阅读说明：本技术 一种积分球量子自旋压缩态冷原子微波钟装置和方法 (Integrating sphere quantum spin compression state cold atom microwave clock device and method ) 是由 王秀梅 陈景标 何进 王亮 刘亚轩 高连山 李春来 胡国庆 于 2021-09-06 设计创作，主要内容包括：本发明公开了一种积分球量子自旋压缩态冷原子微波钟装置和方法,涉及冷原子频标技术领域,本发明装置由内向外包括中心部分,中心部分为冷原子物理部分,外部为所需的光电部分和微波部分,其中冷原子物理由内到外包括冷原子团、光晶格、微波腔、真空系统和平凸光学谐振腔；所需的光电部分包括冷却光、再抽运光和抽运光、囚禁光、腔频探测光、滤光片、腔频探测器；本发明方法首次原创性地提出积分球量子自旋压缩态冷原子微波钟的实现方案,交叉融合了自旋压缩态技术、积分球冷原子钟技术和光晶格囚禁技术,突破传统方案中标准量子噪声极限对频率稳定度限制的技术瓶颈和解决传统方案相干时间短的问题,显著提高积分球冷原子钟的频率稳定度。(The invention discloses an integrating sphere quantum spin compression state cold atom microwave clock device and a method, and relates to the technical field of cold atom frequency standard, the device comprises a central part from inside to outside, the central part is a cold atom physical part, and the outside is a needed photoelectric part and a microwave part, wherein the cold atom physical part comprises a cold atom group, a light crystal lattice, a microwave cavity, a vacuum system and a plano-convex optical resonant cavity from inside to outside; the needed photoelectric part comprises cooling light, re-pumping light and pumping light, trapping light, cavity frequency detection light, an optical filter and a cavity frequency detector; the method originally provides an implementation scheme of the integrating sphere quantum spin compression state cold atom microwave clock for the first time, alternately fuses a spin compression state technology, an integrating sphere cold atom clock technology and a photo-lattice imprisoning technology, breaks through the technical bottleneck of limiting the frequency stability by a standard quantum noise limit in the traditional scheme, solves the problem of short coherence time in the traditional scheme, and obviously improves the frequency stability of the integrating sphere cold atom clock.)

1. An integrating sphere quantum spin compression state cold atom microwave clock device is characterized in that: the integrating sphere quantum spin compression state cold atom microwave clock device comprises a central part from inside to outside, wherein the central part is a cold atom physical part, the outside is a needed photoelectric part and a needed microwave part, and the cold atom physical part comprises a cold atom group, a light crystal lattice, a microwave cavity, a vacuum system and a plano-convex optical resonant cavity from inside to outside; the required photoelectric part comprises cooling light, re-pumping light, trapping light, cavity frequency detection light, an optical filter, a cavity frequency detector, a 0-degree reflector, clock signal detection light, a 45-degree reflector and a photoelectric detector; the microwave part comprises a clock signal, a servo circuit, a servo signal, a local oscillator, a microwave link, a GHz signal and an output signal.

2. The integrating-sphere quantum spin compression-state cold-atom microwave clock device according to claim 1, wherein: in the physical part, the cold atomic group is used as a core research object, the microwave cavity simultaneously carries out diffuse reflection laser cooling and provides a microwave field to interact with the cold atoms, the plano-convex optical resonant cavity forms a photo lattice to imprison the cold atoms for a long time, diffusion and downward free falling motion are avoided, and the vacuum system provides a high-vacuum storage environment for the cold atoms and avoids collision and dissipation effects.

3. The integrating-sphere quantum spin compression-state cold-atom microwave clock device according to claim 1, wherein: in the optical part, three light beams of cooling light, re-pumping light and pumping light are injected into the microwave cavity at a certain divergence angle to form a diffuse-reflection isotropic optical field.

4. The integrating-sphere quantum spin compression-state cold-atom microwave clock device according to claim 1, wherein: in the microwave part, a clock signal is used as a signal required when the whole clock is locked in a closed loop mode, the clock signal is mainly obtained through interaction of cold atoms and a microwave separation oscillation field and is reflected on the light intensity of the absorbed clock signal detection light, the clock signal is processed by the servo circuit to form an error signal of a zero crossing point, the error signal is further formed into a servo signal through a PID algorithm, the local oscillator mainly provides a radio frequency signal and outputs two paths, one path is multiplied by frequency through a microwave link to form a GHz signal to enter a physical part, the other path is used as an output signal, and the performance characteristic of the closed loop locking of the whole clock is represented.

5. The integrating-sphere quantum spin compression-state cold-atom microwave clock device according to claim 4, wherein: in the microwave part, a microwave link receives a radio frequency signal of a local oscillator, the radio frequency signal is multiplied into a GHz signal which is in resonance with an atomic ground state energy level, the GHz signal is injected into a microwave cavity through a microwave cable, a microwave field is formed in the microwave cavity to interact with cold atoms, the output signal is used as the output signal of the local oscillator, namely the whole clock, and is compared with a standard signal, so that the frequency stability characteristic of the output signal is obtained.

6. An integrating sphere quantum spin compression state cold atom microwave clock method is characterized by comprising the following steps:

step 1: a diffuse reflection laser cooling stage;

step 2: a state preparation stage;

step 3: preparing a spin coherent state phase;

step 4: preparing a spin compression state stage;

step 5: a 90-degree spinning phase;

step 6: a quantum state free evolution stage;

step 7: a spin-encoding entry population phase;

step 8: a detection stage;

step 9: a full closed loop locking phase.

7. The method of claim 6, wherein the method comprises: in the Step1 diffuse reflection laser cooling stage, in the diffuse reflection laser cooling time, atoms are cooled to the upper energy level of the ground state by utilizing an isotropic optical field formed by cooling light through multiple times of diffuse reflection in a microwave cavity, and in the cooling process, pumping light is used for keeping the cold atoms at the energy level all the time; in the Step2 state preparation stage, in the later state preparation time, pumping light uniformly prepares atoms of an upper energy level of a ground state to a lower energy level of the ground state, and preparation is made for quantum spin compression state preparation and separation of an oscillating field interaction process.

8. The method of claim 6, wherein the method comprises: in the Step3 spin coherent state preparation stage, after cold atoms are all in the lower energy level of the ground state, a plano-convex optical resonant cavity is used for forming a photo lattice to load and trap the cold atoms, and then in the first microwave pulse interaction, the cold atoms and microwaves perform the first pi/2 interaction to form a spin coherent state; the Step4 is used for preparing a spin compression state, and the spin compression state is prepared within the preparation time of the spin compression state on the basis of the spin coherent state; in the Step5, in the 90-degree spinning stage, after a spinning compression state is prepared within the interaction time of the second microwave pulse, the spinning is rotated by 90 degrees, the population compression is converted into phase compression, and the free evolution process begins at this time.

9. The method of claim 6, wherein the method comprises: in the Step6 quantum state free evolution stage, a certain phase is accumulated in a self-spinning state in free evolution time; and the Step7 spin codes in a state population stage, and in the third microwave pulse interaction time, the interaction codes the spin information of atoms in the population difference between the two internal states, so that the detection is convenient.

10. The method of claim 6, wherein the method comprises: in the Step8 detection stage, after the interaction interference process of all cold atoms and microwaves is completed, in the detection time, the generated cold atom interference signal containing the frequency deviation of the local oscillator is finally obtained by clock signal detection through an absorption detection method; in the Step9 closed-loop locking stage, the clock signal is processed by the servo circuit to generate an error signal representing the frequency variation of the local oscillator, the error signal is further processed to form a servo signal, the servo signal acts on the local oscillator to compensate the variation of the output frequency of the local oscillator, and finally the output frequency of the local oscillator is locked to the transition frequency between the atomic ground state energy levels.

Technical Field

The invention relates to the technical field of cold atom frequency standard, in particular to an integrating sphere quantum spin compression state cold atom microwave clock device and method.

Background

The cold atom frequency standard mainly utilizes the interaction of a separation oscillation field between cold atoms and microwaves to generate a frequency discrimination curve, so that a local oscillator outputs a frequency signal with high stability and high accuracy, wherein the cold atom of an integrating sphere is a novel miniaturized cold atomic clock, not only has excellent performance advantages of high stability, high accuracy, low drift rate and the like, but also has quite high engineering values of small volume, light weight, low power consumption and the like, based on the advantages, the cold atom frequency standard not only can be used as a ground watch clock, but also can increase the microwave interrogation time by about half order of magnitude under the space microgravity environment, so that the performance of the cold atomic clock of the integrating sphere can be further improved under the microgravity environment, a high-precision time signal is provided for a next generation satellite navigation system, and the cold atom frequency standard fundamentally determines the navigation, the frequency discrimination curve and the frequency of the future navigation positioning system in China, The precision of positioning and time service is related to the service performance of the whole system, namely the function of the whole system is indispensable, the development requirement is self-evident, the performance index of the system is further improved, and the system is of great significance to a satellite navigation system, in addition, the integrating sphere cold atomic clock is also used for space engineering such as future deep space exploration, earth-moon space time-frequency system and the like in China, high-precision time signals are also provided, the future space exploration capability in China is determined, and the improvement of the performance of the integrating sphere cold atomic clock is of great significance to the aerospace industry in China in a comprehensive manner;

at present, in the face of the urgent high-precision performance and the satellite-borne engineering requirements of the above major projects on the integrating sphere cold atomic clock, the development trend of the integrating sphere cold atomic clock can be summarized into two aspects: on one hand, the precision index is continuously improved by adopting a new principle and a new method; on the other hand, the engineering characteristics are compressed by a new technology to realize a microminiature engineering prototype, the high-precision index performance of the microminiature engineering prototype is taken as an important scientific problem at present, particularly, the frequency stability is taken as the core precision characteristic, the basic service and the space detection level holding capability of the important engineering are determined, however, the integrating sphere cold atomic clock is mainly limited by the standard quantum noise limit of the frequency discrimination curve generated by the conventional atomic spin coherent state at present, and the technical bottleneck that the frequency stability is difficult to be continuously improved exists, so that the integrating sphere cold atomic clock cannot meet the wider and deeper development and application requirements of the important engineering in the future, the clear application scene of the integrating sphere cold atomic clock is faced at the blank stage in the aspect of the quantum technology research for improving the frequency stability, therefore, a new scheme and a new technology need to be developed through the research modes such as cross fusion and the like are urgently needed, the technical bottleneck of the method is broken through, the development blank is filled, and the application of the method is promoted; therefore, an integrating sphere quantum spin compression state cold atom microwave clock device and method are provided.

Disclosure of Invention

The invention mainly aims to provide an integrating sphere quantum spin compression state cold atomic microwave clock device and method, aims to break through the standard quantum noise limit of the traditional atomic spin coherent state, solves the problems that the frequency stability is difficult to continuously improve and the like in the prior art, and provides technical reserve for further developing an ultra-high-precision integrating sphere cold atomic clock.

In order to achieve the purpose, the invention adopts the technical scheme that: an integrating sphere quantum spin compression state cold atom microwave clock device comprises a central part from inside to outside, wherein the central part is a cold atom physical part, and the outside is a needed photoelectric part and a microwave part, wherein the cold atom physical part comprises a cold atom group, a light crystal lattice, a microwave cavity, a vacuum system and a plano-convex optical resonant cavity from inside to outside; the required photoelectric part comprises cooling light, re-pumping light, trapping light, cavity frequency detection light, an optical filter, a cavity frequency detector, a 0-degree reflector, clock signal detection light, a 45-degree reflector and a photoelectric detector; the microwave part comprises a clock signal, a servo circuit, a servo signal, a local oscillator, a microwave link, a GHz signal and an output signal.

Preferably, in the physical part, the cold atomic group is used as a core research object, the microwave cavity simultaneously performs diffuse reflection laser cooling and provides a microwave field to interact with the cold atoms, the plano-convex optical resonant cavity forms a photo lattice to trap the cold atoms for a long time, diffusion and downward free falling motion are avoided, and the vacuum system provides a high vacuum storage environment for the cold atoms, so that collision dissipation is avoided.

Preferably, in the optical part, three light beams of cooling light, re-pumping light and pumping light are injected into the microwave cavity at a certain divergence angle to form a diffuse-reflected isotropic light field, wherein the cooling light can perform laser cooling on the upper energy level of the ground state of the cold atoms, the re-pumping light can pump the atoms at the lower energy level of the ground state to the upper energy level of the ground state so as to be cooled, and the pumping light pumps the cold atoms at the upper energy level of the ground state to the lower energy level of the ground state so as to achieve the effect of state preparation; trapping light can be injected into the plano-convex optical resonant cavity in the physical part to form a photo lattice, so that cold atomic groups are trapped; cavity frequency probe light can be injected into the plano-convex optical resonant cavity to perform quantum nondestructive measurement on cold atoms, so that a quantum spin compression state is prepared; the filter can block trapped light passing through the optical resonant cavity from entering the cavity frequency detector, so that the influence of the trapped light on the cavity frequency detection light is avoided; the cavity frequency detector is used as a detection device of cavity frequency detection light and is mainly used for identifying the influence of cold atoms as a light cavity medium on the resonant frequency of the light cavity; the 0-degree reflector is mainly used for reflecting clock signal detection light to perform bidirectional detection on cold atoms, so that the heating effect of the detection light on the cold atoms is avoided; the clock signal detection light is mainly based on an absorption detection method, and the number or the density of cold atoms is judged by detecting the light intensity change of the clock signal detection light; the 45-degree reflecting mirror is used for reflecting the clock signal detection light, and the clock signal detection light can be vertically injected into the upper microwave cavity; the photoelectric detector can receive the transmitted clock signal detection light after the interaction with the cold atoms, and the light intensity of the transmitted clock signal detection light is subtracted from the background of the light intensity of the clock signal detection light to obtain the light intensity of the absorbed clock signal detection light.

Preferably, in the microwave part, a clock signal is used as a signal necessary for the closed-loop locking of the whole clock, is mainly obtained through the interaction of cold atoms and a microwave separation oscillation field and is reflected on the light intensity of the absorbed clock signal detection light, the servo circuit processes the clock signal to form an error signal of a zero crossing point, the error signal is further formed into a servo signal through a PID algorithm, the local oscillator mainly provides a radio frequency signal and outputs two paths, one path is multiplied by a frequency through a microwave link to form a GHz signal to enter the physical part, and the other path is used as an output signal to represent the performance characteristic of the closed-loop locking of the whole clock.

Preferably, in the microwave part, the microwave link receives a radio frequency signal of the local oscillator, multiplies the frequency of the radio frequency signal into a GHz signal which resonates with an atomic ground state energy level, the GHz signal is injected into the microwave cavity through the microwave cable, a microwave field is further formed in the microwave cavity to interact with cold atoms, the output signal is used as an output signal of the local oscillator, that is, an entire clock, and is compared with a standard signal, so that the frequency stability characteristic of the output signal is obtained.

An integrating sphere quantum spin compression state cold atom microwave clock method comprises the following steps:

step 1: a diffuse reflection laser cooling stage;

step 2: a state preparation stage;

step 3: preparing a spin coherent state phase;

step 4: preparing a spin compression state stage;

step 5: a 90-degree spinning phase;

step 6: a quantum state free evolution stage;

step 7: a spin-encoding entry population phase;

step 8: a detection stage;

step 9: a full closed loop locking phase.

Preferably, in the Step1 diffuse reflection laser cooling stage, in the diffuse reflection laser cooling time, the atoms are cooled to the upper energy level of the ground state by using the isotropic optical field formed by the cooling light through multiple times of diffuse reflection in the microwave cavity, and the re-pumping light is kept at the energy level by using the cold atoms in the cooling process; in the Step2 state preparation stage, in the later state preparation time, pumping light uniformly prepares atoms of an upper energy level of a ground state to a lower energy level of the ground state, and preparation is made for quantum spin compression state preparation and separation of an oscillating field interaction process.

Preferably, in the Step3, in the Step of preparing the spin coherent state, after the cold atoms are all at the lower energy level of the ground state, the plano-convex optical resonant cavity is used for forming a photo lattice to load and trap the cold atoms, and then in the first microwave pulse interaction, the cold atoms and the microwaves perform the first pi/2 interaction to form the spin coherent state; the Step4 is used for preparing a spin compression state, and the spin compression state is prepared within the preparation time of the spin compression state on the basis of the spin coherent state; in the Step5, in the 90-degree spinning stage, after a spinning compression state is prepared within the interaction time of the second microwave pulse, the spinning is rotated by 90 degrees, the population compression is converted into phase compression, and the free evolution process begins at this time.

Preferably, in the Step6 quantum state free evolution stage, a certain phase is accumulated by a spin state in a free evolution time; and the Step7 spin codes in a state population stage, and in the third microwave pulse interaction time, the interaction codes the spin information of atoms in the population difference between the two internal states, so that the detection is convenient.

Preferably, in the Step8 detection stage, after the interaction interference process of all cold atoms and microwaves is completed, in the detection time, the generated cold atom interference signal containing the frequency deviation of the local oscillator is finally obtained by clock signal detection by an absorption detection method; in the Step9 closed-loop locking stage, the clock signal is processed by the servo circuit to generate an error signal representing the frequency variation of the local oscillator, the error signal is further processed to form a servo signal, the servo signal acts on the local oscillator to compensate the variation of the output frequency of the local oscillator, and finally the output frequency of the local oscillator is locked to the transition frequency between the atomic ground state energy levels.

The invention has the following beneficial effects:

firstly, the method originally provides an implementation scheme of an integrating sphere quantum spin compression state cold atom microwave clock for the first time, and a spin compression state technology, an integrating sphere cold atom clock technology and a photo-lattice trapping technology are alternately fused, so that the technical bottleneck that the frequency stability is limited by a standard quantum noise limit in the traditional scheme can be broken through, the problem that the coherence time of the traditional scheme is short is solved, and the frequency stability of the integrating sphere cold atom clock is remarkably improved.

The integrating sphere quantum spin compression state cold atom microwave clock device and the method can repeatedly trap cold atoms through the optical lattices in the periodic time sequence operation process, realize the repeated spin compression state preparation and the separation oscillation field action of the cold atoms and microwaves, and further generate clock signals to lock the output frequency of a local oscillator.

The integrating sphere quantum spin compression state cold atom microwave clock device and the method not only can break through the standard quantum noise limit, but also solve the problems of short free evolution time, low frequency discrimination curve signal-to-noise ratio and the like in the prior art, and the device has the advantages of simple structure, easy realization, low material and processing cost, reasonable method and easy operation.

Drawings

FIG. 1 is a schematic structural diagram of an integrating sphere quantum spin compression state cold atom microwave clock device;

FIG. 2 is a schematic diagram of the operation timing sequence of an integrating sphere quantum spin compression state cold atom microwave clock;

FIG. 3 is a flow chart of the integrating sphere quantum spin compression state cold atom microwave clock method.

In the figure: 1. a cold radical; 2. a photonic lattice; 3. cooling light, re-pumping light and pumping light; 4. a microwave cavity; 5. a vacuum system; 6. a plano-convex optical resonant cavity; 7. trapping light; 8. cavity frequency probe light; 9. an optical filter; 10. a cavity frequency detector; 11. a 0 ° mirror; 12. detecting light by a clock signal; 13. a 45 ° mirror; 14. a photodetector; 15. a clock signal; 16. a servo circuit; 17. a servo signal; 18. a local oscillator; 19. a microwave link; 20. a GHz signal; 21. outputting the signal; 22. the central axis of the microwave cavity.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "both ends", "one end", "the other end", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "connected," and the like are to be construed broadly, such as "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The first embodiment is as follows:

please refer to fig. 1: an integrating sphere quantum spin compression state cold atom microwave clock device, which comprises a cold atom physical schematic diagram in a central frame from inside to outside, a required photoelectric part and a required microwave part from outside, wherein the cold atom physical diagram comprises from inside to outside: the device comprises a cold atomic group 1, a light crystal lattice 2, a microwave cavity 4, a vacuum system 5 and a plano-convex optical resonant cavity 6; the required photovoltaic portions include: cooling light, re-pumping light, pumping light 3, trapping light 7, cavity frequency detection light 8, an optical filter 9, a cavity frequency detector 10, a 0-degree reflector 11, clock signal detection light 12, a 45-degree reflector 13 and a photoelectric detector 14; the microwave part comprises: clock signal 15, servo circuit 16, servo signal 17, local oscillator 18, microwave link 19, GHz signal 20, output signal 21.

In the physical part, the cold radical 1 is the core development object; the microwave cavity 2 can simultaneously perform diffuse reflection laser cooling and provide microwave fields for interaction; the plano-convex optical resonant cavity 6 can form a photo lattice 2 to trap cold atoms for a long time, so that diffusion and downward free falling body movement are avoided; the vacuum system 5 provides a high vacuum storage environment for cold atoms, and the central axis of the microwave cavity is used as a reference line of the whole physical part;

in the optical part, each light beam of cooling light, re-pumping light and pumping light 3 is injected into a microwave cavity at a certain divergence angle to form a diffuse-reflected isotropic light field, wherein the cooling light can carry out laser cooling on the upper energy level of the ground state of the cold atoms, the re-pumping light can pump the atoms of the lower energy level of the ground state to the upper energy level of the ground state so as to be cooled, and the pumping light pumps the cold atoms in the upper energy level of the ground state to the lower energy level of the ground state so as to achieve the effect of state preparation; the confining light 7 is injected into the plano-convex optical resonant cavity 6 in the physical part to form a photo lattice, so that cold atoms are confined; the cavity frequency probe light 8 is also injected into the plano-convex optical resonant cavity to perform nondestructive measurement on cold atoms, so that a spin compression state is realized; the optical filter 9 can block the trapped light passing through the optical resonant cavity from entering the cavity frequency detector 10, so as to avoid the influence of the trapped light on the cavity frequency detection light 8; the cavity frequency detector 10 is used as a detection device in the cavity frequency detection light 8 and is mainly used for identifying the influence of cold atoms as a light cavity medium on the resonant frequency of the light cavity; the 0-degree reflector 11 is mainly used for reflecting the clock signal detection light 12 to perform bidirectional detection on cold atoms, so that the heating effect of the detection light on the cold atoms is avoided; the clock signal detection light 12 judges the number or density of cold atoms mainly by an absorption detection method and by detecting the light intensity change; the 45-degree reflector 13 is used for reflecting the clock signal detection light 12, and can be vertically injected into the upper microwave cavity 4; the photoelectric detector 14 can receive the transmitted clock signal detection light 12 after the interaction with the cold atoms, and the light intensity of the transmitted clock signal detection light 12 is subtracted from the light intensity background of the clock signal detection light 12 to obtain the light intensity of the absorbed clock signal detection light 12;

in the microwave part, a clock signal 15 is used as a signal necessary for the closed-loop locking of the whole clock, is mainly obtained through the interaction of cold atoms and a microwave separation oscillation field and is reflected on the light intensity of the absorbed clock signal detection light 12; the servo circuit 16 will process the clock signal 15 to form an error signal that can zero-cross the point, and the error signal will be further processed by the PID algorithm to form a servo signal 17; the local oscillator 18 mainly provides a radio frequency signal and outputs two paths, wherein one path is frequency-doubled into a GHz signal 20 through a microwave link 19 and enters a physical part, and the other path is used as an output signal 21 to represent the performance characteristic of closed-loop locking of the whole clock; the microwave link 19 receives the radio frequency signal of the local oscillator 18, and frequency-multiplies the radio frequency signal into a GHz signal 20 which resonates with the atomic ground state energy level; the GHz signal 20 is injected into the microwave cavity 4 through the microwave cable, and a microwave field is formed in the microwave cavity 4 to interact with the cold atoms; the output signal 21, which is the output signal of the local oscillator 18, i.e. the whole clock, needs to be compared with the standard signal, so as to obtain the performance characteristics of the output signal, such as frequency stability, accuracy and drift rate.

Example two:

as shown in fig. 2: t is_CFor diffuse reflection of laser cooling time, T_PFor the preparation time of state, τ_p1For the first microwave pulse interaction time, T_SFor the preparation time of the spin-compressed state, τ_p2For the second microwave pulse interaction time, T_FFor free evolution of time, τ_p3For the third microwave pulse interaction time, T_dFor detecting time, T₀Is the running period;

as shown in fig. 3: an integrating sphere quantum spin compression state cold atom microwave clock method is used for the device provided by the embodiment of the invention and is used for controlling the clock to run according to the clock running period T₀The concrete method comprises the following steps:

and (3) a diffuse reflection laser cooling stage: at diffuse reflection laser cooling time T_CIn the microwave cavity, the atoms are cooled to the ground state upper energy level by utilizing the isotropic optical field formed by the cooling light through multiple diffuse reflection in the microwave cavity, and the light can be pumped in the cooling processThe energy level is maintained at all times using cold atoms;

a state preparation stage: preparation time T in the later state_PPumping light to uniformly prepare the interaction process of cold atoms and microwaves;

preparing a spin coherent state stage: when cold atoms are all at the lower energy level of the ground state, a plano-convex optical resonant cavity is used for forming a photo lattice to load and trap the cold atoms, and then tau is interacted with the cold atoms through a first microwave pulse_p1Carrying out first pi/2 interaction between cold atoms and microwaves to form a spin coherent state;

preparing a spin compression state stage: preparation time T in spin-compressed state based on spin coherent state_SIn the first place, the spin-compression state is prepared: the cavity frequency detection light realizes quantum nondestructive measurement through detection cavity frequency change, after the measurement is finished, a spin compression state with high compression coefficient is prepared, the method for generating the spin compression state at present mainly adopts quantum nondestructive measurement, when the method is used for measuring the physical quantity of atoms, the measurement process has no adverse effect on the physical quantity while obtaining the atomic information, and the result of repeated measurement is consistent with the result of first measurement, and the specific process is as follows: encoding information to be measured in an atomic system into an optical variable through transformation of an interaction Hamilton quantity, wherein the information to be measured is kept unchanged in the measurement process, then the information to be measured can be obtained through destructive measurement of the optical variable, the feedback action in the measurement process can be transferred to a conjugate variable to be measured, quantum nondestructive measurement is realized through the process operation, and spin fluctuation can be spin-compressed through continuous nondestructive measurement in the interaction process, namely atoms are collapsed to a spin compression state;

spinning for 90 degrees: at the second microwave pulse interaction time tau_p2After the spin compression state is prepared, the spin needs to be rotated by 90 degrees, the population compression is converted into phase compression, and the free evolution process can be started at the moment;

and (3) a quantum state free evolution stage: at free evolution time T_FInternal, spin states accumulate a certain phaseA bit;

spin-encoding entry population phase: at the third microwave pulse interaction time tau_p3The interaction can encode the spin information of the atom in the population difference between the two internal states for detection;

a detection stage: after the whole cold atom and microwave interaction interference process is completed, at the detection time T_dThe generated cold atom interference signal containing the frequency deviation of the local oscillator is finally obtained by clock signal detection through an absorption detection method;

the whole closed loop locking stage: the clock signal is processed by the servo circuit to generate an error signal which can represent the frequency variation of the local oscillator, the error signal is further processed to form a servo signal, the servo signal acts on the local oscillator to compensate the variation of the output frequency of the local oscillator, and finally the output frequency of the local oscillator is locked to the transition frequency between atomic ground state energy levels.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.