Slotted diffuse reflection laser cooling microwave cavity device

Abstract

The invention provides a slotted diffuse reflection laser cooling microwave cavity device, so as to improve the cold atom utilization rate and further reduce the quantum projection noise, and the device comprises a glass bulb, a slotted tube, a medium ring, a cavity cylinder, a cavity end cover and a coupling ring. The glass bulb is a cylindrical glass bulb and is arranged in the slotted tube, the longitudinal central axis of the glass bulb coincides with the longitudinal central axis of the slotted tube, the height of the glass bulb is the same as that of the slotted tube, a glass bulb inflation end is arranged on the side face of the glass bulb, and an upper laser through hole and a lower laser through hole are formed in the centers of the upper end face and the lower end face of the glass bulb respectively; the slotted pipe is arranged in the medium ring, and a slotted seam is arranged above the slotted pipe to form at least one pole piece; the medium ring is arranged in the cavity cylinder; the cavity cylinder is cylindrical, the cavity end cover is circular and is arranged above the cavity cylinder, a laser through hole is formed in the center of the cavity end cover, and the laser through hole and the laser through hole above the cavity cylinder are coaxial and are the same in size; the coupling ring is arranged in the cavity end cover and penetrates through the cavity end cover.

Description

Technical Field

[0001] The present application relates to the technical field of cold atomic frequency standards, and in particular to a slotted diffuse reflection laser cooling microwave cavity device. Background Art

[0002] Cold atomic frequency standards mainly use the interaction between the separated oscillation field of cold atoms and microwaves to generate a discrimination curve, so that the local oscillator outputs a frequency signal with high stability and high accuracy. Among them, the integrating sphere cold atomic clock is a new type of miniaturized cold atomic clock, which not only has excellent performance advantages such as high stability, high accuracy and low drift rate, but also has a very high engineering value such as small size, light weight and low power consumption. At present, the development trend of integrating sphere cold atomic clocks can be summarized in two aspects: on the one hand, the use of new principles and new methods to continuously improve the accuracy index; on the other hand, the engineering characteristics are compressed through new technologies to achieve ultra-small engineering prototypes. At present, its high-precision index performance is an important scientific issue, especially the frequency stability as the core accuracy feature, which determines the basic service of the above-mentioned major projects and the ability to maintain the level of space exploration.

[0003] However, in terms of frequency stability, quantum projection noise, which is directly related to the number of cold atoms, is currently one of the important physical factors that limit the frequency stability of the whole clock. In the existing technical solutions, spherical or cylindrical microwave cavities are mainly used to form isotropic light fields to diffusely reflect laser cooling of atoms, and to form a uniform microwave oscillation field in the central area only to interact with atoms, and to detect the number of atoms by single-beam absorption detection. In the entire scheme, only the cold atomic clusters in the central area can generate clock signals and be detected, while most of the cold atoms in the non-central area of ​​the microwave cavity, that is, the peripheral area, do not participate in the generation of microwave clock signals, that is, the utilization rate of cold atoms in the microwave cavity is very low. The utilization rate of cold atoms is one of the main factors that limit the frequency stability of the integrating sphere cold atomic clock through quantum projection noise. This leads to the inability of integrating sphere cold atomic clocks to meet the broader and deeper development and application needs of the above-mentioned major projects in the future.

[0004] In view of the above-mentioned distinct application scenarios of integrating sphere cold atomic clocks, research on improving the utilization rate of cold atoms is still in a blank stage. Therefore, it is urgent to develop new solutions and new technologies to improve the utilization rate of cold atoms, thereby reducing quantum projection noise and significantly improving the frequency stability of integrating sphere cold atomic clocks. Summary of the invention

[0005] The embodiment of the present application provides a slotted diffuse reflection laser cooling microwave cavity device to improve the utilization rate of cold atoms, thereby reducing quantum projection noise and significantly improving the frequency stability of an integrating sphere cold atomic clock.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a slotted diffuse reflection laser cooling microwave cavity device, the device comprising: a glass bulb, a slotted tube, a dielectric ring, a cavity tube, a cavity end cover and a coupling ring;

[0008] The glass bulb is a cylindrical glass bulb, which is arranged inside the slotted tube, the longitudinal center axis of the glass bulb coincides with the longitudinal center axis of the slotted tube, the height of the glass bulb is the same as the height of the slotted tube, and a glass bulb inflation end is arranged on the side of the glass bulb, and an upper laser through hole and a lower laser through hole are respectively opened at the center positions of the upper end surface and the lower end surface of the glass bulb;

[0009] The slotted tube is cylindrical and arranged inside the dielectric ring. A slotted seam is arranged above the slotted tube to form at least one pole piece.

[0010] The medium ring is cylindrical and is arranged inside the cavity;

[0011] The cavity tube is cylindrical, the cavity end cover is circular, the cavity end cover is arranged above the cavity tube, and a laser through hole is opened at the center of the cavity end cover, the laser through hole is coaxial with the upper laser through hole and has the same size;

[0012] The coupling ring is arranged inside the cavity end cover and passes through the cavity end cover;

[0013] Wherein, the glass bulb, except for the outer surfaces of the upper laser through hole and the lower laser through hole, and the side surface where the slotted tube and the glass bulb are bonded, are all sprayed with a diffuse reflection coating layer.

[0014] In a possible design solution, the device of the first aspect further includes that the glass bulb is made of quartz material.

[0015] In a possible design scheme, the device of the first aspect further includes that the difference between the inner diameter of the slotted tube and the bottom diameter of the glass bulb is as small as possible, so that the volume of the glass bulb is as large as possible.

[0016] In a possible design solution, the device of the first aspect further includes that the number, width and depth of the slots provided on the slotted tube are adjustable.

[0017] In a possible design solution, the device of the first aspect further includes that the dielectric ring is made of a material with a large dielectric constant.

[0018] In a possible design solution, the device of the first aspect further includes that the height of the dielectric ring is adjustable.

[0019] In a possible design scheme, the device of the first aspect further includes that the cavity tube and the cavity end cover are circumferentially connected and fixed by gluing or mechanical screws.

[0020] In a possible design solution, the device of the first aspect further includes that the coupling ring is made of a coaxial line.

[0021] In a possible design scheme, the device of the first aspect further includes that the upper laser through hole, the lower laser through hole and the laser through hole are circular.

[0022] In a possible design scheme, the device of the first aspect further includes that the diffuse reflection coating layer is a silver layer.

[0023] In the embodiment of the present application, a diffuse reflection coating layer is sprayed on the outer surface of the glass bubble part, and a plurality of grooves are provided above the slotted tube to form a pole piece, and a diffuse reflection coating layer is sprayed on the inner surface of the pole piece. The diffuse reflection coating layer has a certain roughness, which can realize diffuse reflection of the injected laser, forming an isotropic light field to laser cool the atoms; at the same time, the slotted tube and the cavity tube can form a sensing and capacitive structure, forming a large-scale uniform microwave oscillation field inside the microwave cavity, so that the two processes of laser cooling and interaction between cold atoms and microwaves can occur in situ inside the microwave cavity, so that most of the cold atoms after laser cooling can participate in the microwave interaction and detection process, so that most of the cold atoms in the microwave cavity can participate in the generation of clock signals and be detected. This method can greatly improve the utilization rate of cold atoms, thereby reducing quantum projection noise, and significantly improving the frequency stability of the integrating sphere cold atomic clock. In short, the device of the present application can not only reduce the limitation of the quantum projection noise directly related to the number of cold atoms on the frequency stability of the integrating sphere cold atomic clock, but also has a simple structure and is easy to implement, while the material and processing costs are low, the method is reasonable, and it is easy to operate.

[0024] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 Schematic diagram of the structure of the slotted diffuse reflection laser cooling microwave cavity device provided in the embodiment of the present application Figure 1 ;

[0027] Figure 2 Schematic diagram of the structure of the slotted diffuse reflection laser cooling microwave cavity device provided in the embodiment of the present application Figure 2 ;

[0028] Explanation of the reference numerals: 1. glass bulb, 2. glass bulb filling end, 3. diffuse reflection coating layer, 4. slotted tube, 5. slotted seam, 6. pole piece, 7. dielectric ring, 8. cavity tube, 9. cavity end cover, 10. coupling ring, 11. lower laser through hole, 12. upper laser through hole, 13. central axis. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of this specification more clear, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are part of the embodiments of this specification, not all of the embodiments. The components of the embodiments of this specification described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present specification provided in the accompanying drawings is not intended to limit the scope of the present specification to be protected, but merely represents selected embodiments of the present specification. Based on the embodiments in the present specification, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present specification.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0032] In the description of the embodiments of this specification, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the product of the application is usually placed when in use. It is only for the convenience of describing this specification and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on this specification. In addition, if the terms "first", "second", "third", etc. appear, they are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0033] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components must be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0034] In the description of the embodiments of this specification, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this specification can be understood according to specific circumstances.

[0035] A slotted diffuse reflection laser cooling microwave cavity device of the present application is specifically introduced below, which is intended to achieve.

[0036] Figure 1 Schematic diagram of the structure of the slotted diffuse reflection laser cooling microwave cavity device provided in the embodiment of the present application Figure 1 , mainly the overall structure of the microwave cavity; Figure 2 Schematic diagram of the structure of the slotted diffuse reflection laser cooling microwave cavity device provided in this application Figure 2 , mainly a combination structure of a slotted tube 4 and a glass bulb 1. Figure 1 and Figure 2 The device of the present application is described in detail.

[0037] like Figure 1 As shown, the slotted diffuse reflection laser cooling microwave cavity device mainly includes: a glass bulb 1, a slotted tube 4, a dielectric ring 7, a cavity tube 8, a cavity end cover 9 and a coupling ring 10 from the inside to the outside.

[0038] The glass bubble 1 is a cylindrical glass bubble, which is arranged inside the slotted tube 4. The longitudinal center axis of the glass bubble 1 coincides with the longitudinal center axis of the slotted tube 4. The height of the glass bubble 1 is the same as the height of the slotted tube 4. In addition, a glass bubble inflation end 2 is provided on the side of the glass bubble 1, and an upper laser through hole 12 and a lower laser through hole 11 are respectively provided at the center positions of the upper end face and the lower end face of the glass bubble 1.

[0039] The slotted tube 4 is cylindrical and is arranged inside the dielectric ring 7. A slotted seam 5 is arranged above the slotted tube 4 to form at least one pole piece 6.

[0040] The dielectric ring 7 is cylindrical and is arranged inside the cavity 8;

[0041] The cavity tube 8 is cylindrical, the cavity end cover 9 is circular, and the cavity end cover 9 is arranged above the cavity tube 8. In addition, a laser through hole is opened at the center of the cavity end cover 9. The laser through hole is coaxial with the upper laser through hole 12 and has the same size.

[0042] The coupling ring 10 is arranged inside the cavity end cover 9 and passes through the cavity end cover 9;

[0043] The glass bulb 1 is sprayed with a diffuse reflection coating layer 3 except for the outer surfaces of the upper laser through hole 12 and the lower laser through hole 11 , and the side surface where the slotted tube 4 and the glass bulb 1 are attached.

[0044] It can be understood that for the above-mentioned glass bubble, there is a protrusion on the outer side wall of the middle part, which serves as the glass bubble filling end 2, so that in actual operation, a high vacuum environment can be prepared and alkali metal atomic gas, such as rubidium, cesium, etc., can be filled in through the glass bubble filling end 2 to achieve vacuum sealing.

[0045] Optionally, the glass bulb 1 is made of quartz material. Quartz is a natural mineral, usually referring to a crystal composed of silicon dioxide (SiO2). The glass bulb made of this material has strong light transmittance.

[0046] It can be understood that the slotted tube 4 is the core of the microwave cavity, and the slotted tube 4 is arranged inside the dielectric ring 7 and outside the glass bulb 1, and a plurality of slots 5 are arranged on the top of the dielectric ring 7 to form at least one pole piece 6. The specific shape of the pole piece 6 can be referred to Figure 2 understand.

[0047] Optionally, the number, width and depth of the slotted slits 5 provided above the slotted tube 4 are adjustable. By adjusting the number, width and depth of the slotted tubes, the resonant frequency and microwave field mode of the microwave cavity can be adjusted so that the resonant frequency of the microwave cavity is the ground state transition frequency of rubidium atoms, 6.834 GHz, or the ground state transition frequency of cesium atoms, 9.192 GHz.

[0048] Optionally, the difference between the inner diameter of the slotted tube 4 and the bottom diameter of the glass bulb 1 is as small as possible, so that the volume of the glass bulb is as large as possible, so that the glass bulb can store more atoms.

[0049] It should be noted that the longitudinal center axis of the glass bulb 1 coincides with the longitudinal center axis of the slotted tube 4. The position where the longitudinal center axis of the glass bulb 1 coincides with the longitudinal center axis of the slotted tube 4 is Figure 2 The central axis position in.

[0050] It should also be noted that, except for the outer surfaces of the upper laser through hole 12 and the lower laser through hole 11, and the side surface of the slotted tube 4 in contact with the glass bulb 1, the above-mentioned glass bulb 1 is sprayed with a diffuse reflection coating layer 3. The surface area of ​​these diffuse reflection coating layers can diffusely reflect the incident cooling light, re-pumping light and pumping light. The surface area covered by the diffuse reflection coating layer and the silver layer covered area on the inner surface of the pole piece together constitute a laser diffuse reflection interface, which diffusely reflects the incident laser to form an isotropic light field in the glass bulb, thereby realizing laser cooling of the atoms in the glass bulb. In addition, several pole pieces can be formed by grooving. After the inner surface of the pole piece is sandblasted with a silver-plated layer, it will have a certain degree of roughness, which can play two roles: one is to serve as a laser diffuse reflection interface on the pole piece; the other is to serve as a microwave medium surface for microwaves to form an oscillation field in the microwave cavity.

[0051] Optionally, the diffuse reflection coating layer 3 is a silver layer, and considering that there should be no stray magnetic field in the microwave cavity, the silver layer should not contain any magnetic impurities. It should be ensured that the silver layer is firm and does not fall off, and the thickness of the silver layer should be higher than the microwave skin depth to ensure that the microwave signal can oscillate in the microwave cavity to form an oscillating field. Aluminum, titanium dioxide, silver alloy coating (such as silver-copper alloy), etc. can also be selected according to actual conditions, and are not limited here.

[0052] Optionally, the dielectric ring 7 is made of a material with a relatively large dielectric constant, such as barium titanate, lithium niobate, etc. The material with a relatively large dielectric constant is selected to reduce the size of the microwave cavity and facilitate adjustment of the cavity resonance frequency.

[0053] Optionally, the height of the dielectric ring 7 is adjustable, and the resonant frequency and microwave field mode of the microwave cavity can be adjusted by adjusting the height of the dielectric ring 7. Alternatively, the position of the dielectric ring 7 can also be adjusted, and the resonant frequency and microwave field mode of the microwave cavity can also be adjusted. Figure 1 As shown, the height of the dielectric ring is consistent with the height of the cavity tube, or the height of the dielectric ring can be reduced and moved up and down. The specific adjustment is made according to the actual situation and is not limited here.

[0054] It can be understood that the cavity tube 8 is cylindrical and the cavity end cover 9 is circular, and the two are combined to form the external frame of the microwave cavity. The cavity tube 8 and the cavity end cover 9 can be connected and fixed in a circumferential position by gluing or mechanical screws, so that the connection is closed and flat without gaps, and the interior of the microwave cavity has a stable spatial structure. In addition, the size of the cavity tube 8 and the cavity end cover 9 is jointly determined by the glass bulb 1 and the slotted tube 4 inside them.

[0055] It should also be noted that a laser through hole is provided at the center of the cavity end cover 9, which is coaxial with the upper laser through hole 12. The laser through hole is used to detect light passing up and down twice to form a standing wave.

[0056] Optionally, the upper laser through hole 12, the lower laser through hole 11 and the laser through hole are circular, and are used to inject cooling light, re-pumping light, pumping light and detection light, and detect cold atoms. The cooling light, re-pumping light, pumping light and detection light share the lower laser through hole 11, and the detection light needs to be reflected back through the original reflection path above the microwave cavity, so it also needs to pass through the laser through hole of the cavity end cover 9. In addition, the upper laser through hole 12, the lower laser through hole 11 and the laser through hole can also be elliptical, or other possible shapes, which are not limited here.

[0057] Optionally, the coupling ring 10 is made of a coaxial line and is located inside the cavity end cover 9 . It needs to penetrate the cavity end cover 9 . The microwave signal can be fed into the microwave cavity through the coupling ring 10 .

[0058] In summary, the slotted diffuse reflection laser cooling microwave cavity device provided in the embodiment of the present application forms a pole piece by spraying a diffuse reflection coating layer on the outer surface of the glass bubble part, and providing a plurality of slots above the slotted tube, spraying a diffuse reflection coating layer on the inner surface of the pole piece, and the diffuse reflection coating layer has a certain roughness, which can realize diffuse reflection of the injected laser, forming an isotropic light field to laser cool the atoms; at the same time, the slotted tube and the cavity tube can form a sensing and capacitive structure, forming a large-scale uniform microwave oscillation field inside the microwave cavity, that is, the two processes of laser cooling and interaction between cold atoms and microwaves can occur in situ inside the microwave cavity, so that most of the cold atoms after laser cooling can participate in the microwave interaction and detection process, so that most of the cold atoms in the microwave cavity can participate in the generation of clock signals and be detected. This method can greatly improve the utilization rate of cold atoms, thereby reducing quantum projection noise, and significantly improve the frequency stability of the integrating sphere cold atomic clock. In summary, the device of the present application can not only reduce the limitation of quantum projection noise directly related to the number of cold atoms on the frequency stability of the integrating sphere cold atomic clock, but also has a simple structure and is easy to implement. At the same time, the material and processing costs are low, the method is reasonable, and it is easy to operate.

[0059] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present application as above, which are not provided in detail for the sake of simplicity.

[0060] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A slotted diffuse reflection laser cooling microwave cavity device, characterized in that: The device comprises: a glass bulb, a slotted tube, a dielectric ring, a cavity tube, a cavity end cover and a coupling ring; The glass bubble is a cylindrical glass bubble, and the glass bubble is arranged inside the slotted tube. The longitudinal center axis of the glass bubble coincides with the longitudinal center axis of the slotted tube, and the height of the glass bubble is the same as the height of the slotted tube. In addition, a glass bubble inflation end is provided on the side of the glass bubble, and an upper laser through hole and a lower laser through hole are respectively provided at the center positions of the upper end surface and the lower end surface of the glass bubble; The slotted tube is cylindrical and arranged inside the dielectric ring. A slotted seam is arranged above the slotted tube to form at least one pole piece. The medium ring is cylindrical and is arranged inside the cavity; The cavity tube is cylindrical, the cavity end cover is circular, the cavity end cover is arranged above the cavity tube, and a laser through hole is opened at the center of the cavity end cover, the laser through hole is coaxial with the upper laser through hole and has the same size; The coupling ring is arranged inside the cavity end cover and passes through the cavity end cover; Wherein, the glass bulb, except for the outer surface of the upper laser through hole and the lower laser through hole, and the side surface where the slotted tube and the glass bulb are bonded, are all sprayed with a diffuse reflection coating layer.

2. The slotted diffuse reflection laser cooling microwave cavity device according to claim 1, characterized in that: The glass bulb is made of quartz material.

3. The slotted diffuse reflection laser cooling microwave cavity device according to claim 1, characterized in that: The difference between the inner diameter of the slotted tube and the bottom diameter of the glass bubble is as small as possible, so that the volume of the glass bubble is as large as possible.

4. The slotted diffuse reflection laser cooling microwave cavity device according to claim 1, characterized in that: The number, width and depth of the slots provided on the top of the slotted tube are adjustable.

5. The slotted diffuse reflection laser cooling microwave cavity device according to claim 1, characterized in that: The dielectric ring is made of a material with a large dielectric constant.

6. The slotted diffuse reflection laser cooling microwave cavity device according to claim 1, characterized in that: The height of the dielectric ring is adjustable.

7. The slotted diffuse reflection laser cooling microwave cavity device according to claim 1, characterized in that: The cavity tube and the cavity end cover are connected and fixed in circumferential position by gluing or machine screws.

8. The slotted diffuse reflection laser cooling microwave cavity device according to claim 1, characterized in that: The coupling loop is made of a coaxial line.

9. The slotted diffuse reflection laser cooling microwave cavity device according to claim 1, characterized in that: The upper laser via, the lower laser via and the laser via are circular.

10. The slotted diffuse reflection laser cooling microwave cavity device according to claim 1, characterized in that: The diffuse reflection coating layer is a silver layer.

Images