Device and method for generating lammer-type thermal atomic beam light clock based on periodic pulse

Abstract

The invention provides a device and a method for generating a Lammer-type hot atomic beam light clock based on periodic pulses. The device comprises a pulse laser, a laser frequency stabilization system, an optical switch, a Laammer type hot atom chamber and a laser detection feedback system. Wherein the pulse laser is used for emitting first laser, and the pulse time is nanosecond magnitude. The laser frequency stabilization system is used for carrying out pre-frequency stabilization on the first laser to obtain second laser, and the second laser is conveyed to the Laammer type hot atom chamber through the optical switch; the switching period of the optical switch is set to be microsecond magnitude; the lamplug type hot atom chamber is used for outputting a lamplug type hot first atom beam; and the laser detection feedback system is used for detecting the first atomic beam, feeding back and controlling the pulse laser, locking the frequency of the pulse laser on a transition spectral line of atoms, and obtaining a hot atomic beam light clock. According to the invention, the interaction time of laser and atoms can be controlled, and the utilization rate of the atoms of the Lammer-type hot atomic beam light clock can be improved.

Description

Technical Field

[0001] The present application relates to the field of optical frequency atomic clocks, and in particular to a device and method for generating a Ramsey-type thermal atomic beam optical clock based on periodic pulses. Background Art

[0002] Optical clocks use pre-stabilized lasers to detect the extremely narrow transition lines of atoms between specific energy levels, and generate highly stable laser sources based on this. High-precision optical clocks have made significant progress in basic physics, precision measurement, and advanced technology applications, such as laser frequency stabilization, atomic gravimeters, global positioning systems, and quantum information. At present, the measurement accuracy of high-performance optical clocks has reached 10E-19, making frequency the most accurately measured physical quantity, which also provides important support for the revision of the international definition of the second. However, high-performance optical clocks are often based on cold atom platforms, which leads to problems such as large size and high system complexity. In fact, high-performance cold atom optical clocks are almost all very dependent on laboratory environments, difficult to transport, and difficult to use in the development of commercial atomic clocks. These limitations make it difficult for cold atom optical clocks to play their high-performance advantages, and are not conducive to the development of time-frequency related fields.

[0003] Thermal atom beam optical clocks are an option that balances high performance and portability. They have the advantages of simple structure and easy portability, making them suitable for use in systems with changing environments. At the same time, they can take advantage of higher performance indicators than microwave clocks, and can provide a new possibility for the realization of portable optical frequency atomic clocks. However, the atom utilization rate of traditional thermal atom beam optical clock solutions is extremely low, and only atoms with a transverse velocity close to zero can contribute to the final spectral line signal. In fact, nearly 99% of thermal atoms will be wasted because they cannot interact with lasers, which limits the development potential of thermal atom beam optical clocks.

[0004] In view of the above-mentioned defects, the present application provides a device and method for generating a Ramsey-type thermal atomic beam optical clock based on periodic pulses. Summary of the invention

[0005] The embodiments of the present application provide a device and method for generating a Ramsey-type thermal atom beam optical clock based on periodic pulses, so as to solve the problem of low atom utilization rate of existing thermal atom beam optical clocks.

[0006] In a first aspect, an embodiment of the present application provides a device for generating a Ramsey-type thermal atom beam optical clock based on periodic pulses, comprising: a pulsed laser, a laser frequency stabilization system, an optical switch, a Ramsey-type thermal atom chamber, and a laser detection feedback system, wherein:

[0007] The pulse laser is used to emit a first laser with a pulse time of a first preset time;

[0008] The laser frequency stabilization system is used to pre-stabilize the first laser to obtain the second laser, and the second laser is transmitted to the Ramsey type thermal atom chamber through the optical switch; the switching cycle of the optical switch is set to a second preset time; the first preset time is set at 0ns to 300ns; the value of the second preset time is set at 0ms to 300ms;

[0009] The Ramsey-type hot atom chamber is used to output a first atomic beam, wherein the first atomic beam is an atomic beam after the second laser passes through the optical switch and interacts with the second atomic beam, and the second atomic beam is an atomic beam emitted by an atomic furnace;

[0010] The laser detection feedback system is used to detect the first atomic beam, generate a servo feedback signal to the pulse laser, lock the frequency of the pulse laser to the transition spectrum line of the atom, and obtain a thermal atomic beam optical clock.

[0011] In a possible design, the second preset time is set to a ratio of a waist size of the first laser to a most probable velocity of the atoms in the longitudinal direction.

[0012] In a possible design, the first preset time is set to a ratio of a wavelength of the pulsed laser to a maximum transverse velocity of the atom.

[0013] In a possible design, it also includes a spectroscope, the pulse laser is connected to the input end of the spectroscope, the spectroscope includes a first output end and a second output end, the first output end can guide the input light into the laser frequency stabilization system, and the second output end can guide the input light into the optical switch.

[0014] In a possible design, the Ramsey-type hot atom chamber comprises a vacuum chamber, an atomic furnace and a mirror assembly, wherein:

[0015] The atomic reactor and the reflector group are arranged on the front window of the vacuum;

[0016] The atomic furnace is used to spray the atomic beam to the rear window of the vacuum; the reflector group is used to form an optical path so that the second laser passes through the second atomic beam four times in parallel after passing through the optical switch.

[0017] In one possible design, the laser detection feedback system includes a detection laser, a photodetector, and a servo feedback controller; wherein:

[0018] The laser detection feedback system includes a detection laser, a photodetector and a servo feedback controller; wherein: the detection laser is used to emit a detection laser through the rear window of the vacuum chamber to the photodetector, and the photodetector is connected to the servo feedback controller and the pulse laser in turn.

[0019] In one possible design, the wavelength of the pulsed laser is the clock transition wavelength of the atoms in the Ramsey-type hot atoms.

[0020] In one possible design, the wavelength of the detection laser is also the detection wavelength corresponding to the atomic beam.

[0021] In a second aspect, an embodiment of the present application provides a method for generating a Ramsey type thermal atom beam optical clock based on periodic pulses, using the above-mentioned device for generating a Ramsey type thermal atom beam optical clock based on periodic pulses, and the method includes:

[0022] The pulse laser emits a first laser with a first preset pulse time;

[0023] The first laser obtains a pre-stabilization feedback signal through a laser frequency stabilization system, and the pulse laser emits a second laser according to the pre-stabilization feedback signal, wherein the second laser is the first laser after pre-stabilization;

[0024] The second laser is introduced into the Ramsey type hot atom chamber through an optical switch with a switching cycle set to a second preset time;

[0025] The Ramsey type hot atom chamber outputs a first atomic beam after the second laser and the second atomic beam interact with each other, and the second atomic beam is an atomic beam emitted by an atomic furnace in the Ramsey type hot atom chamber;

[0026] The laser detection feedback system emits a detection laser to detect the first atomic beam, generates a servo feedback signal to the pulse laser, locks the frequency of the pulse laser to the transition spectrum line of the atom, and obtains a thermal atomic beam optical clock.

[0027] In a possible design, the first laser obtains a pre-frequency stabilization feedback signal through a laser frequency stabilization system, including:

[0028] The first laser passes through a beam splitter and is introduced into the laser frequency stabilization system through a first output optical path of the beam splitter to obtain the pre-frequency stabilization feedback signal;

[0029] The second laser is introduced into the Ramsey type thermal atom chamber through an optical switch with a switching cycle set to a second preset time; comprising:

[0030] The second laser passes through a beam splitter and is introduced into the Ramsey-type thermal atom chamber through a second output light path of the beam splitter.

[0031] The embodiments of the present application provide a device and method for generating a Ramsey-type thermal atom beam optical clock based on periodic pulses, which can improve the utilization rate of atoms in the Ramsey-type thermal atom beam optical clock by controlling the duration of the pulsed laser to control the cycle time of the optical switch to control the interaction time between the laser and the atoms. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0033] Figure 1 A schematic diagram of the structure of a device for generating a Ramsey-type thermal atomic beam optical clock based on periodic pulses provided in an embodiment of the present application;

[0034] Figure 2 Schematic diagram of the enhancement ratio between the embodiment of the present application and the traditional solution at different pulse times;

[0035] Figure 3 Schematic diagram of detuned spectral lines of the embodiment of the present application and the traditional solution at different pulse times;

[0036] Figure 4 A schematic flow chart of a method for generating a Ramsey-type thermal atomic beam optical clock based on periodic pulses provided in an embodiment of the present application.

[0037] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments.

[0038] Description of reference numerals:

[0039] 110-pulse laser; 120-laser frequency stabilization system; 130-beam splitter; 140-optical switch; 150-atomic furnace; 160-vacuum chamber; 170-detection laser; 180-photodetector; 190-servo feedback controller;

[0040] 210 - a first reflector; 220 - a second reflector; 230 - a third reflector; 240 - a fourth reflector. DETAILED DESCRIPTION

[0041] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims, rather than all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0042] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, or it can be an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0043] In the description of the present application, it should be understood that the terms used include "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. to indicate orientation or positional relationships. They are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the equipment or method of the present application. They are not used to indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0044] In the specification and claims of the present application and the above-mentioned drawings, the terms "first", "second", and "third" are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the objects used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example.

[0045] In addition, the described terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions; for example, a process, method, system, product, or maintenance tool that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but also includes other steps or units not explicitly listed or inherent to these processes, methods, products, or maintenance tools.

[0046] It should be noted that the “at…” in the embodiments of the present application may be the instant when a certain situation occurs, or may be a period of time after the occurrence of a certain situation, and the embodiments of the present application do not specifically limit this.

[0047] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0048] Glossary:

[0049] Thermal atom beam optical clock: a laser that uses the narrow linewidth transitions of a thermal atom beam (a thermal atom beam ejected from a hot furnace) between specific energy levels to achieve high-precision time measurement.

[0050] Clock transition wavelength: refers to the wavelength corresponding to a specific atomic energy level transition used in an atomic clock to achieve high-precision frequency measurement.

[0051] Optical waist size: refers to the minimum diameter of the laser beam at its focus. The location of this minimum diameter is called the "optical waist", which is the smallest cross-section of the laser beam after focusing.

[0052] Most probable velocity: a concept in statistical physics, usually used to describe the velocity distribution of ideal gas molecules. It refers to the most likely velocity value in the velocity distribution of gas molecules under certain temperature and pressure conditions.

[0053] Vacuum chamber: The vacuum chamber includes a front window and a rear window. The front window is usually located at the front end of the vacuum chamber and is used to introduce the laser into the vacuum chamber. The rear window is usually located at the end of the vacuum chamber and is used to lead the laser out of the vacuum chamber after the atomic interaction.

[0054] In the traditional implementation of a thermal atomic clock, the implementation equipment includes a main laser emitter based on the atomic clock transition wavelength, a thermal atom chamber, a laser frequency stabilization system and a laser detection feedback system. The laser frequency stabilization system is used to pre-stabilize the laser emitted by the main laser emitter. After pre-stabilization, the main laser emitter emits the laser to the thermal atom chamber to interact with the atomic beam. The laser detection feedback system is used to monitor the signal changes of the detection laser through the thermal atom chamber to generate a feedback signal to adjust the laser frequency to keep it at the frequency of the atomic energy level transition.

[0055] The atom utilization rate of the traditional thermal atom beam optical clock scheme is extremely low. Only atoms with transverse velocities close to zero can contribute to the final spectral line signal. In the specific implementation of the traditional method, when atoms interact with lasers, the laser frequency felt by the atoms will change due to the movement of the atoms. The atomic velocity is decomposed into longitudinal velocity (the velocity in the direction of the atoms ejected from the hot furnace in the vacuum chamber) and transverse velocity (the velocity in the direction of the laser acting on the atomic beam in the vacuum chamber). The longitudinal velocity will not affect the frequency felt by the atoms, but the transverse velocity will. The phenomenon of frequency changes felt by atoms due to transverse velocity is called Doppler broadening. This effect prevents atoms with large transverse velocities from participating in the Ramsey process and is wasted. According to reliable data, nearly 99% of thermal atoms will be wasted because they cannot interact with lasers, limiting the development potential of thermal atom beam optical clocks.

[0056] The present application provides a device and method for generating a Ramsey-type thermal atomic beam optical clock based on periodic pulses. By controlling the pulse time of the laser and the switching period of the optical switch, the interaction time between the laser and the atom is controlled to avoid the non-uniformity of the laser wavefront caused by compressing the optical waist width, and the atoms of different transverse velocity groups can be fully utilized to improve the utilization rate of atoms, thereby reducing the quantum projection noise of the optical clock and improving the signal-to-noise ratio of the spectrum line.

[0057] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0058] Figure 1 A schematic diagram of a device for generating a periodic pulse Ramsey-type thermal atomic beam optical clock is provided in this application, such as Figure 1 As shown, the device includes a pulse laser 110, a laser frequency stabilization system 120, an optical switch 140, a Ramsey-type hot atom chamber and a laser detection feedback system, wherein:

[0059] The pulse laser 110 is used to emit a first laser with a pulse time of a first preset time;

[0060] The laser frequency stabilization system 120 is used to pre-stabilize the first laser to obtain the second laser, and the second laser is transmitted to the Ramsey type thermal atom chamber through the optical switch 140; the switching cycle of the optical switch 140 is set to the second preset time; the first preset time is set to 0ns to 300ns; the value of the second preset time is set to 0ms to 300ms;

[0061] The Ramsey type hot atom chamber is used to output a first atomic beam, the first atomic beam is an atomic beam after the second laser passes through the optical switch 140 and interacts with the second atomic beam, and the second atomic beam is an atomic beam emitted by the atomic furnace 150;

[0062] The laser detection feedback system is used to detect the first atomic beam, generate a servo feedback signal to the pulse laser 110, lock the frequency of the pulse laser 110 to the atomic transition spectrum, and obtain a thermal atomic beam optical clock.

[0063] Specifically, the first preset time is in the order of nanoseconds, the second preset time is in the order of microseconds, and the first preset time is significantly greater than the second preset time. Generally, the first preset time is 0ns to 300ns; the second preset time is 0ms to 300ms.

[0064] In the embodiment of the present application, the pulse time (first preset time) is set by the pulse laser 110, and the pulse interval time (second preset time) of the pulse laser is controlled by the optical switch 140 to match the lateral and longitudinal velocity distributions of the atoms respectively. When the pulse time of the laser is in the nanosecond order and the pulse interval is in the microsecond order, the velocity distribution of the atoms and the interaction time between the atoms and the laser can be accurately matched, and the atomic utilization rate can be maximized at this time, which improves the signal-to-noise ratio of the Ramsey spectrum obtained by the servo feedback control system, thereby improving the stability of the optical clock.

[0065] Furthermore, the second preset time is set to be the ratio of the optical waist size of the first laser to the most probable velocity of the atoms in the longitudinal direction.

[0066] Specifically, the second preset time of the optical switch 140 can be obtained according to the longitudinal velocity of the atom. Under a given vacuum chamber temperature, the longitudinal velocity of the atom has a most probable velocity v 0 The pulse interval of the laser pulse can be defined as the laser waist size w divided by the most probable velocity v of the atom. 0 , so that the duration can match the velocity distribution of the atoms:

[0067] (1)

[0068] Among them, T 2 It is the second preset time.

[0069] Specifically, in order to achieve the maximum output result of this scheme, the pulse time should be obtained from the transverse velocity of the atom. Given the temperature of the vacuum chamber, the Doppler broadening induced by the transverse velocity of the atom is known. Because of the Doppler broadening, it is difficult for the atom to interact with the laser, so the core of this scheme is to use the interaction broadening to compensate for the Doppler broadening. The interaction broadening is equivalent to the inverse of the interaction time (that is, the pulse time), that is, 1 / T1 , the maximum Doppler broadening at a certain vacuum chamber temperature is equal to the maximum transverse velocity v of the atom zmax Divide by the clock transition wavelength.

[0070] So the pulse time T 1 is equal to the clock transition wavelength divided by the maximum transverse velocity, that is,

[0071] (2)

[0072] Among them, T 1 is the first preset time, λ is the atomic clock transition wavelength. It can be seen from this expression that when the pulse time is shorter, the corresponding supplementary Doppler broadening is greater, and the number of atoms that can be used is greater.

[0073] Preferably, similarly, the first preset time is set to be the ratio of the wavelength of the pulse laser 110 to the maximum transverse velocity of the atoms.

[0074] Specifically, the device also includes a pulse laser 110, which is connected to the input end of the pulse laser 110. The spectroscope 130 includes a first output end and a second output end. The first output end can guide the input light into the laser frequency stabilization system 120, and the second output end can guide the input light into the optical switch 140.

[0075] Specifically, the laser light received by the pulse laser 110 is divided into two beams, one of which is introduced into the laser frequency stabilization system 120 through the first output end, and the laser frequency stabilization system 120 outputs a pre-stabilized signal value to the pulse laser 110. The pulse laser 110 emits a pre-stabilized second laser, and the other beam is introduced into the optical switch 140 through the second output end, and enters the Ramsey-type thermal atom chamber through the optical switch 140.

[0076] Preferably, the laser frequency stabilization system 120 adopts an ultra-stable laser frequency stabilization system, which can narrow the laser line width while pre-stabilizing the pulse laser 110 .

[0077] Furthermore, the Ramsey type thermal atomic chamber comprises a vacuum chamber 160, an atomic furnace 150 and a reflector assembly, wherein:

[0078] The atomic furnace 150 and the reflector group are arranged at the front window of the vacuum chamber 160; the atomic furnace 150 is used to spray the atomic beam to the rear window of the vacuum chamber 160; the reflector group is used to form an optical path so that the second laser passes through the optical switch 140 and then passes through the second atomic beam four times in parallel.

[0079] Specifically, through the setting of the light-emitting mirror group, the direction of the four parallel laser beams should be set perpendicular to the direction of the atomic beam; then the second atomic beam is ejected from the atomic furnace 150, and the direction of the path of the atomic beam is the direction of the longitudinal velocity of the atomic beam, and the direction of the four parallel laser beams is the direction of the transverse velocity of the atomic beam.

[0080] As an implementation method, Figure 1 The reflector group may include a first reflector 210, a second reflector 220, a third reflector 230 and a fourth reflector 240. The first reflector 210 and the second reflector 220 are arranged on one side of the path through which the atomic beam passes, and the third reflector 230 and the fourth reflector 240 are arranged on the other side of the atomic beam. The first reflector 210 is arranged in a direction close to the atomic furnace 150 at a 45 degree angle to the direction of the atomic beam, the second reflector 220 is -45 degrees to the direction of the atomic beam, and the third reflector 230 is arranged in a direction close to the atomic furnace 150 at a 45 degree angle to the direction of the atomic beam. The direction of the atomic furnace 150 is 45 degrees to the direction of the atomic beam, and the fourth reflector 240 is 45 degrees to the direction of the atomic beam; the second laser after passing through the optical switch 140 can be injected into the vacuum chamber 160 from the other side of the atomic beam, and after passing through the atomic beam for the first time perpendicular to the atomic beam, it can pass through the first reflector 210, the second reflector 220, the fourth reflector 240, the third reflector 230, the first reflector 210 and the second reflector 220 in sequence; thereby generating four parallel light rays that pass through the atomic beam path.

[0081] Specifically, the parameters in the vacuum chamber 160 may be set to achieve conventional or typical values ​​for a thermal atomic beam optical clock;

[0082] As an implementation method, the parameters are set as follows: the vacuum range can take a typical value of 1E-5Pa, and the temperature is 600°C.

[0083] Furthermore, the wavelength of the pulse laser 110 is the wavelength of the clock transition of atoms in the Ramsey-type hot atoms.

[0084] Specifically, the optical clock obtained can be a cesium atomic clock, a rubidium atomic clock, a strontium atomic clock, an ytterbium atomic clock, an aluminum atomic clock and a calcium atomic clock, etc., then correspondingly, it is necessary to use the atomic furnace 150 of the above-mentioned atoms and the clock transition wavelength corresponding to its atoms. For example, the clock transition wavelength of the calcium atom is 657nm, and the wavelength of the pulse laser 110 is set to 657nm.

[0085] Specifically, the laser detection feedback system includes a detection laser 170, a photodetector 180 and a servo feedback controller 190; wherein: the detection laser 170 is used to emit a detection laser through the rear window of the vacuum chamber 160 to the photodetector 180, and the photodetector 180 is connected to the servo feedback controller 190 and the pulse laser 110 in turn.

[0086] Specifically, the wavelength of the detection laser 170 is the detection wavelength corresponding to the atomic beam.

[0087] Specifically, the detection laser 170 is used to emit detection laser light, the wavelength of which is the wavelength of the detection state energy level associated with the clock transition energy level in the atom.

[0088] For example, the wavelength of the detection state energy level of calcium atoms is 423nm or 431nm.

[0089] Specifically, after the second laser passes through the optical switch 140, it interacts with the second atomic beam in the vacuum chamber 160 to generate a Ramsey spectrum line. The detection laser 170 is used to emit the detection laser, and the detection laser is used to detect the Ramsey spectrum line at the rear window. The photodetector 180 obtains the Ramsey spectrum line by detecting the number of atoms at the detection state energy level related to the clock transition energy level. Since the interaction time matches the atomic velocity distribution, the atomic utilization rate is greatly improved, so the signal-to-noise ratio of the obtained Ramsey spectrum line will also be greatly improved. The photodetector 180 inputs the spectrum line signal into the servo feedback controller 190, and the servo feedback controller 190 feedback controls the laser to lock the frequency of the laser to the atomic transition spectrum line.

[0090] Furthermore, the servo feedback controller 190 may be a discrete circuit device or an integrated circuit device.

[0091] Furthermore, in the embodiments of the present application, there is no restriction on the placement position and direction of devices such as the pulse laser 110, the laser frequency stabilization system 120, the optical switch 140, the Ramsey-type thermal atom chamber, the laser, the photodetector 180 and the servo feedback controller 190. One or more reflective devices can be added to the above-mentioned devices to realize the mode of interconnecting the above-mentioned devices through optical paths.

[0092] Figure 2 It is a schematic diagram of the spectral line amplitude enhancement ratio of the embodiment of the present application and the traditional solution at different pulse times. Figure 3 Schematic diagram of detuned spectral lines of the embodiment of the present application and the traditional solution at different pulse times.

[0093] Specifically, Figure 2 and Figure 3 The simulation parameters are as follows: the wavelength of the pulse laser 110 is set to 657nm, the detection laser with a wavelength of 423nm is used, and the atomic furnace 150 is a calcium atomic furnace. The temperature in the vacuum chamber 160 is set to 600℃, at which time the most probable longitudinal velocity of the calcium atom is 610 meters per second, and the transverse velocity is approximately between -70m / s and 70m / s (Doppler broadening is about 100MHz). The laser waist width is set to 0.6mm.

[0094] according to Figure 2It can be seen that when the pulse time is reduced to 1 nanosecond, almost all atoms are used, so the amplitude is the largest at this time, and the amplitude has almost no change when the time is reduced. At this time, the maximum amplitude enhancement ratio is about 2500, which means that compared with the traditional solution, its amplitude has increased by three orders of magnitude; in addition, according to the stability calculation formula, its stability has increased by two orders of magnitude.

[0095] like Figure 3 It can be seen that, using the traditional solution, the interaction time can only be reduced by reducing the size of the optical waist. The general optical waist size is 0.6 mm, and the corresponding interaction time is 1 microsecond. If the size of the optical waist is further reduced (in order to reduce the interaction time), it will cause the non-uniformity of the laser wavefront and thus be unfavorable for the increase of the spectral line amplitude. However, when the implementation method of the present application is adopted, when the pulse time is reduced, more atoms are compensated due to the interaction broadening, and the spectral line amplitude is larger. According to the above formula, the time of the optical switch 140 (the second preset time) is approximately 1 microsecond, and the pulse time (the first preset time) is set to 1 nanosecond. At this time, the pulse time and the optical switch 140 time match the transverse and longitudinal velocity distribution of the atoms, and the most atoms are utilized (almost all atoms with transverse velocities are utilized), and the final result is the best.

[0096] The embodiment of the present application provides a generation device of a Ramsey type thermal atom beam optical clock based on periodic pulses, including: a pulse laser 110, a laser frequency stabilization system 120, an optical switch 140, a Ramsey type thermal atom chamber and a laser detection feedback system, wherein: the pulse laser 110 is used to emit a first laser with a pulse time of a first preset time; the laser frequency stabilization system 120 is used to pre-stabilize the first laser to obtain a second laser, and the second laser is transmitted to the Ramsey type thermal atom chamber through the optical switch 140; the switching period of the optical switch 140 is set to the second preset time; the first preset time is set at 0ns to 300ns; the value of the second preset time is set at 0ms to 300ms; the Ramsey type thermal atom chamber is used to output the first atomic beam, and the laser detection feedback system is used to detect the first atomic beam, generate a servo feedback signal to the pulse laser 110, lock the frequency of the pulse laser 110 to the transition spectrum of the atom, and obtain a thermal atom beam optical clock. It has the following technical effects:

[0097] In the embodiment of the present application, the pulse time of the pulse laser 110 is controlled according to the first preset time, and the switching period of the optical switch 140 is controlled according to the second preset time. When the first preset time is in the order of nanoseconds and the second preset time is in the order of microseconds, the interaction broadening can be generated through the interaction between the first preset time and the second preset time to compensate for the Doppler broadening, thereby avoiding the non-uniformity of the laser wavefront caused by the compression of the light waist width, further making full use of atoms of different transverse velocity groups, improving the utilization rate of atoms, reducing the quantum projection noise of the optical clock, and improving the signal-to-noise ratio of the spectral line.

[0098] According to the first preset time and the second preset time determined by the above formula (1) and formula (2), the pulse time, the pulse interval time and the atomic rate distribution can be accurately matched, and the atomic utilization rate of the spectral line will be maximized.

[0099] Figure 4 A method for generating a Ramsey-type thermal atomic beam optical clock based on periodic pulses is provided in this application, such as Figure 4 As shown, the method is implemented by the above-mentioned generation device of a Ramsey type thermal atomic beam optical clock based on periodic pulses, and the method comprises:

[0100] S410, the pulse laser emits a first laser with a first preset pulse time;

[0101] Specifically, the wavelength of the pulsed laser is the wavelength of the clock transition of atoms in the Ramsey-type hot atoms.

[0102] S420, the first laser obtains a pre-stabilization feedback signal through the laser frequency stabilization system, and the pulse laser emits a second laser according to the pre-stabilization feedback signal, and the second laser is the first laser after pre-stabilization;

[0103] Specifically, the first laser passes through a beam splitter and is introduced into a laser frequency stabilization system through a first output optical path of the beam splitter to obtain a pre-frequency stabilization feedback signal;

[0104] S430, the second laser is introduced into the Ramsey type thermal atom chamber through an optical switch whose switching cycle is set to a second preset time;

[0105] Specifically, the second laser passes through a beam splitter and is introduced into the Ramsey-type hot atom chamber through a second output light path of the beam splitter.

[0106] S440, the Ramsey type hot atom chamber outputs a first atomic beam after the second laser and the second atomic beam interact with each other, and the second atomic beam is an atomic beam emitted by an atomic furnace in the Ramsey type hot atom chamber;

[0107] Specifically, the first atomic beam can produce Ramsey spectral lines;

[0108] S450, the laser detection feedback system emits a detection laser to detect the first atomic beam, generates a servo feedback signal to the pulse laser, locks the frequency of the pulse laser to the transition spectrum line of the atom, and obtains the thermal atomic beam optical clock.

[0109] Specifically, the laser detection feedback system receives the third laser after the first atomic beam interacts with the detection laser at the rear window of the vacuum chamber. The photodetector obtains the Ramsey spectrum line by detecting the number of atoms in the detection state energy level related to the clock transition energy level and transmits it to the servo feedback controller. The servo feedback controller obtains the servo feedback signal and sends it to the pulse laser, locks the frequency of the pulse laser to the transition spectrum line of the atom, and obtains the thermal atomic beam optical clock.

[0110] An embodiment of the present application provides a method for generating a Ramsey-type thermal atom beam optical clock based on periodic pulses, which is used for the above-mentioned generation device of a Ramsey-type thermal atom beam optical clock based on periodic pulses. Its implementation principle and technical effects are similar, and this embodiment will not be described in detail here.

[0111] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0112] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A device for generating a Ramsey-type thermal atomic beam optical clock based on periodic pulses, characterized in that: include: Pulsed laser, laser frequency stabilization system, optical switch, Ramsey type hot atom chamber and laser detection feedback system, including: The pulse laser is used to emit a first laser with a pulse time of a first preset time; The laser frequency stabilization system is used to pre-stabilize the first laser to obtain the second laser, and the second laser is transmitted to the Ramsey type thermal atom chamber through the optical switch; the switching cycle of the optical switch is set to a second preset time; the first preset time is set at 0ns to 300ns; the value of the second preset time is set at 0ms to 300ms; The Ramsey-type hot atom chamber is used to output a first atomic beam, wherein the first atomic beam is an atomic beam after the second laser passes through the optical switch and interacts with the second atomic beam, and the second atomic beam is an atomic beam emitted by an atomic furnace; The laser detection feedback system is used to detect the first atomic beam, generate a servo feedback signal to the pulse laser, lock the frequency of the pulse laser to the transition spectrum line of the atom, and obtain a thermal atomic beam optical clock.

2. The device according to claim 1, characterized in that The second preset time is set to be a ratio of the optical waist size of the first laser to the most probable velocity of the atoms in the longitudinal direction.

3. The device according to claim 2, characterized in that The first preset time is set to the ratio of the wavelength of the pulse laser to the maximum transverse velocity of the atom.

4. The device according to any one of claims 1 to 3, characterized in that: It also includes a spectroscope, the pulse laser is connected to the input end of the spectroscope, the spectroscope includes a first output end and a second output end, the first output end can guide the input light into the laser frequency stabilization system, and the second output end can guide the input light into the optical switch.

5. The device according to any one of claims 1 to 3, characterized in that: The Ramsey type thermal atom chamber comprises a vacuum chamber, an atomic furnace and a reflector group, wherein: The atomic furnace and the reflector group are arranged on the front window of the vacuum chamber; The atomic furnace is used to spray an atomic beam to the rear window of the vacuum chamber; the reflector group is used to form an optical path so that the second laser passes through the second atomic beam four times in parallel after passing through the optical switch.

6. The device according to claim 5, characterized in that The laser detection feedback system comprises a detection laser, a photoelectric detector and a servo feedback controller; wherein: The laser detection feedback system includes a detection laser, a photodetector and a servo feedback controller; wherein: the detection laser is used to emit a detection laser through the rear window of the vacuum chamber to the photodetector, and the photodetector is connected to the servo feedback controller and the pulse laser in turn.

7. The device according to any one of claims 1 to 3, characterized in that: The wavelength of the pulse laser is the clock transition wavelength of the atoms in the Ramsey-type hot atoms.

8. The device according to any one of claims 1 to 3, characterized in that: The wavelength of the detection laser is the detection wavelength corresponding to the atomic beam.

9. A method for generating a Ramsey-type thermal atomic beam optical clock based on periodic pulses, characterized in that: The method is implemented by using the device as described in any one of claims 1 to 8, and includes: The pulse laser emits a first laser with a first preset pulse time; The first laser obtains a pre-stabilization feedback signal through a laser frequency stabilization system, and the pulse laser emits a second laser according to the pre-stabilization feedback signal, wherein the second laser is the first laser after pre-stabilization; The second laser is introduced into the Ramsey type hot atom chamber through an optical switch with a switching cycle set to a second preset time; The Ramsey type hot atom chamber outputs a first atomic beam after the second laser and the second atomic beam interact with each other, and the second atomic beam is an atomic beam emitted by an atomic furnace in the Ramsey type hot atom chamber; The laser detection feedback system emits a detection laser to detect the first atomic beam, generates a servo feedback signal to the pulse laser, locks the frequency of the pulse laser to the transition spectrum line of the atom, and obtains a thermal atomic beam optical clock.

10. The method according to claim 9, characterized in that The first laser obtains a pre-frequency stabilization feedback signal through a laser frequency stabilization system, including: The first laser passes through a beam splitter and is introduced into the laser frequency stabilization system through a first output optical path of the beam splitter to obtain the pre-frequency stabilization feedback signal; The second laser is introduced into the Ramsey type thermal atom chamber through an optical switch with a switching cycle set to a second preset time; comprising: The second laser passes through a beam splitter and is introduced into the Ramsey-type thermal atom chamber through a second output light path of the beam splitter.

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