Metastructure surface device for laser beam overlapping and focusing and dipole trap and magneto-optical trap integrated chip prepared by same

Abstract

The invention provides a metasurface device for laser beam overlapping and focusing and a dipole trap and magneto-optical trap integrated chip manufactured by the metasurface device, and belongs to the technical field of optics, and the metasurface device for laser beam overlapping and focusing is designed by adjusting the position of a nanorod on the metasurface; the device enables the cooling light emitted from the rear end to form three deflection light beams, and the three deflection light beams deflect towards the center of the device and are overlapped; the device focuses dipole light emitted from the rear end into array conical dipole light beams, the vertexes of the conical dipole light beams form a dipole trap array in a three-beam deflection light overlapping area, a transmission type magneto-optical trap chip is designed through combination of double light beams and a planar coil, the contradiction between the requirements for integrated construction of single-beam cooling light and the dipole trap array is solved, and the requirement for integrated construction of the single-beam cooling light and the dipole trap array is met. The defects that an optical path system is large in occupied area, heavy in mass and incapable of being integrated in preparation of the dipole trap array and the magneto-optical trap in the prior art are overcome, and the dipole trap array and the magneto-optical trap are prepared at the same time under the action of dipole light and cooling light.

Description

Technical Field

[0001] The present invention relates to the field of optical technologies, and particularly to a metasurface device for laser beam overlapping and focusing, and an integrated chip of a dipole trap and a magneto-optical trap prepared thereby. Background Art

[0002] The development of quantum computers is regarded as a disruptive revolution in the field of computer science, and its further development will have a profound impact on various future fields. However, traditional single-atom experimental platforms all include various complex systems, and the components of these systems are numerous, large in volume, and heavy in mass, which seriously hinder the development of the field of quantum computing. Therefore, for the further development of single-atom-based quantum computers, integration and chipization are the only way forward.

[0003] As the most important and core components in single-atom quantum computers, the miniaturized design and integration of magneto-optical traps and dipole trap arrays are of great significance. Among them, in 2013, the Nshii team proposed a scheme for constructing a chip-level magneto-optical trap by using a single beam passing through a specifically etched diffraction grating (Non-Patent Document 1), but in this scheme, the four-stage magnetic field device still uses a traditional anti-Helmholtz coil. To further improve the integration level, in 2022, Chen L. et al. developed a planar coil chip that can generate a quadrupole magnetic field and constructed a magneto-optical trap with a higher integration level (Non-Patent Document 2). There are mainly two methods for preparing traditional dipole trap arrays: the SLM (Spatial Light Modulator) method and the AOD (Acousto-Optic Deflector) method, and these systems are often complex in structure and large in volume. In April 2023, X. Huang et al. from Columbia University in the United States proposed a design scheme for a dipole trap array based on a dielectric metasurface and prepared one-dimensional, two-dimensional, and three-dimensional optical trap structures (Non-Patent Document 3). However, the current research progress of this scheme is limited to the preparation of the dipole trap array, and the compatibility between the dipole trap array chip and the magneto-optical trap chip has not been achieved.

[0004] The prior art (202311259171.1) discloses a grating chip of a miniaturized dipole trap and its vacuum chamber, which realizes the MOT and the dipole trap on the same chip. The focal point of a partial structure of the dipole trap coincides with the center of the MOT beam, so that atoms are cooled and slowed down in the MOT region and finally captured at the focal point of the dipole trap grating. However, this chip is realized by using a grating and an anti-Helmholtz coil, and the integration level and the compact effect are not ideal.

[0005] A metasurface is a two-dimensional metamaterial that uses the structural variations of periodically or aperiodically arranged sub-wavelength unit cells to regulate parameters such as the amplitude, phase, and polarization of the optical field, thereby arbitrarily shaping the optical wavefront, changing the propagation direction of light, and affecting the polarization state of light. Among them, the phase is one of the key attributes of electromagnetic waves. By regulating the phase, the metasurface can achieve various functions. The metasurface lens is an important application in the development process of the metasurface structure. The present invention proposes a new design that integrates a magneto-optical trap and a dipole trap array into an integrated chip based on the metasurface structure to enable the preparation of a dipole trap array while also being able to prepare a magneto-optical trap.

[0006] Non-patent literature: Non-patent literature 1: C.C. Nshii, M. Vangeleyn, J.P. Cotter, et al., A surface-patterned chip as a strong source of ultracold atoms for quantum technologies, Nat. Nanotech. 8, 321 (2013). Non-patent literature 2: Chen, Liang et al. “Planar-Integrated Magneto-Optical Trap.” Physical review applied 17.3 (2022): Physical review applied, 2022 - 03, Vol. 17(3), Article 034031. Print. Non-patent literature 3: X. Huang, W. Yuan, A. Holman, et al., Metasurface holographic optical traps for ultracold atoms, Progress in Quantum Electronics 89, 100470 (2023). Summary of the invention

[0007] In the traditional magneto-optical trap preparation scheme, there is a contradiction between the requirement of the single-beam reflection cooling light of the magneto-optical trap and the need for dipole light transmission when integrating the magneto-optical trap and the dipole trap array. The integration and compactness effect of the existing grating chips for miniaturized dipole traps are not ideal. To solve the above problems, a metasurface device for laser beam overlap and focusing and an integrated chip of a dipole trap and a magneto-optical trap prepared thereby are provided.

[0008] The present invention is implemented in the following manner: A metasurface device for laser beam overlapping and focusing, the metasurface device includes a SiO2 substrate as the metasurface substrate and TiO2 nanorods arranged in an array on the SiO2 substrate. Taking the center of the metasurface substrate as the origin, draw three dividing lines outward. The dividing lines divide the metasurface substrate into three parts. Adjacent two dividing lines form a part. The unit structures of the three parts are arranged according to the same phase gradient magnitude and different gradient change directions. Adjacent two dividing lines form an included angle, which are α, β, γ respectively. The phases of the unit structures in each part decrease in the direction pointed to the origin along the angle bisector of the included angle; the metasurface device can make a cooling light beam incident from its rear end pass through the metasurface device and form three deflected light beams in three regions respectively. The light rays in each deflected light beam are parallel to each other. The refraction angles of the three deflected light beams at the metasurface device interface are the same, and the deflection directions are different. The three deflected light beams are deflected towards the center direction of the metasurface device and overlap; the metasurface device focuses the even polarized light incident from its rear end into an array of conical dipole light beams, and the vertices of the array of conical dipole light beams form an array of dipole traps in the overlapping region of the three cooling light beams.

[0009] Further, the design method of the metasurface device includes the following steps: S1: Change the unit structure size. Through simulation, establish a database of unit structures, which includes the size data of the unit structures and the actual transmittance and actual transmission phase corresponding to the unit structure size at working wavelengths λ1 and λ2. S2: Establish a metasurface substrate, divide the substrate into multiple unit structure arrays. Taking the center of the metasurface substrate as the origin, draw three dividing lines outward. The dividing lines divide the metasurface substrate into three parts. Adjacent two dividing lines form a part. The unit structures of the three parts are arranged according to the same phase gradient magnitude and different gradient change directions. Adjacent two dividing lines form an included angle, which are α, β, γ respectively. The three parts are respectively provided with unit structures arranged with decreasing phase along the direction pointed to the origin along the angle bisector of the included angle; then establish a rectangular coordinate system and determine the central position coordinates of each unit structure in the unit structure array. S3: Here, set an evaluation function to evaluate the matching degree of the unit structure at two working wavelengths. The evaluation function is: Among them, the smaller the evaluation function value, the higher the matching degree of the unit structure with the theoretical phase value of the position coordinate. S4: Calculate the theoretical phase values c ,y c ) at each central position coordinate (x and Select the unit structure with the highest matching degree with the central position coordinates (x c , y c ) from the database according to the set evaluation function, and denote it as Scc; S5: Determine whether the evaluation function of the selected unit structure Scc at the central position coordinates is less than a specific value Φ. If it is less, place the selected unit structure at the central position coordinates (x c , y c ); If it is greater than or equal to, use the position optimization algorithm to optimize the position of the unit structure; S6: Place the selected unit structure on the metasurface substrate through the position optimization algorithm. Specifically: Move the position of the unit structure within the "position adjustment area" centered on the position coordinates (x c , y c ). The "position adjustment area" is a square area with a side length of 2△v and an area of 2△v×2△v, where △v is a boundary parameter and △v is less than 1 / 4 of the unit structure period; According to the coordinate position (x i , y j ) of the unit structure after movement, where i, j ∈ (1, n) are positive integers, calculate the theoretical phase value and Select the unit structure Sij with the highest matching degree with the position coordinates (x i , y j ) from the database according to the theoretical phase value after movement. Determine whether the evaluation function of the unit structure Sij and the position coordinates (x i , y j ) is less than a specific value Φ. If it is less, stop moving the placement position of the unit structure and place the corresponding unit structure Sij at the corresponding position coordinates (x i , y j ); If it is greater than or equal to the specific value Φ, move the position of the unit structure again within the "position adjustment area" centered on the position coordinates (x c , y c ) and repeat step S6; If the requirements are still not met after i and j are taken, change △v and continue to repeat step S5 and step S6 until the requirements are met; Form the final phase gradient metasurface device; The actual transmission phase c at the position of the central coordinates (x c ) is selected from the database obtained by scanning the unit structure size. The theoretical phase value is obtained from formula (1), and the theoretical phase value ​ Obtained from formula (7); The actual transmission phase value after movement and is selected from the database, and the theoretical phase value after movement is obtained from formula (1), and the theoretical phase value after movement is obtained from formula (7); The obtaining of the ideal phase value includes the following steps: (a) Import the set optical trap array matrix into any iterative algorithm of the ADAPTIVE-ADDITIVE ALGORITHM, GS algorithm or WGS algorithm, and calculate the modulation phase in MATLAB (b) Based on the specifications and size of the designed dipole trap, use the traditional focusing algorithm to calculate the focusing phase of the strongly focused system for the dual laser beam The calculation formula is: where f and λ respectively refer to the focal length of the metasurface and the wavelength of the light wave, and (x, y) is the central position coordinate of the unit structure; (c) Superimpose the modulation phase and the focusing phase to obtain the theoretical phase value The calculation formula is: The calculation formula of the theoretical phase value is: where θ t is the refraction angle of the metasurface, λ0 is the working wavelength, x and y are the two-dimensional coordinates of the central position of the unit structure when placed on the substrate, and X is the distance between the unit structure in the three regions and the origin in the direction of decreasing phase; Step S2 specifically includes the following steps: S21: After dividing the substrate into multiple unit arrays, draw three dividing lines outward with the center of the metasurface substrate as the origin. These dividing lines divide the metasurface substrate into three parts. The unit structures of the three parts are arranged according to the same phase gradient magnitude and different gradient change directions. Two adjacent dividing lines form a part, and two adjacent dividing lines form an included angle. Denote the upper left region as region A, with the corresponding included angle as α, the upper right region as region B, with the corresponding included angle as β, and the lower region as region C, with the corresponding included angle as γ; The phase is set to decrease along the direction pointing from the center of the included angle α to the origin in region A, the phase is set to decrease along the direction pointing from the center of the included angle β to the origin in region B, and the phase is set to decrease along the direction pointing from the center of the included angle γ to the origin in region C; S22: Establish a rectangular coordinate system with the center of the metasurface substrate as the origin, and determine the center position coordinates (x c , y c ) of each unit structure in the unit structure array; The selection of the unit structure with the highest matching degree with the center position coordinates (x c , y c ) in step S4 includes the following steps: S41: Calculate the theoretical phase values c , y c ) at each center position coordinate (x and Select unit structures from the database, and calculate the evaluation function of the unit structure at the center position coordinate according to the set evaluation function formula where the evaluation function The unit structure with the smallest value is the unit structure with the highest matching degree with the center position coordinates (x c , y c ), denoted as Scc; The steps for moving the unit structure position in step S6 include the following steps: S61: With the position coordinates (x i , y i ) of the unit structure as the center, establish a square area with a side length of 2Δv. The four vertex coordinates of the square area are A(x i - Δv, y j - Δv), B(x i + Δv, y j - Δv), C(x i - Δv, y j + Δv) and D(x i + Δv, y j + Δv), where A, B, C, and D respectively represent the four vertex values of the square area, and Δv ≤ 100um; S62: Construct n*n grids within the square region, and simultaneously calculate the central point coordinates of each grid; S63: Starting from the grid where any vertex is located, with the x-axis or y-axis as the moving direction, move the placement position of the unit structure grid by grid.

[0010] An integrated chip of a dipole trap and a magneto-optical trap, comprising the metasurface device for laser beam overlap and focusing as described in any one of claims 1 or 2. There is dipole light and cooling light 1 at the rear end of the metasurface device. The metasurface device focuses the dipole light incident from its rear end into an array of conical dipole beams through the metasurface device. The vertices of the array of conical dipole beams form a dipole trap array, that is, the vertices of the conical dipole beams are the working points of the dipole trap array; After passing through the metasurface device, cooling light 1 forms three deflected light beams. The light rays in each deflected light beam are parallel to each other. The three deflected light beams are all deflected towards the center direction of the metasurface device and overlap; There is cooling light 2 opposite to cooling light 1 at the front end of the metasurface device. Cooling light 1 and cooling light 2 form the light field required for preparing the magneto-optical trap at the overlapping region of the three deflected light beams. A planar coil is arranged on the periphery of the metasurface device, so that the magnetic field zero point of the planar coil coincides with the overlapping region to form a magneto-optical trap. The point with the strongest electric field in the overlapping region is the working point of the magneto-optical trap. The working point of the magneto-optical trap coincides with the working point of the dipole trap array.

[0011] Furthermore, the design method of the integrated chip of the dipole trap and the magneto-optical trap includes the design method of the metasurface device and the design method of the planar coil: Among them, the design method of the metasurface device is steps S1 to S6 in the design method of the metasurface device in a metasurface device for laser beam overlap and focusing as described in claim 2; The design method of the planar coil includes the following steps: S1: Simulate the metasurface device in CST to obtain the electric field distribution data after the cooling light propagates through the metasurface device. The point with the highest electric field strength is recorded as the working site of the magneto-optical trap, and the position coordinates (x c , y c , z c ) of the working site of the magneto-optical trap are obtained; S2: Input the radius, current, and number of turns parameters of the inner coil and the outer coil in the planar coil into Maxwell software, use Maxwell software to perform electromagnetic simulation on the coil, and record the point where the magnetic field component is zero as the working point (x0, y0, z0) of the planar coil; Adjust the parameters of the inner coil and the outer coil by observing the position where the working point is located, so that the working point of the planar coil coincides with the working site of the magneto-optical trap, and determine the radius, current, and number of turns of the inner coil and the outer coil in the planar coil.

[0012] Compared with the prior art, the present invention designs a metasurface device for laser beam overlapping and focusing by adjusting the positions of the nanocolumns on the metasurface, and designs a transmissive magneto-optical trap chip by combining a dual-beam with a planar coil, solving the contradiction between the requirements for the integrated construction of a single-beam cooling light and a dipole trap array, and solving the disadvantages of the large floor area, heavy weight, and inability to integrate of the optical path systems in the preparation of dipole trap arrays and magneto-optical traps in the past, realizing the function of simultaneously preparing a dipole trap array and a magneto-optical trap under the action of dipole light and cooling light. Description of the Drawings

[0013] Figure 1 It is a schematic diagram of the chip structure. In the figure, light red represents dipole light, light blue represents cooling light, the gray thin plate refers to the SiO2 substrate, the light blue small cylinders refer to TiO2 nanocolumns, the red solid line is the dividing line of the three regions of the GMOT, and the orange circles are planar magnetic field coils; the gray small balls are schematic diagrams of the controlled neutral atoms.

[0014] Figure 2 It is a schematic diagram of the unit structure of the metasurface. In the figure, the gray cuboid is the SiO2 substrate, and the blue cylinder is the TiO2 nanocolumn.

[0015] Figure 3 It is a schematic plan view of the metasurface chip. Figure 3 -a: Schematic plan view of the metasurface chip. The gray part is the SiO2 thin plate substrate, the blue dots are the top views of SiO2, and the red solid line is the dividing line of the three regions; Figure 3 -b: The phase gradient of the three regions decreases in the direction of the white arrow.

[0016] Figure 4 It is a schematic diagram of the optical path of one of the deflected beams after the cooling light 1 is transmitted through the metasurface device.

[0017] Figure 5 It is a schematic diagram of the optical paths of two of the deflected beams after the cooling light 1 is transmitted through the metasurface device.

[0018] Figure 6 It is a schematic diagram of the optical paths of three of the deflected beams after the cooling light 1 is transmitted through the metasurface device.

[0019] Figure 7 It is a schematic diagram of the 3×3 dipole trap array formed by the chip.

[0020] Figure 8 It is a plane electric field diagram formed by the cooling light beam of the chip in the z-axis.

[0021] Figure 9It is a schematic diagram of a peripheral planar coil, where the parameters R, N, and I are the radius, number of turns, and current of each toroidal coil respectively. The magnetic field lines are represented by blue curves. Specific embodiments

[0022] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description progresses.

[0023] The integrated preparation of atomic chips has always been the focus of research in major laboratories. The traditional experimental platform for trapping single atoms is still split and modular. We draw on the development process of current classical computers and believe that integration and chipization are the inevitable paths for the development of single-atom system quantum computers.

[0024] Metasurface refers to an ultrathin non-uniform planar medium, usually composed of unit structures on the subwavelength scale. Through the effective artificial construction of the electromagnetic characteristics and spatial arrangement order of the unit structures, the metasurface can effectively control the polarization, amplitude, phase and other properties of the light field on the subwavelength spatial scale.

[0025] The present invention proposes a novel design method. Based on the metasurface, combined with the design of dipole trap and magneto-optical trap, it is further combined into an integrated atomic chip, so as to realize the simultaneous preparation of dipole trap arrays and magneto-optical traps.

[0026] A metasurface device for laser beam overlap and focusing, the metasurface device includes a SiO2 substrate as the metasurface substrate and TiO2 nanorods arrayed on the SiO2 substrate. Taking the center of the metasurface substrate as the origin, draw three dividing lines outward, as Figure 3 shown, the dividing lines are red lines. The dividing lines divide the metasurface substrate into three parts. Adjacent two dividing lines form a part. The unit structures of the three parts are arranged according to the same phase gradient magnitude and different gradient change directions. Adjacent two dividing lines form an included angle, which are α, β, and γ respectively. The phases of the unit structures of each part decrease in the direction pointed to the origin by the angular bisector of the included angle; the metasurface device can deflect the cooling light incident from its bottom into three deflected light beams after passing through the metasurface device. The refraction angles of the three deflected light beams at the interface of the metasurface device are the same, and the deflection directions are different. The three deflected light beams are all deflected towards the center direction of the metasurface device and overlap, as Figures 4 - 6As shown, after the cooling light 1 is transmitted through the metasurface device, the cooling light 1 is deflected in three regions of the metasurface device to become three deflected light beams. The three deflected light beams are deflected towards the center of the metasurface device and overlap. The light rays in each deflected light beam are parallel to each other. The metasurface device deflects a plane-wave cooling light 1 by 20° in three directions in three regions respectively; the metasurface device focuses the even polar light incident from its rear end into an array of conical dipole light beams, and the vertices of the array of conical dipole light beams form an array of dipole traps in the overlapping region of the three cooling light beams.

[0027] The design method of the metasurface device for laser beam overlap and focusing is as follows: S1: Change the unit structure size. Through simulation, establish a database of unit structures, which includes the size data of the unit structures and the actual transmittance and actual transmission phase corresponding to the unit structure size at the working wavelengths λ1 and λ2.

[0028] S2: Establish a metasurface substrate, divide the substrate into multiple unit structure arrays, draw three dividing lines outward from the center of the metasurface substrate as the origin. The dividing lines divide the metasurface substrate into three parts. The unit structures of adjacent two parts form an included angle, which are α, β, and γ respectively. The unit structures of the three parts are arranged according to the same phase gradient magnitude and different gradient change directions. The unit structures arranged with decreasing phase are set along the angular bisector directions of the included angles pointing towards the origin; then establish a rectangular coordinate system and determine the central position coordinates (x c , y c ) of each unit structure in the unit structure array.

[0029] S3: Set an evaluation function here to evaluate the matching degree of the unit structure at two working wavelengths. The evaluation function is: where the smaller the evaluation function value, the higher the matching degree of the unit structure with the theoretical phase value of the position coordinates.

[0030] S4: Calculate the theoretical phase values c , y c ) at each central position coordinate (x and Select the unit structure with the highest matching degree with the central position coordinate (x c , y c ) from the database according to the set evaluation function, and denote it as Scc.

[0031] S5: Determine the evaluation function of the selected unit structure Scc at the central position coordinates Whether it is less than a specific value Φ. If it is less, place the selected unit structure at the central position coordinates (x c ,y c ); If it is greater than or equal to, use the position optimization algorithm to optimize the position of the unit structure.

[0032] S6: Place the selected unit structure on the metasurface substrate through the position optimization algorithm. Specifically: Move the position of the unit structure within the "position adjustment area" centered at the position coordinates (x c ,y c ). The "position adjustment area" is a square area with a side length of 2△v and an area of 2△v×2△v, where △v is a boundary parameter and △v is less than 1 / 4 of the unit structure period; According to the coordinate position (x i ,y j ) after the unit structure is moved, where i, j ∈ (1, n) are positive integers, calculate the theoretical phase value and Re - select the unit structure Sij with the highest matching degree with the position coordinates (x i ,y j ) from the database according to the theoretical phase value after movement. Determine whether the evaluation function i ,y j of the unit structure Sij and the position coordinates (x is less than the specific value Φ. If it is less, stop moving the placement position of the unit structure and place the corresponding unit structure Sij at the corresponding position coordinates (x i ,y j ); If it is greater than or equal to the specific value Φ, move the position of the unit structure again within the "position adjustment area" centered at the position coordinates (x c ,y c ) and repeat step S6; If the requirements are still not met after i and j are exhausted, change △v and continue to repeat step S5 and step S6 until the requirements are met; Form the final phase gradient metasurface device.

[0033] The actual transmission phase c ,y c at the central coordinate position (x is selected from the database obtained by scanning the unit structure size. The theoretical phase value is obtained from formula (1), and the theoretical phase value is obtained from formula (7); The actual transmission phase value after movement and is selected from the said database, and the theoretical phase value after movement is obtained from formula (1), and the theoretical phase value after movement is obtained from formula (7).

[0034] The obtaining of the ideal phase value includes the following steps: (a) Import the set optical trap array matrix into any iterative algorithm of the ADAPTIVE-ADDITIVE ALGORITHM, GS algorithm or WGS algorithm, and calculate the modulation phase in MATLAB (b) Based on the specifications and sizes of the designed dipole trap, use the traditional focusing algorithm to calculate the focusing phase of the strong focusing system for the dual laser beam The calculation formula is: where f and λ respectively refer to the focal length of the metasurface and the wavelength of the light wave, and (x, y) are the central position coordinates of the unit structure; (c) Superimpose the modulation phase and the focusing phase to obtain the theoretical phase value The calculation formula is: The said theoretical phase value has the calculation formula: where θ t is the refraction angle of the metasurface, λ0 is the working wavelength, x and y are the two-dimensional coordinates of the central position of the unit structure when it is placed on the substrate, and X is the distance between the unit structure in the three regions and the origin in the direction of phase decrease; in region A, on the angular bisector of the α angle or on the ray parallel to the angular bisector of the α angle, the distance between the unit structure and the origin is denoted as X; in region B, on the angular bisector of the β angle or on the ray parallel to the angular bisector of the β angle, the distance between the unit structure and the origin is denoted as X; in region C, on the angular bisector of the γ angle or on the ray parallel to the angular bisector of the γ angle, the distance between the unit structure and the origin is denoted as X.

[0035] Step S2 specifically includes the following steps: S21: After dividing the substrate into multiple unit arrays, draw three dividing lines outward with the center of the metasurface substrate as the origin, as Figure 3As shown, the demarcation line is a red line. The demarcation line divides the metasurface substrate into three parts. The unit structures of the three parts are arranged according to the same phase gradient magnitude and different gradient change directions. Two adjacent demarcation lines form a part, and two adjacent demarcation lines form an included angle. Denote the upper left region as region A, with the corresponding included angle as α, the upper right region as region B, with the corresponding included angle as β, and the lower region as region C, with the corresponding included angle as γ; Region A sets the phase to decrease along the direction pointing to the origin along the angular bisector of angle α, region B sets the phase to decrease along the direction pointing to the origin along the angular bisector of angle β, and region C sets the phase to decrease along the direction pointing to the origin along the angular bisector of angle γ, as Figure 3 shown in -b, the structural units of each region are arranged with the actual transmission phase decreasing along the direction of the white arrow.

[0036] S22: Establish a rectangular coordinate system with the center of the metasurface substrate as the origin, and determine the central position coordinates (x c , y c ) of each unit structure in the unit structure array.

[0037] In step S4, the selection of the unit structure with the highest matching degree with the central position coordinates (x c , y c ) includes the following steps: S41: Calculate the theoretical phase values c , y c ) at each central position coordinate (x and [[ID=2,6]] Select unit structures from the database, and calculate the evaluation function of the unit structure at the central position coordinate according to the set evaluation function formula where the evaluation function [[ID=,31]]The unit structure with the smallest value is the unit structure with the highest matching degree with the central position coordinates (x c , y c ), denoted as Scc.

[0038] In step S6, moving the position of the unit structure includes the following steps: S61: With the position coordinates (x i , y j ) of the unit structure as the center, establish a square area with a side length of 2Δv. The four vertex coordinates of the square area are A(x i -Δv, y j -Δv), B(x i +Δv, y j -Δv), C(x i -Δv, y j +Δv), and D(x i +Δv, y j+Δv), where A, B, C, and D respectively represent the four vertex values of the square region, and Δv ≤ 100 um.

[0039] S62: Construct n*n grids within the square region, and simultaneously calculate the central point coordinates of each grid.

[0040] S63: Starting from the grid where any vertex is located, and using the x-axis or y-axis as the moving direction, move the placement position of the unit structure grid by grid.

[0041] The movement of the placement position of the unit structure is the movement of the placement position of the unit structure in the method for designing a metasurface based on position adjustment to achieve phase matching of the unit structure with the patent number CN202210530334.4 and the patent name.

[0042] An integrated chip of a dipole trap and a magneto-optical trap includes the above-mentioned metasurface device for laser beam overlap and focusing. There is dipole light and cooling light 1 at the rear end of the metasurface device. The dipole light incident from the rear end of the metasurface device is focused into an array of conical dipole beams through the metasurface device. The vertices of the array of conical dipole beams form a dipole trap array, that is, the vertices of the conical dipole beams are the working points of the dipole trap array; after passing through the metasurface device, cooling light 1 forms three deflected light beams. The light rays in each deflected light beam are parallel to each other. The three deflected light beams are all deflected towards the center direction of the metasurface device and overlap; there is cooling light 2 opposite to the incoming cooling light 1 at the front end of the metasurface device. Cooling light 1 and cooling light 2 form the light field required for preparing the magneto-optical trap at the overlapping region of the three deflected light beams. A planar coil is arranged on the periphery of the metasurface device such that the magnetic field zero point of the planar coil coincides with the overlapping region to form a magneto-optical trap. The point with the strongest electric field in the overlapping region is the working point of the magneto-optical trap, and the working point of the magneto-optical trap coincides with the working point of the dipole trap array.

[0043] The design method of the integrated chip of the dipole trap and the magneto-optical trap includes the design method of the metasurface device and the design method of the planar coil: Among them, the design method of the metasurface device is steps S1 - S6 in the design method of the metasurface device for laser beam overlap and focusing as described above; The design method of the planar coil includes the following steps: S1: Simulate the metasurface device in CST to obtain the electric field distribution data after the laser beam propagates through the metasurface device. The point with the highest electric field intensity is recorded as the working site of the magneto-optical trap, and obtain the position coordinates (x c , y c , z c ) of the working site of the magneto-optical trap; S2: Input the radius, current, and number of turns of the inner coil and outer coil in the planar coil into Maxwell software. Use Maxwell software to perform electromagnetic simulation on the coil, and mark the point where the magnetic field component is zero as the working point (x0, y0, z0) of the planar coil. Adjust the parameters of the inner coil and outer coil by observing the position of the working point to make the working point of the planar coil coincide with the working position of the magneto-optical trap, and determine the radius, current, and number of turns of the inner coil and outer coil in the planar coil.

[0044] The structure of the integrated atom chip designed by the present invention is as Figure 1 shown. Figure 1 In the integrated chip, silicon dioxide is used as the substrate, and titanium dioxide is selected as the unit material of the metasurface.

[0045] The metasurface device includes an array of unit structures. The unit structure includes a dielectric substrate and a dielectric nanocylinder. The dielectric nanocylinder is placed on the dielectric substrate, as Figure 2 shown.

[0046] The present invention uses the dielectric substrate as a cuboid. The length and width of the cuboid are 5.2 μm and 5.2 μm, and the height is 500 nm. The material of the dielectric substrate is SiO2, and the relative dielectric constant of SiO2 is 2.0736. The dielectric nanocylinder is cylindrical, and the height of the cylinder is H, where the range of H is 600 nm < H < 650 nm. The radius of the cylinder is R, where the range of R is 50 nm < R < 200 nm. The height H and radius R of the cylinder are uncertain values. By changing the values of the height H and radius R, the phase of the unit structure can cover 0 - 2π, and different phase adjustments can be achieved. The material of the dielectric nanocylinder is TiO2, and the relative dielectric constant of TiO2 is 6.4516. Both silicon dioxide and titanium dioxide have the advantages of low loss and high refractive index.

[0047] As Figure 3 shown, the metasurface is divided into three parts. The red line is the region boundary, and the same phase gradient is set in the three parts. The phase gradient decreases along the arrow direction. Finally, a newly designed planar coil is added to the peripheral part of the chip.

[0048] The chip designed by the present invention generates a dipole trap array and a magneto-optical trap simultaneously. Therefore, the metasurface device must satisfy the conditions for forming a dipole trap array at the same time.

[0049] The nanocylinders on the metasurface device have a specific transmission phase distribution, which can meet the conditions for a dipole trap array. At the same time, the phase difference dφ between adjacent unit structures can be controlled by setting the phase gradient dφ / dx, so that the phase distribution of the nanocylinders meets the conditions for a magneto-optical trap.

[0050] By selecting appropriate meta - surface structural units and setting a specific phase gradient simultaneously. When the even - polarized light and cooling light 1 are incident into the chip at the same time, the even - polarized light forms an array of dipole traps at specific positions through the meta - surface. After the cooling light 1 passes through the meta - surface, it is deflected under the action of the phase gradient, and the cooling light 2 emitted in the opposite direction also forms a three - dimensional cooling light beam at this position. Coupled with the quadrupole magnetic field formed by the planar coil here, the generation conditions of the magneto - optical trap are satisfied. At this time, the simultaneous preparation of the dipole trap array and the magneto - optical trap is achieved.

[0051] The function of the chip prepared by the present invention is to enable the dipole trap array and the magneto - optical trap to manipulate atoms simultaneously. The magneto - optical trap cools the atoms at room temperature, and the dipole trap array can capture and manipulate the cooled single atoms. Therefore, the working positions of the magneto - optical trap and the dipole trap array are the same. Set the focal length f and the deflection angle so that the working positions of the dipole trap array and the magneto - optical trap coincide. The focal length f is the working point of the dipole trap array and also the working point of the integrated chip, which is set artificially. By setting and adjusting the refraction angle θ of the cooling light of the magneto - optical trap t , make the strongest light field where the three deflected cooling lights converge cover the working point of the focal length f. By setting the focal length f and the refraction angle θ t make the dipole trap array and the magneto - optical trap work at the same position.

[0052] The specific steps are as follows: Select a linearly polarized light with λ1 = 830 nm as the even - polarized light and a left - hand circularly polarized light with λ2 = 780 nm as the cooling light to generate the dipole trap array and the magneto - optical trap respectively. Use wavelength - division multiplexing technology to achieve simultaneous laser input.

[0053] First, use silica as the substrate and titanium dioxide as the unit structure of the nanorods. Through CST simulation, a large number of unit structures with different sizes are analyzed, and the actual transmittance and actual transmission phase corresponding to each unit structure at the two working wavelengths λ1 and λ2 are obtained Based on this, a database is established.

[0054] For the traditional method of constructing a dipole trap array by combining a spatial light modulator (SLM) with a strong - focusing optical system, where refers to the modulation phase of the SLM for the even - polarized light, refers to the focusing phase of the strong - focusing system for the even - polarized light in the traditional method. According to the parameters such as the column pattern, size, and interval of the dipole trap array designed by us, the modulation phase can be obtained according to the ADAPTIVE - ADDITIVE ALGORITHM According to the working distance set by the meta - surface device, the focusing phase can be calculated by formula (1)

[0055] Among them, f and λ respectively refer to the focal length of the metasurface and the wavelength of the light wave, and (x, y) is the central position coordinate of the unit structure. The focal length f of the metasurface is the working distance set for the metasurface device.

[0056] According to the further derivation formula of the generalized Snell's law (Formula 2), the phase required for each position to deflect the incident cooling light 1 by a specific angle can be calculated.

[0057] Since the other side of the chip is air, so n t is 1, and the light beam is incident perpendicularly from the metasurface substrate, and the incident angle θ i is 0. Therefore, the formula can be further derived as: Formula 4 indicates that if an appropriate phase gradient is introduced at the interface, refracted light beams in any direction can be obtained.

[0058] Each unit structure of the metasurface acts as a low-quality factor resonator. When the light wave passes through these carefully arranged microstructures, the resulting phase accumulation effect can be approximately expressed as a specific function, thereby achieving precise control of the light wavefront phase. The phase accumulation generated can be approximately expressed as: ΔΦ = 2πn eff h / λ0 (5) In the formula: n eff represents the effective refractive index of the microstructure, h represents the height of the microstructure, and λ0 represents the working wavelength.

[0059] Formula (4) can be transformed into Formula (6) is the refraction angle θ t of the set specific metasurface and the working wavelength λ0 of the magneto-optical trap. According to the phase gradient arrangement method, the phase difference between adjacent unit structures can be obtained.

[0060] By integrating Formula (6), the theoretical phase value required for any coordinate position on the metasurface device can be calculated The theoretical phase value The calculation formula is: Among them, x and y are the two-dimensional coordinates of the center position of the unit structure when it is placed on the substrate, and X is the distance between the unit structure in the three regions and the origin in the direction of decreasing phase; for example: in region A, the distance between the unit structure and the origin is denoted as X along the angle bisector of the α angle or on the ray parallel to the angle bisector of the α angle; in region B, the distance between the unit structure and the origin is denoted as X along the angle bisector of the β angle or on the ray parallel to the angle bisector of the β angle; in region C, the distance between the unit structure and the origin is denoted as X along the angle bisector of the γ angle or on the ray parallel to the angle bisector of the γ angle.

[0061] Using the design method steps S1-S6 of the above metasurface device, a corresponding metasurface array model is established in CST simulation, as Figure 3 shown.

[0062] Traditional magneto-optical traps use a pair of anti-Helmholtz coils to generate this magnetic field, which consists of a pair of identical coils (with the same radius R, current I, and number of turns N), with opposite current directions. The working point of this coil configuration is exactly its geometric center. This cylindrical geometry poses limitations on compact cold atom systems. For example, the vacuum chamber needs to be inserted between the coil pair, thus restricting the minimum size of the coils. To achieve the required field gradient of approximately 10 G / cm, the current in the coils increases with the cube of the coil size, which leads to heat dissipation problems. These limitations can be overcome by planar coil designs to achieve a compact system.

[0063] During the design process of the planar coil chip, a coplanar toroidal coil chip such as Figure 9 , which consists of two coaxial coils with different radii R1 and R2 (R1 < R2), different numbers of turns N1 and N2, and opposite currents I1 and -I2 (I 1,2 > 0). The center of the coil is defined as the origin of the cylindrical coordinate system, and the z-axis is perpendicular to the coil plane. At the point on the z-axis, the coil generates a magnetic field strength where: and the corresponding magnetic field gradient: Due to cylindrical symmetry, on the z-axis For simplicity, first consider the case of balanced currents I1 = I2 = I, which allows the two coils to be connected in series to a current supply. For appropriate R1 and R2, N1 and N2 can be adjusted such that at the desired height h, i.e., the target MOT working point (0, 0, h), the field strength is zero. Therefore, this coplanar coil configuration can provide the quadrupole magnetic field required to achieve MOT, and its working point is located above the coil plane.

[0064] Electromagnetic simulations of the coil were performed using Maxwell software. After the simulations were completed, post-processing was performed in Maxwell, and a field calculator was set to extract the z- and x-axis magnetic field components. The point where the magnetic field component reached zero was designated the operating point. The location of the z-axis magnetic field operating point was used to adjust the dimensions of the inner and outer rings. As the radius of the inner and outer rings decreased, the operating point also decreased. The operating point height of the coil was set to ensure that the operating point of the coil chip matched the beam overlap of the metasurface.

[0065] Finally, a planar coil is added to the outer ring of the chip. This planar coil is designed based on a coplanar annular coil, using two coaxial coils of different radii (R1 and R2) and exciting the magnetic field through opposite current directions (I and -I). The number of turns of the winding is fixed to 1, and the excitation current of the inner and outer coils is set to 2A, but in opposite directions (the excitation current direction of the inner coil is counterclockwise, and the excitation current direction of the outer coil is clockwise). By changing the radius of the two coils R1 and R2, the point where the magnetic field component is 0 is at the desired magneto-optical trap operating point. This coil configuration can achieve the quadrupole magnetic field of the MOT.

[0066] At this point, the chip designed by the present invention simultaneously meets the conditions for generating a dipole trap array and a magneto-optical trap. By selecting dipole light and cooling light of specific wavelength and polarization, when the dipole light and cooling light 1 are incident from the chip substrate, a dipole trap array and a magneto-optical trap can be simultaneously generated at a specific position, achieving the goal of simultaneously preparing a dipole trap array and a magneto-optical trap on a single atom chip.

[0067] To verify the method described in this embodiment, 780nm left-handed circularly polarized light is used as cooling light and 830nm linearly polarized light is used as dipole light. The refraction angle θ of the metasurface is t Taking 20 degrees as an example, the required theoretical phase can be calculated and The corresponding metasurface array model is established in the CST simulation, such as Figure 3 As shown in Figure 2, the metasurface device is simulated in CST to obtain the electric field distribution data after the cooling light 1 propagates through the metasurface device. The part with the highest electric field intensity is the center of the light field, as shown in Figure 2. Figure 8 The electric field diagram of the three-region deflected light in the Z plane is used to calculate the working point. Figure 8 It can be seen directly that the working point is the red point with the highest light intensity. If z is 3um, then h is 3um. The radii of the inner and outer circles of the corresponding coplanar coil are 5.5um and 11um respectively.

[0068] At the transmitting end, cooling light and dipole light are simultaneously emitted by wavelength division multiplexing, such as Figure 1As shown, the light beam can simultaneously prepare the dipole trap array and the magneto-optical trap cooling light beam. The specific schematic diagram is as shown in Figure 7 and Figure 8 shown.

[0069] The design of the metasurface device is the focus of the present invention. The device is composed of metasurface unit structures. Draw three lines from the center of the device to divide the device into three regions. After calculating the ideal phases of the dipole trap array and the magneto-optical trap required for each region, select appropriate structural units from the established metasurface structure unit database and place them at specific coordinate positions through a position optimization algorithm. Then, through wavelength division multiplexing technology, the dipole light and the cooling light 1 are simultaneously incident from the bottom end of the chip. After passing through the chip, the dipole light forms a dipole trap array. The cooling light 1 and the cooling light 2 emitted in the opposite direction also form a three-dimensional cooling light beam required for preparing the magneto-optical trap at the dipole trap array. Finally, a set of planar coils is added to the external region of the metasurface device, and the point where the magnetic field component formed by the coils is 0 also coincides with the dipole trap array to complete the preparation of the magneto-optical trap, thereby realizing the integrated preparation of the dipole trap array and the magneto-optical trap.

[0070] Based on the metasurface, the present invention designs a transmissive magneto-optical trap chip by combining double light beams and planar coils, solves the contradiction between the single light beam cooling light and the integrated construction requirement of the dipole trap array, and integrates the improved magneto-optical trap and the dipole trap array into an integrated chip to realize the preparation of the magneto-optical trap while preparing the dipole trap array.

[0071] Based on the metasurface, the present invention designs a brand-new integrated atom chip, solves the disadvantages of the large floor area, heavy mass, and inability to be integrated of the optical path system in the preparation of the dipole trap array and the magneto-optical trap in the past, realizes the function of simultaneously preparing the dipole trap array and the magneto-optical trap under the action of the dipole light and the cooling light, and provides a new idea for the miniaturization and integration of quantum chips in the future.

[0072] The above are only the preferred embodiments of the present invention. It should be noted that for those skilled in the art, without departing from the overall concept of the present invention, several changes and improvements can still be made, and these should also be regarded as the protection scope of the present invention.

Claims

1. A metasurface device for laser beam overlapping and focusing, characterized in that The metasurface device includes a SiO2 substrate serving as the metasurface substrate and TiO2 nanorods arranged in an array on the SiO2 substrate. Taking the center of the metasurface substrate as the origin, draw three dividing lines outward. The dividing lines divide the metasurface substrate into three parts. Adjacent two dividing lines form a part. The unit structures of the three parts are arranged according to the same phase gradient magnitude and different gradient change directions. Adjacent two dividing lines form an included angle, which are α, β, and γ respectively. The phases of the unit structures in each part decrease in the direction pointed to the origin along the angle bisector of the included angle. The metasurface device can make a beam of cooling light incident from its rear end pass through the metasurface device and then form three deflected light beams in the three regions respectively. The light rays in each deflected light beam are parallel to each other. The refraction angles of the three deflected light beams at the metasurface device interface are the same, but the deflection directions are different. The three deflected light beams are deflected towards the center direction of the metasurface device and overlap. The metasurface device focuses the even polarized light incident from its rear end into an array of conical dipole light beams, and the vertices of the array of conical dipole light beams form an array of dipole traps in the overlapping region of the three beams of cooling light.

2. The metasurface device for laser beam overlapping and focusing according to claim 1, wherein, The design method of the metasurface device includes the following steps: S1: Change the unit structure size. Through simulation, establish a database of the unit structure, where the database includes the size data of the unit structure and the actual transmittance and actual transmission phase corresponding to the unit structure size at working wavelengths λ1 and λ2. S2: Establish a metasurface substrate, divide the substrate into multiple unit structure arrays. Taking the center of the metasurface substrate as the origin, draw three dividing lines outward. The dividing lines divide the metasurface substrate into three parts. Adjacent two dividing lines form a part. The unit structures of the three parts are arranged according to the same phase gradient magnitude and different gradient change directions. Adjacent two dividing lines form an included angle, which are α, β, and γ respectively. The three parts are respectively provided with unit structures arranged with decreasing phases along the direction pointed to the origin along the angle bisector of the included angle. Then establish a rectangular coordinate system and determine the central position coordinates of each unit structure in the unit structure array. S3: Here, set an evaluation function to evaluate the matching degree of the unit structure at two working wavelengths. The evaluation function is: Among them, the smaller the evaluation function value, the higher the matching degree of the unit structure with the theoretical phase value of the position coordinate. S4: Calculate the theoretical phase values at each central position coordinate (x c , y c ) in sequence and Select the unit structure with the highest matching degree with the central position coordinate (x c , y c ) from the database according to the set evaluation function, and denote it as Scc; S5: Determine the evaluation function of the selected unit structure Scc at the central position coordinates Whether it is less than a specific value Φ. If it is less than, place the selected unit structure at the central position coordinates (x c , y c ); If it is greater than or equal to, use the position optimization algorithm to optimize the position of the unit structure. S6: Place the selected unit structure on the metasurface substrate through a position optimization algorithm. Specifically: Move the position of the unit structure within the "position adjustment area" centered at the position coordinates (x c , y c ). The "position adjustment area" is a square area with a side length of 2Δv and an area of 2Δv × 2Δv, where Δv is a boundary parameter and Δv is less than 1 / 4 of the unit structure period; According to the coordinate positions (x i , y i ) of the unit structure after movement, where i, j ∈ (1, n) are positive integers, calculate the theoretical phase values and Re-select the unit structure Sij with the highest matching degree with the position coordinates (x i , y i ) from the database according to the theoretical phase values after movement, and judge whether the evaluation function of the unit structure Sij and the position coordinates (x i , y i ) is less than a specific value Φ. If it is less, stop moving the placement position of the unit structure and place the corresponding unit structure Sij at the corresponding position coordinates (x i , y i ); If it is greater than or equal to the specific value Φ, move the position of the unit structure again within the "position adjustment area" centered at the position coordinates (x c , y c ) and repeat step S6; If the requirements are still not met after i and j are taken completely, then change △v, and continue to repeat steps S5 and S6 until the requirements are met; form the final phase gradient metasurface device. The actual transmission phase at the center coordinate (x c , y c ) is selected from a database obtained from the structural dimensions of the scanning unit. The theoretical phase value is obtained from formula (1), and the theoretical phase value is obtained from formula (7); ​ The actual transmission phase value after movement and is selected from the database, and the theoretical phase value after movement is obtained from formula (1), and the theoretical phase value after movement is obtained from formula (7); The obtaining of the ideal phase value comprises the following steps: (a) Import the set optical trap array matrix into any one of the iterative algorithms of the ADAPTIVE-ADDITIVE ALGORITHM, GS algorithm, or WGS algorithm, and calculate the modulation phase in MATLAB (b) Based on the specifications and size of the designed dipole trap, the focusing phase of the strong focusing system for dual aurora is calculated using traditional focusing algorithms. The calculation formula is as follows: Among them, f and λ respectively refer to the focal length of the metasurface and the wavelength of the light wave, and (x, y) is the central position coordinate of the unit structure. (c) Superimpose the modulation phase and the focusing phase to obtain the theoretical phase value The calculation formula is as follows: The theoretical phase value The calculation formula is as follows: where θ t is the refraction angle of the metasurface, λ0 is the working wavelength, x and y are the two-dimensional coordinates of the center position of the unit structure when it is placed on the substrate, and X is the distance between the unit structure in the three regions and the origin along the direction of decreasing phase; Step S2 specifically includes the following steps: S21: After dividing the substrate into multiple unit arrays, draw three dividing lines outward with the center of the metasurface substrate as the origin. The dividing lines divide the metasurface substrate into three parts. The unit structures of the three parts are arranged according to the same phase gradient magnitude and different gradient change directions. Adjacent two dividing lines form a part, and adjacent two dividing lines form an included angle. Denote the upper left region as region A, with the corresponding included angle as α, the upper right region as region B, with the corresponding included angle as β, and the lower region as region C, with the corresponding included angle as γ; Region A sets the phase to decrease along the direction of the angle bisector of angle α pointing to the origin, region B sets the phase to decrease along the direction of the angle bisector of angle β pointing to the origin, and region C sets the phase to decrease along the direction of the angle bisector of angle γ pointing to the origin; S22: Establish a rectangular coordinate system with the center of the metasurface substrate as the origin, and determine the central position coordinates (x c , y c ) of each unit structure in the unit structure array; In step S4, the selection of the unit structure with the highest matching degree with the central position coordinates (x c , y c ) includes the following steps: S41: Calculate the theoretical phase values at each central position coordinate (x c , y c ) in sequence and Select the unit structure from the database, and calculate the evaluation function of the unit structure at the central position coordinate according to the set evaluation function formula where the evaluation function The unit structure with the smallest evaluation function is the unit structure with the highest matching degree with the central position coordinate (x c , y c ), denoted as Scc; The steps of moving the position of the unit structure in step S6 include the following steps: S61: Taking the position coordinates (x i , y j ) of the unit structure as the center, establish a square area with a side length of 2Δv. The four vertex coordinates of the square area are A(x i -Δv, y j -Δv), B(x i +Δv, y j -Δv), C(x i -Δv, y j +Δv) and D(x i +Δv, y j +Δv), where A, B, C, and D respectively represent the four vertex values of the square area, and Δv ≤ 100um; S62: Construct n*n grids within the square region, and calculate the center point coordinates of each grid at the same time; S63: Starting from the grid where any vertex is located, with the x-axis or y-axis as the moving direction, move the position where the unit structure is placed grid by grid.

3. An integrated chip of a dipole trap and a magneto-optical trap, comprising the metasurface device for laser beam overlap and focusing according to any one of claims 1 or 2, characterized in that, At the back end of the metasurface device, there are even laser light and cooling light 1. The metasurface device focuses the even laser light incident from its back end into an array of conical dipole beams through the metasurface device. The vertices of the array of conical dipole beams form a dipole trap array, that is, the vertices of the conical dipole beams are the working points of the dipole trap array; Cooling light 1 forms three deflected light beams after passing through the metasurface device. The light rays in each deflected light beam are parallel to each other. The three deflected light beams are all deflected towards the center direction of the metasurface device and overlap; At the front end of the metasurface device, there is cooling light 2 that shoots opposite to cooling light 1. Cooling light 1 and cooling light 2 form the optical field required for preparing the magneto-optical trap at the overlapping region of the three deflected light beams. A planar coil is arranged around the metasurface device, so that the magnetic field zero point of the planar coil coincides with the overlapping region to form a magneto-optical trap. The point where the electric field is the strongest in the overlapping region is the working point of the magneto-optical trap. The working point of the magneto-optical trap coincides with the working point of the dipole trap array.

4. The integrated chip of a dipole trap and a magneto-optical trap according to claim 3, characterized in that The design method of the integrated chip of the dipole trap and the magneto-optical trap includes the design method of the metasurface device and the design method of the planar coil: Among them, the design method of the metasurface device is steps S1 to S6 in the design method of the metasurface device in a metasurface device for laser beam overlap and focusing as described in claim 2; The design method of the planar coil includes the following steps: S1: Simulate the metasurface device in CST to obtain the electric field distribution data of the cooling light after propagating through the metasurface device. Mark the position with the highest electric field intensity as the working site of the magneto-optical trap, and obtain the position coordinates (x c , y c , z c ) of the working site of the magneto-optical trap; S2: Input the radius, current, and number of turns parameters of the inner coil and the outer coil in the planar coil into the Maxwell software. Use the Maxwell software to perform electromagnetic simulation on the coil, and denote the point where the magnetic field component is zero as the working point (x0, y0, z0) of the planar coil; By observing the position where the working point is located, adjust the parameters of the inner coil and the outer coil so that the working point of the planar coil coincides with the working site of the magneto-optical trap, and determine the radius, current, and number of turns of the inner coil and the outer coil in the planar coil.

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