frequency shift of 5 GHz on this rare-earth ion-doped crystal thin film. The optical absorption center of the rare-earth ion-doped crystal thin film at a temperature of 3.5 K corresponds to the frequency of the signal light after the action of the film stress adjustment device.

[0050] According to an embodiment of the present invention, the fiber microcavity adopts a plano-concave cavity structure, which can achieve high-efficiency mode matching of the fiber microcavity to the signal light, facilitating the absorption of the signal light by the microcavity storage unit. For the fiber microcavity combined with the rare-earth doped crystal film, according to the specific absorption band prepared by the pump light, high-efficiency impedance matching of the fiber microcavity to the signal light can be achieved. Combining with the high-efficiency mode matching is conducive to achieving complete absorption of the signal light by the microcavity storage unit. The rare-earth ion doped crystal film is obtained from a bulk rare-earth ion doped crystal by means of physical polishing and thinning, and the excellent optical coherence properties of the bulk rare-earth ion doped crystal at low temperature can be retained.

[0051] According to an embodiment of the present invention, the rare-earth ion doped crystal film can be a europium-doped yttrium silicate film, and isotope purification with a concentration of 0.07% is used 151 Eu 3+ as an example of the doped yttrium silicate crystal with an absorption coefficient of 4.6 per centimeter length. This europium-doped yttrium silicate crystal can be thinned and polished physically, and the preferred instrument is a precision lapping and polishing machine. The size of the prepared rare-earth doped crystal film is 4×5×0.2 mm 3 , and the surface roughness is 0.2 nm. The microcavity storage unit can be placed in a cryostat without a liquid helium compression mechanism to make the rare-earth doped crystal film in a low-temperature environment of about 3.5 K, ensuring its long optical coherence lifetime and spin energy level lifetime.

[0052] According to an embodiment of the present invention, the solid-state quantum storage device based on the fiber microcavity further includes a detection unit; the detection unit is used to receive the stored signal light output from the microcavity storage unit, and count the cumulative number of the stored signal light within a period of time, and extract the qubit information in the stored signal light.

[0053] According to an embodiment of the present invention, the light generation unit includes a first laser, a second laser, an acousto-optic modulator, a signal light source, and a feedback optimization system; the first laser is used to generate reference light; the second laser is used to generate initial laser light; the signal light source is used to generate signal light; the acousto-optic modulator is used to modulate the initial laser light to obtain pump light; the feedback optimization system is used to adjust the parameters of the pump light based on the cumulative number of the stored signal light determined by the detection unit within a period of time according to the atomic frequency comb dephasing principle, so as to further improve the quantum storage efficiency of the signal light in a way of reducing the atomic frequency comb dephasing.

[0054] According to an embodiment of the present invention, the solid-state quantum storage device based on an optical fiber microcavity includes a debugging stage and a storage stage. In the debugging stage, the solid-state quantum storage device based on an optical fiber microcavity further includes a signal light acousto-optic modulator; the signal light acousto-optic modulator is configured to modulate an initial laser to obtain a signal light. Wherein, a first laser generates a reference light with a linewidth within a specified range and a tunable frequency, and outputs the reference light to a microcavity storage unit for adjusting and locking the length of the optical fiber microcavity; a second laser generates a laser with a linewidth within a specified range and a frequency within a specified range; the acousto-optic modulator modulates and generates a pump light required by the microcavity storage unit according to the laser generated by the second laser, and outputs the pump light to the microcavity storage unit; the signal light acousto-optic modulator modulates and generates a signal light carrying qubits to be stored according to the laser generated by the second laser, and outputs the signal light to the microcavity storage unit. By applying the signal light generated by the signal light acousto-optic modulator, parameters of the solid-state quantum storage device based on an optical fiber microcavity under different signal lights are obtained, for example, parameters of the reference light, parameters of the pump light, the length of the optical fiber microcavity, the voltage of a thin film stress adjusting device, etc. The parameters of the solid-state quantum storage device based on an optical fiber microcavity under different signal lights obtained in the debugging stage are stored, so that in the storage stage, the parameters of the solid-state quantum storage device based on an optical fiber microcavity can be adjusted according to the signal light generated by a signal light source, and the storage of the signal light in the storage stage is realized. Further, according to different signal lights, corresponding parameter values of the solid-state quantum storage device based on an optical fiber microcavity, such as parameters of the reference light, parameters of the pump light, the length of the optical fiber microcavity, the voltage of a thin film stress adjusting device, etc., are realized.

[0055] According to an embodiment of the present invention, the feedback optimization system can select a simulated annealing algorithm controlled by a computer program. The feedback optimization system can be connected to a single-photon counting and time-correlation device under a control detection unit and an arbitrary waveform generator under an acousto-optic modulator.

[0056] According to an embodiment of the present invention, the wavelength difference between the lasers generated by the first laser and the second laser is greater than 5 nanometers, that is, the wavelength difference between the reference light and the initial laser is greater than 5 nanometers. Such a setting is to effectively separate each other through an optical filtering device.

[0057] In the present invention, the linewidth within a specified range can be a linewidth below 10 kHz. The frequency of the second laser within a specified range is related to the optical transition frequency of the selected rare-earth ion-doped crystal thin film; the first laser can select a frequency-doubled semiconductor laser, which outputs a frequency-stabilized laser of 606 nm, with a power of 900 mW and a linewidth of the order of 1 kHz. The laser is locked to a temperature-controlled optical reference cavity by the Pound-Drever-Hall frequency locking technique to overcome the long-term drift caused by temperature changes and enhance the stability of the continuous operation of the system.

[0058] The second laser can be a frequency-doubled semiconductor laser, which outputs frequency-stabilized laser light at 580 nm, with a power of 900 mW and a linewidth on the order of 1 kHz. The frequency of this laser resonates with the optical absorption band of the yttrium orthosilicate crystal doped with europium. The laser is locked to a temperature-controlled optical reference cavity by the Pound-Drever-Hall frequency-locking technique to overcome the long-term drift caused by temperature changes and enhance the stability of the system's continuous operation.

[0059] Both the acousto-optic modulator and the signal light acousto-optic modulator include an arbitrary waveform generator, a radio frequency amplifier, and an acousto-optic modulation optical path. The acousto-optic modulator can be an acousto-optic modulator with a center frequency of 200 MHz; the signal light acousto-optic modulator is an acousto-optic modulator with a center frequency of 200 MHz. Among them, the signal light acousto-optic modulator modulates and generates signal light carrying time-bin qubits, and the optical field frequency of the signal light is the center frequency of 200 MHz.

[0060] According to an embodiment of the present invention, the detection unit includes a chopping device, a filtering device, a projective basis measurement device, and a single-photon counting and time-correlation device; the chopping device is used to remove the pump light from the optical signal output from the microcavity storage unit to obtain a detection optical signal; the filtering device is used to filter out the reference light in the detection optical signal to obtain the stored signal light; the projective basis measurement device is used to extract the qubit information in the stored signal light; the single-photon counting and time-correlation device is used to perform single-photon detection on the signal light after extracting the qubit information and count the cumulative number of the signal light after extracting the qubit information within a period of time.

[0061] According to an embodiment of the present invention, the chopping device can be a mechanical optical shutter switch; the filtering device can be a 580 nm band-pass narrowband filter; the single-photon counting and time-correlation device can be an avalanche silicon-based detector and a time-correlated single-photon counter. A projective basis measurement device can be arranged before the single-photon counting and time-correlation device, and then the bit information of the signal light read after storage is detected by the single-photon counting and time-correlation device.

[0062] According to an embodiment of the present invention, under the detuning of the fiber microcavity, the time-correlated photon statistical histogram of the signal light detected by the single-photon counting and time-correlation device; in the case where the fiber microcavity achieves resonance (not detuned), the time-correlated photon statistical histogram of the stored signal light detected by the single-photon counting and time-correlation device; the ratio of the sum of these two counts is the access efficiency of the signal light. This value will be output to the feedback optimization system in the mode of optimizing the comb-making parameters, and the feedback optimization system adjusts the pulse parameters of the pump light according to this ratio.

[0063] Among them, when the fiber optic microcavity is detuned, the number of prepared signal lights can be used as the statistical value of the photon statistical histogram of the time correlation of the signal lights detected by the detection unit; in the case where the fiber optic microcavity achieves resonance (not detuned), the statistical value of the number of signal lights detected by the detection unit is obtained, and the ratio of the sum of the two counts is calculated. When the access efficiency of the signal light is low, that is, when the ratio of the number of stored signal lights to the number of prepared signal lights is less than a preset value, it is considered that the pulse parameters of the pump light need to be adjusted to improve the access efficiency.

[0064] Since the number of prepared signal lights can be used as the statistical value of the photon statistical histogram of the time correlation of the signal lights detected by the detection unit, it can be considered that the number of prepared signal lights is known and does not need to be detected. Instead, the statistical value of the number of stored signal lights detected by the detection unit can be directly obtained, and the pulse parameters of the pump light can be adjusted according to this statistical value.

[0065] Figure 2 The structural block diagram of a solid-state quantum storage device based on a fiber optic microcavity according to another embodiment of the present invention is shown.

[0066] As Figure 2 shown, taking the solid-state quantum storage device based on a fiber optic microcavity in the debugging stage as an example, the solid-state quantum storage device based on a fiber optic microcavity will be described. The solid-state quantum storage device based on a fiber optic microcavity includes: an optical generation unit 11, a microcavity storage unit 12, and a detection unit 13; the optical generation unit 11 is used to generate the pump light and reference light required by the microcavity storage unit 12, prepare the signal light carrying quantum bits to be stored, and output the pump light, reference light, and signal light to the microcavity storage unit 12.

[0067] The optical generation unit 11 includes a first laser 111, a second laser 112, an acousto-optic modulator 113, a signal light acousto-optic modulator 114, and a feedback optimization system 115. The first laser 111 is used to generate a reference light for locking the cavity length of the fiber optic microcavity with a linewidth within a specified range and a tunable frequency, and output the reference light to the microcavity storage unit 12; the second laser 112 is used to generate a laser with a linewidth within a specified range and a frequency within a specified range; the acousto-optic modulator 113 is used to modulate the pump light required by the microcavity storage unit 12 according to the laser generated by the second laser 112, and output the pump light to the microcavity storage unit 12; the signal light acousto-optic modulator 114 is used to modulate the signal light carrying quantum bits to be stored according to the laser generated by the second laser 112, and output the signal light to the microcavity storage unit 12; the feedback optimization system 115 is used to feedback-optimize the pump light generated by the acousto-optic modulator 113 according to the readout efficiency of the signal light read out after storage detected by the detection unit 13.

[0068] The microcavity storage unit 12 includes: an optical fiber microcavity 121, a rare-earth ion-doped crystal thin film 122, a spring shock-absorbing platform 1231, a cavity length locking system 1232, and a thin film stress adjusting device 1233. The optical fiber microcavity 121 is an open Fabry-Perot cavity composed of a microscopic optical fiber concave mirror and a macroscopic plane mirror, and is used to enhance the interaction between the signal light and the rare-earth ion-doped crystal thin film 122; the rare-earth doped crystal thin film 122 is used to absorb the signal light according to a specific absorption band prepared by the pump light, and release the signal light after a specified time; the spring shock-absorbing platform 1231 is used to isolate the influence of vibration on the cavity length of the optical fiber microcavity 121; the cavity length locking system 1232 is used to adjust and lock the cavity length of the optical fiber microcavity 121 according to the reference light by using a specified feedback technique. The thin film stress adjusting device 1233 is used to change the absorption frequency of the rare-earth ion-doped crystal thin film for the signal light by adjusting the stress applied to the rare-earth ion-doped crystal thin film based on the piezophotoluminescence effect.

[0069] The detection unit 13 includes a chopping device 131, a filtering device 132, and a single-photon counting and time-correlation device 133; the chopping device 131 is used to separate the pump light in the time domain; the filtering device 132 is used to separate the reference light in the frequency domain; the single-photon counting and time-correlation device 133 is used to perform single-photon detection on the signal light read out after storage and complete the time-correlated photon counting statistical analysis.

[0070] When the solid-state quantum storage device based on the optical fiber microcavity is in the storage stage, the main difference from when it is in the debugging stage is that the signal light is output by the signal light source instead of being realized by the signal light acousto-optic modulator 114, which will not be elaborated here.

[0071] In Figure 2Among them, the object of action indicated by the dashed arrow means that the cavity length locking system 1232 has an adjustment effect on the fiber microcavity 121, the thin film stress adjustment device 1233 has an adjustment effect on the rare earth ion doped crystal thin film 122, the spring shock absorption platform 1231 has an adjustment effect on the fiber microcavity 121, the single photon counting and time correlation device 133 has an adjustment effect on the feedback optimization system 115, and the feedback optimization system 115 has an adjustment effect on the acousto-optic modulator 113. Specifically, the dashed arrow between the thin film stress adjustment device 1233 and the rare earth ion doped crystal thin film 122 indicates that the thin film stress adjustment device 1233 applies stress to the rare earth ion doped crystal thin film 122, the dashed arrow between the cavity length locking system 1232 and the fiber microcavity 121 indicates that the cavity length locking system 1232 adjusts the cavity length of the fiber microcavity 121, and the dashed arrow between the spring shock absorption platform 1231 and the fiber microcavity 121 indicates that the spring shock absorption platform 1231 isolates the influence of vibration on the cavity length of the fiber microcavity 121. The single photon counting and time correlation device 133 transmits the result of single photon detection to the feedback optimization system 115, the feedback optimization system 115 determines the parameters of the pump light according to the result of single photon detection, and the acousto-optic modulator 113 generates the corresponding pump light according to the parameters of the pump light.

[0072] Figure 3 Fig. shows a schematic diagram of component connections of a solid-state quantum storage device based on a fiber microcavity according to another embodiment of the present invention.

[0073] As Figure 3As shown, taking the solid-state quantum storage device based on an optical fiber microcavity in the debugging stage as an example, the solid-state quantum storage device based on an optical fiber microcavity will be described. The light emitted by the second laser 112 is modulated by the acousto-optic modulator 113 and the signal-light acousto-optic modulator 114 to generate pump light and signal light. At this time, the signal light is the signal light to be stored. The pump light and the signal light to be stored are first combined by the first optical beam splitter 116, and after passing through a single-mode optical fiber, they are combined with the reference light generated by the first laser 111 again through the 580 nm filter 14. This filter 14 is a signal-light wavelength filter. The single-mode optical fiber has an optical fiber collimating emission head. The reference light generated by the first laser 111 passes through the optical fiber collimating emission head and is reflected by the mirror 15 and then combined with the pump light and the signal light to be stored; the pump light and the signal light to be stored come out from the same single-mode emission head and have the same spatial mode. The pump light, the signal light to be stored, and the reference light are coupled into the optical fiber microcavity 121 through the lens group 16. The lens group 16 can adopt an anastigmatic lens group, and the mode matching efficiency can reach 99.9%. The thin-film stress adjustment device 1233 in the microcavity storage unit 12 applies stress to the rare-earth-ion-doped crystal thin film 122. Based on the piezospectroscopy effect, the light absorption frequency of the rare-earth-ion-doped crystal thin film 122 is changed, and the central frequency of the light absorption frequency is made consistent with the frequency of the signal light to be stored. The signal light to be stored will be fully absorbed by the rare-earth-ion-doped crystal thin film 122. Among them, after a period of time, the stored signal light is released in a way that propagates in the opposite direction to the signal light to be stored. The stored signal light can be extracted by the second optical beam splitter 117, and after passing through the chopping device 131 and the filtering device 132, it is detected by the single-photon counting and time-correlation device 133. In order to extract the stored signal light without loss, the second optical beam splitter 117 can be replaced by a Faraday rotator and an optical polarization beam splitter, and the stored signal light is extracted using the polarization dimension of light.

[0074] The solid-state quantum storage device based on an optical fiber microcavity further includes a chopping device 118 for pump light; the chopping device 118 for pump light is turned on when the pump light is emitted, and the chopping device 131 is turned off to realize the preparation of the absorption band by the pump light and protect the detection unit. When the signal light is emitted, the chopping device 118 for pump light is turned off, and the chopping device 131 is turned on. Because the pump light is relatively strong and the turn-off effect of the acousto-optic modulator 113 is insufficient, there will be leaked pump photons entering the microcavity storage unit and the detection unit. Although the leaked light is extremely weak and invisible to the naked eye, it is still fatal to the detection unit because the detection unit is to detect the signal light of single photons. The second optical beam splitter 117 is used to separate the stored optical signal output from the microcavity storage unit and the signal photons to be stored. The stored signal light and the signal light to be stored are collinear on the optical path, but the directions are opposite. The signal light to be stored goes to the storage unit, and the stored signal light returns from the microcavity storage unit, and can be completely separated by polarization.

[0075] Figure 4 Fig. shows a timing schematic diagram of the storage process of the solid-state quantum storage device based on an optical fiber microcavity according to another embodiment of the present invention.

[0076] As Figure 4 shown, before the storage process, the cavity length locking system locks the cavity length, and the reference light resonates with the optical fiber microcavity; adjusting the frequency of the reference light generated by the first laser will synchronously change the cavity length of the optical fiber microcavity, and find a specific frequency value of the reference light so that the signal light also resonates with the optical fiber microcavity; adjusting the voltage of the thin film stress adjusting device will synchronously change the light absorption frequency of the rare-earth ion-doped crystal thin film, and find a specific voltage value of the thin film stress adjusting device so that the central frequency of the light absorption frequency of the rare-earth ion-doped crystal thin film is consistent with the frequency of the signal light. During the storage process, the pump light modulated by the acousto-optic modulator completes the energy level population initialization and atomic frequency comb preparation by repeatedly using different swept-frequency pulses. The atomic frequency comb preparation pulse is preferably a parallel complex hyperbolic secant swept-frequency pulse. The acousto-optic modulator of the signal light modulates a signal light of a specific time pattern and outputs it to the microcavity storage unit. After a specific time, the microcavity storage unit releases the stored signal light. This specific time is related to the atomic frequency comb preparation parameters. In the comb parameter optimization mode, the feedback optimization system can feedback and optimize the pulse parameters of the atomic frequency comb preparation pulse of the pump light modulated by the acousto-optic modulator according to the cumulative count of the stored signal light detected by the detection unit during a period of storage process.

[0077] The storage efficiency η using the cavity-enhanced atomic frequency comb scheme can be simplified as:

[0078] .

[0079] Where η Mis the mode matching efficiency of the signal light coupled into the fiber microcavity, η deph represents the efficiency loss caused by the dephasing of the atomic frequency comb scheme, ε, and respectively represent the additional loss of the optical field in the round-trip cavity and the effective absorption depth of the rare-earth ion-doped crystal film.

[0080] When the ratio of the absorption of the film to the additional loss of the cavity is higher than 10 and the comb fineness, one of the preparation parameters of the atomic frequency comb, is higher than 5, the expected theoretical storage efficiency exceeds 75%.

[0081] The above describes the embodiments of the present invention. However, these embodiments are for illustrative purposes only and not for limiting the scope of the present invention. Although the embodiments are described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should all fall within the scope of the present invention.

Claims

1. A solid-state quantum storage device based on an optical fiber microcavity, characterized in that The solid-state quantum storage device based on an optical fiber microcavity includes: an optical generation unit and a microcavity storage unit; The optical generation unit is used to generate pump light, reference light, and signal light, and transmit the pump light, the reference light, and the signal light to the microcavity storage unit; wherein, the signal light carries qubit information to be stored; The microcavity storage unit is used to implement the quantum storage of signal light with different frequencies; The microcavity storage unit includes an optical fiber microcavity, a rare-earth ion-doped crystal thin film, and an adjustment system; The rare-earth ion-doped crystal thin film is disposed inside the optical fiber microcavity; the rare-earth ion-doped crystal thin film is used to store the signal light; According to the atomic frequency comb scheme, the pump light generates a specific absorption band corresponding to the parameters of the pump light on the rare-earth ion-doped crystal thin film to adjust the storage time of the signal light; The adjustment system is used to apply stress to the rare-earth ion-doped crystal thin film, change the light absorption frequency of the rare-earth ion-doped crystal thin film based on the piezospectroscopy effect, and make the central frequency of the light absorption frequency consistent with the frequency of the signal light, and is also used to adjust the cavity length of the optical fiber microcavity to a cavity length corresponding to the frequency of the reference light according to the frequency of the reference light, lock the cavity length of the optical fiber microcavity, so as to realize the resonance of the signal light in the optical fiber microcavity and isolate the influence of vibration on the cavity length of the optical fiber microcavity.

2. The solid-state quantum storage device based on an optical fiber microcavity according to claim 1, characterized in that The optical fiber microcavity includes an optical fiber concave mirror and a plane mirror; the optical fiber concave mirror and the plane mirror form an open Fabry-Perot cavity.

3. The solid-state quantum storage device based on an optical fiber microcavity according to claim 2, wherein The rare-earth ion-doped crystal thin film includes an inner surface and an outer surface; the inner surface is the side facing the optical fiber concave mirror; the outer surface is the side opposite to the inner surface; The plane mirror is obtained by coating an optical high-reflection film on the outer surface of the rare-earth ion-doped crystal thin film.

4. The solid-state quantum storage device based on an optical fiber microcavity according to claim 1, wherein The adjustment system includes a cavity length locking system and a spring shock-absorbing platform; The cavity length locking system is used to adjust the cavity length of the optical fiber microcavity to a cavity length corresponding to the frequency of the reference light according to the frequency of the reference light, lock the cavity length of the optical fiber microcavity, and is used to actively isolate the influence of vibration on the cavity length of the optical fiber microcavity and realize the resonance of the signal light in the optical fiber microcavity; The spring shock-absorbing platform is used to passively isolate the influence of vibration on the cavity length of the optical fiber microcavity.

5. The solid-state quantum storage device based on an optical fiber microcavity according to claim 4, wherein The adjustment system further includes a thin film stress adjustment device; The thin film stress adjustment device is disposed on the outer surface or the inner surface of the rare-earth ion-doped crystal thin film; The thin film stress adjustment device is used to apply stress to the rare-earth ion-doped crystal thin film, change the light absorption frequency of the rare-earth ion-doped crystal thin film based on the piezospectroscopy effect, and make the central frequency of the light absorption frequency consistent with the frequency of the signal light.

6. The solid-state quantum storage device based on an optical fiber microcavity according to claim 1, wherein The solid-state quantum storage device based on an optical fiber microcavity further includes a detection unit; The detection unit is used to receive the stored signal light output from the microcavity storage unit, count the cumulative number of the stored signal light within a period of time, and extract the qubit information in the stored signal light.

7. The solid-state quantum storage device based on an optical fiber microcavity according to claim 6, characterized in that, The optical generation unit includes a first laser, a second laser, an acousto-optic modulator, a signal light source, and a feedback optimization system; The first laser is used to generate the reference light; The second laser is used to generate the initial laser; The signal light source is used to generate the signal light; The acousto-optic modulator is used to modulate the initial laser to obtain the pump light; The feedback optimization system is used to adjust the parameters of the pump light based on the atomic frequency comb dephasing principle according to the cumulative number of the stored signal light determined by the detection unit within the period of time.

8. The solid-state quantum storage device based on an optical fiber microcavity according to claim 6, characterized in that, The detection unit includes a chopping device, a filtering device, a projective measurement device, and a single-photon counting and time-correlation device; The chopping device is used to remove the pump light from the optical signal output from the microcavity storage unit to obtain a detection optical signal; The filtering device is used to filter out the reference light from the detection optical signal to obtain the stored signal light; The projective measurement device is used to extract the qubit information from the stored signal light; The single-photon counting and time-correlation device is used to perform single-photon detection on the signal light after extracting the qubit information and count the cumulative number of the signal light after extracting the qubit information within the period of time.

9. The solid-state quantum storage device based on an optical fiber microcavity according to claim 1, characterized in that, The cavity length of the fiber microcavity is set in the range of 0.1 micrometer to 900 micrometers to increase the cavity resonance linewidth; the storage bandwidth of the solid-state quantum storage device based on the fiber microcavity is improved by the increased cavity resonance linewidth to achieve time multimode multiplexing.

10. The solid-state quantum storage device based on an optical fiber microcavity according to claim 5, wherein The thickness of the rare-earth ion-doped crystal film is set in the range of 0.1 micrometer to 900 micrometers, so that the stress is evenly distributed under the action of the film stress adjustment device for the rare-earth ion-doped crystal film.

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