System and method for determining atom passing time in cold atom microwave clock

Abstract

The invention discloses a system and a method for determining atom passing time in a cold atom microwave clock, and belongs to the technical field of atom frequency standard, and the system comprises a signal control and analysis module, a microwave switch, a microwave source, a microwave cavity and an atomic transition probability detection device. A first control signal, a second control signal and a third control signal are generated, and the relationship between the atomic transition probability and microwave pulses at different moments is analyzed by using the spatial distribution of the magnetic field amplitude of the microwave standing wave field in the microwave cavity and the Labian transition in the atomic microwave clock. According to the invention, the system is small in size, is light in weight, and can effectively inhibit the microwave leakage frequency shift.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of atomic frequency standard, and particularly relates to a system and method for determining the passing time of atoms in a cold atom microwave clock. BACKGROUND

[0002] The cold atom microwave clock is a time frequency measuring instrument, and has wide application in the fields of measurement, time keeping, navigation, finance, high speed communication and the like due to its advantages of high frequency stability, high frequency accuracy and low frequency drift. The microwave cavity of the cold atom microwave clock generally adopts a cylindrical microwave resonator. Any microwave field close to the clock transition frequency leaked out of the cylindrical microwave resonator will interact with the atoms participating in the clock transition, thereby inducing microwave leakage frequency shift. The microwave leakage frequency shift becomes one of the important factors for limiting the frequency accuracy of the cold atom microwave clock.

[0003] At present, there are two methods for inhibiting the microwave leakage frequency shift in the cold atom microwave clock. One method is to calculate the time when the atoms enter and leave the microwave cavity by using the geometric size of the microwave cavity and the physical vacuum system of the clock, and the initial position and initial velocity of the atom cloud, and then to open the microwave when the atoms enter the microwave cavity and to close the microwave when the atoms leave the microwave cavity by using the microwave switch. However, this method cannot well inhibit the microwave leakage frequency shift due to the time calculation error caused by the error of the geometric size and the initial parameters of the atoms. The other method is to set a relatively long cutoff waveguide at the upper and lower ports of the cavity axis of the microwave cavity. The cutoff waveguide can inhibit the leakage of the microwave field in the cavity to the outside of the cavity, thereby inhibiting the microwave leakage frequency shift. This method has the advantage that the time when the atoms enter and leave the microwave cavity does not need to be accurately known. However, the microwave cavity with the relatively long cutoff waveguide makes the volume and weight of the clock system large, which is not conducive to the miniaturization of the clock system. SUMMARY

[0004] To solve the problems in the prior art, the application provides a system and method for determining the passing time of atoms in a cold atom microwave clock.

[0005] In a first aspect, a system for determining the passing time of atoms in a cold atom microwave clock is provided, comprising: a signal control and analysis module, a microwave switch, a microwave source, a microwave cavity, and an atomic transition probability detection device.

[0006] The signal control and analysis module is connected with the microwave source and the microwave switch, and is configured to generate a first control signal and a second control signal.

[0007] The microwave switch is connected with the microwave cavity, and is configured to control the opening time and the closing time of the microwave switch according to the first control signal.

[0008] The microwave source is connected with the microwave switch and is used for generating a microwave signal corresponding to a power according to a second control signal;

[0009] The microwave cavity is connected with the microwave switch and is used for providing a space for atomic transition.

[0010] The atomic transition probability detection device is connected with the signal control and analysis module and is used for detecting the population number of two energy states of the atom in the microwave cavity after the microwave signal is fed into the microwave cavity and calculating the transition probability of the atom.

[0011] The opening time is T1 and the closing time is T2, and τ=T2-T1, where τ is the length of the microwave pulse acting on the atom.

[0012] The power of the microwave signal linearly increases with the increase of the second control signal.

[0013] The power regulation module of the microwave source is a voltage-controlled attenuator.

[0014] The signal control and analysis module is further used for generating a third control signal.

[0015] The microwave switch is further used for controlling the opening time of the microwave switch to be T1+nT0 according to the third control signal, where n is a positive integer, T1 is the initial opening time of the microwave switch, and T0 is a time interval.

[0016] The atomic transition probability detection device is further used for detecting the atomic transition probability P(T1+nT0) signal of the atom after the atom is affected by the microwave pulse in the microwave cavity and sending the P(T1+nT0) signal to the signal control and analysis module, where P is the atomic transition probability calculated by detecting the population number of two energy states of the atom.

[0017] The signal control and analysis module is further used for drawing a curve of the opening time value T1+nT0 and the atomic transition probability value P(T1+nT0) according to the opening time T1+nT0 of the microwave switch and the corresponding atomic transition probability value P(T1+nT0), and obtaining the corresponding time when the atom passes through different positions of the cavity axis of the microwave cavity according to the curve, where the power of the microwave pulse with the length τ is set to p0, the atomic transition probability P(T1+nT0) reaches the maximum value, and the corresponding time value T1+nT0+τ / 2 is the time when the atom passes through the center of the cavity axis of the microwave cavity in the cold atom microwave clock; the power of the microwave pulse with the length τ is set to p1, the atomic transition probability P(T1+nT0) reaches the minimum value, and the corresponding time value T1+nT0+τ / 2 is the time when the atom passes through the center of the cavity axis of the microwave cavity in the cold atom microwave clock.

[0018] In a second aspect, a method for determining the passing time of an atom in a cold atom microwave clock is provided, which comprises:

[0019] The signal control and analysis module generates a first control signal;

[0020] According to the first control signal, the opening time and the closing time of the microwave switch are controlled;

[0021] The signal control and analysis module generates a second control signal;

[0022] The microwave source generates a microwave signal corresponding to the power according to the second control signal;

[0023] When the microwave signal is fed into the microwave cavity, the atomic transition probability detection device detects the population number of the two energy states of the atom in the microwave cavity, and calculates the atomic transition probability.

[0024] A method for determining the passing time of an atom in a cold atom microwave clock, further comprising:

[0025] The signal control and analysis module generates a third control signal;

[0026] According to the third control signal, the microwave switch controls the opening time of the microwave switch to be T1+nT0, wherein n is a positive integer, T1 is the initial opening time of the microwave switch, and T0 is a time interval;

[0027] The atomic transition probability detection device detects the atomic transition probability P(T1+nT0) signal after the atom and the microwave pulse in the microwave cavity act on each other, and sends the P(T1+nT0) signal to the signal control and analysis module, wherein P is the atomic transition probability calculated by detecting the population number of the two energy states of the atom;

[0028] The signal control and analysis module draws a curve of the opening time value T1+nT0 and the atomic transition probability value P(T1+nT0) according to the opening time T1+nT0 of the microwave switch and the corresponding atomic transition probability value P(T1+nT0), and obtains the corresponding time when the atom passes through different positions of the cavity axis of the microwave cavity according to the curve. When the power of the microwave pulse with a length of τ is set to p0, the atomic transition probability P(T1+nT0) reaches a maximum value, and the corresponding time value T1+nT0+τ / 2 is the time when the atom in the cold atom microwave clock passes through the center of the cavity axis of the microwave cavity. When the power of the microwave pulse with a length of τ is set to p1, the atomic transition probability P(T1+nT0) reaches a minimum value, and the corresponding time value T1+nT0+τ / 2 is the time when the atom in the cold atom microwave clock passes through the center of the cavity axis of the microwave cavity.

[0029] The technical scheme provided by some embodiments of the present application has at least the following beneficial effects:

[0030] The present application provides a system and method for determining the time when an atom passes through a cold atomic microwave clock. A signal control and analysis module is used to generate a first control signal, a second control signal, and a third control signal. The spatial distribution of the magnetic field amplitude of the microwave standing wave field in the microwave cavity and the Rabi transition in the atomic microwave clock are used to obtain the corresponding time when the atom passes through different positions of the cavity axis of the microwave cavity. The system of the present application is small in size and light in weight, and can effectively suppress microwave leakage frequency shift.

[0031] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or understood by practicing the present application. The objectives and other advantages of the present application are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0032] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings.

[0033] Advantages of additional aspects of the present application will be given in part in the following description, and in part will become apparent from the following description, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0035] Figure 1 A system for determining the time of atomic passage in a cold atomic microwave clock as shown in an embodiment of the present application;

[0036] Figure 2 This is a flow chart of a method for determining the passage time of atoms in a cold atomic microwave clock as shown in an embodiment of the present application;

[0037] Figure 3 A schematic diagram of atomic transition probability shown in an embodiment of the present application;

[0038] Among them, 1-microwave source, 2-microwave switch, 3-signal control and analysis module, 4-atom, 5-microwave cavity, 6-atomic transition probability detection device. DETAILED DESCRIPTION

[0039] In order to make the objectives, technical solutions and advantages of this application clearer, the embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0040] The following description refers to the accompanying drawings. Unless otherwise noted, reference to a term in

[0041] In the description of the present application, it should be understood that the terms "first", "second" and the like are used to describe various elements, but not necessarily used to describe a relative importance. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In addition, in the description of the present application, "a plurality of" means two or more, unless otherwise specified. The "and / or" describes the relationship between the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the following three cases: A exists alone, A and B exist together, and B exists alone. The character " / " generally represents that the associated objects before and after are in an "or" relationship.

[0042] In the prior art, a microwave switch, a microwave source, a microwave cavity and an atomic transition probability detection device are generally used, but a signal control and analysis module is not used to accurately determine the atomic passing time. Among them, the microwave switch, the microwave source, the microwave cavity and the atomic transition probability detection device are devices or systems of the cold atom microwave clock. The present application provides a cold atom microwave clock atomic passing time determination system and method, which accurately determines the atomic passing time. The system of the present application has small volume, light weight, and can effectively suppress microwave leakage frequency shift.

[0043] Embodiment one

[0044] The following will be combined with the accompanying drawings Figure 1 A cold atom microwave clock atomic passing time determination system provided by the embodiment of the present application will be described in detail.

[0045] The embodiment utilizes the spatial distribution of the magnetic field amplitude of the microwave standing wave field in the cavity of the microwave cavity and the Rabi transition in the atomic microwave clock. (1) The spatial distribution of the magnetic field amplitude of the microwave standing wave field in the microwave cavity. In the cold atomic microwave clock, the atoms interact with the magnetic field component of the microwave standing wave field in the cavity; the distribution of the magnetic field amplitude of the microwave standing wave field along the central axis of the cavity axis follows the law of the first Bessel function, that is, the magnetic field amplitude is the strongest at the center of the cavity axis, gradually weakens along both sides of the axis center, and is the weakest at both ends of the microwave standing wave field and is equal in size. (2) The Rabi transition in the atomic microwave clock. The Rabi transition is a well-known phenomenon resulting from the interaction between the atom and the single microwave pulse in the microwave cavity, so that the atom transitions from one energy state to another energy state, and the atomic transition probability P can be obtained by detecting the atomic population of the two energy states. When the length τ and the frequency of the microwave pulse acting on the atom are fixed, the magnetic field amplitude b of the microwave pulse is changed, and the corresponding atomic transition probability P(b) under different magnetic field amplitudes b is measured; when the magnetic field amplitude b < π / τ, the atomic transition probability P(b) monotonically increases with the increase of the magnetic field amplitude b.

[0046] An atomic passing time determination system in a cold atomic microwave clock, comprising: a signal control and analysis module 3, a microwave switch 2, a microwave source 1, a microwave cavity 5, and an atomic transition probability detection device 6;

[0047] The signal control and analysis module 3 is connected with the microwave source 1 and the microwave switch 2 respectively, and is used to generate first, second and third control signals;

[0048] In the embodiment, the signal control and analysis module 3 is used to control the power of the microwave signal, control the opening time and the closing time of the microwave switch, and analyze the relationship between the atomic transition probability and the microwave pulse at different times to determine the corresponding time when the atom passes through different positions of the cavity axis of the microwave cavity.

[0049] The microwave switch 2 is connected with the microwave cavity 5, and is used to control the opening time and the closing time of the microwave switch according to the first control signal;

[0050] In the embodiment, the microwave switch 2 is used to control the opening and closing of the microwave signal fed into the microwave cavity 5, so as to generate microwave pulses of different lengths.

[0051] The microwave source 1 is connected with the microwave switch 2, and is used to generate a microwave signal with a corresponding power according to the second control signal;

[0052] In the embodiment, the microwave source generates a microwave signal acting on the atom according to the second control signal.

[0053] The microwave cavity 5 is connected with the microwave switch 2, and is used to provide a space for the atomic transition 4;

[0054] The atomic transition probability detection device 6 is connected to the signal control and analysis module 3 and is used to detect the population of the two energy states of the atoms in the microwave cavity 5 and calculate the atomic transition probability after the microwave signal is fed into the microwave cavity 5.

[0055] The signal control and analysis module 3 is further configured to generate a third control signal;

[0056] The microwave switch 2 is further configured to control the microwave switch to be turned on at a time T1+nT0 according to the third control signal, wherein n is a positive integer, T1 is the initial turn-on time of the microwave switch, and T0 is the time interval;

[0057] The atomic transition probability detection device 6 is also used to detect the atomic transition probability P(T1+nT0) signal after the atom 4 is acted upon by the microwave pulse in the microwave cavity 5, and send the P(T1+nT0) signal to the signal control and analysis module 3, wherein P is the atomic transition probability calculated from the population of the two energy states of the detected atom;

[0058] The signal control and analysis module 3 is also used to draw a curve of the opening time value T1+nT0 and the atomic transition probability value P(T1+nT0) according to the opening time T1+nT0 of the microwave switch and its corresponding atomic transition probability value P(T1+nT0), and obtain the corresponding time when the atom 4 passes through different positions of the cavity axis of the microwave cavity according to the curve. When the power of the microwave pulse with a length of τ is set to p0 and the atomic transition probability P(T1+nT0) reaches a maximum value, the corresponding time value T1+nT0+τ / 2 is the time when the atom 4 in the cold atom microwave clock passes through the center of the microwave cavity axis; when the power of the microwave pulse with a length of τ is set to p1 and the atomic transition probability P(T1+nT0) reaches a minimum value, the corresponding time value T1+nT0+τ / 2 is the time when the atom 4 in the cold atom microwave clock passes through the center of the microwave cavity axis.

[0059] Specifically:

[0060] (1) Generate a microwave pulse of length τ to stimulate atomic transitions, generally ≤ 1 ms. Use the signal control and analysis module to generate a first control signal, which controls the on and off times of the microwave switch. The on time is set to T1, and the off time is set to T2, satisfying τ = T2 - T1.

[0061] (2) Set the power of the microwave pulse with length τ to be p0 or pl. The signal control and analysis module generates a second control signal, which controls the power adjustment module in the microwave source, so that the power of the microwave pulse is p0 or pl. Generally, the power of the microwave pulse increases linearly with the second control signal. Generally, the power adjustment module can be a voltage-controlled attenuator. The condition for judging whether the power of the microwave pulse meets the requirement is that, according to the theoretically calculated value of the atom entering the center of the microwave standing wave field in the microwave cavity, the cold atom microwave clock operation timing condition is set to be that the microwave pulse with length τ is turned on to feed into the microwave cavity when the atom is near the center of the microwave standing wave field in the microwave cavity. The cold atom microwave clock is continuously operated, and the power of the microwave pulse is increased once by using the second control signal in each operation. The relationship curve between the transition probability and the power of the microwave pulse is obtained. When the transition probability is in the rising change curve of the transition probability with the increase of the microwave pulse, and the value of the transition probability is close to 50%, the power of the microwave pulse corresponding to this time is p0; when the transition probability is in the falling change curve of the transition probability with the increase of the microwave pulse, and the value of the transition probability is close to 50%, the power of the microwave pulse corresponding to this time is pl. The purpose of this step is to find the appropriate power of the microwave pulse with length τ, and to judge whether the power is in the rising trend or the falling trend in the curve of the transition probability with the power of the microwave pulse. Figure 3

[0062] (3) The microwave pulse at different time instants excites the atom to transition and obtains the atom transition probability. The signal control and analysis module generates a third control signal, which controls the opening time T1 of the microwave switch to change in turn according to the time interval T0, while keeping the frequency, length τ and power p0 or pl of the microwave pulse unchanged. At each opening time T1 + nT0 (n is an integer), the atom transition probability detection device will obtain the atom transition probability P(T1 + nT0) signal after the atom is affected by the microwave pulse in the microwave cavity.

[0063] (4) Obtain the corresponding time when the atom passes through different positions of the microwave cavity axis. Input the different opening time values T1 + nT0 and the corresponding atom transition probability values P(T1 + nT0) into the signal control and analysis module, and draw the curve of the opening time value T1 + nT0 and the atom transition probability value P(T1 + nT0), as shown in Figure 3 According to the curve, the corresponding time when the atom passes through different positions of the microwave cavity axis can be obtained. When the power of the microwave pulse with length τ is set to be p0, the atom transition probability P(T1 + nT0) reaches the maximum value, and the corresponding time value T1 + nT0 + τ / 2 is the time when the atom passes through the center of the microwave cavity axis in the cold atom microwave clock. Specifically, if the power is set to be Figure 3 ​The first point in the first point, the probability increases with the increase of microwave power, at this time, according to the opening time T1+nT0 of the microwave switch and the corresponding atomic transition probability value P(T1+nT0), the curve of the opening time value T1+nT0 and the atomic transition probability value P(T1+nT0) is drawn, and the corresponding time when the atom passes through the cavity axis of the microwave cavity is obtained according to the curve. When the atomic transition probability P(T1+nT0) reaches the maximum value, the corresponding time value T1+nT0+τ / 2 is the time when the atom passes through the center of the microwave cavity in the cold atom microwave clock.

[0064] When the power of the microwave pulse with a length of τ is p1, the atomic transition probability P(T1+nT0) reaches the minimum value, and the corresponding time value T1+nT0+τ / 2 is the time when the atom passes through the center of the microwave cavity in the cold atom microwave clock. Specifically: if the power is set at Figure 3 The second point in the first point, the probability increases with the increase of microwave power, at this time, according to the opening time T1+nT0 of the microwave switch and the corresponding atomic transition probability value P(T1+nT0), the curve of the opening time value T1+nT0 and the atomic transition probability value P(T1+nT0) is drawn, and the corresponding time when the atom passes through the cavity axis of the microwave cavity is obtained according to the curve. When the atomic transition probability P(T1+nT0) reaches the minimum value, the corresponding time value T1+nT0+τ / 2 is the time when the atom passes through the center of the microwave cavity in the cold atom microwave clock.

[0065] Embodiment two

[0066] The embodiment provides a method for determining the passing time of atoms in a cold atom microwave clock, as shown in the figure, which comprises the following steps: Figure 2 As shown in the figure, it comprises the following steps:

[0067] Step S1: generating a first control signal by using a signal control and analysis module;

[0068] Step S2: controlling the opening time and the closing time of the microwave switch according to the first control signal;

[0069] Step S3: generating a second control signal by using a signal control and analysis module;

[0070] Step S4: generating a microwave signal with a corresponding power by the microwave source according to the second control signal;

[0071] Step S5: detecting the population number of two energy states of the atom in the microwave cavity by using an atomic transition probability detection device when the microwave signal is fed into the microwave cavity, and calculating the atomic transition probability.

[0072] A method for determining the passing time of atoms in a cold atom microwave clock further comprises the following steps:

[0073] Step S6: generating a third control signal by using the signal control and analysis module;

[0074] Step S7: according to the third control signal, the microwave switch controls the opening time of the microwave switch as T1+nT0, wherein n is a positive integer, T1 is the initial opening time of the microwave switch, and T0 is a time interval;

[0075] Step S8: the atomic transition probability detection device 6 detects the atomic transition probability P(T1+nT0) signal of the atom after the atom interacts with the microwave pulse in the microwave cavity, and sends the P(T1+nT0) signal to the signal control and analysis module, wherein P is the atomic transition probability calculated by detecting the population number of two energy states of the atom;

[0076] Step S9: the signal control and analysis module draws a curve of the opening time value T1+nT0 and the atomic transition probability value P(T1+nT0) according to the opening time T1+nT0 of the microwave switch and the corresponding atomic transition probability value P(T1+nT0), and obtains the corresponding time when the atom passes through different positions of the cavity axis of the microwave cavity according to the curve, when the power of the microwave pulse with the length of τ is set as p0, the atomic transition probability P(T1+nT0) reaches the maximum value, and the corresponding time value T1+nT0+τ / 2 is the time when the atom 4 in the cold atom microwave clock passes through the center of the cavity axis of the microwave cavity; when the power of the microwave pulse with the length of τ is set as p1, the atomic transition probability P(T1+nT0) reaches the minimum value, and the corresponding time value T1+nT0+τ / 2 is the time when the atom 4 in the cold atom microwave clock passes through the center of the cavity axis of the microwave cavity.

[0077] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented by other manners. The above-described embodiments are only illustrative. For example, the division of the units is only a logical function division, and another division manner can be used in actual implementation. For another example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units or components shown or discussed can be indirect coupling or communication connection through some communication interfaces, devices or units, which can be electrical, mechanical or other forms.

[0078] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e. they can be located in one place or distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0079] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit.

[0080] It should be noted that the flowchart and block diagrams in the drawings show the architectural, functional and operational views of possible implementations of systems, methods and computer program products according to the embodiments of the present application. In this regard, each block in the flowchart or block diagram can represent a module, a program segment or a portion of code that contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions noted in the blocks can occur in a different order than that shown in the figure. For example, two consecutive blocks can actually be executed substantially in parallel, and they can also be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system that performs the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0081] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present application, and are used to illustrate the technical solutions of the present application, rather than limit the same. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can make modifications or easily think of changes to the technical solutions described in the foregoing embodiments, or make equivalent replacements to some of the technical features; and these modifications, changes or replacements do not cause the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0082] The applicant of the present application has made a detailed description and explanation of the embodiments of the present application in combination with the drawings of the specification, but those skilled in the art should understand that the above embodiments are only preferred embodiments of the present application, and the detailed description is only to help the reader better understand the spirit of the present application, and is not a limitation on the protection scope of the present application. On the contrary, any improvement or modification based on the spirit of the present application should fall within the protection scope of the present application.

Claims

1. A system for determining the time of atomic passage in a cold atomic microwave clock, characterized in that: include: Signal control and analysis module, microwave switch, microwave source, microwave cavity, atomic transition probability detection device; The signal control and analysis module is connected to the microwave source and the microwave switch respectively, and is used to generate a first control signal and a second control signal; The microwave switch is connected to the microwave cavity and is used to control the opening and closing time of the microwave switch according to the first control signal; The microwave source is connected to the microwave switch and is used to generate a microwave signal with corresponding power according to the second control signal; The microwave cavity is connected to the microwave switch and is used to provide a space for atomic transition; The atomic transition probability detection device is connected to the signal control and analysis module, and is used to detect the population of the two energy states of atoms in the microwave cavity and calculate the atomic transition probability when the microwave signal is fed into the microwave cavity.

2. The system for determining the time of atomic passage in a cold atomic microwave clock according to claim 1, characterized in that: The on time is T1, the off time is T2, and τ=T2-T1 is satisfied, where τ is the length of the microwave pulse acting on the atom.

3. In the system for determining the time of passage of atoms in a cold atomic microwave clock according to claim 1, the power of the microwave signal increases linearly with the increase of the second control signal.

4. In the system for determining the passage time of atoms in a cold atomic microwave clock according to claim 1, the power regulation module of the microwave source is a voltage-controlled attenuator.

5. The system for determining the time of atomic passage in a cold atomic microwave clock according to claim 1, wherein the signal control and analysis module is further configured to generate a third control signal; The microwave switch is further configured to control the microwave switch to be turned on at T1+nT0 according to a third control signal, wherein: n is a positive integer, T1 is the initial opening time of the microwave switch, and T0 is the time interval; The atomic transition probability detection device is also used to detect the atomic transition probability P(T1+nT0) signal after the atom is acted upon by the microwave pulse in the microwave cavity, and send the P(T1+nT0) signal to the signal control and analysis module, wherein P is the atomic transition probability calculated from the population of the two energy states of the detected atom; The signal control and analysis module is also used to draw a curve of the opening time value T1+nT0 and the atomic transition probability value P(T1+nT0) according to the opening time T1+nT0 of the microwave switch and its corresponding atomic transition probability value P(T1+nT0), and obtain the corresponding time when the atom passes through different positions of the cavity axis of the microwave cavity according to the curve. When the power of the microwave pulse with a length of τ is set to p0 and the atomic transition probability P(T1+nT0) reaches a maximum value, the corresponding time value T1+nT0+τ / 2 is the time when the atom in the cold atom microwave clock passes through the center of the microwave cavity axis; when the power of the microwave pulse with a length of τ is set to p1 and the atomic transition probability P(T1+nT0) reaches a minimum value, the corresponding time value T1+nT0+τ / 2 is the time when the atom in the cold atom microwave clock passes through the center of the microwave cavity axis.

6. A method for determining the time of atomic passage in a cold atomic microwave clock, characterized in that: include: Using a signal control and analysis module to generate a first control signal; Controlling the on and off timings of the microwave switch according to the first control signal; Using a signal control and analysis module to generate a second control signal; The microwave source generates a microwave signal with corresponding power according to the second control signal; When the microwave signal is fed into the microwave cavity, the atomic transition probability detection device detects the population of the two energy states of the atoms in the microwave cavity and calculates the atomic transition probability.

7. A method for determining the time of atomic passage in a cold atomic microwave clock, characterized in that: Also includes: Using a signal control and analysis module to generate a third control signal; According to the third control signal, the microwave switch controls the microwave switch to be turned on at a time T1+nT0, where n is a positive integer, T1 is the initial turn-on time of the microwave switch, and T0 is the time interval; The atomic transition probability detection device detects the atomic transition probability P(T1+nT0) signal after the atom interacts with the microwave pulse in the microwave cavity, and sends the P(T1+nT0) signal to the signal control and analysis module, where P is the atomic transition probability calculated from the population of the two energy states of the detected atom; The signal control and analysis module draws a curve of the turn-on time value T1+nT0 and the atomic transition probability value P(T1+nT0) according to the turn-on time T1+nT0 of the microwave switch and its corresponding atomic transition probability value P(T1+nT0), and obtains the corresponding time when the atom passes through different positions of the cavity axis of the microwave cavity according to the curve. When the power of the microwave pulse with a length of τ is set to p0 and the atomic transition probability P(T1+nT0) reaches a maximum value, the corresponding time value T1+nT0+τ / 2 is the time when the atom in the cold atom microwave clock passes through the center of the microwave cavity axis; when the power of the microwave pulse with a length of τ is set to p1 and the atomic transition probability P(T1+nT0) reaches a minimum value, the corresponding time value T1+nT0+τ / 2 is the time when the atom in the cold atom microwave clock passes through the center of the microwave cavity axis.

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