Single fiber magneto-optical trap system without trapping singularity

Abstract

The present application relates to the technical field of quantum optics, and particularly relates to a single-fiber magneto-optical trap system without trapped singularities, which comprises an input optical fiber, a collimating lens barrel, a folding mirror unit, a vacuum cavity, a hollow corner cube reflector, a pair of anti-Helmholtz coils and a coated wave plate mirror group. The input optical fiber is connected with the collimating lens barrel; the collimating lens barrel is fixed at the lower end of the folding mirror unit. The lower end of the folding mirror unit is fixedly connected with the upper end of the vacuum cavity. The hollow corner cube reflector is arranged in the vacuum cavity, and the center of the hollow corner cube reflector forms a magneto-optical trap area. The vacuum cavity is provided with a closed structure with a transparent window at the top, and contains a rubidium vapor background gas. The coated wave plate mirror group is fixed at the bottom of the vacuum cavity; and the pair of anti-Helmholtz coils are fixed outside the vacuum cavity. The single-fiber magneto-optical trap system without trapped singularities reduces the complexity of the equipment, the difficulty of beam alignment and the difficulty of equipment adjustment, and effectively compresses the system volume by using the folding mirror group.

Description

Technical Field

[0001] This invention relates to the field of quantum optics technology, and in particular to a single-fiber magneto-optical trap system without trapped singularities. Background Technology

[0002] Quantum precision measurement uses atoms or other particles that obey the Schrödinger equation as information sensors to detect the angular motion, linear motion, gravitational acceleration, and gravitational gradient of the carrier. Navigation calculations are then performed to determine the carrier's position, heading, and attitude. Quantum precision measurement technology has verified its high-precision measurement capabilities and is currently moving towards further improvements in accuracy and engineering applications. Rapid progress in this field provides crucial support for national high-precision autonomous navigation capabilities, including the construction of gravity fields and weak magnetic field detection. Various quantum precision measurement devices that use cold atom clusters as the verification medium, such as cold atom gyroscopes, cold atom accelerometers, cold atom gravimeters, and cold atom gravity gradiometers, are typical examples of quantum precision measurement sensors.

[0003] Rb atoms (rubidium atoms) are alkali metal atoms. Quantum precision measurement devices that use cold atom clusters as the verification medium typically use its isotope 87Rb atoms as the verification mass. The ground state of 87Rb has two hyperfine levels. To achieve quantum precision measurement, magneto-optical trap technology is usually required to trap a sufficient number of atoms to form cold atom clusters. However, traditional magneto-optical trap technology relies on six opposing cooling beams, one pump beam, and a gradient magnetic field formed by a pair of anti-Helmholtz coils to construct the magneto-optical trap to trap the atom clusters. Such a structural design places extremely high demands on beam alignment and equipment installation. At the same time, the structure is generally quite large, which hinders the widespread application of quantum precision measurement. Summary of the Invention

[0004] To address the challenges of traditional magneto-optical trap technology, which relies on six opposing cooling beams, one pump beam, and a pair of anti-Helmholtz coils to form a gradient magnetic field to trap atomic clusters, this invention offers the following technical solution:

[0005] A single-fiber magneto-optical trap system without trapped singularities includes: an input fiber, a collimating lens tube, a folding-reflection unit, a vacuum cavity, a hollow pyramidal reflector, an anti-Helmholtz coil, and a coated waveplate reflector assembly.

[0006] The input optical fiber is connected to the collimating lens tube, and the cooling light-return pump light input from the input optical fiber is collimated by the collimating lens tube to form a parallel beam.

[0007] The collimating lens tube is fixed to the lower end of the folding and reflecting unit, and the parallel light beam emitted from the collimating lens tube is incident on the folding and reflecting unit;

[0008] The lower end of the folding and reflecting unit is fixedly connected to the upper end of the vacuum cavity. The hollow pyramidal reflector is disposed in the vacuum cavity, and a magneto-optical trap region is formed at the center of the hollow pyramidal reflector. The vacuum cavity is configured as a closed structure with a transparent window at the top and contains rubidium vapor background gas. The folding and reflecting unit reflects the parallel light beam and then incident it perpendicularly onto the hollow pyramidal reflector.

[0009] The coated waveplate reflector assembly is fixed at the bottom of the vacuum cavity; the parallel beam of cooling light-return pump light located at the center of the hollow pyramid reflector passes through the central hollow region and is reflected by the coated waveplate reflector assembly to form a vertical cooling light-return pump light that is opposed to the light passing through the region; the parallel beam of cooling light-return pump light located around the hollow pyramid reflector is reflected by the hollow pyramid reflector to form a uniformly distributed propagation direction that all points towards the cooling light-return pump light of the magneto-optical trap region;

[0010] A pair of anti-Helmholtz coils are fixed to the outside of the vacuum cavity; the center of the integral coil group formed by the pair of anti-Helmholtz coils coincides with the center of the hollow cone reflector in the height direction.

[0011] Furthermore: the folding and reflecting unit includes: a reflector mounting base and a folding and reflecting mirror assembly;

[0012] The reflector mounting base is a semi-closed structure with one end open; the open end of the reflector mounting base is fixed to the end of the vacuum chamber with the transparent window.

[0013] The folding mirror assembly includes two mirrors arranged at a 90° angle; the parallel light beam emitted from the collimating lens tube is incident on one of the mirrors, and after being reflected by the other mirror, it is incident perpendicularly on the hollow cone mirror.

[0014] Furthermore: the hollow cone reflector is positioned at the transverse center of the vacuum cavity;

[0015] The hollow cone-shaped reflector is parallel to the transparent window at the upper end of the vacuum cavity.

[0016] Furthermore, the coated waveplate reflector assembly is a stacked structure of λ / 4 waveplate and coated reflector.

[0017] Furthermore: the collimating lens tube is fixed to the end of the reflector mounting base with a transparent window using a non-magnetic titanium screw;

[0018] One end of the reflector mounting bracket opening is fixed to the end of the vacuum cavity with the transparent window by a non-magnetic titanium screw.

[0019] The coated waveplate reflector assembly is fixed to the bottom of the vacuum cavity by non-magnetic titanium screws;

[0020] The pair of anti-Helmholtz coils are fixed to the outside of the vacuum chamber by non-magnetic titanium screws.

[0021] Furthermore: the hollow pyramidal reflector is a frustum-shaped structure; or the hollow pyramidal reflector is a polyhedral frustum with an even number of symmetrical faces, such as an octagonal frustum, a dodecagonal frustum, or an icosahedral frustum.

[0022] Furthermore, the vacuum cavity and the reflector mounting base are made of non-magnetic materials and employ a magnetic shielding structure to shield and isolate stray magnetic fields from the outside.

[0023] The single-fiber magneto-optical trap system without trapped singularities provided by this invention has at least the following beneficial effects or advantages:

[0024] The single-fiber magneto-optical trap system without a confined singularity provided by this invention reduces the number of input fibers required by traditional magneto-optical traps from six to a single fiber, significantly reducing equipment complexity, beam alignment difficulty, and equipment assembly and adjustment difficulty. Furthermore, the use of a folding mirror assembly effectively compresses the system size. Simultaneously, the horizontally and vertically directed cooling-pumping light generated by the employed technique completely covers the entire magneto-optical trap region, enabling the trapping of rubidium atom clusters without a central singularity, similar to that in traditional magneto-optical traps. This technology strongly supports the miniaturization and engineering requirements of quantum precision measurement applications. Attached Figure Description

[0025] Figure 1 A schematic diagram of a single-fiber magneto-optical trap system without trapped singularities provided in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the hollow cone reflector structure provided in an embodiment of the present invention.

[0027] The attached diagram lists the components represented by each number as follows:

[0028] 1-Hollow cone reflector, 2-Anti-Helmholtz coil, 3-Vacuum cavity, 4-Coated waveplate reflector group, 5-Input fiber, 6-Collimating tube, 7-Folding reflector group, 8-Reflector mounting base, 9-Cooling light-return pump light parallel beam, 10-Magneto-optical trap area. Detailed Implementation

[0029] This invention addresses the problem that traditional magneto-optical trap technology relies on six opposing cooling beams, one pump beam, and a gradient magnetic field formed by a pair of anti-Helmholtz coils to trap atomic clusters. Such a structural design places extremely high demands on beam alignment and equipment installation. Furthermore, the structure is generally quite large, hindering the application and promotion of quantum precision measurement. This invention provides a single-fiber magneto-optical trap system without trapping singularities.

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] like Figure 1 The single-fiber magneto-optical trap system without trapped singularities provided in this embodiment of the invention includes: an input fiber 5, a collimating lens tube 6, a folding-reflection unit, a vacuum cavity 3, a hollow pyramidal reflector 1, an anti-Helmholtz coil 2, and a coated waveplate reflector group 4. Wherein:

[0032] The input fiber optic cable 5 is connected to the collimating lens tube 6. The focal length and size of the collimating lens tube 6 should ensure that the size of the collimated cooling-pump parallel beam 9 is comparable to the size of the reflection area of ​​the hollow pyramidal reflector 1. The cooling-pump light input from the input fiber optic cable 5 enters the collimating lens tube 6, which is used to collimate the beam to form a parallel beam. The collimating lens tube is fixed to the lower end of the folding and reflecting unit by non-magnetic titanium screws, and the parallel beam emitted from the collimating lens tube is incident on the folding and reflecting unit.

[0033] The vacuum chamber is a closed structure with a transparent window at the top. The vacuum chamber 3 contains rubidium vapor and maintains an ultra-high vacuum environment. While providing background rubidium vapor for atomic clusters, it isolates other impurity gases, minimizes collisions between impurity gases and rubidium atomic clusters, and increases the lifespan and trapping efficiency of the trapped rubidium atomic clusters.

[0034] The lower end of the folding and reflecting unit is fixedly connected to the upper end of the vacuum cavity 3 by a non-magnetic titanium screw. Specifically, the folding and reflecting unit includes a reflector mounting base 8 and a folding and reflecting mirror assembly 7. The reflector mounting base 8 is a semi-closed structure with an opening on one side; one end of the open reflector mounting base 8 is fixed to the end of the vacuum cavity with a transparent window by a non-magnetic titanium screw. The folding and reflecting mirror assembly 7 includes two reflectors, which are set at a 90° angle to ensure that the collimated cooling light-return pump light parallel beam 9 of the vacuum cavity 3 containing rubidium vapor background gas is perpendicular to the window of the vacuum cavity 3, and the space formed by the fixed reflectors is the light path of the collimated cooling light-return pump light parallel beam 9.

[0035] like Figure 1 and Figure 2 A hollow pyramidal reflector 1 is disposed within the vacuum cavity 3. The hollow pyramidal reflector 1 has a frustum-shaped structure; or it can be a polyhedral symmetrical frustum with an even number of symmetrical planes, such as an octagonal frustum, a dodecagonal frustum, or an icosahedral frustum. The hollow pyramidal reflector 1 is positioned at the transverse center of the vacuum cavity to ensure that the entire collimated parallel beam 9 of the input cooling-pump light is within the reflection area of ​​the hollow pyramidal reflector 1. The hollow pyramidal reflector 1 is parallel to the transparent window at the upper end of the vacuum cavity, ensuring that the collimated parallel beam 9 of the cooling-pump light reflected by the hollow pyramidal reflector 1 is perpendicular to the input light. A magneto-optical trap region 10 is formed at the center of the hollow pyramidal reflector 1, which is used to trap rubidium atoms. The parallel beam emitted from the collimating lens tube 6 is incident on one reflector and, after being reflected by another reflector, is incident perpendicularly on the hollow pyramidal reflector 1.

[0036] The coated waveplate reflector assembly 4 is a stacked structure of a λ / 4 waveplate and a coated reflector. The λ / 4 waveplate and the coated reflector are bonded together with vacuum adhesive and fixed to the bottom of the vacuum cavity 3 as a whole with non-magnetic titanium screws. The λ / 4 waveplate is used for polarization adjustment of the reflected light. The fixed coated waveplate reflector assembly 4 should be parallel to the window above the vacuum cavity 3 to ensure that the collimated cooling light-return pump parallel beam 9 can return along the original path.

[0037] The parallel beam 9 of cooling-pumping light, located at the center of the hollow pyramidal reflector 1, passes through the central hollow region and is reflected by the coated waveplate reflector group 4, forming a vertical cooling-pumping light beam that opposes the light passing through this region. Through the Doppler effect, it interacts with the atomic cluster to reduce the vertical velocity of the atomic cluster. The parallel beam 9 of cooling-pumping light, located around the hollow pyramidal reflector 1, is reflected by the hollow pyramidal reflector 1, forming a uniformly distributed cooling-pumping light beam with a propagation direction all pointing towards the magneto-optical trap region 10. Through the Doppler effect, it interacts with the atomic cluster to reduce the horizontal velocity of the atomic cluster in all directions.

[0038] A pair of anti-Helmholtz coils 2 are fixed to the outside of the vacuum cavity 3 by non-magnetic titanium screws; the center of the integral coil group formed by the pair of anti-Helmholtz coils coincides with the center of the hollow pyramidal reflector 1 in the height direction. The anti-Helmholtz coils 2 generate a vertical gradient magnetic field to trap the rubidium atom clusters by a constant current provided by an external constant current source. The center of the gradient magnetic field is a point with a magnetic field strength of 0, which coincides with the center point of the counter-projected cooling light-return pump light, forming a magneto-optical trap region 10. Since the counter-projected cooling light-return pump light in both the horizontal and vertical directions can completely cover the entire magneto-optical trap region 10, the trapped rubidium atom clusters are rubidium atom clusters without a central singularity.

[0039] To avoid the adverse effects of stray magnetic fields on the trapping of atomic clusters, the selected fixing screws, vacuum cavity 3 and reflector mounting base 8 are made of non-magnetic materials and adopt a magnetic shielding structure to shield and isolate external stray magnetic fields.

[0040] The single-fiber magneto-optical trap system without trapped singularities provided in this invention has at least the following beneficial effects or advantages:

[0041] The single-fiber magneto-optical trap system without a confined singularity provided in this invention reduces the number of input fibers required by traditional magneto-optical traps from six to a single fiber, significantly reducing equipment complexity, beam alignment difficulty, and equipment assembly and adjustment difficulty. Furthermore, the use of a folding mirror assembly effectively compresses the system size. Simultaneously, the horizontally and vertically directed cooling-pumping light generated by the employed technique completely covers the entire magneto-optical trap region, enabling the trapping of rubidium atom clusters without a central singularity, similar to those in traditional magneto-optical traps. This technology strongly supports the miniaturization and engineering requirements of quantum precision measurement applications.

[0042] In the description of this invention, it should be noted that the terms used in the various embodiments, such as "upper," "lower," "front," "rear," "left," and "right," which indicate orientation, are only used to simplify the description of the positional relationships based on the accompanying drawings and do not mean that the components and devices referred to must be operated in accordance with the specific orientations and defined operations, methods, and structures in the specification. Such directional terms do not constitute a limitation of this invention.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A single fiber magneto-optical trap system without trapped dark spots, characterized by: include: Input fiber, collimating lens tube, folding and reflecting unit, vacuum cavity, hollow cone reflector, anti-Helmholtz coil and coated waveplate reflector assembly; The input optical fiber is connected to the collimating lens tube, and the cooling light-return pump light input from the input optical fiber is collimated by the collimating lens tube to form a parallel beam. The collimating lens tube is fixed to the lower end of the folding and reflecting unit, and the parallel light beam emitted from the collimating lens tube is incident on the folding and reflecting unit. The lower end of the folding and reflecting unit is fixedly connected to the upper end of the vacuum cavity. The hollow pyramidal reflector is disposed in the vacuum cavity, and a magneto-optical trap region is formed at the center of the hollow pyramidal reflector. The vacuum cavity is configured as a closed structure with a transparent window at the top and contains rubidium vapor background gas. The folding and reflecting unit reflects the parallel light beam and then incident it perpendicularly onto the hollow pyramidal reflector. The coated waveplate reflector group is fixed at the bottom of the vacuum cavity; the parallel beam of cooling light-return pump light located at the center of the hollow pyramid reflector passes through the central hollow region and is reflected by the coated waveplate reflector group to form a vertical cooling light-return pump light that is opposed to the light passing through the region; The parallel beam of cooling light-return pump light located around the hollow pyramidal reflector is reflected by the hollow pyramidal reflector to form a uniformly distributed propagation direction that all points towards the magneto-optical trap region. A pair of anti-Helmholtz coils are fixed to the outside of the vacuum cavity; the center of the integral coil group formed by the pair of anti-Helmholtz coils coincides with the center of the hollow cone reflector in the height direction.

2. The single-fiber magneto-optical trap system without trapped singularities according to claim 1, characterized in that: The folding and reflecting unit includes: a reflector mounting base and a folding and reflecting mirror assembly; The reflector mounting base is a semi-closed structure with one end open; the open end of the reflector mounting base is fixed to the end of the vacuum chamber with a transparent window. The folding mirror assembly includes two mirrors arranged at a 90° angle; the parallel light beam emitted from the collimating lens tube is incident on one of the mirrors, and after being reflected by the other mirror, it is incident perpendicularly on the hollow cone mirror.

3. The single fiber magneto-optical trap system without trapping dark without trapping dark spots according to claim 2, wherein: The hollow cone reflector is positioned at the transverse center of the vacuum cavity; The hollow cone-shaped reflector is parallel to the transparent window at the upper end of the vacuum cavity.

4. The single fiber magneto-optical trap system without trapped dark spots of claim 2, wherein: The coated waveplate reflector assembly is a stacked structure of λ / 4 waveplate and coated reflector.

5. The single fiber magneto-optical trap system without trapped dark spots according to any one of claims 2-4, characterized in that: The collimating lens tube is fixed to one end of the opening of the reflector mounting base using a non-magnetic titanium screw. One end of the reflector mounting bracket opening is fixed to the end of the vacuum cavity with the transparent window by a non-magnetic titanium screw. The coated waveplate reflector assembly is fixed to the bottom of the vacuum cavity by non-magnetic titanium screws; The pair of anti-Helmholtz coils are fixed to the outside of the vacuum chamber by non-magnetic titanium screws.

6. The single fiber magneto-optical trap system without trapped dark spots according to any one of claims 1-4, characterized in that: The hollow pyramidal reflector has a frustum-shaped structure; or the hollow pyramidal reflector is a polyhedral frustum with an even number of symmetrical surfaces.

7. The single-fiber magneto-optical trap system without trapped singularities according to any one of claims 2-4, characterized in that: The vacuum cavity and reflector mounting base are made of non-magnetic materials and employ a magnetic shielding structure to shield and isolate stray magnetic fields from the outside.

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