CN111900982A - Ultra-long free evolution time cold atom frequency standard device and method - Google Patents
Ultra-long free evolution time cold atom frequency standard device and method Download PDFInfo
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Abstract
The invention discloses a device and a method for a cold atomic frequency standard with ultra-long free evolution time, relates to the technical field of cold atomic frequency standards, and aims to solve the problems that the free evolution time of cold atoms is limited and the stability index of the cold atomic frequency standard is limited in the existing mode. Wherein the device includes: the cold atom preparation device is used for preparing high-energy-state cold atoms with vertical upward speed; the cold atom transition component is used for transitioning the high-energy-state cold atoms into low-energy-state cold atoms and providing microwave pulses for the low-energy-state cold atoms; the grating assembly traps the low-energy-state cold atoms and limits the spatial displacement and diffusion of the low-energy-state cold atoms until the rising speed of the low-energy-state cold atoms becomes zero; the cold atom transition component carries out secondary microwave pulse on cold atoms which freely fall into the cold atom transition component; the signal collector collects the energy state distribution of the prepared high-energy state cold atoms; collecting a microwave frequency signal contained by a cold atom free falling through the cold atom transition assembly.
Description
Technical Field
The invention relates to the technical field of cold atom frequency standard, in particular to an ultra-long free evolution time cold atom frequency standard device and method.
Background
The cold atom frequency standard mainly utilizes the interaction of a separation oscillation field between cold atoms and microwaves to generate a frequency discrimination curve, so that a local oscillator outputs a frequency signal with high stability and high accuracy. The line width of the central stripe of the frequency discrimination curve is inversely proportional to the free evolution time of the cold atom, and the stability of the output frequency of the local oscillator is inversely proportional to the line width of the central stripe, namely the stability of the output frequency of the local oscillator is directly proportional to the free evolution time of the cold atom. Therefore, the free evolution time is used as an important physical quantity of the cold atom frequency standard, and the stability index of the cold atom frequency is fundamentally determined. At present, effectively improving the stability of cold atom frequency by increasing free evolution time is one of important means for the development of cold atom frequency standard.
In the existing scheme for increasing the free evolution time of cold atoms, the coherence can be gradually weakened along with the time due to the diffusion of cold atomic groups, and the state enters a decoherence state. Therefore, the free evolution time of the cold atoms is limited, and the further improvement of the stability index of the cold atom frequency standard is limited.
Disclosure of Invention
The invention aims to provide a device and a method for a cold atom frequency standard with ultra-long free evolution time, which are used for prolonging the limited free evolution time of cold atoms and improving the stability index of the cold atom frequency standard.
In order to achieve the above purpose, the invention provides the following technical scheme:
the utility model provides a cold atomic frequency standard device of overlength free evolution time, includes: the cold atom preparation device, the cold atom transition assembly, the signal collector and the optical lattice assembly are arranged in the vacuum cavity;
the cold atom preparation device is used for preparing high-energy-state cold atoms with vertical upward speed;
the cold atom transition component is used for transitioning the high-energy-state cold atoms into low-energy-state cold atoms and providing microwave pulses for the low-energy-state cold atoms;
the grating assembly is used for trapping the low-energy-state cold atoms, limiting the spatial displacement and diffusion of the low-energy-state cold atoms until the rising speed of the low-energy-state cold atoms becomes zero, and enabling the low-energy-state cold atoms to fall freely;
the cold atom transition assembly is used for carrying out secondary microwave pulse on cold atoms which freely fall into the cold atom transition assembly;
the signal collector is used for collecting the energy state distribution of cold atoms entering the cold atom transition assembly upwards; and is also used for collecting microwave frequency signals contained by cold atoms which freely fall through the cold atom transition assembly.
Compared with the prior art, the ultra-long free evolution time cold atom frequency standard device provided by the invention can realize the separation oscillating field effect of repeated cold atoms and microwaves by repeatedly trapping the cold atoms through the optical lattices in the periodic time sequence operation process, so that a clock signal is generated to lock the output frequency of the local oscillator. The cold atoms are effectively trapped in the photo lattices by utilizing the photo lattice trapping technology, so that the thermal diffusion process is effectively limited, and the aim of increasing the free evolution time of the cold atoms is fulfilled. The obtained central stripe of the frequency discrimination curve has the characteristic of ultra-narrow line width, and the whole clock can finally output a frequency signal with ultra-high frequency stability and accuracy through closed-loop locking. The device not only can reduce the diffusion effect of cold radicals, but also solves the problems of short free evolution time, large width of the central fringe line of a frequency discrimination curve and the like in the prior art, has simple structure, is easy to realize, can reduce the volume and the weight of a whole physical system, and has low material and processing cost and reasonable method.
The invention also provides a method for the ultra-long free evolution time cold atom frequency standard, which comprises the following steps:
preparing high energy state cold atoms with a vertical upward velocity;
collecting the energy state distribution of the high-energy state cold atoms;
transferring the high-energy-state cold atoms into low-energy-state cold atoms, and providing microwave pulses for the low-energy-state cold atoms;
trapping the low-energy-state cold atoms, and limiting the spatial displacement and diffusion of the low-energy-state cold atoms until the rising speed of the low-energy-state cold atoms becomes zero and the low-energy-state cold atoms fall freely;
performing secondary microwave pulse on the free falling cold atoms;
and collecting microwave frequency signals contained in the cold atoms after the secondary microwave pulse.
Compared with the prior art, the beneficial effects of the ultra-long free evolution time-cooled atomic frequency standard method provided by the invention are the same as the beneficial effects of the ultra-long free evolution time-cooled atomic frequency standard device in the technical scheme, and the details are not repeated herein.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic block diagram of an ultra-long free-evolution time-cooled atomic frequency standard device according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart of a method for ultra-long free evolution time-cooled atomic frequency scaling according to an embodiment of the present invention;
fig. 3 is a schematic timing diagram illustrating the operation of the ultra-long free evolution time-cooling atomic frequency standard method according to the embodiment of the present invention.
Reference numerals:
1-is an atom source, 2-a vacuum cavity, 3-a laser, 4-an upper polished beam, 5-a magneto-optical trap cooling group, 6-a state selection cavity, 7-a microwave cavity, 8-a signal collector, 9-an optical lattice component, 10-cold atoms and 11-an axial central line.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise. The meaning of "a number" is one or more unless specifically limited otherwise.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
The cold atom frequency standard mainly utilizes the interaction of a separation oscillation field between cold atoms and microwaves to generate a frequency discrimination curve, so that a local oscillator outputs a frequency signal with high stability and high accuracy. The line width of the central stripe of the frequency discrimination curve is inversely proportional to the free evolution time of the cold atom, and the stability of the output frequency of the local oscillator is inversely proportional to the line width of the central stripe, namely the stability of the output frequency of the local oscillator is directly proportional to the free evolution time of the cold atom. Therefore, the free evolution time is used as an important physical quantity of the cold atom frequency standard, and the stability index of the cold atom frequency is fundamentally determined. At present, effectively improving the stability of cold atom frequency by increasing free evolution time is one of important means for the development of cold atom frequency standard.
The existing technical schemes for increasing the free evolution time of cold atoms mainly comprise two schemes, one is a space free falling body scheme, and the other is a free evolution scheme of cold atoms. The first scheme is applied to a cold atom fountain clock, when cold atoms are prepared and selected, the cold atoms have a certain upward throwing speed in the vertical direction through a laser beam, enter a free falling body motion state, and are in a free evolution stage in two processes of upward throwing and falling of the free falling body; the second scheme is applied to an integrating sphere cold atomic clock, when the cold atoms are prepared and the state selection is completed, the cold atoms are kept in situ, the microwave pulse is closed, and the cold atomic groups are in a free evolution stage in the free diffusion process. In both schemes, the coherence gradually decreases with time due to the diffusion of cold radicals, and enters a decoherence state. Therefore, the free evolution time of cold atoms is limited, wherein the free evolution time of the two schemes is about 1s and 20ms respectively. Namely, the two schemes have the defects of high diffusion speed of cold atomic groups, short free evolution time, large width of central fringe lines of a frequency discrimination curve and the like, and simultaneously limit the further improvement of the stability index of the cold atomic frequency standard.
With reference to fig. 1 in detail, the ultra-long free evolution time-cooled atomic frequency standard device provided by the embodiment of the present invention includes: a cold atom preparation device, a cold atom transition component, a signal collector 8 and a light lattice component 9 which are arranged in the vacuum cavity 2;
a cold atom preparation device for preparing high-energy-state cold atoms with a vertical upward velocity;
the cold atom transition assembly is used for transitioning the cold atoms in the high energy state into cold atoms in the low energy state and providing microwave pulses for the cold atoms in the low energy state;
the grating assembly is used for trapping low-energy-state cold atoms, limiting the spatial displacement and diffusion of the low-energy-state cold atoms until the rising speed of the low-energy-state cold atoms becomes zero and the low-energy-state cold atoms fall freely;
the cold atom transition assembly is used for carrying out secondary microwave pulse on cold atoms which freely fall into the cold atom transition assembly;
the signal collector 8 is used for collecting the energy state distribution of the prepared high-energy-state cold atoms; and is also used to collect the microwave frequency signal contained by the cold atoms that are free falling through the cold atom transition assembly.
In the specific implementation:
during the operation of the ultra-long free evolution time-cooled atomic frequency standard device, the corresponding operation is executed at the corresponding stage according to the clock cycle running time sequence. According to the clock cycle operation permission, the device operation steps and operations are as follows: the cold atom producing device produces cold atoms 10 having a high energy state with a vertical upward velocity; the signal collector 8 collects the energy state distribution of the high-energy state cold atoms; the cold atom transition component is used for transitioning the cold atoms in the high energy state into cold atoms in the low energy state and providing microwave pulses for the cold atoms in the low energy state; the grating assembly traps the low-energy-state cold atoms, limits the spatial displacement and diffusion of the low-energy-state cold atoms until the rising speed of the low-energy-state cold atoms becomes zero, and falls freely; the cold atom transition component carries out secondary microwave pulse on the cold atoms falling freely; the signal collector 8 collects microwave frequency signals contained in the cold atoms after the secondary microwave pulse.
Compared with the prior art, the ultra-long free evolution time cold atom frequency standard device provided by the invention can realize the separation oscillating field effect of repeated cold atoms and microwaves by repeatedly trapping the cold atoms through the optical lattices in the periodic time sequence operation process, so that a clock signal is generated to lock the output frequency of the local oscillator. The cold atoms are effectively trapped in the photo lattices by utilizing the photo lattice trapping technology, so that the thermal diffusion process is effectively limited, and the aim of increasing the free evolution time of the cold atoms is fulfilled. The obtained central stripe of the frequency discrimination curve has the characteristic of ultra-narrow line width, and the whole clock can finally output a frequency signal with ultra-high frequency stability and accuracy through closed-loop locking. The device not only can reduce the diffusion effect of cold atoms and solve the problems of short free evolution time, large width of the central stripe line of a frequency discrimination curve and the like in the prior art, but also has simple structure, easy realization, low volume and weight of the whole physical system, low material and processing cost and reasonable method,
as an implementable manner, the cold atom preparation apparatus includes an atom source 1, a laser 3, and a magneto-optical trap cooling assembly 5;
an atom source 1 for providing atoms;
the magneto-optical trap cooling assembly 5 is used for cooling the atoms provided by the atom source 1 to finish the preparation of cold atoms 10;
and the laser 3 is used for projecting the cold atoms 10 in the vertical direction, providing the speed of the static cold atoms moving in the vertical direction and converting the static cold atoms into high-energy-state cold atoms.
Firstly, the magneto-optical trap cooling assembly 5 cools the atoms provided by the atom source 1, and the atoms are cooled to uK magnitude and loaded into cold atoms 10, and the cold atoms are static cold atoms. The laser 3 provides the upper polishing beam 4 for the cold atoms 10, the cold atoms 10 obtain a certain macroscopic longitudinal speed under the action of the upper polishing beam 4 and move vertically upwards, at the moment, the cold atoms 10 are converted into high-energy-state cold atoms with energy efficiency, and the high-energy-state cold atoms continue to move vertically upwards under the action of self inertia.
As an implementable manner, the atomic transition assembly comprises a state selection cavity 6 and a microwave cavity 7;
the state selection cavity 6 is used for providing a microwave oscillation field corresponding to the ground state energy level of the high-energy-state cold atoms for the entering high-energy-state cold atoms and preparing the high-energy-state cold atoms to a low-energy state;
and the microwave cavity 7 is used for providing a microwave field for the entering low-energy-state cold atoms and separating the oscillation effect carried by the low-energy-state cold atoms after passing through the state selection cavity 6.
As an implementation mode, the laser 3, the magneto-optical trap cooling assembly 5, the state selection cavity 6, the microwave cavity 7 and the optical lattice assembly 9 are sequentially arranged from bottom to top along the axial center line 11 of the vacuum cavity 2.
The laser 3, the magneto-optical trap cooling assembly 5, the state selection cavity 6, the microwave cavity 7 and the optical lattice assembly 9 are arranged along the axial central line 11 of the vacuum cavity 2, so that when cold atoms 10 move in the vertical direction, the cold atoms can sequentially pass through the magneto-optical trap cooling assembly 5, the state selection cavity 6, the microwave cavity 7 and the optical lattice assembly 9, and the accuracy of final detection data is ensured.
As an implementation, the magneto-optical trap cooling assembly 5 includes an anti-helmholtz coil and 6 laser beams, the center line of the vacuum chamber 2 passes through the center of the anti-helmholtz coil, and the 6 laser beams are uniformly distributed around the anti-helmholtz coil.
Furthermore, the temperature of atoms after being cooled by the magneto-optical trap cooling assembly is of the uK magnitude.
6 even settings of beam bundle are at anti Helmholtz coil, have ensured the cooling effect of magneto-optical trap cooling module 5 to the atom, can reduce the atom temperature to the uK order of magnitude, have guaranteed to accord with the preparation of temperature condition cold atom 10.
Further, the vacuum chamber 2 has a cylindrical hollow structure.
The vacuum cavity with the columnar hollow structure can better reasonably arrange the positions of internal components, and is simpler when a central line is determined.
Specifically, the method comprises the following steps: wherein, the atom source 1 provides cold atoms 10, and the vacuum cavity 2 provides a high vacuum environment for atom storage, so as to avoid the interference of redundant impurity gas to atoms; the magneto-optical trap cooling assembly 5 consists of 6 beams of laser and an anti-Helmholtz coil, and can cool the atom temperature to uK magnitude order to complete the preparation of cold atoms 10; the state selecting cavity 6 provides cold atoms 10 with corresponding micro ground state energy levelA wave oscillating field for preparing cold atoms in a high energy state to a corresponding low energy state by interacting with the cold atoms 10; the microwave cavity 7 provides a microwave field required for atom and microwave to carry out separated oscillation field interaction; the upper polishing beam 4 propels the prepared cold atoms 10 in a vertical direction along the axial center line 11 of the device to obtain a certain speed macroscopically, so that the cold atoms 10 can move upwards and enter the optical lattice component. The signal collector 88 can detect the energy state population of the cold atoms 10; the photo-lattice assembly 9 is composed of a laser beam of a specific wavelength according to the principle of interference, and cold atoms 10 are trapped in the photo-lattice for a long time to 10 according to dipole force induced by the atoms1s magnitude, limiting its spatial displacement and diffusion.
Referring to fig. 2 in detail, the present invention also provides a method for ultra-long free evolution time-cooled atomic frequency standard, which applies an ultra-long free evolution time-cooled atomic frequency standard device, comprising:
preparing high energy state cold atoms with a vertical upward velocity;
collecting the energy state distribution of the high-energy state cold atoms;
transferring the high-energy-state cold atoms into low-energy-state cold atoms, and providing microwave pulses for the low-energy-state cold atoms;
trapping the low-energy-state cold atoms, and limiting the spatial displacement and diffusion of the low-energy-state cold atoms until the rising speed of the low-energy-state cold atoms becomes zero and the low-energy-state cold atoms fall freely;
performing secondary microwave pulse on the free falling cold atoms;
and collecting microwave frequency signals contained in the cold atoms after the secondary microwave pulse.
The overlength free evolution time cold atom frequency scaling method provided by the invention can realize the repeated separation oscillation field effect of cold atoms and microwaves by repeatedly trapping the cold atoms in the periodic time sequence operation process, and further generate a clock signal to lock the output frequency of the local oscillator. The cold atoms are effectively trapped by the photo-lattice trapping technology, the thermal diffusion process is limited, and the purpose of increasing the free evolution time of the cold atoms is achieved. The obtained central stripe of the frequency discrimination curve has the characteristic of ultra-narrow line width, and the whole clock can finally output a frequency signal with ultra-high frequency stability and accuracy through closed-loop locking. The method can not only reduce the diffusion effect of cold atomic groups and solve the problems of short free evolution time, large width of the central fringe line of a frequency discrimination curve and the like in the prior art, but also has simple device structure, easy realization, low volume and weight of the whole physical system, low material and processing cost and reasonable method,
as an embodiment, the preparation of high energy state cold atoms with a vertical upward velocity comprises:
cooling the received atoms to finish the preparation of cold atoms;
and (3) projecting the cold atoms in the vertical direction, providing a vertical movement speed for the static cold atoms, and converting the static cold atoms into high-energy-state cold atoms.
Firstly, the magneto-optical trap cooling assembly cools atoms provided by an atom source, the atoms are cooled to uK magnitude and loaded into cold atoms, and the cold source atoms are static cold atoms. The laser provides an upward polishing beam for cold atoms, the cold atoms obtain a certain macroscopic longitudinal speed under the action of the upward polishing beam and move vertically upwards, the cold atoms at the moment are converted into high-energy-state cold atoms with energy efficiency, and the high-energy-state cold atoms continue to move vertically upwards under the action of self inertia.
As an embodiment, the method for transferring cold atoms in high energy state to cold atoms in low energy state and providing microwave pulses for cold atoms in low energy state includes:
providing a microwave oscillating field corresponding to the ground state energy level of the high-energy cold atoms for the entering high-energy cold atoms, and preparing the high-energy cold atoms to a low-energy state;
providing a microwave field for the entering low-energy-state cold atoms, and separating the oscillation effect carried by the low-energy-state cold atoms after passing through the microwave oscillation field.
Cold atoms in an upward motion state can enter a state selection cavity, the state selection cavity provides a microwave oscillation field corresponding to the cold atom ground state energy level, and the cold atoms are prepared to corresponding low energy states through interaction with the cold atoms; the microwave cavity provides the microwave field required for the atoms to undergo separate oscillating field interactions with the microwaves, with which the first microwave pulse interaction is performed.
Specifically, the method comprises the following steps: the operation time sequence of the ultra-long free evolution time-cooling atomic frequency standard method is shown in figure 3. In the operating period TCIn the first place, the magneto-optical trap is cooled for a time T1In the method, a magneto-optical trap cools atoms to a uK magnitude to prepare cold atomic groups, and the cold atoms obtain a certain macroscopic longitudinal speed and move upwards under the action of an upper polishing beam; the cold radicals in the upward motion state will be in the phase selection time T2Completing the state population of the desired energy level, followed by time T3The first microwave pulse interaction with the microwave field is completed; the cold radicals that have completed the first pulsed microwave interaction will peak at the photo-lattice and be trapped by the photo-lattice for a time T4(ii) a The internal state of the cold atom in the caged state can enter a free evolution stage without external interference, and the cold atom group has no heat diffusion effect; after the photolattice trapping process is finished, the cold atoms begin to fall freely under the action of gravity, and in the falling process, the cold atoms can fall at the time T4Performing a second microwave pulse interaction with the microwave field in the microwave cavity; the atomic internal state in the cold atomic group which completes the second microwave pulse interaction comprises the frequency deviation information of the microwave; the frequency deviation information may be at the detection time T6And detecting. In the process, the cold atoms are effectively trapped in the optical lattices by the method by using the optical lattice trapping technology, so that the thermal diffusion process is effectively limited, and the aim of increasing the free evolution time of the cold atoms is fulfilled. The central stripe of the frequency discrimination curve obtained by the method has the characteristic of ultra-narrow line width, and the whole clock can finally output a frequency signal with ultra-high frequency stability and accuracy through closed-loop locking.
In the foregoing description of embodiments, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (10)
1. An overlength free evolution time cooling atomic frequency standard device, characterized by, includes: the cold atom preparation device, the cold atom transition assembly, the signal collector and the optical lattice assembly are arranged in the vacuum cavity;
the cold atom preparation device is used for preparing high-energy-state cold atoms with vertical upward speed;
the cold atom transition component is used for transitioning the high-energy-state cold atoms into low-energy-state cold atoms and providing microwave pulses for the low-energy-state cold atoms;
the grating assembly is used for trapping the low-energy-state cold atoms, limiting the spatial displacement and diffusion of the low-energy-state cold atoms until the rising speed of the low-energy-state cold atoms becomes zero, and enabling the low-energy-state cold atoms to fall freely;
the cold atom transition assembly is used for carrying out secondary microwave pulse on cold atoms which freely fall into the cold atom transition assembly;
the signal collector is used for collecting the energy state distribution of the prepared high-energy-state cold atoms; and is also used for collecting microwave frequency signals contained by cold atoms which freely fall through the cold atom transition assembly.
2. The ultra-long free-evolution time-cooled atomic frequency standard device according to claim 1, wherein the cold atom preparation device comprises an atom source, a laser and a magneto-optical trap cooling assembly;
the atom source is used for providing atoms;
the magneto-optical trap cooling assembly is used for cooling the atoms provided by the atom source to complete cold atom preparation;
the laser is used for projecting cold atoms in the vertical direction, providing the speed of motion in the vertical direction for the static cold atoms and converting the static cold atoms into high-energy-state cold atoms.
3. The ultra-long free-evolution time-cooled atomic frequency standard device according to claim 2, wherein the atomic transition assembly comprises a state-selection cavity and a microwave cavity;
the state selection cavity is used for providing a microwave oscillation field corresponding to the ground state energy level of the high-energy-state cold atoms for the entering high-energy-state cold atoms and preparing the high-energy-state cold atoms to a low-energy state;
the microwave cavity is used for providing a microwave field for the entering low-energy-state cold atoms and separating the oscillation effect carried by the low-energy-state cold atoms after passing through the state selection cavity.
4. The apparatus according to claim 3, wherein the laser, the magneto-optical trap cooling assembly, the state selection cavity, the microwave cavity and the optical lattice assembly are sequentially arranged from bottom to top along an axial center line of the vacuum cavity.
5. The apparatus according to claim 1, wherein the magneto-optical trap cooling assembly comprises an anti-helmholtz coil and 6 lasers, a center line of the vacuum chamber passes through a center of the anti-helmholtz coil, and the 6 lasers are uniformly distributed around the anti-helmholtz coil.
6. The apparatus according to claim 5, wherein the temperature of atoms cooled by the magneto-optical trap cooling assembly is of the order of uK.
7. The apparatus of claim 1, wherein the vacuum chamber is a cylindrical hollow structure.
8. A method for ultra-long free-evolution time-cooled atomic frequency standard, which is characterized by applying the apparatus for ultra-long free-evolution time-cooled atomic frequency standard of any one of claims 1 to 7, comprising:
preparing high energy state cold atoms with a vertical upward velocity;
collecting the energy state distribution of the high-energy state cold atoms;
transferring the high-energy-state cold atoms into low-energy-state cold atoms, and providing microwave pulses for the low-energy-state cold atoms;
trapping the low-energy-state cold atoms, and limiting the spatial displacement and diffusion of the low-energy-state cold atoms until the rising speed of the low-energy-state cold atoms becomes zero and the low-energy-state cold atoms fall freely;
performing secondary microwave pulse on the free falling cold atoms;
and collecting microwave frequency signals contained in the cold atoms after the secondary microwave pulse.
9. The method of ultra-long free-evolution time-cooled atomic frequency standard according to claim 8, wherein the preparing high-energy-state cold atoms with vertical upward velocity comprises:
cooling the received atoms to finish the preparation of cold atoms;
and (3) projecting the cold atoms in the vertical direction, providing a vertical movement speed for the static cold atoms, and converting the static cold atoms into high-energy-state cold atoms.
10. The method for ultra-long free-evolution time-cooled atomic frequency scaling according to claim 9, wherein the step of transitioning the high-energy-state cold atoms into low-energy-state cold atoms and providing microwave pulses to the low-energy-state cold atoms comprises:
providing a microwave oscillating field corresponding to the ground state energy level of the high-energy cold atoms for the entering high-energy cold atoms, and preparing the high-energy cold atoms to a low-energy state;
providing a microwave field for the entering low-energy-state cold atoms, and separating the oscillation effect carried by the low-energy-state cold atoms after passing through the microwave oscillation field.
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| CN120415430A (en) * | 2025-07-04 | 2025-08-01 | 中国计量科学研究院 | A method and system for detecting atomic transitions in a cold atomic microwave clock |
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| CN120415430B (en) * | 2025-07-04 | 2025-11-07 | 中国计量科学研究院 | Method and system for detecting atomic transition in cold atomic microwave clock |
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| CN111900982B (en) | 2022-08-23 |
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