Magneto-optical trap device, physical package, physical package for optical lattice clock, physical package for atomic clock, physical package for atomic interferometer, physical package for quantum information processing device, and physical package system

Abstract

The atoms are captured by a quadrupole magnetic field formed by magnets (106), (108) and three sets of laser pairs. A region (114), which is a non-atom trapping space, is formed in an intersection region (112) where the three laser pairs intersect by shielding a part of the laser pairs (LZ) with magnets (106, 108). By irradiating laser light (118) into the intersection region (112), atoms in the non-atom trapping space move to the outside of the intersection region (112).

Description

Technical Field

[0001] The 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 atomic interferometer, a physical package for a quantum information processing device and a physical package system. Background Art

[0002] The optical lattice clock is an atomic clock proposed by Hidetoshi Katori, one of the inventors of this application, in 2001. In the optical lattice clock, atomic groups are enclosed in an optical lattice formed by lasers, and the resonant frequency in the visible light region is measured. Therefore, it is possible to measure with an accuracy of 18 bits, which is far higher than the accuracy of the current cesium clock. Optical lattice clocks are being researched and developed not only by the inventor group, but also by various groups at home and abroad, and are being developed into the next generation of atomic clocks.

[0003] As for the recent technology of optical lattice clocks, for example, the following patent documents 1 to 3 can be cited. Patent document 1 describes the formation of a one-dimensional moving optical lattice inside an optical waveguide having a hollow channel. Patent document 2 describes a scheme for setting an effective magic frequency. In fact, the magic wavelength has been determined theoretically and experimentally using strontium, ytterbium, mercury, cadmium, and magnesium. In addition, patent document 3 describes a radiation shield that reduces the influence of black body radiation emitted from the surrounding walls.

[0004] In an optical lattice clock, time is measured with high precision, so a height difference of 1 cm on the earth based on the general relativity effect of gravity can be detected as a deviation in the time process. Therefore, if the optical lattice clock can be miniaturized and portable and used in the field outside the laboratory, the applicability will be expanded to new geodetic technologies such as underground resource exploration, underground caves, and magma chamber detection. By mass-producing optical lattice clocks and deploying them in various places, it is possible to continuously monitor the time changes of gravitational potential, detect crustal changes, and spatial mapping of gravity fields. In this way, optical lattice clocks are expected to exceed the limits of high-precision time measurement and contribute to society as a new basic technology.

[0005] The physical package of a general optical lattice clock includes an atomic oven, a Zeeman slower, and a magneto-optical trap (MOT). The atomic oven and the Zeeman slower generate a cooling atomic beam, which is then output to the magneto-optical trap.

[0006] Generally, a Zeeman slowdown device includes a bore and a magnetic field generator that generates a magnetic field along the central axis of the bore. The Zeeman slowdown device uses the Zeeman slowdown method to slow down the speed of an atomic beam with a fast initial velocity emitted from an atomic reactor to a speed that can be captured by a magneto-optical trap device. Laser light is irradiated into the bore from the opening of the bore. The laser light travels in a direction opposite to the direction of travel of the atomic beam and has a frequency obtained by correcting the Doppler shift term from the atomic migration resonance frequency. The atomic beam is slowed down by the strong radiation force of the laser light. Furthermore, by forming a magnetic field with a gradient in space with the bore as the center by a magnetic field generator, the change in the Doppler shift caused by the deceleration can be compensated by the Zeeman shift, creating a situation in which the deceleration laser always resonates with the atoms.

[0007] The magneto-optical trap device located after the Zeeman reducer captures atoms using multiple laser beams and a quadrupole magnetic field formed around the location where the atoms are trapped.

[0008] The frequency of the laser is set to a value that is negatively detuned from the resonance frequency of the atom. When a photon of the laser is absorbed by an atom, the momentum of the photon is imparted to the atom, acting on the atom as radiation pressure. When the atom moves at a finite speed, the frequency of the laser relative to the movement is Doppler shifted so as to approach the resonance frequency of the atom. On the other hand, the frequency of the laser parallel to the direction of the movement is Doppler shifted so as to move away from the resonance frequency of the atom. Therefore, the atom is more strongly subjected to the radiation pressure from the laser relative to the movement, and as a result, the atom slows down.

[0009] Furthermore, the quadrupole magnetic field can generate radiation pressure with position dependence. Specifically, the radiation pressure with position dependence is a radiation pressure that causes the resonance frequency of atoms to undergo a larger Zeeman frequency shift as it moves away from the center of the capture space. In addition, by selecting the polarization of the laser, the direction of applying the radiation pressure can be directed toward the center.

[0010] As described above, by combining the Zeeman slowdown device and the magneto-optical trap device, it is possible to slow down a high-speed atomic beam and trap atoms in a trapping space.

[0011] For example, when strontium atoms are used as the atomic source, a wavelength of 461 nm (equivalent to 1 S 0 - 1 P 1 A laser with a wavelength of energy between energy levels) is used as a deceleration laser.

[0012] However, there is known a technique for supplying trapped cooling atoms toward a subsequent device.

[0013] As another technique, a technique using moving molasses is known (see Patent Document 4). By increasing the frequency of the laser light in the direction in which the cooled atoms are to be moved in the laser pair used to realize the magneto-optical trap and decreasing the frequency of the laser light in the opposite direction, the atoms can be moved from the trapped position while maintaining the cooling state.

[0014] As another technique, a technique using a mirror with a hole is known (see non-patent document 1). Specifically, the laser light in the direction in which the cooling atoms are to be moved in the laser pair used to realize the magneto-optical trap is generated by the reflected light from the laser paired therewith. A hole is formed in the center of the mirror used to generate the reflected light, and the mirror is arranged close to a position in contact with the area where the multiple groups of laser pairs intersect. According to this structure, a columnar area where the laser light is not reflected is formed by the hole. The cooling atoms entering this area are subjected to radiation pressure in the direction of release from the hole, and as a result, the cooling atoms are probabilistically pulled out of the hole of the mirror. The same is true when using a conical mirror, a pyramid mirror, etc. with a hole formed on the central axis.

[0015] As another technique, there is known a technique of providing a member for shielding laser light in the optical paths of two of the three mutually orthogonal laser pairs. In this technique, in addition to generating isotropic radiation pressure in the region where the three laser pairs intersect, anisotropic radiation pressure is also generated in a direction away from the region. This anisotropic radiation pressure probabilistically pulls out cooling atoms.

[0016] As another technique, there is known a technique in which the trapping method is switched from the magneto-optical trap method to the optical trap method, and the cooled atoms are moved by scanning the optical potential that confines the cooled atoms (Patent Document 3).

[0017] As another technique, there is known a technique in which the trapping method is switched from the magneto-optical trap method to the magnetic trap method, and the cooled atoms are moved by scanning the magnetic potential that confines the cooled atoms (Non-Patent Document 2).

[0018] In addition, there is known a method of optically pumping atoms in a magneto-optical trap to a non-trapped state and then pulling out and cooling the atoms by gravity (Non-Patent Document 3).

[0019] As methods for generating a quadrupole magnetic field required for a magneto-optical trap, for example, a method using an anti-Helmholtz coil and a method using a pair of permanent magnets magnetized in antiparallel relation to each other are known. Patent document 5 describes the use of an annular magnet through which one pair of laser beams from among three laser beam pairs passes together with an excitation coil.

[0020] Prior art literature

[0021] Patent Literature

[0022] Patent Document 1: Japanese Patent No. 6206973

[0023] Patent Document 2: Japanese Patent No. 6635608

[0024] Patent Document 3: Japanese Patent No. 7189588

[0025] Patent Document 4: U.S. Patent No. 5,274,232

[0026] Patent Document 5: U.S. Patent No. 10371763

[0027] Non-patent literature

[0028] Non-patent document 1: Phys. Rev. Lett 77 (1996) 3331 Z. T. Liu et al.

[0029] Non-patent document 2: Phys. Rev. A 63 (2001) 031401 M. Greiner et al.

[0030] Non-patent document 3: Phys. Rev. A 46 (1992) R17 F. Shimizu et al. Summary of the invention

[0031] Problem that the invention aims to solve

[0032] However, in devices such as atomic clocks and atomic interferometers, it is desired to continuously supply cooled atomic gas and continuously perform measurement.

[0033] An object of the present invention is to capture atoms and continuously supply them to a subsequent device.

[0034] Solutions for solving problems

[0035] One scheme of the present invention is a magneto-optical trap device, characterized in that it includes: a first forming unit, which forms an atomic capture space for capturing atoms by using a first light group and a magnetic field; a second forming unit, which forms a non-atomic capture space in an intersection area where the first light group intersects; and a light irradiation unit, which irradiates the second light into the intersection area to cause the atoms in the non-atomic capture space to emerge from the intersection area.

[0036] The first forming unit and the second forming unit may include a pair of magnets that generate a magnetic field, each of the pair of magnets may have a hole through which light passes, and the light irradiation unit may irradiate the second light toward the intersection region through the hole.

[0037] Alternatively, the pair of magnets may be arranged on a light path in which a portion of the first light group travels, partially shielding a portion of the first light group, and the atomic capture space may be formed between the pair of magnets through the light group in the first light group that is not shielded by the pair of magnets and the magnetic field generated by the pair of magnets, and the non-atomic capture space may be formed in the space in which the light is shielded by the pair of magnets.

[0038] Alternatively, the magneto-optical trap device further includes an auxiliary magnet for forming the atom trapping space.

[0039] Alternatively, the second forming unit is a pair of shielding members formed with holes for allowing light to pass through, the pair of shielding members are arranged on a light path along which a portion of the first light group travels, and partially shield a portion of the first light group, and the light irradiation unit irradiates the second light toward the intersection area through the holes.

[0040] Alternatively, the pair of shielding members may be made of paramagnetic material.

[0041] The second light may be a push laser.

[0042] The first light group may be a laser beam having a wavelength of 461 nm or a laser beam having a wavelength of 689 nm.

[0043] One embodiment of the present invention is a physical package, characterized by including the above-mentioned magneto-optical trap device.

[0044] One embodiment of the present invention is a physical package for an optical lattice clock, characterized by including the above-mentioned physical package.

[0045] One embodiment of the present invention is a physical package for an atomic clock, characterized by including the above-mentioned physical package.

[0046] One embodiment of the present invention is a physics package for an atom interferometer, characterized by including the above-mentioned physics package.

[0047] One embodiment of the present invention is a physical package for a quantum information processing device for atoms or ionized atoms, characterized by including the above-mentioned physical package.

[0048] One aspect of the present invention is a physical packaging system, comprising: the above-mentioned physical packaging; and a control device that controls the operation of the physical packaging.

[0049] Effects of the Invention

[0050] According to the present invention, atoms can be captured and continuously supplied to a subsequent device. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 : is a block diagram showing the overall structure of the optical lattice clock according to the embodiment.

[0052] Figure 2 This is a cross-sectional view showing a schematic configuration of a magneto-optical trap device according to the first embodiment.

[0053] Figure 3 This is a cross-sectional view showing a schematic configuration of a magneto-optical trap device according to the first embodiment.

[0054] Figure 4 It is a perspective view showing a pair of magnets.

[0055] Figure 5 It is a diagram showing calculated values ​​of the magnetic field distribution formed by the magneto-optical trap device according to the first embodiment.

[0056] Figure 6 It is a diagram showing calculated values ​​of the magnetic field distribution formed by the magneto-optical trap device according to the first embodiment.

[0057] Figure 7 It is a diagram showing calculated values ​​of the magnetic field distribution formed by the magneto-optical trap device according to the first embodiment.

[0058] Figure 8 It is a diagram showing calculated values ​​of the magnetic field distribution formed by the magneto-optical trap device according to the first embodiment.

[0059] Fig. 9 It is a perspective view showing a modified example of a pair of magnets.

[0060] Fig.10 It is a perspective view showing a modified example of a pair of magnets.

[0061] Fig.11 A diagram schematically showing a physical package.

[0062] Fig.12 It is a cross-sectional view showing a schematic structure of a magneto-optical trap device according to a second embodiment.

[0063] Fig.13 It is a diagram showing calculated values ​​of the magnetic field distribution formed by the magneto-optical trap device according to the second embodiment.

[0064] Fig.14 It is a diagram showing calculated values ​​of the magnetic field distribution formed by the magneto-optical trap device according to the second embodiment.

[0065] Fig.15 It is a diagram showing five laser beams.

[0066] Fig.16This is a cross-sectional view showing a schematic structure of a magneto-optical trap device according to a third embodiment.

[0067] Fig.17 This is a cross-sectional view for explaining how to attach a pair of magnets.

[0068] Fig.18 This is a cross-sectional view for explaining how to attach a pair of magnets. DETAILED DESCRIPTION

[0069] <Structure of the optical lattice clock>

[0070] Reference Figure 1 A schematic configuration of an optical lattice clock 10 using a magneto-optical trap device according to an embodiment will be described. Figure 1 1 is a block diagram showing the overall structure of the optical lattice clock 10. Here, the optical lattice clock 10 is described as an example of a device using the magneto-optical trap device of the embodiment, but the magneto-optical trap device of the embodiment can also be used for devices other than the optical lattice clock 10.

[0071] The optical lattice clock 10 includes, for example, a physics package 12 , an optical system device 14 , a control device 16 , and a PC (Personal Computer) 18 .

[0072] The physical package 12 is a device that captures an atomic group and seals it in an optical lattice to cause a clock transition. The optical system device 14 is a device equipped with optical devices such as a laser source for atom capture, a laser source for clock transition excitation, and a laser frequency control device. In addition to sending laser light to the physical package 12, the optical system device 14 also receives the fluorescence signal released by the atomic group in the physical package 12 and converts it into an electrical signal and feeds it back to the laser source to match the resonant frequency of the atoms. The control device 16 is a device that controls the physical package 12 and the optical system device 14. The control device 16, for example, performs operation control of the physical package 12, operation control of the optical system device 14, and analysis processing such as frequency analysis of the clock transition obtained by measurement. The function of the optical lattice clock 10 is realized by the cooperation of the physical package 12, the optical system device 14, and the control device 16.

[0073] PC18 is a general-purpose computer including a processor and a memory. The functions of PC18 are realized by executing software by hardware including a processor and a memory. An application for controlling the optical lattice clock 10 is installed in PC18. PC18 is connected to the control device 16, and can control not only the control device 16 but also the entire optical lattice clock 10 including the physical package 12 and the optical system device 14. In addition, PC18 provides a UI (User Interface) of the optical lattice clock 10. The user can start the optical lattice clock 10, measure time, and confirm the results through PC18.

[0074] In addition, a system including the physical package 12 and the configuration required for controlling the physical package 12 is sometimes referred to as a "physical package system". The configuration required for control may be included in the control device 16 or the PC 18, or may be included in the physical package 12. In addition, part or all of the functions of the control device 16 may also be included in the physical package 12.

[0075] Hereinafter, the magneto-optical trap device according to the embodiment will be described in detail.

[0076] <Magneto-optical trap device according to the first embodiment>

[0077] Reference Figures 2 to 4 The magneto-optical trap device 100 according to the first embodiment will be described. Figure 2 and Figure 3 It is a cross-sectional view showing a schematic structure of the magneto-optical trap device 100 according to the first embodiment. Figure 4 It is a perspective view showing a pair of magnets.

[0078] Here, a coordinate system consisting of mutually orthogonal X-axis, Y-axis and Z-axis is defined. The point where the X-axis, Y-axis and Z-axis intersect each other is determined as the center O of the atom trapping space 102. The center O coincides with the symmetric point of the quadrupole magnetic field B for the magneto-optical trap.

[0079] The magneto-optical trap device 100 includes: a vacuum chamber; a first irradiation device 104 that irradiates laser light to an atom trapping space 102 for atoms; and a pair of magnets (a pair of magnets is composed of a magnet 106 and a magnet 108), which is an example of a magnetic field generating device that generates a quadrupole magnetic field B.

[0080] The first irradiation device 104 includes: one or more light sources that emit laser light; and one or more optical elements (such as mirrors, beam splitters, etc.) that are used to irradiate the laser light emitted from the one or more light sources to the atom trapping space 102. The first irradiation device 104 irradiates three mutually orthogonal laser pairs. The three laser pairs are composed of a total of six resonant laser beams that are negatively detuned with respect to the target atoms.

[0081] Specifically, the three laser pairs are composed of a laser pair LX irradiated along the X axis, a laser pair LY irradiated along the Y axis, and a laser pair LZ irradiated along the Z axis.

[0082] The laser pair LX is composed of laser light LX1 that travels in the positive direction on the X-axis and laser light LX2 that travels in the negative direction on the X-axis (that is, laser light that travels in the direction opposite to the direction of travel of laser light LX1 ).

[0083] Although laser treatment of LY Figure 2 and Figure 3 Although not shown in the figure, it is composed of laser light LY1 that travels in the positive direction on the Y axis and laser light LY2 that travels in the negative direction on the Y axis (that is, laser light that travels in the direction opposite to the traveling direction of laser light LY1).

[0084] Laser pair LZ is composed of laser light LZ1 that travels in the positive direction on the Z axis and laser light LZ2 that travels in the negative direction on the Z axis (that is, laser light that travels in the direction opposite to the travel direction of laser light LZ1 ).

[0085] Figure 2 The area 110 irradiated by the laser is schematically shown. Figure 3 The dotted line in FIG. 1 shows the intersection region 112. The intersection region 112 is a region where the three laser pairs intersect. The atoms in the intersection region 112 interact with the three laser pairs, and radiation pressure is applied to the atoms from a direction opposite to the direction of motion of the atoms.

[0086] In the intersection region 112 , the radiation pressure has spatial dependence due to the quadrupole magnetic field B. The radiation pressure having this spatial dependence acts as a restoring force toward the center point of the quadrupole magnetic field B for the atoms.

[0087] The quadrupole magnetic field B is generated by the pair of magnets (magnets 106 and 108) described above. Magnets 106 and 108 are, for example, annular magnets. A hole 106a is formed in the center of magnet 106 so as to pass through magnet 106 in the magnetization direction. Similarly, a hole 108a is formed in the center of magnet 108 so as to pass through magnet 108 in the magnetization direction. The shapes of holes 106a and 108a may be circular or rectangular.

[0088] For example, the magnets 106 and 108 are permanent magnets magnetized along the Z axis. That is, the magnets 106 and 108 are arranged on the Z axis in such a manner that the magnetization direction is parallel to the direction of the Z axis. Specifically, the magnets 106 and 108 are arranged in such a manner that the center O of the intersection region 112 is interposed therebetween and the magnetization direction 106b of the magnet 106 and the magnetization direction 108b of the magnet 108 are in opposite directions to each other. The distance between the magnet 106 and the center O is equal to the distance between the magnet 108 and the center O. In addition, the magnets 106 and 108 are arranged at a position close to the intersection region 112 in such a manner that the laser pairs LX and LY are not blocked.

[0089] The width of the magnets 106 and 108 in the X-axis direction and the width in the Y-axis direction are smaller than the diameter of the lasers LZ1 and LZ2. Since the magnets 106 and 108 are arranged on the Z-axis, a part of the lasers LZ1 and LZ2 are shielded by the magnets 106 and 108. As a result, a region 114 not irradiated by the lasers LZ1 and LZ2 is formed in the intersection region 112. This region 114 is a region where the light is shielded by the magnets 106 and 108, and is equivalent to an example of a non-atom trapping space.

[0090] That is, the magnets 106 and 108 are disposed on the optical path of the laser pair LZ, which is one of the three laser pairs, and partially shield a part of the laser pair LZ (that is, the laser light LZ1 and LZ2). Thus, the atom trapping space 102 is formed by the laser light group that is not shielded by the magnets 106 and 108 (that is, the laser light group including the laser pair LX, the laser pair LY, and the laser light that is not shielded in the laser pair LZ) and the quadrupole magnetic field B formed by the magnets 106 and 108. In addition, in the space where the light is shielded by the magnets 106 and 108, a region 114 that is a non-atom trapping space is formed.

[0091] In addition, the magneto-optical trap device 100 includes a second irradiation device 116. The second irradiation device 116 includes: a light source that emits laser light; and one or more optical elements (such as a mirror, a beam splitter, etc.) that are used to irradiate the laser light emitted from the light source to the intersection area 112. The second irradiation device 116 irradiates the intersection area 112 with a laser light 118. The laser light 118 passes through the hole 106a of the magnet 106 and the hole 108a of the magnet 108 along the Z axis and irradiates the atom trapping space 102.

[0092] The relationship between the size (eg, diameter) of the magnets 106 and 108 , the size (eg, diameter) of the holes 106 a and 108 a , and the diameter of the laser light for the magneto-optical trap (laser light LZ1 , etc.) is as shown below.

[0093] The size of holes 106a and 108a is less than the size of magnets 106 and 108 and less than the diameter of the laser used for the magneto-optical trap.

[0094] Laser 118 is a laser used for optically trapping atoms. As an example of optical trapping, a method of trapping atoms by a dipole force induced by an optical electric field can be cited. When this method is used, a laser for an optical dipole trap is used as laser 118. As another example, a method of trapping atoms by a standing wave of light can be cited. When this method is used, a laser for an optical lattice is used as laser 118. As yet another example, a push laser composed of a resonant laser can also be used as laser 118. In this case, the radiation force can be used to impart motion force to the atoms.

[0095] In addition, the three groups of lasers are equivalent to an example of the first light group, the first irradiation device 104 and the magnets 106 and 108 are equivalent to an example of the first forming unit, the magnets 106 and 108 are equivalent to an example of the second forming unit, the second irradiation device 116 is equivalent to an example of the light irradiation unit, and the laser 118 is equivalent to an example of the second light.

[0096] Next, the operation of the magneto-optical trap device 100 will be described.

[0097] The first irradiation device 104 irradiates the laser light pair LX, LY, and LZ to form the intersection region 112. In addition, the magnets 106 and 108 form a quadrupole magnetic field B. In addition, the second irradiation device 116 irradiates the atom trapping space 102 with laser light 118.

[0098] The atoms entering the intersection region 112 are subjected to radiation pressure which serves as a restoring force, and move toward the center O of the quadrupole magnetic field B while being decelerated.

[0099] As described above, in the intersection region 112, there is a region 114 where light is shielded by the magnets 106 and 108. The region 114 is irradiated with the laser pair LX and LY, but is not irradiated with the laser pair LZ. In this region 114, the speed of atoms in the X direction (+X direction, -X direction) and the speed of atoms in the Y direction (+Y direction, -Y direction) are decelerated, but the speed of atoms in the Z direction (+Z direction, -Z direction) is not decelerated. Therefore, the movement of atoms in the region 114 in the Z direction is not restricted, but diffuses in the Z direction. Figure 2 Reference numeral 120 in FIG. 1 indicates the movement of atoms whose movement in the Z direction is not restricted.

[0100] It is assumed that the atoms diffused in the Z direction move to the outside or inside of the light-shielded region 114 while further diffusing.

[0101] The atoms moved to the outside of the region 114 are irradiated with the laser pair LZ, and are therefore pulled back toward the center O of the quadrupole magnetic field B by the laser pairs LX, LY, and LZ and the quadrupole magnetic field B.

[0102] On the other hand, the atoms moved to the inner side of the region 114 interact with the laser 118. Here, as an example, the laser 118 is irradiated in the -Z direction. In the case where the laser 118 is a push laser, the atoms are subjected to the radiation pressure and move in the -Z direction. In the case where the laser 118 is a laser for a light trap, the atoms can be moved in the -Z direction by controlling the potential of the light trap from the outside. The atoms moving in the -Z direction pass through the hole 108a of the magnet 108 and are pushed outward from the intersection region 112.

[0103] As described above, it is possible to impart a motion amount to atoms with a limited probability relative to the traveling direction of the laser 118, so that the atoms move to the outside of the intersection region 112. The atoms moved to the outside of the intersection region 112 are supplied to the subsequent device. Thus, cooled atoms can be continuously supplied to the subsequent device. For example, in order to move the atoms captured in the atom capture space 102, even if the laser pairs LX, LY, and LZ are not turned off, the cooled atoms can be supplied to the subsequent device.

[0104] As a specific example of the first embodiment, the wavelength of the laser light pair LX, LY, and LZ is 689 nm. In addition, as an example, the width (outer diameter) of the magnets 106 and 108 in the X and Y directions is about 0.8 mm, the width (inner diameter) of the holes 106a and 108a in the X and Y directions is about 0.27 mm, and the distance between the magnets 106 and 108 is about 10 mm to 15 mm.

[0105] Figures 5 to 8 Calculated values ​​of the distribution of the magnetic field generated between the magnet 106 and the magnet 108 are shown.

[0106] Figure 5 The calculated value shown is the calculated value (BY(G)) of the Y component of the magnetic field in the YZ plane (the plane formed by the Y axis and the Z axis). Figure 6 The calculated values ​​shown are calculated values ​​of the Z component of the magnetic field in the YZ plane (BZ(G)). The calculated values ​​are expressed in shades.

[0107] Figure 7 The calculated values ​​of the magnetic field components on the Y-axis are shown. Figure 7The horizontal axis in the figure shows the position on the Y axis, and the vertical axis shows the calculated value of the magnetic field. Reference numeral 122 indicates the calculated value (BX) of the X component of the magnetic field and the calculated value (BZ) of the Z component of the magnetic field. Reference numeral 124 indicates the calculated value (BY) of the Y component of the magnetic field. As indicated by reference numeral 126, a straight magnetic field gradient of +3.5 G / cm is formed between -2 mm and +2 mm.

[0108] Figure 8 The calculated values ​​of the magnetic field component on the Z axis are shown. Figure 8 The horizontal axis in the figure shows the position on the Z axis, and the vertical axis shows the calculated value of the magnetic field. Reference numeral 128 indicates the calculated value (BX) and the calculated value (BZ). Reference numeral 130 indicates the calculated value (BY). Between -2 mm and +2 mm, a straight magnetic field gradient of -7.1 G / cm is formed.

[0109] like Figure 7 and Figure 8 As shown, in the first embodiment, a quadrupole magnetic field having a relatively small magnetic field gradient is formed. The atoms are cooled to a temperature of about μK by a magneto-optical trap formed by such a quadrupole magnetic field and a laser having a wavelength of 689 nm. The atoms cooled to a temperature of about μK are supplied from the magneto-optical trap device 100 to a subsequent device.

[0110] As described above, the annular magnets 106 and 108 function as a mask for the laser beam, so that the cooling atoms can be taken out from the magneto-optical trap device 100 and supplied to the subsequent device without adding a new structure. In addition, the cooling atoms can be continuously emitted without performing precise position adjustment or parameter adjustment of each structure.

[0111] There is a possibility that the atomic gas will adhere to the shielding member and the shielding member will be contaminated. In the case where the shielding member is an optical element such as a mirror with a hole, the optical characteristics of the optical element may be degraded due to the contamination. In contrast, since the magnets 106 and 108 with holes function as shielding members, there will be no problem of degradation of the optical characteristics of the optical element.

[0112] Fig. 9 and Fig.10 A modified example of a pair of magnets that forms a quadrupole magnetic field B is shown. Fig. 9 and Fig.10 It is a perspective view showing a magnet according to a modified example.

[0113] exist Fig. 9In the example shown, a pair of magnets is formed by magnets 140 and 142. Magnets 140 and 142 have rectangular shapes, respectively. In addition, a hole 140a is formed in magnet 140, which passes through magnet 140 in the magnetization direction. Similarly, a hole 142a is formed in magnet 142, which passes through magnet 142 in the magnetization direction. The magnetization direction of magnets 140 and 142 is the same as that of magnets 106 and 108. Laser light 118 is irradiated to atom trapping space 102 through holes 140a and 142a. As in the first embodiment described above, the relationship between the size of magnets 140 and 142 (e.g., the length of the diagonal line), the size of holes 140a and 142a (e.g., the diameter), and the diameter of the laser light for magneto-optical trap (laser light LZ1, etc.) is as shown below.

[0114] The size of holes 140a and 142a is less than the size of magnets 140 and 142 and less than the diameter of the laser used for the MOT.

[0115] exist Fig.10 In the example shown, a pair of magnets is formed by magnets 144 and 146. Magnet 144 is formed by arranging a plurality of magnets axially symmetrically so as to form a hole 144a at the center. Similarly, magnet 146 is formed by arranging a plurality of magnets axially symmetrically so as to form a hole 146a at the center. Specifically, magnets 144 and 146 are magnets that are divided into four parts axially symmetrically. The magnetization direction of magnets 144 and 146 is the same as that of magnets 106 and 108. Laser light 118 is irradiated to the atom trapping space 102 through holes 144a and 146a. Similar to the first embodiment described above, the relationship between the size of magnets 144 and 146, the size of holes 144a and 146a, and the diameter of the laser light used for the magneto-optical trap is the relationship shown below.

[0116] The size of holes 144a and 146a is less than the size of magnets 144 and 146 and less than the diameter of the laser used for the magneto-optical trap.

[0117] Below, refer to Fig.11 The physical package of the MOT device 100 is described below. Fig.11 It is a diagram showing a schematic structure of the physical package 150 .

[0118] The physics package 150 includes an atomic reactor 152 , a Zeeman slowdown device 154 , and a magneto-optical trap device 100 .

[0119] The atomic furnace 152 includes a sample container for storing a sample, a heater, a thermometer, an electrical connector, a capillary nozzle, and a thermal radiation shield. The sample container is stored in a vacuum container whose interior is maintained as an ultra-high vacuum. By heating the sample by the heater, an atomic gas is generated from the sample. The atomic gas is emitted from the capillary nozzle toward the Zeeman reducer 154. By emitting the atomic gas from the capillary nozzle, a directional atomic beam is formed. As a sample, for example, strontium, ytterbium, etc. are used, but atoms other than these can also be used as samples.

[0120] The Zeeman slowdown device 154 includes a bore and a magnetic field generator. The magnetic field generator includes a solenoid coil and generates a magnetic field along the central axis of the bore. The atomic beam emitted from the atomic reactor 152 is irradiated into the bore.

[0121] The Zeeman slowdown device 154 uses the Zeeman slowdown method to slow down the speed of the atomic beam having a large initial velocity emitted from the atomic reactor 152 to a speed at which the subsequent magneto-optical trap device 100 can capture the atomic beam.

[0122] The laser beam is irradiated into the bore from a direction opposite to the traveling direction of the atomic beam. The laser beam may also be used as a laser beam for a magneto-optical trap.

[0123] In the Zeeman decelerator 154, the speed of the atomic beam irradiated from the atomic reactor 152 into the bore is decelerated by the magnetic field and laser generated by the magnetic field generator. The high-temperature atomic beam is decelerated by the magnetic field and laser generated by the magnetic field generator according to the Zeeman deceleration method while traveling toward the magneto-optical trap device 100 in the bore.

[0124] In addition, as the nuclear reactor 152 and the Zeeman slowdown device 154 , well-known nuclear reactors and Zeeman slowdown devices can be used.

[0125] As described above, the magneto-optical trap device 100 includes a vacuum chamber, and the vacuum chamber is maintained as an ultra-high vacuum. The interior of the vacuum chamber is connected to the bore of the Zeeman reducer 154 and the vacuum container of the atomic furnace 152, and the bore and the vacuum container of the atomic furnace 152 are maintained as an ultra-high vacuum. In the vacuum chamber of the magneto-optical trap device 100, an atomic capture space 102, an intersection region 112, and a region 114 (non-atomic capture space) are formed.

[0126] Next, the operation of the physical package 150 will be described.

[0127] In the physics package 150 , the interior of the vacuum chamber is evacuated. The atomic beam emitted from the atomic reactor 152 to the Zeeman slowdown device 154 is sufficiently slowed down according to the Zeeman slowdown method and reaches the magneto-optical trap device 100 .

[0128] In the magneto-optical trap device 100 , as described above, atoms are trapped by the laser light pairs LX, LY, and LZ and the quadrupole magnetic field B, and the atoms at extremely low temperatures are probabilistically moved to the outside of the intersection region 112 by the laser light 118 .

[0129] For the extremely low temperature atoms that move to the outside of the intersection region 112, for example, an optical lattice trap is applied. For example, the optical lattice beam is incident on the vacuum chamber of the magneto-optical trap device 100 and is reflected by the optical resonator provided in the vacuum chamber, thereby forming an optical lattice potential in which a standing wave extends in the traveling direction of the optical lattice beam. The atomic group is trapped by the optical lattice potential.

[0130] By slightly changing the wavelength, the optical lattice can be moved in the direction of travel of the optical lattice beam. The atomic group is moved to the clock transition space through the moving unit formed by the moving optical lattice.

[0131] In the clock transition space, atoms are irradiated with frequency-controlled laser light to perform high-precision spectrometry of clock transitions (i.e., resonant transitions of atoms that serve as the clock reference) and measure the atoms' inherent and unchanging frequencies. This enables an accurate atomic clock.

[0132] In order to improve the accuracy of atomic clocks, it is necessary to eliminate the disturbances surrounding the atoms and accurately read the frequency. It is particularly important to remove the frequency shift caused by the Doppler effect caused by the thermal motion of the atoms. In an optical lattice clock, the atoms are confined in a space that is sufficiently small compared to the wavelength of the clock laser by using an optical lattice generated by the interference of lasers to freeze the movement of the atoms. On the other hand, within the optical lattice, the frequency of the atoms will shift due to the laser that forms the optical lattice. Therefore, by selecting a specific wavelength and frequency called the "magic wavelength" or "magic frequency" as the optical lattice beam, the influence of the optical lattice on the resonant frequency can be eliminated.

[0133] As a result of the clock transition, the emitted light is received by the optical system device 14 and subjected to spectroscopic processing by the control device 16 to determine the frequency.

[0134] <Magneto-optical trap device according to the second embodiment>

[0135] Reference Fig.12 A magneto-optical trap device 100A according to the second embodiment will be described. Fig.12 It is a cross-sectional view showing a schematic structure of a magneto-optical trap device 100A according to the second embodiment.

[0136] The MOT device 100A of the second embodiment further includes a pair of auxiliary magnets in addition to the configuration of the MOT device 100 of the first embodiment. The pair of auxiliary magnets is composed of annular auxiliary magnets 160 and 162. A hole 160a is formed in the center of the auxiliary magnet 160 so as to pass through the auxiliary magnet 160 in the magnetization direction. Similarly, a hole 162a is formed in the center of the auxiliary magnet 162 so as to pass through the auxiliary magnet 162 in the magnetization direction. The auxiliary magnets 160 and 162 are magnets magnetized along the Z axis. That is, the auxiliary magnets 160 and 162 are arranged on the Z axis in such a manner that the magnetization direction is parallel to the direction of the Z axis. Specifically, the auxiliary magnets 160 and 162 are arranged at a position that is farther from the center O of the intersection region 112 than the magnets 106 and 108. In addition, the auxiliary magnets 160 and 162 are arranged in such a manner that the magnetization direction of the auxiliary magnet 160 and the magnetization direction of the auxiliary magnet 162 are opposite to each other. The distance between the auxiliary magnet 160 and the center O is equal to the distance between the auxiliary magnet 162 and the center O. In addition, the diameter of the hole 160a of the auxiliary magnet 160 and the diameter of the hole 162a of the auxiliary magnet 162 are larger than the diameter of the laser pair LZ. The laser pair LZ travels through the holes 160a and 162a, and a part of the laser pair LZ is shielded by the magnets 106 and 108. Fig.12 In the example shown, the intersection region 112 is formed by six laser beams {LX1, LX2, LY1, LY2, LZ1, LZ2} as an example, but this is only an example. Fig.12 A Zeeman slowdown device 154 is shown including a bore 156 and a magnetic field generator 158 .

[0137] In the second embodiment, a quadrupole magnetic field having a relatively large magnetic field gradient (e.g., about 50 G / cm) is formed. The atoms are cooled to a temperature of about mK by a magneto-optical trap composed of such a quadrupole magnetic field and a laser having a wavelength of 461 nm. In order to generate such a quadrupole magnetic field having a strong magnetic field gradient, a strong magnet made of, for example, samarium cobalt is used as the magnets 106 and 108. Auxiliary magnets 160 and 162 are used in such a way that the magnetic field distribution formed by the magnetic field generator 158 of the Zeeman reducer 154 and the magnetic field distribution formed by the magnets 106 and 108 are connected in space without waste.

[0138] Fig.13 The figure shows the calculated results of the magnetic field distribution formed by the magneto-optical trap device 100A of the second embodiment. The horizontal axis shows the position on the Z axis, and the vertical axis shows the calculated value of the magnetic field. Reference numeral 166 (solid line) indicates the calculated results of the ideal magnetic field. Reference numeral 168 (dot) indicates the calculated results of the magnetic field obtained by the magneto-optical trap device 100A. Fig.13 , the value shown by reference numeral 166 and the value shown by reference numeral 168 are almost identical.

[0139] Fig.14 The difference between the calculation result of the ideal magnetic field and the calculation result of the magnetic field obtained by the magneto-optical trap device 100A is shown. The horizontal axis shows the position on the Z axis, and the vertical axis shows the difference.

[0140] According to the second embodiment, an ideal magnetic field distribution can be formed by using the magnets 106 and 108 and the auxiliary magnets 160 and 162 .

[0141] In addition, the calculated value of the magnitude of the magnetic field gradient formed at the center O is 35 G / cm, and a quadrupole magnetic field with a relatively large magnetic field gradient can be formed. As a result, atoms cooled to a temperature of about mK can be extracted.

[0142] The magnetization direction of the auxiliary magnets 160 and 162 may be the same as the magnetization direction of the magnets 106 and 108 , or the magnetization direction of the auxiliary magnets 160 and 162 may be the radial direction.

[0143] A pair of magnets obtained by dividing a cylindrical magnet into 2n (n≥2) pieces may be used as auxiliary magnets 160 and 162. By dividing, auxiliary magnets 160 and 162 are less likely to interfere with laser pair LX and LY. As another example, bar magnets, cylindrical magnets, etc. may be arranged at symmetrical positions so as to form a quadrupole magnetic field.

[0144] In the second embodiment, the magnets 106 and 108 may be soft magnets. For example, the shape of the soft magnets is designed so that the magnetic lines of force emitted from the auxiliary magnets 160 and 162 are bound by the magnets 106 and 108, which are soft magnets, and a quadrupole magnetic field is formed near the center O. In addition, instead of the auxiliary magnets 160 and 162, anti-Helmholtz coils may be used to adjust the magnetic field distribution.

[0145] In the first and second embodiments described above, three mutually orthogonal laser beam pairs LX, LY, and LZ are described as an example corresponding to the first light group. Fig.15 Another example equivalent to the first light group is shown. Fig.15As shown, a combination of a total of 5 laser beams {LXY1, LXY2, LXY3, LZ1, LZ2} can also be used as the first light group. Laser LZ is composed of laser LZ1 traveling in the positive direction on the Z axis and laser LZ2 traveling in the negative direction on the Z axis. Laser LXY1 is a laser traveling in the positive direction on the X axis. Laser LXY2 is a laser that rotates laser LXY1 by +120 degrees around the center O on the XY plane. Laser LXY3 is a laser that rotates laser LXY1 by -120 degrees around the center O on the XY plane. A magneto-optical trap using a combination of 5 laser beams is proposed in Japanese Patent Application No. 2022-014486.

[0146] In the first and second embodiments described above, a laser pair LZ may also be generated from a laser beam by a mirror. In this case, in order to supply cooling atoms to a subsequent device, a hole for cooling atoms to pass through may also be formed in the center of the mirror. As another example, in order to supply cooling atoms to a subsequent device, a deflector composed of a resonant laser may also be used. The deflector has the function of bending cooling atoms in an arbitrary direction.

[0147] <Magneto-optical trap device according to the third embodiment>

[0148] Below, refer to Fig.16 A magneto-optical trap device 100B according to the third embodiment will be described. Fig.16 It is a cross-sectional view showing a schematic structure of a magneto-optical trap device 100B according to the third embodiment.

[0149] The magneto-optical trap device 100B of the third embodiment includes a pair of magnets for forming a quadrupole magnetic field B and a pair of shielding members. The pair of magnets is composed of annular magnets 170 and 172. The pair of shielding members is composed of annular shielding members 174 and 176. The shielding members 174 and 176 are an example of the second forming means.

[0150] A hole 170a is formed at the center of the magnet 170, which passes through the magnet 170 in the magnetization direction. A hole 172a is formed at the center of the magnet 172, which passes through the magnet 172 in the magnetization direction. In the third embodiment, the magnets 170 and 172 are magnets magnetized along the X-axis. That is, the magnets 170 and 172 are arranged on the X-axis in such a manner that the magnetization direction is parallel to the direction of the X-axis. Specifically, the magnets 170 and 172 are arranged in such a manner that the magnetization direction of the magnet 170 and the magnetization direction of the magnet 172 are opposite to each other with the center O of the intersection area 112 in between. The distance between the magnet 170 and the center O is equal to the distance between the magnet 172 and the center O. In addition, the diameter of the holes 170a and 172a is larger than the diameter of the laser pair LX. The magnets 170 and 172 are arranged in such a manner that they do not hinder the movement of the laser pairs LY and LZ. That is, the length between the magnet 170 and the magnet 172 is longer than the diameter of the laser pairs LY and LZ.

[0151] A hole 174a is formed at the center of the shielding member 174 and penetrates in the thickness direction of the shielding member 174. A hole 176a is formed at the center of the shielding member 176 and penetrates in the thickness direction of the shielding member 176. The shielding members 174 and 176 are arranged on the Z axis with the center O of the intersection area 112 interposed therebetween. The distance between the shielding member 174 and the center O is equal to the distance between the shielding member 176 and the center O. The outer diameters of the shielding members 174 and 176 are smaller than the diameter of the laser pair LZ. A portion of the laser pair LZ is shielded by the shielding members 174 and 176.

[0152] Laser light 118 for optically trapping atoms is irradiated to the atom trapping space through the hole 174 a of the shielding member 174 and 176 a of the shielding member 176 .

[0153] The shielding members 174 and 176 are made of paramagnetic materials. Paramagnetic materials do not perform optical effects and can shield a portion of the laser beam LZ. The shielding members 174 and 176 are only used for shielding, so even if the surfaces of the shielding members 174 and 176 on the side of the intersection region 112 are contaminated by atomic gas, no problem will occur.

[0154] The magneto-optical trap device 100B further includes mirrors 178 and 180. A hole 178a is formed in the center of the mirror 178 and penetrates the mirror 178 in the thickness direction. The mirror 178 is set at a position farther from the center O than the shielding member 176 on the Z axis. The laser 118 travels through the hole 178a. One laser (for example, the laser LZ2) included in the laser pair LZ is reflected by the mirror 178, thereby generating the other laser (for example, the laser LZ1).

[0155] The mirror 180 is provided on the X-axis at a position farther from the center O than the magnet 172. One laser beam included in the laser beam pair LX is reflected by the mirror 180, thereby generating the other laser beam.

[0156] The mirrors 178 and 180 are merely examples of optical elements for generating laser beam pairs, and laser beam pairs may be generated by using other optical elements (for example, a beam splitter). This is also the case in the first and second embodiments.

[0157] In the third embodiment, as in the first and second embodiments described above, a motion amount with respect to the traveling direction of the laser light 118 can be given to atoms with a finite probability, so that the atoms can be moved to the outside of the intersection region 112 .

[0158] Below, refer to Fig.17 and Fig.18 The following describes a method for mounting annular magnets (eg, magnets 106, 108, etc.). Fig.17 and Fig.18 For example, a method can be considered in which a ring-shaped magnet is attached to a disk plate such as glass or sapphire that transmits light and the disk plate is supported by a magneto-optical trap device.

[0159] exist Fig.17 In the example shown, magnet 200 is provided on one surface of a disk plate 204 having a hole 204a formed in the center, and magnet 202 is provided on the opposite surface of disk plate 204. Magnets 200 and 202 are fixed to disk plate 204 by their own magnetic force with disk plate 204 interposed therebetween.

[0160] exist Fig.18 In the example shown, the magnet 200 is fixed to the disk plate 204 by an adhesive with little outgassing or indium ultrasonic solder.

[0161] As yet another example, a metal pattern may be plated on glass, and the magnet 200 may be mounted to the pattern using indium solder.

[0162] In the above description, an optical lattice clock is used as an example. However, if a person skilled in the art is skilled in the art, the technology of each of the above-mentioned embodiments can also be applied to other than optical lattice clocks. Specifically, it can also be applied to atomic clocks other than optical lattice clocks or atom interferometers as interferometers using atoms. For example, a physical package for an atomic clock including a magneto-optical trap device 100, a magneto-optical trap device 100A or a magneto-optical trap device 100B, or a physical package for an atom interferometer can also be constructed. In addition, the first to third embodiments can also be applied to various quantum information processing devices for atoms or ionized atoms. A quantum information processing device refers to a device that uses the quantum state of atoms or light for measurement, sensing and information processing. In addition to atomic clocks and atom interferometers, magnetic field meters, electric field meters, quantum computers, quantum simulators, quantum repeaters, etc. can also be exemplified. In the physical packaging of a quantum information processing device, by using the technology of the first to third embodiments, miniaturization or portability can be achieved in the same way as the physical packaging of an optical lattice clock. Furthermore, it should be noted that in such a device, the clock transition space is sometimes not a space for the purpose of time measurement, but is merely regarded as a space that causes clock transition dispersion.

[0163] In the above description, specific aspects are shown for easy understanding, but these are merely examples of implementation, and various other implementations are possible.

[0164] Description of Reference Numerals

[0165] 100, 100A, 100B magneto-optical trap device; 102 atomic trapping space; 104 first irradiation device; 106, 108 magnets; 112 intersection area; 116 second irradiation device; 118 laser.

Claims

1. A magneto-optical trap device, characterized in that: Include: a first forming unit that forms an atom trapping space for trapping atoms by using a first light group and a magnetic field; a second forming unit that forms a non-atomic trapping space in an intersection region where the first light groups intersect; as well as The light irradiation unit irradiates the intersection region with a second light to cause the atoms in the non-atom trapping space to be emitted from the intersection region.

2. The magneto-optical trap device according to claim 1, characterized in that: The first forming unit and the second forming unit include a pair of magnets that generate a magnetic field. Each magnet in the pair of magnets is formed with a hole through which light passes, The light irradiation unit irradiates the second light toward the intersection region through the hole.

3. The magneto-optical trap device according to claim 2, characterized in that: The pair of magnets is disposed on the optical path of a portion of the first light group, and partially shields a portion of the first light group. The atom trapping space is formed between the pair of magnets by the light group in the first light group that is not blocked by the pair of magnets and the magnetic field generated by the pair of magnets. The non-atomic trapping space is formed in a space where light is shielded by the pair of magnets.

4. The magneto-optical trap device according to claim 3, characterized in that: The invention also comprises an auxiliary magnet for forming the atom capturing space.

5. The magneto-optical trap device according to claim 1, characterized in that: The second forming unit is a pair of shielding members formed with holes for allowing light to pass through. The pair of shielding members are arranged on the optical path of a part of the first light group, and partially shield a part of the first light group. The light irradiation unit irradiates the second light toward the intersection region through the hole.

6. The magneto-optical trap device according to claim 5, characterized in that: The pair of shielding members are made of paramagnetic material.

7. The magneto-optical trap device according to claim 1, characterized in that: The second light is a boost laser.

8. The magneto-optical trap device according to claim 1, characterized in that: The first light group is a laser beam having a wavelength of 461 nm or a laser beam having a wavelength of 689 nm.

9. A physical package, characterized in that: A magneto-optical trap device comprising any one of claims 1 to 8.

10. A physical package for an optical lattice clock, characterized in that: A physical package comprising the method of claim 9.

11. A physical package for an atomic clock, characterized in that: Comprising the physical package of claim 9.

12. A physical package for an atomic interferometer, characterized in that: A physical package comprising the method of claim 9.

13. A physical package for a quantum information processing device for atoms or ionized atoms, characterized in that: Comprising the physical package of claim 9.

14. A physical packaging system, characterized in that: Include: The physical package of claim 9; and A control device controls the actions of the physical package.

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