Apparatus and method for generating a Ramsey-type thermal atomic beam optical clock based on periodic pulses

Abstract

The application provides a generation device and method of a Ramsey-type hot atom beam optical clock based on a periodic pulse. The device comprises a pulse laser, a laser frequency stabilization system, an optical switch, a Ramsey-type hot atom chamber and a laser detection feedback system. The pulse laser is used for emitting first laser, and the pulse time is nanosecond. The laser frequency stabilization system is used for pre-stabilizing the first laser to obtain second laser, and the second laser is delivered to the Ramsey-type hot atom chamber through the optical switch. The switching period of the optical switch is set to be microsecond. The Ramsey-type hot atom chamber is used for outputting a Ramsey-type hot first atom beam. The laser detection feedback system is used for detecting the first atom beam, and feedback controls the pulse laser to lock the frequency of the pulse laser on the transition spectrum of the atom to obtain a hot atom beam optical clock. The application can control the interaction time of the laser and the atom, and can improve the utilization rate of the atom of the Ramsey-type hot atom beam optical clock.

Description

Technical Field

[0001] This application relates to the field of optical frequency atomic clocks, and more particularly to a device and method for generating a Ramsay-type thermal atomic beam optical clock based on periodic pulses. Background Technology

[0002] Optical clocks utilize pre-stabilized lasers to detect extremely narrow transition lines between specific energy levels in atoms, thereby generating a highly stable laser source. High-precision optical clocks have made significant progress in fundamental physics, precision measurement, and advanced technological applications, such as laser frequency stabilization, atomic gravimeters, GPS, and quantum information. Currently, the measurement accuracy of high-performance optical clocks has reached 10E-19, making frequency the most precisely 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, resulting in large size and high system complexity. In fact, high-performance cold atom optical clocks are almost entirely dependent on laboratory environments, difficult to transport, and unsuitable for the development of commercial atomic clocks. These limitations hinder the full realization of the high-performance advantages of cold atom optical clocks and impede the development of time-frequency related fields.

[0003] Thermoacrylonitrile (thermoacrylonitrile) atomic beam optical clocks offer a balance between high performance and portability. They are simple in structure, easy to carry, and suitable for use in environments with varying conditions. Furthermore, they offer higher performance than microwave clocks, providing a new possibility for the realization of portable optical frequency atomic clocks. However, traditional thermoacrylonitrile atomic beam optical clock schemes have extremely low atomic utilization; only atoms with transverse velocities close to zero contribute to the final spectral signal. In reality, nearly 99% of the hot atoms are wasted because they cannot interact with the laser, limiting the development potential of thermoacrylonitrile atomic beam optical clocks.

[0004] To address the aforementioned shortcomings, this application provides a device and method for generating a Ramsay-type thermal atomic beam optical clock based on periodic pulses. Summary of the Invention

[0005] This application provides a device and method for generating a Ramsay-type thermal atomic beam optical clock based on periodic pulses, in order to solve the problem of low atomic utilization in existing thermal atomic beam optical clocks.

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

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

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

[0009] The Ramsey-type thermal atom chamber is used to output a first atomic beam, which is the atomic beam resulting from the interaction between the second laser and the second atomic beam after the second laser passes through the optical switch, and the second atomic beam is the atomic beam emitted by the atomic furnace.

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

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

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

[0013] In one possible design, the beam splitter is also included, with the pulsed laser connected to the input of the beam splitter. The beam splitter includes a first output and a second output. The first output can guide the input light to the laser frequency stabilization system, and the second output can guide the input light to the optical switch.

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

[0015] The atomic furnace and the reflector assembly are located in the front window of the vacuum chamber;

[0016] The atomic furnace is used to eject atomic beams into the vacuum through the rear window; 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 detection laser light through the rear window of the vacuum chamber to the photodetector, and the photodetector is connected in sequence to the servo feedback controller and the pulsed laser.

[0019] In one possible design, the wavelength of the pulsed laser is the clock transition wavelength of the atom within the Ramsay-type hot atom.

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

[0021] Secondly, embodiments of this application provide a method for generating a Ramsay-type thermal atomic beam optical clock based on periodic pulses, employing the aforementioned apparatus for generating a Ramsay-type thermal atomic beam optical clock based on periodic pulses. The method includes:

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

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

[0024] The second laser is introduced into the Ramsey-type thermal atom chamber via an optical switch with a switching period set to a second preset time;

[0025] The Ramsay-type thermal atomic chamber outputs a first atomic beam resulting from the interaction between the second laser and the second atomic beam, wherein the second atomic beam is an atomic beam emitted from the atomic furnace inside the Ramsay-type thermal atomic chamber.

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

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

[0028] The first laser beam passes through a beam splitter, and is then introduced into the laser frequency stabilization system through the 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 via an optical switch with a switching period set to a second preset time; including:

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

[0031] This application provides a device and method for generating a Ramsay-type thermal atomic beam optical clock based on periodic pulses. By controlling the duration of the pulsed laser and the period of the optical switch, the interaction time between the laser and atoms can be controlled, thereby improving the utilization rate of atoms in the Ramsay-type thermal atomic beam optical clock. Attached Figure Description

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

[0033] Figure 1 A schematic diagram of the structure of a generation device for a periodic pulse-based Ramsay thermal atomic beam optical clock provided in an embodiment of this application;

[0034] Figure 2 A schematic diagram showing the enhancement ratio between the embodiments of this application and the conventional solution under different pulse times;

[0035] Figure 3 The diagram shows the detuning spectra of the embodiments of this application and the conventional scheme under different pulse times;

[0036] Figure 4 This is a flowchart illustrating a method for generating a Ramsay-type thermal atomic beam optical clock based on periodic pulses, as provided in an embodiment of this application.

[0037] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments.

[0038] Explanation of reference numerals in the attached figures:

[0039] 110 - Pulsed laser; 120 - Laser frequency stabilization system; 130 - Beam splitter; 140 - Optical switch; 150 - Atomic furnace; 160 - Vacuum chamber; 170 - Probe laser; 180 - Photodetector; 190 - Servo feedback controller;

[0040] 210 - First reflector; 220 - Second reflector; 230 - Third reflector; 240 - Fourth reflector. Detailed Implementation

[0041] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of devices and methods consistent with some aspects of this application as detailed in the appended claims, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0042] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0043] In the description of this application, it should be understood that the terms used, including "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", and "outer", are used to indicate orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the equipment or method of this application and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0044] In the specification, claims, and accompanying drawings of this application, 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 such uses of these terms can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein.

[0045] Furthermore, the terms “comprising” and “having”, and any variations thereof, in the description are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or maintenance tool that includes a series of steps or units is not limited to those steps or units that are explicitly listed, but also includes other steps or units that are not explicitly listed or that are inherent to such process, method, product, or maintenance tool.

[0046] It should be noted that "at the time of..." in the embodiments of this application can be either at the instant when a certain situation occurs, or for a period of time after the occurrence of a certain situation. The embodiments of this application do not make specific limitations on this.

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

[0048] Definitions:

[0049] Thermal atomic beam optical clock: a type of laser that uses narrow-linewidth transitions between specific energy levels of a thermal atomic beam (a thermal atomic beam ejected from a hot furnace) 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 a laser beam at its focal point. The location of this minimum diameter is called the "optical waist," which is the smallest cross-section reached by the laser beam after focusing.

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

[0053] Vacuum Chamber: A vacuum chamber consists of a front window and a rear window. The front window is usually located at the front 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 guide the laser, after atomic interactions, out of the vacuum chamber.

[0054] In traditional implementations of thermal atomic clocks, the equipment includes a main laser emitter based on the clock transition wavelength of atoms, 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 into the thermal atom chamber to interact with the atomic beam. The laser detection feedback system is used to monitor the signal changes of the probe laser through the thermal atom chamber and generate feedback signals to adjust the laser frequency so that it remains at the frequency of atomic energy level transitions.

[0055] Traditional hot atom beam optical clock schemes have extremely low atom utilization; only atoms with near-zero transverse velocities can contribute to the final spectral signal. In practical implementation, when atoms interact with the laser, the laser frequency perceived by the atoms changes due to their motion. Atom velocity can be decomposed into longitudinal velocity (the velocity of the atom in the direction it is ejected from the furnace in the vacuum chamber) and transverse velocity (the velocity of the atom in the direction it interacts with the laser beam in the vacuum chamber). Longitudinal velocity does not affect the frequency perceived by the atom, but transverse velocity does. This phenomenon of frequency change due to transverse velocity is called Doppler broadening. This effect prevents atoms with high transverse velocities from participating in the Ramsey process, resulting in wasted atom activity. Reliable data suggests that nearly 99% of hot atoms are wasted because they cannot interact with the laser, limiting the development potential of hot atom beam optical clocks.

[0056] This 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 atoms is controlled. This avoids the non-uniformity of the laser wavefront caused by the compression of the optical waist, further making full use of atoms with different transverse velocity groups, improving the utilization rate of atoms, thereby reducing the quantum projection noise of the optical clock and improving the signal-to-noise ratio of the spectral lines.

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

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

[0059] The pulsed laser 110 is used to emit a first laser with a pulse duration 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. The second laser is delivered to the Ramsey-type thermal atom chamber through the optical switch 140. The switching period of the optical switch 140 is set to a 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 thermal atom chamber is used to output the first atomic beam, which is the atomic beam generated by the interaction between the second laser and the second atomic beam after passing through the optical switch 140. The second atomic beam is the 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 pulsed laser 110, lock the frequency of the pulsed laser 110 to the transition spectrum line of the atom, and obtain the thermal atomic beam optical clock.

[0063] Specifically, the first preset time is on the order of nanoseconds, and the second preset time is on the order of microseconds, with the first preset time being significantly longer than the second preset time. Generally, the first preset time is set to 0 ns to 300 ns, and the second preset time is set to 0 ms to 300 ms.

[0064] In this embodiment, the pulse duration (first preset time) is set by the pulsed laser 110, and the pulse interval (second preset time) is controlled by the optical switch 140 to match the transverse and longitudinal velocity distributions of the atoms, respectively. When the pulse duration of the laser is on the order of nanoseconds and the pulse interval is on the order of microseconds, the velocity distribution of the atoms and the interaction time between the atoms and the laser can be precisely matched. At this time, the atomic utilization rate can be maximized, which improves the signal-to-noise ratio of the Ramsey spectrum obtained by the servo feedback control system and thus improves the stability of the optical clock.

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

[0066] Specifically, the second preset time of the optical switch 140 can be obtained based on the longitudinal velocity of the atoms. Given a vacuum chamber temperature, there exists a most probable longitudinal velocity v0 for the atoms. The pulse interval of the laser pulse can be defined as the laser waist size w divided by the most probable atomic velocity v0. The resulting duration can then match the velocity distribution of the atoms.

[0067] (1)

[0068] Where T2 is the second preset time.

[0069] Specifically, to achieve the maximum output of this scheme, the pulse time should be derived from the transverse velocity of the atoms. Given the vacuum chamber temperature, the Doppler broadening induced by the transverse velocity of the atoms is known. Due to Doppler broadening, it is difficult for atoms to interact with the laser. Therefore, the core of this scheme is to compensate for Doppler broadening by utilizing interaction broadening. Interaction broadening is equivalent to the reciprocal of the interaction time (i.e., the pulse time), i.e., 1 / T1. At a given vacuum chamber temperature, the maximum Doppler broadening is equal to the maximum transverse velocity v of the atoms.zmax Divide by the clock transition wavelength.

[0070] Therefore, the pulse time T1 is equal to the clock transition wavelength divided by the maximum transverse velocity, i.e.

[0071] (2)

[0072] Where T1 is the first preset time and λ is the clock transition wavelength of the atom. It can also be seen from this expression that when the pulse time is shorter, the corresponding Doppler broadening is greater and the number of atoms that can be utilized is greater.

[0073] Preferably, similarly, the first preset time is set as the ratio of the wavelength of the pulsed laser 110 to the maximum transverse velocity of the atom.

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

[0075] Specifically, the laser light received by the pulsed laser 110 is split into two beams. One beam is guided to the laser frequency stabilization system 120 through the first output terminal. The laser frequency stabilization system 120 outputs a pre-stabilized signal value to the pulsed laser 110. The pulsed laser 110 emits a second laser light with pre-stabilized frequency. The other beam is guided to the optical switch 140 through the second output terminal 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 linewidth while pre-stabilizing the pulsed laser 110.

[0077] Furthermore, the Ramsey-type thermal atom chamber includes a vacuum chamber 160, an atom furnace 150, and a mirror assembly, wherein:

[0078] The atomic furnace 150 and the reflector assembly are located at the front window of the vacuum chamber 160; the atomic furnace 150 is used to eject the atomic beam to the rear window of the vacuum chamber 160; the reflector assembly 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 140.

[0079] Specifically, by setting up the light-emitting mirror group, the direction of the four parallel laser beams should be perpendicular to the direction of the atomic beam; then the direction of the path of the second atomic beam ejected from the atomic furnace 150 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 one implementation method, such as Figure 1 The reflector assembly may include a first reflector 210, a second reflector 220, a third reflector 230, and a fourth reflector 240. The first and second reflectors 210 and 220 are positioned on one side of the atomic beam path, while the third and fourth reflectors 230 are positioned on the other side of the atomic beam. The first reflector 210 is positioned at a 45-degree angle to the atomic beam direction near the furnace 150, the second reflector 220 is positioned at a -45-degree angle to the atomic beam direction, and the third reflector 230 is positioned near the atomic beam direction... The direction of the atomic furnace 150 is 45 degrees to the direction of the atomic beam, and the fourth reflector 240 is also 45 degrees to the direction of the atomic beam. After passing through the optical switch 140, the second laser can enter the vacuum chamber 160 from the other side of the atomic beam. 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 within the vacuum chamber 160 can be set to conventional or typical values ​​to achieve a thermal atomic beam optical clock;

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

[0083] Furthermore, the wavelength of the pulsed laser 110 is the clock transition wavelength of atoms within a Ramsay-type hot atom.

[0084] Specifically, the optical clock obtained can be a cesium atomic clock, a rubidium atomic clock, a strontium atomic clock, a ytterbium atomic clock, an aluminum atomic clock, and a calcium atomic clock, etc. Correspondingly, the atomic furnace 150 of the above atoms and the clock transition wavelength of the atoms need to be used. For example, the clock transition wavelength of calcium atoms 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 in sequence to the servo feedback controller 190 and the pulsed laser 110.

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

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

[0088] For example, the wavelengths at the probe state energy levels corresponding to calcium atoms are 423 nm or 431 nm.

[0089] Specifically, the second laser, after passing through the optical switch 140, interacts with the second atomic beam in the vacuum chamber 160 to generate Ramsay lines. A probe laser 170 emits a probe laser, which is used to detect the Ramsay lines in the rear window. A photodetector 180 obtains the Ramsay lines by detecting the number of atoms at the probe state energy level related to the clock transition energy level. Because the interaction time matches the atomic velocity distribution, the atomic utilization rate is greatly improved, thus significantly increasing the signal-to-noise ratio of the obtained Ramsay lines. The photodetector 180 inputs the spectral line signal to a servo feedback controller 190, which controls the laser to lock its frequency onto the atomic transition lines.

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

[0091] Furthermore, in the embodiments of this application, there are no restrictions on the placement and orientation of devices such as the pulsed 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 devices to achieve interconnection between the above devices through optical paths.

[0092] Figure 2 This diagram illustrates the spectral amplitude enhancement ratio between the embodiments of this application and conventional solutions at different pulse times. Figure 3 The diagram shows the detuning spectral lines of the embodiments of this application and the conventional scheme under different pulse times.

[0093] Specifically, Figure 2 and Figure 3 The simulation parameters are as follows: the wavelength of the pulsed laser 110 is set to 657nm, a 423nm wavelength probe laser is used, and the atomic furnace 150 is a calcium atomic furnace. The temperature inside its vacuum chamber 160 is set to 600℃, at which point the most probable longitudinal velocity of calcium atoms is 610 m / s, and the transverse velocity is approximately between -70 m / s and 70 m / s (Doppler broadening is approximately 100 MHz). The laser beam waist width is set to 0.6 mm.

[0094] according to Figure 2 It can be seen that when the pulse time is reduced to the order of 1 nanosecond, almost all atoms are utilized, resulting in the largest amplitude. Further reduction in pulse time yields almost no change in amplitude. At this point, the maximum amplitude enhancement ratio is approximately 2500, meaning that compared to the traditional method, the amplitude is increased by three orders of magnitude. Furthermore, according to the stability calculation formula, the stability is improved by two orders of magnitude.

[0095] like Figure 3 It is known that using traditional methods, the interaction time can only be reduced by decreasing the optical waist size. A typical optical waist size is 0.6 mm, corresponding to an interaction time of 1 microsecond. Further reducing the optical waist size (to reduce the interaction time) leads to non-uniformity in the laser wavefront, which is detrimental to increasing the spectral amplitude. However, using the implementation method of this application, when the pulse time is reduced, more atoms are compensated for by interaction broadening, resulting in a larger spectral amplitude. According to the above formula, the time of the optical switch 140 (the second preset time) is approximately 1 microsecond, while the pulse time (the first preset time) is set to 1 nanosecond. At this point, the pulse time and the optical switch 140 time are matched with the transverse and longitudinal velocity distribution of the atoms, maximizing the utilization of atoms (almost all atoms with transverse velocities are utilized), ultimately yielding the best results.

[0096] This application provides a device for generating a Ramsay-type thermal atomic beam optical clock based on periodic pulses, comprising: a pulsed laser 110, a laser frequency stabilization system 120, an optical switch 140, a Ramsay-type thermal atomic chamber, and a laser detection feedback system. The pulsed laser 110 emits a first laser with a pulse duration of a first preset time. The laser frequency stabilization system 120 pre-stabilizes the first laser to obtain a second laser. The second laser is transmitted to the Ramsay-type thermal atomic chamber via the optical switch 140. The switching period of the optical switch 140 is set to a second preset time. The first preset time is set between 0 ns and 300 ns. The second preset time is set between 0 ms and 300 ms. The Ramsay-type thermal atomic chamber outputs a first atomic beam. The laser detection feedback system detects the first atomic beam and generates a servo feedback signal to the pulsed laser 110, locking the frequency of the pulsed laser 110 onto the atomic transition lines to obtain the thermal atomic beam optical clock. This device offers the following technical advantages:

[0097] In this embodiment, the pulse time of the pulsed 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 on the order of nanoseconds and the second preset time is on the order of microseconds, the interaction between the first preset time and the second preset time can produce interaction broadening to compensate for Doppler broadening. This can avoid the non-uniformity of the laser wavefront caused by the compression of the optical waist width, further make full use of atoms of different transverse velocity groups, improve the atomic utilization rate, reduce the quantum projection noise of the optical clock, and improve the signal-to-noise ratio of the spectral lines.

[0098] The first and second preset times determined by the above formulas (1) and (2) can accurately match the pulse time and pulse interval time with the atomic velocity distribution, thereby maximizing the atomic utilization rate of the spectral lines.

[0099] Figure 4 This application provides a method for generating a Ramsey-type thermal atomic beam optical clock based on periodic pulses, such as... Figure 4 As shown, this method is implemented using the aforementioned generation device of a Ramsay-type thermal atomic beam optical clock based on periodic pulses. The method includes:

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

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

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

[0103] Specifically, the first laser beam passes through a beam splitter, and the first output optical path of the beam splitter is then introduced into the laser frequency stabilization system 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 with a switching cycle set to the second preset time;

[0105] Specifically, the second laser passes through a beam splitter, and its second output optical path is then introduced into the Ramsey-type thermal atom chamber.

[0106] The first atomic beam is produced by the interaction between the second laser and the second atomic beam output from the S440 Ramsay-type thermal atomic chamber. The second atomic beam is the atomic beam emitted by the atomic furnace inside the Ramsay-type thermal atomic chamber.

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

[0108] The S450 laser detection feedback system emits a detection laser to detect the first atomic beam, generating a servo feedback signal to the pulsed laser, locking the frequency of the pulsed laser to the transition lines of the atoms, and obtaining the thermal atomic beam optical clock.

[0109] Specifically, the laser detection feedback system receives the third laser after the interaction between the first atomic beam and the detection laser at the rear window of the vacuum chamber. The photodetector obtains the Ramsey spectral line by detecting the number of atoms on the detection state energy level that is 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, locking the frequency of the pulse laser to the transition spectral line of the atom, thereby obtaining the thermal atomic beam optical clock.

[0110] This application provides a method for generating a Ramsay-type thermal atomic beam optical clock based on periodic pulses, which is used in the aforementioned device for generating a Ramsay-type thermal atomic beam optical clock based on periodic pulses. The implementation principle and technical effects are similar, and will not be described in detail here.

[0111] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0112] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the 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, Ramsay-type hot atom chamber, and laser detection feedback system, among which: The pulsed laser is used to emit a first laser with a pulse duration of a first preset time. The laser frequency stabilization system is used to pre-stabilize the first laser to obtain a second laser. The second laser is transmitted to the Ramsey-type thermal atom chamber through the optical switch. The switching period of the optical switch is set to a second preset time. The first preset time is set to 0 ns to 300 ns. The value of the second preset time is set to 0 ms to 300 ms. The Ramsey-type thermal atom chamber is used to output a first atomic beam, which is the atomic beam resulting from the interaction between the second laser and the second atomic beam after the second laser passes through the optical switch, and the second atomic beam is the atomic beam emitted by the atomic furnace. The laser detection feedback system is used to detect the first atomic beam, generate a servo feedback signal to the pulsed laser, lock the frequency of the pulsed laser to the transition lines of the atoms, and obtain a thermal atomic beam optical clock.

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

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

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

5. The device according to any one of claims 1-3, characterized in that, The Ramsey-type thermal atom chamber includes a vacuum chamber, an atom furnace, and a mirror assembly, wherein: The atomic furnace and the reflector assembly are located at the front window of the vacuum chamber; The atomic furnace is used to spray an atomic beam into 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 includes a detection laser, a photodetector, 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 detection laser light through the rear window of the vacuum chamber to the photodetector, and the photodetector is connected in sequence to the servo feedback controller and the pulsed laser.

7. The device according to any one of claims 1-3, characterized in that, The wavelength of the pulsed laser is the clock transition wavelength of the atoms within the Ramsay-type thermal atom.

8. The device according to any one of claims 6, characterized in that, The wavelength of the probe laser is the same as 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 using the apparatus described in any one of claims 1-8, and includes: The pulsed laser emits a first laser pulse with a first preset time. The first laser obtains a pre-stabilization feedback signal through a laser frequency stabilization system, and the pulsed laser emits a second laser according to the pre-stabilization feedback signal. The second laser is the first laser after pre-stabilization. The second laser is introduced into the Ramsey-type thermal atom chamber via an optical switch with a switching period set to a second preset time; The Ramsay-type thermal atomic chamber outputs a first atomic beam resulting from the interaction between the second laser and the second atomic beam, wherein the second atomic beam is an atomic beam emitted from the atomic furnace inside the Ramsay-type thermal atomic chamber. The laser detection feedback system emits a detection laser to detect the first atomic beam, generates a servo feedback signal to the pulsed laser, locks the frequency of the pulsed laser to the transition lines of the atoms, and obtains a thermal atomic beam optical clock.

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

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