Magneto-optical trapping devices, physical packages, physical packages for optical lattice clocks, physical packages for atomic clocks, physical packages for atomic interferometers, physical packages for quantum information processing devices, and physical package systems.

Abstract

In this magneto-optical trap device, five laser beams are irradiated in a capture space in which atoms are captured. Of the five laser beams, three laser beams (laser beams a1, a2, a3) pass through the inside of the same plane (Z plane) and are irradiated in the capture space. The two laser beams that intersect that plane (laser beams a4, a5) are irradiated in the capture space. The laser beam a1 is used together as a laser beam b for Zeeman slowing.

Description

[Technical Field]

[0001] The present invention relates to a magneto-optical trap device, a physical package, a physical package for an optical lattice clock, a physical package for an atomic clock, a physical package for an atom interferometer, a physical package for a quantum information processing device, and a physical package system. [Background Art]

[0002] An optical lattice clock is an atomic clock proposed in 2001 by Hidetoshi Katori, one of the inventors of the present application. In an optical lattice clock, an atomic group is confined in an optical lattice formed by laser light, and the resonance frequency in the visible light region is measured. This enables measurement with 18-digit accuracy, which far exceeds the accuracy of the current cesium clock. The optical lattice clock has been intensively researched and developed by the group of the inventors, and also researched and developed by various groups at home and abroad, and has been developed as a next-generation atomic clock.

[0003] For recent technologies related to optical lattice clocks, the following Patent Documents 1 to 3 can be cited as examples, for example. Patent Document 1 describes forming a one-dimensional moving optical lattice inside an optical waveguide having a hollow passage. Patent Document 2 describes an aspect of setting an effective magic frequency. In practice, magic wavelengths have been determined theoretically and experimentally for strontium, ytterbium, mercury, cadmium, magnesium, and the like. Further, Patent Document 3 describes a radiation shield that reduces the influence of blackbody radiation emitted from surrounding walls.

[0004] Optical lattice clocks enable high-precision time measurement, allowing them to detect even a 1cm difference in altitude on Earth, based on the effects of general relativity due to gravity, as a discrepancy in the passage of time. Therefore, miniaturizing and making optical lattice clocks portable for use in the field outside of laboratories will broaden their potential applications in new geodesic technologies, such as the exploration of underground resources, the detection of underground cavities, and magma chambers. By mass-producing and deploying optical lattice clocks in various locations and continuously monitoring the time variation of gravitational potential, applications such as the detection of crustal deformation and spatial mapping of gravity fields will also become possible. In this way, optical lattice clocks are expected to contribute to society as a new foundational technology, going beyond the realm of high-precision time measurement.

[0005] A typical optical lattice clock physical package includes an atomic oven and a Zeeman reducer as its front-end configuration. This front-end configuration generates a cooled atomic beam, which is then output to a magneto-optical trapping device (MOT) as its rear-end configuration.

[0006] Generally, a Zeeman decelerator includes a bore and a magnetic field generator that generates a magnetic field along the central axis of the bore. The Zeeman decelerator uses the Zeeman deceleration method to reduce the speed of an atomic beam with a high initial velocity emitted from an atomic oven to a speed that can be captured by a magneto-optical trapping device, which is a later configuration. Laser light is shone into the bore from the bore's opening. This laser light travels in the opposite direction to the direction of atomic beam propagation and has a frequency obtained by correcting the Doppler shift term from the atomic transition resonance frequency. The atomic beam is decelerated by the strong radiating force of this laser light. Furthermore, by creating a spatially gradient magnetic field around the bore using the magnetic field generator, the change in Doppler shift associated with deceleration is compensated for by the Zeeman shift, creating a situation in which the deceleration laser light always resonates with the atoms.

[0007] The magneto-optical trapping device, located downstream of the Zeeman decelerator, captures atoms using multiple laser beams and a quadrupole magnetic field formed around the position where the atoms are trapped.

[0008] The frequency of the laser light is set to a value negatively detuned from the atomic resonance frequency. When laser photons are absorbed by an atom, the momentum of the photons is transferred to the atom, acting as radiation pressure on the atom. When an atom is moving at a finite speed, the frequency of the laser light opposing its motion is Doppler-shifted to approach the atom's resonance frequency. On the other hand, the frequency of the laser light parallel to the direction of motion is Doppler-shifted to move away from the atom's resonance frequency. Therefore, the atom experiences stronger radiation pressure from the laser light opposing its motion, and as a result, the atom slows down.

[0009] Furthermore, a quadrupole magnetic field can generate position-dependent radiation pressure. Specifically, this position-dependent radiation pressure is such that the resonance frequency of the atoms undergoes a large Zeeman shift as it moves away from the center of the trapping space. In addition, by selecting the polarization of the laser light, the direction in which the radiation pressure is applied can be directed towards the center.

[0010] As described above, by combining a Zeeman decelerator and a magneto-optical trapping device, a high-speed atomic beam can be slowed down and atoms can be trapped in a trapping space.

[0011] For example, when using strontium atoms as the atomic source, a laser beam with a wavelength of 461 nm is used as the laser beam for slowing down the electron. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Patent No. 6206973 [Patent Document 2] Patent No. 6635608 [Patent Document 3] Patent No. 7189588 [Overview of the project] [Problems that the invention aims to solve]

[0013] Incidentally, when aiming to miniaturize or lighten a device, it is common to consider configurations with fewer parts or components that are easy to install. Zeeman deceleration and magneto-optical trapping methods are generally performed in an ultra-high vacuum environment. In optical devices using a vacuum chamber, reducing the number of vacuum-resistant optical windows that need to be installed in the vacuum wall of the vacuum chamber contributes to miniaturization of the device. On the other hand, if an optical circuit unit consisting of multiple optical elements is installed in a vacuum chamber, the vacuum chamber becomes larger, so it is desirable to reduce the number of parts to the minimum necessary and install the optical circuit unit in the vacuum chamber. Also, when arranging multiple parts, arranging them in a line or on a plane contributes to miniaturization of the device compared to arranging them sparsely in three dimensions.

[0014] Below, we will examine a configuration for realizing "multiple laser beams" used in magneto-optical traps, with the aim of miniaturizing the device.

[0015] The direction of laser light propagation to realize magneto-optical trapping The file is defined as TIFF0007913730000001.tif10170, where "j" is the index for each element (each laser). It is assumed that the intensity of each laser beam is equal.

[0016] In order to decelerate an atom moving in three dimensions, the following condition expressed in equation (1) must be satisfied.

number

[0017] Furthermore, the direction of propagation of the laser beam that constitutes the Zeeman speed reducer Defined as TIFF0007913730000003.tif11170. "b" is antiparallel to the axis of the atomic beam.

[0018] Figure 12 shows a plurality of laser beams according to the prior art (1). A Cartesian coordinate system (X-axis, Y-axis, Z-axis that are orthogonal to each other) is shown in Figure 12. The same applies to Figures 13 and 14.

[0019] In the prior art (1), six laser beams (laser beams a1, a2, a3, a4, a5, a6) are used as laser beams for a magneto-optical trap, and one laser beam (laser beam b) is used as a laser beam for Zeeman slowing. Laser beams a1 and a2 travel in opposite directions to each other, laser beams a3 and a4 travel in opposite directions to each other, and laser beams a5 and a6 travel in opposite directions to each other. The respective traveling directions of the laser beams a1, a2, a3, a4, a5, a6, and b are defined by the following formula (2).

Math

[0020] Here, TIFF0007913730000005.tif10170 represents a unit vector in the Cartesian coordinate system.

[0021] Figure 13 shows a plurality of laser beams according to prior art (2). In the prior art (2), six laser beams (laser beams a1, a2, a3, a4, a5, a6) are used as laser beams for a magneto-optical trap, and one of the laser beams (laser beam b) is also used concurrently as a laser beam for Zeeman slowing. The respective traveling directions of the laser beams a1, a2, a3, a4, a5, a6, and b are defined by the following formula (3).

Math

[0022] Figure 14 shows multiple laser beams related to the prior art (3). In the prior art (3), four laser beams (laser beams a1, a2, a3, a4) are used as laser beams for magneto-optical trapping, and one of these laser beams (laser beam b) is also used as a laser beam for Zeeman deceleration. The propagation directions of each of the laser beams a1, a2, a3, a4, and b are defined by the following equation (4).

number

[0023] The configuration of the prior art (3) is considered to be the minimum configuration that satisfies equation (1) (Optics Letters 16 (1991) 339 F. Shimizu et al). Examples of configurations that realize four laser beams include a configuration that generates the set {a2, a3, a4} using three mirrors (Optics Express 17 (2009) 13601 M. Vangelyn et al), and a configuration that generates the set {a2, a3, a4} using an equilateral triangular grating (U.S. Patent No. 11291103).

[0024] In the conventional technology (1), the seven laser beams are generated, for example, by three mirrors. Specifically, laser beams a2, a4, and a6 are generated from laser beams a1, a3, and a5, respectively. In addition, laser beams a3 and a5 are generated from laser beam a1 using mirrors. Thus, it is not necessarily required to prepare each of the seven laser beams separately, but this presents the problem of increasing the number of optical elements such as mirrors.

[0025] In the conventional technology (2), laser beams a1 and b are used in combination with a single laser beam. Therefore, it might seem that the configuration is simpler compared to the conventional technology (1). However, in order to irradiate with laser beam a2, complex measures are required in the implementation to prevent interference between the atomic beam traveling along the axis of laser beam b, or the atomic oven located on the extension of the axis of laser beam b, and laser beam a2. For example, one of the measures shown in (2-1) to (2-3) below is required. (2-1) To avoid obstructing the propagation of laser beam b, a mirror is placed on a line slightly offset from the path of the atomic beam to generate reflected light of laser beam a1 (i.e., laser beam a2). (2-2) Install a perforated mirror that allows the atomic beam to pass through without obstructing the propagation of laser beam b, and generate reflected light of laser beam a1 (i.e., laser beam a2). (2-3) To avoid obstructing the propagation of laser beam b, a mirror is placed near the location through which laser beam b passes. By irradiating the mirror with laser beam from the outside and reflecting it off the mirror, reflected light of laser beam a1 (i.e., laser beam a2) is generated. Both methods have the problem of being complex.

[0026] In the conventional technology (3), we will examine the configuration (implementation) for actually creating the four laser beams a1, a2, a3, and a4 directed towards the position where atoms are trapped. Below, we will examine implementations (3-1) and (3-2).

[0027] In implementation (3-1), multiple mirrors are installed, and laser beams a1, a2, a3, and a4 are generated by reflection from these multiple mirrors. For example, laser beam a2 is generated from laser beam a1, laser beam a3 is generated from laser beam a2, laser beam a4 is generated from laser beam a3, and laser beams a1, a2, a3, and a4 are concatenated. To generate laser beam a2 from laser beam a1 (that is, to change the position and direction of laser beam a1 to the position and direction of laser beam a2), at least two mirrors are required. Therefore, a total of eight mirrors are required. Furthermore, eight mirrors cannot be arranged on a single plane and must be arranged three-dimensionally, resulting in a larger device.

[0028] In implementation (3-2), for example, a laser beam that travels parallel to laser beam a1 and has a wide spread is used, and three mirrors are placed in a plane perpendicular to the direction of propagation of laser beam a1. Laser beam a2 can be generated by the spread laser beam being reflected by one of the mirrors. Laser beams a3 and a4 are generated in the same way. Laser beam a1 can also be generated by the wide-spreading laser beam.

[0029] However, in implementation (3-2), it is necessary to use a laser beam with a wider spread and greater power than the sum of the powers of the four laser beams used in implementation (3-1). This is because a laser beam with a wider spread inevitably illuminates spaces other than those through which laser beams a1, a2, a3, and a4 travel. The same applies when using a triangular grating with multiple grooves instead of the three mirrors.

[0030] As described above, it has been difficult to miniaturize the device that realizes a magneto-optical trap using conventional technology.

[0031] The objective of this invention is to miniaturize a magneto-optical trapping device through a simple configuration. [Means for solving the problem]

[0032] One aspect of the present invention is a magneto-optical trapping device that traps atoms using a magnetic field formed in a trapping space in which atoms are trapped and a plurality of laser beams supplied to the trapping space, characterized in that it includes a first irradiation unit that irradiates the trapping space with at least three laser beams passing through the same plane and a second irradiation unit that irradiates the trapping space with two laser beams intersecting the plane.

[0033] The first irradiation unit may irradiate the capture space with at least three laser beams passing through the same plane, at equal angles to each other.

[0034] The first irradiation unit may generate at least three laser beams passing through the same plane from a single laser beam by reflection.

[0035] The first irradiation unit may include a plurality of mirrors, which may be arranged such that the at least three laser beams passing through the same plane are irradiated into the capture space at equal angles to each other.

[0036] One of the at least three laser beams passing through the same plane may be used in conjunction with the laser beam of a Zeeman decelerator that slows down an atomic beam using the laser beam and a magnetic field.

[0037] The second irradiation unit may irradiate the capture space with the two laser beams intersecting the plane from opposite directions.

[0038] The second irradiation unit may generate another laser beam from the two laser beams by reflecting one of the two laser beams that intersect the plane.

[0039] The plane may also be a plane that passes through a point of symmetry of the magnetic field formed in the trapping space to trap atoms.

[0040] One aspect of the present invention is a physical package characterized by including the above-described magneto-optical trapping device.

[0041] One aspect of the present invention is a physical package for an optical lattice clock, characterized by including the above-described physical package.

[0042] One aspect of the present invention is a physical package for an atomic clock, characterized by including the above-described physical package.

[0043] One aspect of the present invention is a physical package for an atomic interferometer, characterized by including the above-described physical package.

[0044] One aspect of the present invention is a physical package for a quantum information processing device for an atom or an ionized atom, characterized by comprising the above-described physical package.

[0045] One aspect of the present invention is a physical package system comprising the above-described physical package and a control device for controlling the operation of the physical package. [Effects of the Invention]

[0046] According to the present invention, a magneto-optical trap device can be miniaturized with a simple configuration. [Brief explanation of the drawing]

[0047] [Figure 1] This is a block diagram showing the overall configuration of an optical lattice clock according to an embodiment. [Figure 2A] This is a schematic perspective view showing a magneto-optical trap device according to an embodiment. [Figure 2B] This is a schematic perspective view showing a magneto-optical trap device according to an embodiment. [Figure 3] This is a schematic plan view of the magneto-optical trapping device according to the embodiment, viewed from the Z-axis direction. [Figure 4]This is a perspective view showing a physical package according to an embodiment. [Figure 5] This is a plan view of the physical package according to the embodiment, as seen from the Z-axis direction. [Figure 6] This is a cross-sectional view showing a physical package according to an embodiment. [Figure 7] This diagram shows the upper lid and the lower lid. [Figure 8] This is a diagram showing a splitter. [Figure 9] This is a diagram showing a circulator. [Figure 10] This is a perspective view showing the mirror group and laser beam group according to the embodiment. [Figure 11] This is a perspective view showing the mirror group and laser beam group related to a modified example. [Figure 12] This is a perspective view showing multiple laser beams related to the prior art (1). [Figure 13] This is a perspective view showing multiple laser beams related to the prior art (2). [Figure 14] This is a perspective view showing multiple laser beams related to the prior art (3). [Modes for carrying out the invention]

[0048] <Configuration of an optical lattice clock> Referring to Figure 1, the schematic configuration of the optical lattice clock 10 using the magneto-optical trap device according to this embodiment will be described. Figure 1 is a block diagram showing the overall configuration of the optical lattice clock 10. Here, the optical lattice clock 10 is given as an example of a device in which a magneto-optical trap device is used, but of course, the magneto-optical trap device according to this embodiment may be used in devices other than the optical lattice clock 10.

[0049] The optical lattice clock 10 includes, for example, a physical package 12, an optical system 14, a control device 16, and a PC (Personal Computer) 18.

[0050] The physical package 12 is a device that captures an atomic ensemble, confines it in an optical lattice, and induces a clock transition. The optical system 14 is a device equipped with optical instruments such as an atomic capture laser light source, a clock transition excitation laser light source, and a laser frequency control device. The optical system 14 sends laser light to the physical package 12, receives the fluorescence signal emitted by the atomic ensemble in the physical package 12, converts it into an electrical signal, and processes it to feed back to the laser light source to match the resonance frequency of the atoms. The control device 16 is a device that controls the physical package 12 and the optical system 14. For example, the control device 16 controls the operation of the physical package 12, the operation of the optical system 14, and performs analytical processing such as frequency analysis of the clock transition obtained by measurement. The functions of the optical lattice clock 10 are realized by the mutual cooperation of the physical package 12, the optical system 14, and the control device 16.

[0051] PC18 is a general-purpose computer including a processor and memory. The functions of PC18 are realized through software execution by the hardware, including the processor and memory. An application program for controlling the optical lattice clock 10 is installed on PC18. PC18 is connected to the control unit 16 and may control not only the control unit 16, but also the entire optical lattice clock 10, including the physical package 12 and the optical system 14. Furthermore, PC18 provides the user interface (UI) for the optical lattice clock 10. The user can start the optical lattice clock 10, measure time, and check results via PC18.

[0052] The system including the physical package 12 and the configuration necessary for controlling the physical package 12 is sometimes referred to as the "physical package system." The configuration necessary for control may be included in the control device 16 or the PC 18, or it may be included in the physical package 12. In addition, some or all of the functions of the control device 16 may be included in the physical package 12.

[0053] <Schematic diagram of a magneto-optical trapping device according to an embodiment> The outline of the magneto-optical trapping device according to the embodiment will be described with reference to Figures 2A, 2B and 3. Figures 2A, 2B and 3 show multiple laser beams and multiple mirrors (an example of optical elements) that are irradiated in the magneto-optical trapping device according to the embodiment. Figures 2A, 2B and 3 show a Cartesian coordinate system (mutually orthogonal X, Y, and Z axes). Figures 2A and 2B are perspective views showing the arrangement of the multiple mirrors. Figure 3 is a plan view showing the arrangement of the multiple mirrors as seen from the Z-axis direction.

[0054] The point where the X, Y, and Z axes intersect is defined as the center O of the trapping space. Center O coincides with the point of symmetry of the magnetic field for the magneto-optical trap.

[0055] The magneto-optical trapping device according to this embodiment includes a first irradiation unit that irradiates the trapping space with at least three laser beams passing through the same plane, and a second irradiation unit that irradiates the trapping space with two laser beams intersecting the plane. The trapping space is the space in the magneto-optical trapping device where atoms are trapped by a magneto-optical trap realized by a magnetic field and a plurality of laser beams.

[0056] In the examples shown in Figures 2A, 2B and 3, five laser beams (laser beams a1, a2, a3, a4, a5) are used as laser beams for magneto-optical trapping, and one of these laser beams (laser beam b) is also used as a laser beam for Zeeman deceleration. Here, as an example, laser beam a1 is used as laser beam b for Zeeman deceleration.

[0057] The direction of propagation of each of the laser beams a1, a2, a3, a4, a5, and b is defined by the following equation (5).

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[0058] Laser light c, irradiated from outside the magneto-optical trap device into the magneto-optical trap device, is reflected by mirror 20A towards the center O of the trapping space. The laser light reflected by mirror 20A is laser light a2. Mirror 20B is installed on the opposite side of mirror 20A, with the center O in between. Laser light a2, having passed through the center O, is reflected by mirror 20B towards mirror 20C, and then reflected again by mirror 20C towards the center O of the trapping space. The laser light reflected by mirror 20C is laser light a3. Mirror 20D is installed on the opposite side of mirror 20C, with the center O in between. Laser light a3, having passed through the center O, is reflected by mirror 20D towards mirror 20E, and then reflected again by mirror 20E towards the center O of the trapping space. The laser light reflected by mirror 20E is laser light a1. Laser light a1 passes through the center O and proceeds to the Zeeman decelerator, where it is irradiated into the Zeeman decelerator as laser light b for Zeeman deceleration. Thus, the laser beam a1 used for the magneto-optical trap is also used as the laser beam b for Zeeman deceleration.

[0059] Laser beams a1, a2, and a3 are laser beams that travel within a single Z-plane (a plane perpendicular to the Z-axis) that contains the axis of the atomic beam. Mirrors 20A, 20B, 20C, 20D, and 20E are arranged so that laser beam c, which is irradiated from outside the magneto-optical trap device into the magneto-optical trap device, passes through the same Z-plane. In this way, three laser beams that pass through the Z-plane are generated.

[0060] Mirrors 20A, 20B, 20C, 20D, and 20E correspond to an example of the first irradiation unit. The first irradiation unit irradiates laser beams a1, a2, and a3 passing through the same plane, the Z plane, toward the center O of the capture space at equal angles to each other. For example, that angle is 120°. In other words, mirrors 20A, 20B, 20C, 20D, and 20E are arranged so that the angles between the laser beams a1, a2, and a3 are 120°.

[0061] Furthermore, the first irradiation unit generates three laser beams (laser beams a1, a2, a3) that pass through the same plane, the Z-plane, from a single laser beam c by reflection. In other words, the laser beam c irradiated from outside the magneto-optical trap device into the magneto-optical trap device is sequentially reflected by mirrors 20A, 20B, 20C, 20D, and 20E, and this reflection generates three laser beams (laser beams a1, a2, a3) that pass through the Z-plane.

[0062] Furthermore, along the Z-axis, laser beam a5 is irradiated from the opposite direction to the Z-axis towards the center O. After passing through the center O, laser beam a5 is reflected by mirror 20F. Mirror 20F is positioned to reflect laser beam a5 in the opposite direction to the direction of its propagation. The laser beam reflected by mirror 20F is laser beam a4. Laser beam a4 travels along the Z-axis in the opposite direction to the direction of laser beam a5, passes through the center O, and is irradiated to the outside of the magneto-optical trap device.

[0063] As described above, two laser beams (laser beams a4 and a5) are irradiated into the capture space. Laser beams a4 and a5 are laser beams that intersect the Z-plane and propagate in opposite directions. In the examples shown in Figures 2A, 2B and 3, laser beams a4 and a5 are laser beams perpendicular to the Z-plane.

[0064] Mirror 20F is an example of a second irradiation unit. The second irradiation unit irradiates the center O with two laser beams (laser beams a4 and a5) perpendicular to the Z-plane from opposite directions. In other words, Mirror 20F is installed so that two laser beams perpendicular to the Z-plane are irradiated towards the center O from opposite directions.

[0065] Furthermore, the second irradiation unit generates another laser beam a4 from the two laser beams by reflecting one of the laser beams a5.

[0066] Furthermore, laser beams a1, a2, a3, a4, and a5 may be generated from a single laser beam by using mirrors or beam splitters. For example, laser beam a5 is irradiated into the inside of the magneto-optical trap device, and laser beam a4 is generated when it is reflected by mirror 20F, and laser beam a4 is irradiated to the outside of the magneto-optical trap device. Laser beam a4, which has been irradiated to the outside of the magneto-optical trap device, is reflected by a mirror installed outside the magneto-optical trap device, and laser beam c is generated. When laser beam c is irradiated into the inside of the magneto-optical trap device, laser beams a2, a3, and a1 are generated sequentially as described above. In this way, each laser beam may be generated and irradiated sequentially from a single laser beam.

[0067] This section describes the polarization of the laser light constituting the magneto-optical trap device. In the case of the six-directional laser light shown in Figure 12, it is necessary to set the opposing laser light to be circularly polarized in opposite directions. Regarding the {a1, a2, a3, a4} laser light on the XY plane, in commonly used embodiments, a2(a4), which has circular polarization opposite to a1(a3), is generated as reflected light of a1(a3) by introducing a λ / 4 mirror. In another embodiment, (1) a1 is used as the incident light, (2) two mirrors are provided at the path of a1 to generate a4, (3) a λ / 4 mirror is introduced at the path of a4 to generate a3 as reflected light, and (4) that reflected light passes through the two mirrors in (2) to generate a2. In these examples, in order to satisfy the polarization conditions, it was necessary to prepare at least one λ / 4 mirror to generate the {a1, a2, a3, a4} laser light on the XY plane.

[0068] Figure 2B shows the configuration of five laser beams according to the embodiment and their respective left and right circular polarizations. The arrows in Figure 2B indicate the direction of circular polarization. The circular polarization corresponds to the quadrupole magnetic field B. For ease of explanation, the quadrupole magnetic field B is shown in Figure 2B. The laser beams {a1, a2, a3, a4, b} on the XY plane are generated with a1 as the incident light, passing through mirrors 20A, 20B, 20C, 20D, and 20E. Here, mirrors 20A, 20B, 20C, 20D, and 20E are polarization-independent mirrors that do not change the polarization. In this embodiment, a λ / 4 mirror is not particularly required on the XY plane.

[0069] The configuration and arrangement of the multiple mirrors shown in Figures 2A, 2B and 3 are merely examples, and the configuration and arrangement of the multiple mirrors may be changed as long as the laser beams a1, a2, a3, a4, a5, and b shown in Figures 2A, 2B and 3 are formed. For example, one mirror may be used as another mirror, and that other mirror may not be used. Also, a beam splitter may be used to generate multiple laser beams.

[0070] <Physical package including a magneto-optical trapping device according to an embodiment> The magneto-optical trapping apparatus according to an embodiment will be described below with reference to Figures 4 to 6. Figure 4 is a perspective view showing the physical package. Figure 5 is a plan view of the physical package as seen from the Z-axis direction. Figure 6 is a cross-sectional view of the physical package, which is a cross-sectional view taken from a plane containing the axis of the atomic beam.

[0071] The physical package 100 according to this embodiment includes an atomic oven 110, a Zeeman reducer 120, and a magneto-optical trapping device 130.

[0072] The atomic oven 110 includes a sample chamber 112 for containing the sample, a heater, a thermometer, an electrical connector, a capillary nozzle 114, and a thermal radiation shield. The heater heats the sample, generating an atomic gas from it. The atomic gas is emitted from the capillary nozzle 114 toward the Zeeman decelerator 120. The emission of the atomic gas from the capillary nozzle 114 forms a directional atomic beam. Examples of samples used include strontium and ytterbium, but other atoms may also be used as samples.

[0073] The Zeeman reducer 120 includes a bore 122 and a magnetic field generator 124. The magnetic field generator 124 includes a solenoid coil and generates a magnetic field along the central axis of the bore 122. The atomic beam emitted from the atomic oven 110 is irradiated into the bore 122.

[0074] The Zeeman decelerator 120 uses the Zeeman deceleration method to reduce the velocity of the atomic beam, which has a high initial velocity and is emitted from the atomic oven 110, to a speed that can be captured by the subsequent magneto-optical trapping device (MOT device) 130.

[0075] Laser beam b is shone into bore 122 from a direction opposite to the direction of atomic beam propagation. As mentioned above, laser beam b is also used as laser beam a1 for magneto-optical trapping. In addition, the magnetic field generator 124 creates a magnetic field with a spatial gradient around bore 122 according to the Zeeman deceleration method.

[0076] In the Zeeman decelerator 120, the velocity of the atomic beam irradiated from the atomic oven 110 into the bore 122 is reduced by the magnetic field generated by the magnetic field generator 124 and the laser beam b. The high-temperature atomic beam travels through the bore 122 towards the magneto-optical trap device 130, decelerating according to the Zeeman deceleration method by the magnetic field generated by the magnetic field generator 124 and the laser beam b.

[0077] Furthermore, known atomic ovens and Zeeman reducers can be used as the atomic oven 110 and Zeeman reducer 120.

[0078] The magneto-optical trap device 130 includes a vacuum chamber 132, a magnetic field generator 134, and a plurality of optical elements (e.g., mirrors and beam splitters). Here, mirrors 136A, 136B, 136C, 136D, and 136E are used as examples of optical elements, but beam splitters may also be used. Figure 10 also shows mirrors 136A, 136B, 136C, 136D, and 136E according to this embodiment.

[0079] The vacuum chamber 132 is provided with a vacuum exhaust port 138 and a spare port 140. A vacuum pump is connected to the vacuum exhaust port 138, and the vacuum pump evacuates the inside of the vacuum chamber 132, maintaining an ultra-high vacuum inside the vacuum chamber 132. The inside of the vacuum chamber 132 is connected to the bore 122 in the Zeeman reducer 120 and the sample chamber 112 of the atomic oven 110, and the bore 122 and the sample chamber 112 are maintained at an ultra-high vacuum. The window provided in the vacuum chamber 132 is installed in the vacuum chamber 132 via a gasket, such as an indium seal.

[0080] A trapping space is formed in the space 142 within the vacuum chamber 132, in which atoms are trapped.

[0081] The magnetic field generator 134 includes, for example, a permanent magnet or a coil, and generates a quadrupole magnetic field in the atomic trapping space.

[0082] As shown in Figure 6, for example, the magnetic field generator 134 includes a pair of permanent magnet groups (permanent magnet groups 134A and 134B). The permanent magnet groups 134A and 134B are installed outside the vacuum chamber 132, with the vacuum chamber 132 in between. In the example shown in Figure 6, permanent magnet group 134A is installed on the upper lid 132A side of the vacuum chamber 132 (the upper surface into which the laser beam a5 is incident), and permanent magnet group 134B is installed on the lower lid 132B side of the vacuum chamber 132 (the lower surface into which the laser beam a4 is incident).

[0083] As the magnetic field generator 134, an anti-Helmholtz coil consisting of a pair of electromagnetic coils may be used. As yet another example, four permanent magnets installed on the side of the vacuum chamber 132 may be used as the magnetic field generator 134. Each permanent magnet is magnetized in the radial direction. 2n (n=2,3,4,...) permanent magnets magnetized in the radial direction may be used as the magnetic field generator 134.

[0084] Mirrors 136A, 136B, 136C, and 136D are installed inside the vacuum chamber 132, while mirror 136E is installed outside the vacuum chamber 132, on the lower lid 132B side of the vacuum chamber 132.

[0085] The upper lid 132A and lower lid 132B of the vacuum chamber 132 are equipped with windows through which laser light can pass. Figure 7 shows the upper lid 132A and lower lid 132B. Figure 7 is a plan view showing the upper lid 132A and lower lid 132B.

[0086] The upper cover 132A has, for example, windows 132Aa and 132Ab. The lower cover 132B has, for example, windows 132Ba and 132Bb. Window 132Aa is installed in the upper cover 132A at a position corresponding to mirror 136A. Window 132Ab is installed in the upper cover 132A at a position corresponding to the Z-axis. Window 132Ba is installed in the lower cover 132B at a position on the Z-axis.

[0087] In the magneto-optical trapping device 130, as explained with reference to Figures 2A, 2B and 3, five laser beams (laser beams a1, a2, a3, a4, a5) are used as laser beams for magneto-optical trapping, and one of these laser beams (laser beam b) is also used as a laser beam for Zeeman deceleration. Here, as an example, laser beam a1 is used in conjunction with laser beam b for Zeeman deceleration.

[0088] Laser light c is irradiated from outside the vacuum chamber 132 into the vacuum chamber 132 through the window 132Aa of the upper lid 132A. A mirror 136A is installed in the space 142 inside the vacuum chamber 132 at a position corresponding to the irradiation position of laser light c. Laser light c is reflected by mirror 136A towards the center O of the trapping space. The laser light reflected by mirror 136A is laser light a2. Mirror 136B is installed on the opposite side of mirror 136A with the center O in between. Laser light a2 that has passed through the center O is reflected by mirror 136B towards mirror 136C, and then reflected again by mirror 136C towards the center O of the trapping space. The laser light reflected by mirror 136C is laser light a3. Mirror 136D is installed on the opposite side of mirror 136C with the center O in between. The laser beam a3, having passed through the center O, is reflected by mirror 136D towards mirror 136B, and then reflected again by mirror 136B towards the center O of the trapping space. The laser beam reflected by mirror 136B is laser beam a1. Laser beam a1 passes through the center O and exits through a hole formed on the side of the vacuum chamber 132, and is irradiated into the bore 122 of the Zeeman reducer 120 as laser beam b. In this way, the laser beam a1 for the magneto-optical trap is used in combination as laser beam b for Zeeman reduction.

[0089] Laser beam a1 travels along the axis of the atomic beam emitted from the atomic oven 110 and is used as laser beam b for Zeeman deceleration in the Zeeman decelerator 120.

[0090] Laser beams a1, a2, and a3 are laser beams that travel within a single Z-plane containing the axis of the atomic beam. Mirrors 136A, 136B, 136C, and 136D are positioned so that laser beam c also passes through the same Z-plane. In this way, three laser beams passing through the Z-plane are generated.

[0091] Mirrors 136A, 136B, 136C, and 136D correspond to an example of the first irradiation section. Laser beams a1, a2, and a3, passing through the same plane, the Z plane, are irradiated toward the center O of the capture space at equal angles to each other. For example, that angle is 120°. In other words, mirrors 136A, 136B, 136C, and 136D are arranged so that the angles that the laser beams a1, a2, and a3 make with each other are 120°.

[0092] Furthermore, the laser beam c is sequentially reflected by mirrors 136A, 136B, 136C, and 136D, and this reflection generates three laser beams (laser beams a1, a2, and a3) that pass through the Z-plane.

[0093] Furthermore, the laser beam a5 is irradiated from outside the vacuum chamber 132 into the vacuum chamber 132 through the window 132Ab of the upper lid 132A. The laser beam a5 is irradiated toward the center O. The position of the window 132Ab is adjusted so that the laser beam a5 is irradiated toward the center O. The laser beam a5 that has passed through the center O is irradiated to the outside of the vacuum chamber 132 through the window 132Ba of the lower lid 132B. Outside the vacuum chamber 132, a mirror 136E is installed at a position corresponding to the window 132Ba, and the laser beam a5 is reflected by the mirror 136E. The mirror 136E is positioned to reflect the laser beam a5 in the opposite direction to the direction of propagation of the laser beam a5. The laser beam reflected by the mirror 136E is irradiated again into the inside of the vacuum chamber 132 through the window 132Ba of the lower lid 132B. The laser beam reflected by the mirror 136E is the laser beam a4. The laser beam a4 travels along the Z-axis in the opposite direction to the direction of laser beam a5, passing through the center O. After passing through the center O, the laser beam a4 is irradiated from window 132Ab to the outside of the vacuum chamber 132.

[0094] As described above, two laser beams (laser beams a4 and a5) are irradiated into the trapping space. Laser beams a4 and a5 are perpendicular to the Z-plane and travel in opposite directions. Mirror 136E is an example of a second irradiation unit. Mirror 136E is positioned so that the two laser beams perpendicular to the Z-plane are irradiated toward the center O from opposite directions.

[0095] Each optical element, such as a mirror or beam splitter, may be equipped with a waveplate to obtain a specific polarization. Furthermore, the position (e.g., height) of each optical element, such as a mirror or beam splitter, is adjusted to match the beam diameter of the laser light. Each optical element may be attached, for example, to the window of the vacuum chamber 132 using an optical adhesive.

[0096] The center O of the region where the laser beams a1, a2, a3, a4, and a5 intersect (i.e., the center O of the trapping space) coincides with the point of symmetry of the quadrupole magnetic field formed by the magnetic field generator 134. The positions, shapes, and sizes of each optical element such as mirrors and beam splitters, the magnetic field generator 134, and the window of the vacuum chamber 132 are adjusted so that the center O of the region where the laser beams a1, a2, a3, a4, and a5 intersect coincides with the point of symmetry of the quadrupole magnetic field.

[0097] If the point of symmetry of the quadrupole magnetic field shifts due to leakage of the magnetic field used for Zeeman deceleration, the point of symmetry may be finely adjusted by winding coil wire around a coil bobbin 134C for adjusting the magnetic field to generate an adjustment magnetic field.

[0098] The configuration and position of the magnetic field generator 134 are designed so that it does not obstruct the propagation of the laser beam. For example, the permanent magnet groups 134A and 134B are configured so that the part that introduces the laser beam c, which is the source of the laser beams a1, a2, and a3, into the vacuum chamber 132 (for example, the part including window 132Aa) does not interfere with the magnetic field generator 134. For example, the permanent magnet groups 134A and 134B are each made by dividing a ring-shaped magnet into six sections. In this way, a path is formed for the laser beam to pass through, and the laser beam propagates without being obstructed by the magnetic field generator 134.

[0099] The mechanism for supplying laser light to the magneto-optical trap device 130 will be described below with reference to Figures 8 and 9. Figure 8 shows the beam splitter 150. Figure 9 shows the circulator 160.

[0100] In the example shown in Figure 8, the laser beam is split into two laser beams by the beam splitter 150 and supplied to the magneto-optical trap device 130. One of these two laser beams is used as the laser beam for laser beams a1, a2, and a3 (e.g., laser beam c). The other of these two laser beams is used as the laser beam for laser beams a4 and a5 (e.g., laser beam a5).

[0101] In the example shown in Figure 9, the circulator 160 supplies laser beam a5, which is the source of laser beams a4 and a5, to the magneto-optical trap device 130. The reflected light, laser beam a4, is then supplied to the magneto-optical trap device 130 as laser beam c by the circulator 160.

[0102] The configurations shown in Figures 8 and 9 are merely examples, and the laser light may be supplied to the magneto-optical trap device 130 by configurations other than those shown in Figures 8 and 9.

[0103] The magneto-optical trapping device 130 according to this embodiment can achieve the effects described below.

[0104] In a magneto-optical trap device 130 operating under ultra-high vacuum, reducing the number of windows through which laser light passes simplifies the structure of the vacuum chamber 132, thereby enabling miniaturization of the magneto-optical trap device 130. Furthermore, miniaturization of the magneto-optical trap device 130 can be achieved by arranging the components (e.g., optical elements such as mirrors) installed within the vacuum chamber 132 in the same plane (e.g., the Z-plane) rather than in a three-dimensional arrangement.

[0105] Furthermore, in this embodiment, five laser beams are used, which is fewer than the number of laser beams required to achieve magneto-optical trapping compared to conventional techniques that use six laser beams. In addition, one laser beam a1 can be used as laser beam b for Zeeman deceleration to decelerate the atomic beam.

[0106] Furthermore, in conventional technology that uses four laser beams, it is necessary to arrange multiple mirrors three-dimensionally in order to generate four laser beams from one laser beam, making it difficult to miniaturize the device.

[0107] On the other hand, in this embodiment, a magneto-optical trap can be realized by arranging multiple mirrors on the same plane (for example, the Z-plane) and placing one mirror on the Z-axis perpendicular to that plane. Since a magneto-optical trap can be realized with such a simple configuration, the device can be miniaturized. The window shown in Figure 7 and the configuration shown in Figure 11 are used for this purpose. With these configurations, the number of windows that need to be installed in the vacuum chamber 132 is reduced, thus enabling the device to be miniaturized.

[0108] The following describes modified configurations for supplying laser light into the vacuum chamber 132 with reference to Figures 10 and 11. Figure 10 shows the mirror group and laser light group shown in Figure 4. Figure 11 shows the mirror group and laser light group according to the modified configuration.

[0109] In the example shown in Figure 4, laser beams c and a5 are irradiated into the vacuum chamber 132 from the window 132Aa of the upper lid 132A (see Figure 10).

[0110] In a modified configuration, as shown in Figure 11, an optical port 132C, such as a window, is installed on the side of the vacuum chamber 132, and laser light a1 is irradiated into the vacuum chamber 132 from the optical port 132C. Laser light a5 is irradiated into the interior of the vacuum chamber 132 from the window 132Aa, similar to the example shown in Figure 10.

[0111] Generally, increasing the number of windows attached to the vacuum chamber 132 increases the volume of the vacuum chamber 132 because it requires the installation of components such as vacuum seals. The configuration shown in Figure 10 has one fewer window than the configuration shown in Figure 11, thus contributing to the miniaturization of the device.

[0112] On the other hand, according to the configuration shown in Figure 11, the laser beam a1 is irradiated into the vacuum chamber 132 from the side, making it less likely to interfere with the magnetic field generator 134. In other words, since the permanent magnet group 134A is installed on the upper lid 132A side and the permanent magnet group 134B is installed on the lower lid 132B side, irradiating the vacuum chamber 132 from the side with the laser beam a1 makes it less likely for the laser beam a1 to interfere with the permanent magnet groups 134A and 134B. As a result, the design (e.g., arrangement) of the magnetic field generator 134 becomes easier.

[0113] <Physical package operation> The operation of the physical package 12 of the optical lattice clock according to this embodiment will be described below. Similar to physical package 100, physical package 12 includes an atomic oven 110, a Zeeman reducer 120, and a magneto-optical trap device 130, and realizes magneto-optical trapping and clock transitions. The operation of physical package 12 will be described below. Note that the operation of physical package 100 is the same as that of physical package 12.

[0114] In the physical package 12, the inside of the vacuum chamber 132 is evacuated. The atomic beam emitted from the atomic oven 110 to the Zeeman reducer 120 is sufficiently slowed down according to the Zeeman deceleration method and reaches the magneto-optical trap device 130. In the Zeeman reducer 120, the atomic beam is slowed down using the laser light b described above.

[0115] Within the magneto-optical trapping device 130, a magnetic field generator 134 creates a magnetic field with a linear spatial gradient centered on the trapping space where atoms are trapped, and laser beams a1, a2, a3, a4, and a5 are irradiated as MOT light. The magnetic field created by the magnetic field generator 134 and the laser beams a1, a2, a3, a4, and a5, which are MOT light, trap the atoms in the trapping space. The low-speed atomic beam that reaches the magneto-optical trapping device 130 is decelerated in the trapping space, thereby trapping the atomic group in the trapping space. In addition, an optical lattice light beam is incident on the trapping space and reflected by an optical resonator provided in the vacuum chamber 132, thereby creating an optical lattice potential with standing waves connected in the direction of propagation of the optical lattice light beam. The atomic group is trapped in the optical lattice potential.

[0116] By slightly altering the wavelength, the optical lattice can be moved in the direction of the optical lattice beam's propagation. This movement using the movable optical lattice allows the atomic ensemble to move to the clock transition space. As a result, the clock transition space is shifted away from the beam axis of the low-velocity atomic beam.

[0117] In the clock transition space, atoms are irradiated with laser light of controlled optical frequency, and high-precision spectroscopy of clock transitions (i.e., atomic resonance transitions that serve as the clock reference) is performed to measure the atom's intrinsic and invariant frequencies. This enables the realization of an accurate atomic clock. If it is not necessary to move the atomic ensemble from the trapping space to the clock transition space, spectroscopy may be performed in the trapping space.

[0118] To improve the accuracy of atomic clocks, it is necessary to eliminate perturbations surrounding atoms and accurately read their frequencies. Of particular importance is the elimination of frequency shifts caused by the Doppler effect due to the thermal motion of atoms. In optical lattice clocks, the motion of atoms is frozen by confining them in an optical lattice created by the interference of laser light in a space sufficiently small compared to the wavelength of the clock laser. On the other hand, within the optical lattice, the frequency of the atoms is shifted by the laser light that forms the optical lattice. Therefore, by selecting a specific wavelength and frequency called the "magic wavelength" or "magic frequency" as the optical lattice light beam, the influence of the optical lattice on the resonance frequency is eliminated.

[0119] The light emitted as a result of the clock transition is received by the optical system 14 and subjected to spectral processing by the control device 16 to determine its frequency.

[0120] In the above description, an optical lattice clock was used as an example. However, the technology of the embodiments described above can be applied to devices other than optical lattice clocks to those skilled in the art. Specifically, it can be applied to atomic clocks other than optical lattice clocks, or to atomic interferometers, which are interferometers that use atoms. For example, a physical package for an atomic clock or a physical package for an atomic interferometer may be configured, including the magneto-optical trap device 130 according to the embodiment. Furthermore, this embodiment can also be applied to various quantum information processing devices for atoms or ionized atoms. A quantum information processing device is a device that performs measurement, sensing, and information processing using the quantum state of atoms or light, and examples include, in addition to atomic clocks and atomic interferometers, magnetic field meters, electric field meters, quantum computers, quantum simulators, quantum repeaters, etc. In the physical package of a quantum information processing device, miniaturization or portability can be achieved in the same way as in the physical package of an optical lattice clock by utilizing the technology of the embodiments. Note that in such devices, the clock transition space may be treated not as a space for clock measurement, but simply as a space for causing clock transition spectroscopy.

[0121] In the above explanation, specific embodiments were shown to facilitate understanding. However, these are merely illustrative examples, and various other embodiments are possible. [Explanation of Symbols]

[0122] 10 Optical lattice clock, 12 Physical package, 14 Optical system, a1, a2, a3, a4, a5, b Laser light, 136A, 136B, 136C, 136D, 136E Mirrors.

Claims

1. In a magneto-optical trapping device that traps atoms using a magnetic field formed in a trapping space where atoms are trapped, and a plurality of laser beams supplied to the trapping space, A first irradiation unit having multiple mirrors, the multiple mirrors sequentially reflecting a single laser beam to generate three laser beams that pass through the same plane and irradiate the capture space from different directions, A second irradiation unit that irradiates the capture space with two laser beams intersecting the plane, Includes, The three laser beams from the first irradiation unit and the two laser beams from the second irradiation unit are arranged in the trapping space such that the radiation pressure acting on the atoms by the laser beams balances each other. A magneto-optical trapping device characterized by the following features.

2. In the magneto-optical trapping device according to claim 1, The first irradiation unit irradiates the three laser beams passing through the same plane into the capture space at equal angles to each other. A magneto-optical trapping device characterized by the following features.

3. In the magneto-optical trapping device according to claim 1, The plurality of mirrors are arranged such that the three laser beams passing through the same plane are irradiated into the capture space at equal angles to each other. A magneto-optical trapping device characterized by the following features.

4. In the magneto-optical trapping device according to claim 1, One of the three laser beams passing through the same plane is used in conjunction with the laser beam of a Zeeman decelerator, which slows down an atomic beam using both the laser beam and a magnetic field. A magneto-optical trapping device characterized by the following features.

5. In the magneto-optical trapping device according to claim 1, The second irradiation unit irradiates the capture space with the two laser beams intersecting the plane from opposite directions. A magneto-optical trapping device characterized by the following features.

6. In the magneto-optical trapping device according to claim 5, The second irradiation unit generates another laser beam from the two laser beams by reflecting one of the two laser beams that intersect the plane. A magneto-optical trapping device characterized by the following features.

7. In the magneto-optical trapping device according to claim 1, The plane is a plane that passes through the point of symmetry of the magnetic field formed in the trapping space to trap atoms. A magneto-optical trapping device characterized by the following features.

8. Includes the magneto-optical trapping device described in claim 1, A physical package characterized by the following features.

9. A physical package including the one described in claim 8, A physical package for optical lattice clocks characterized by the following features.

10. A physical package including the one described in claim 8, A physical package for atomic clocks characterized by the following features.

11. A physical package including the one described in claim 8, A physical package for atomic interferometers characterized by the following features.

12. A physical package including the one described in claim 8, A physical package for a quantum information processing device for atoms or ionized atoms, characterized by the above.

13. The physical package according to claim 8, A control device that controls the operation of the physical package, A physical package system that includes this.

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