Atom trap device, atom cooling device, spectroscopic device, optical lattice clock, quantum computer, coil, atom trap method, atom cooling method, and spectroscopic method

Abstract

This atom trap device 10 for trapping atoms comprises an atom trap unit 16 on which an atomic gas beam is incident. The atom trap unit 16 includes a plurality of optical elements that form a laser light group 18, and a magnetic field generation unit 22. The magnetic field generation unit 22 is provided with at least two spiral coils and, if necessary, a tapered solenoid coil, and optimizes a magnetic field in a guide direction. The spiral coils are configured so that the tip becomes thinner and the winding density becomes sparse as the atoms advance in the direction in which the atoms are guided. The spiral coils are arranged so as to face each other so that an interval therebetween becomes narrower as the atoms advance in the direction in which the atoms are guided. The tapered solenoid coil generates a magnetic field that optimizes the guiding of the atoms and the laser cooling during the guiding by adjusting the component in the direction in which the atoms of the magnetic field generated by the spiral coils are guided. The atom trap unit 16 may also include a baseball coil instead of the spiral coils and the tapered solenoid coil.

Description

Atom trapping device, atom cooling device, spectroscopic device, optical lattice clock, quantum computer, coil, atom trapping method, atom cooling method, and spectroscopic method

[0001] The present invention relates to an atom trapping device, an atom cooling device, a spectroscopic device, an optical lattice clock, a quantum computer, a coil, an atom trapping method, an atom cooling method, and a spectroscopic method.

[0002] Magneto-optical trapping (hereinafter also referred to as "MOT") is known as a method for trapping atoms in space (see, for example, Non-Patent Documents 1 and 2). The principle of MOT will be outlined below.

[0003] MOT achieves atom cooling and trapping by utilizing the frictional force of laser cooling and the restoring force generated by the Zeeman effect of a quadrupole magnetic field. In MOT, a quadrupole magnetic field is generated using anti-Helmholtz coils (two coils with currents flowing in opposite directions). Pairs of opposing laser beams are irradiated onto the anti-Helmholtz coil from three mutually orthogonal directions, with the center near the intersection of the laser beams. The strength of this quadrupole magnetic field is zero at the center of the anti-Helmholtz coil and increases with distance from the center. The quadrupole magnetic field causes a significant Zeeman shift in the resonant frequency of atoms with increasing distance from the center. By appropriately selecting the polarization of the laser beam, a restoring force is generated that directs radiation pressure toward the origin. This allows laser-cooled atoms to be trapped. The region in which atoms are trapped using this method is called the MOT region.

[0004] Another background technology of the present invention is the optical lattice clock. The optical lattice clock is an atomic clock proposed by the present inventor in 2001. High-precision atomic clocks not only support the development of science and technology through precision measurements, but also play an important role as infrastructure systems that support modern society, such as satellite-based navigation systems and the construction of high-capacity, high-speed communication networks. Since 1967, when the "second" was defined as the transition frequency of the microwave transition of the cesium atom, cesium atomic clocks have been used as the standard for time and frequency for half a century. During that time, the introduction of laser cooling technology and the development of atomic fountain clocks have improved the accuracy of cesium atomic clocks by a single digit every decade, and they now have an uncertainty of approximately 15 digits, which is shared worldwide as international atomic time.

[0005] Meanwhile, recent research into atomic clocks has been shifting toward the development of optical clocks based on atomic transitions in the optical frequency domain, along with the rapid development of optical frequency control technologies, such as optical frequency combs, narrow-linewidth laser sources, and optical fiber frequency transmission. The accuracy of a clock is proportional to the reference frequency. For this reason, optical clocks based on optical frequencies can achieve precision several orders of magnitude higher than that of cesium clocks based on microwaves.

[0006] The optical lattice clock, proposed by the inventor in 2001, is an atomic clock that can achieve high accuracy in a short time by using the optical resonance frequency of millions of atoms trapped in an optical lattice generated by laser light as a reference. Optical lattice clocks are positioned as next-generation atomic clocks that can achieve 18-digit accuracy, far exceeding the accuracy of cesium clocks, in a short averaging time of just a few seconds.

[0007] In general, the principle of an optical atomic clock is to irradiate an atom with laser light and control the optical frequency of the laser light so that it always resonates with the atomic resonant transition that serves as the clock's reference, thereby realizing an atom's own invariant frequency or time. However, to realize an accurate clock, it is necessary to eliminate perturbations surrounding the atom and accurately read its frequency. Particularly important is the elimination of the frequency shift caused by the Doppler effect due to the thermal motion of the atom.

[0008] Optical lattice clocks, a type of optical atomic clock, eliminate the Doppler effect associated with atomic motion by confining atoms to an area narrower than the wavelength of light using an optical trap created by the interference of laser light. On the other hand, when atoms are confined with laser light, the laser light causes the resonance frequency of the atoms to shift. By selecting a specific wavelength called the "magic wavelength" that reduces this, the effect of the optical lattice itself can also be eliminated. In fact, magic wavelengths have been experimentally determined for strontium, ytterbium, mercury, cadmium, magnesium, and other elements.

[0009] To evaluate the accuracy of the realized clock and link the frequency of the optical lattice clock to International Atomic Time, the absolute frequency of the resonance transition of strontium atoms was measured. This measurement was subsequently confirmed to be reproducible by follow-up tests conducted by research institutes in the United States and France, and in 2006, optical lattice clocks using strontium atoms were adopted as the "second representation of the second" as a leading candidate for the redefinition of the second. As the accuracy of optical lattice clocks improves, the uncertainty of cesium clocks has begun to limit their measurement accuracy. Therefore, in order to conduct even more accurate evaluations, it is essential to develop multiple optical lattice clocks and directly compare them.

[0010] Recent optical lattice clock technologies are disclosed in, for example, Patent Documents 1 to 3. Patent Document 1 describes a "moving optical lattice" that traps atoms near the lattice points of an optical lattice and transports them by moving them along an atomic migration path. Patent Document 2 describes a method for setting an effective magic frequency. Patent Document 3 describes a radiation shield that reduces the effects of blackbody radiation emitted from surrounding walls.

[0011] The next step in the application of optical lattice clocks is to explore new applications for high-precision clocks and put them to practical use. If clock measurements with 18-digit precision become possible, for example, a slight difference in height of 1 cm on the ground could be detected as a deviation in the passage of time due to the general relativity effect of gravity. By utilizing these relativistic effects, high-precision clocks can be used as precision measurement tools to probe new worlds, such as high-precision gravitational potential meters. For example, if optical lattice clocks could be made portable and used in the field, they could be applied to new geodesic technologies, such as measuring elevation between remote locations and observing crustal movements. Furthermore, mass-producing highly reliable miniature clocks and deploying them in various locations to continuously monitor temporal variations in gravitational potential could potentially be used to detect crustal movements and map the gravitational field. It is anticipated that miniaturization and portability of clocks will contribute to society as a new fundamental technology.

[0012] International Publication No. 2014 / 027637 JP 2018-510494 A JP 2019-129166 A

[0013] E.L.Raab et al, M Prentiss, A Cable, S Chu, DE Pritchard, “Trapping of Neutral Sodium Atoms with Radiation Pressure”, Physical. Review. Letters. 59, 2631 (1987).T. Bergeman, G. Erez, and H. J. Metcalf, “Magnetostatic trapping fields for neutral atoms”, Physical Review A 35, 1535 (1987).Hidetoshi Katori, “Longitudinal Ramsey spectroscopy of atoms for continuous operation of optical clocks”, Applied Physics Express 14, 072006 (2021).Ryoto Takeuchi, Hayaki Chiba, Shoichi Okaba, Masao Takamoto, Shigenori Tsuji, and Hidetoshi Katori, “Continuous outcoupling of ultracold strontium atoms combining three different traps”, Applied Physics Express 16, 042003 (2023)Masami Yasuda and Hidetoshi Katori, “Lifetime Measurement of the 3P2 Metastable State of Strontium Atoms”, Phys. Rev. Lett. 92, 153004-Published 15 April 2004S. B. Nagel, C. E. Simen, S. Laha, P. Gupta, V. S. Ashoka, and T. C. Killian, “Magnetic trapping of metastable 3P2 atomic strontium”, PHYSICAL REVIEW A 67, 011401,2003.Tomoya Akatsuka, Koji Hashiguchi, Tadahiro Takahashi, Noriaki Ohmae, Masao Takamoto and Hidetoshi Katori, “Three-stage laser cooling of Sr atoms using the 5s5p3P2 metastable state below Doppler temperatures”, PHYSICAL REVIEW A 103, 023331 (2001).S. Wu, RC Brown, WD Phillips, and JV Porto, "Pulsed Sisyphus scheme for laser cooling of atomic (anti)hydrogen", Physical Review Letters 106, 213001 (2011).

[0014] In devices such as atomic clocks and atomic interferometers, it is desirable to continuously supply cooled atomic gas to perform measurements. However, if the atomic gas is kept in the same place, it is not possible to subject the atomic gas to different processes. As a result, it is difficult to continuously supply the atomic gas to downstream devices.

[0015] To solve this problem, one idea is to create a quasi-three-dimensional quadrupole magnetic field in which the magnetic field gradient in one axis direction is weaker than the magnetic field gradients in the other two axes (see, for example, Non-Patent Document 4). The quasi-three-dimensional quadrupole magnetic field here combines the spherical quadrupole trap required for MOT with a linear quadrupole guide with a bias field that guides and moves atoms that have relaxed to a magnetically trappable state. This allows atoms that have been laser-cooled in the MOT region and relaxed to a metastable state to be magnetically guided and magnetically trapped at the final trapping position.

[0016] One method for generating such a quasi-three-dimensional quadrupole magnetic field compactly is to use a bar-shaped permanent magnet (hereinafter referred to as a bar magnet).

[0017] However, when a quasi-three-dimensional quadrupole magnetic field is generated using a bar magnet, a large leakage magnetic field from the bar magnet becomes a problem. For example, when spectroscopy is performed at a position about 2 cm away from the bar magnet, the leakage magnetic field in the spectroscopy region will be several tens of G. Such a strong leakage magnetic field is undesirable because it adversely affects spectroscopy. Therefore, when generating a quasi-three-dimensional quadrupole magnetic field, the challenge is how to reduce the leakage magnetic field.

[0018] The magnetic field gradient created by the anti-Helmholtz coils will be explained below with reference to Figure 1. Figure 1 is a schematic diagram of anti-Helmholtz coils with a radius R and a center-to-center distance of 1.25R. The direction of the line passing through the centers of the two coils is taken as the x-axis. A current of I (A) flows through the two coils in opposite directions. In this case, the magnetic field gradient created by these coils in the x-axis direction is For example, if I=100 A and R=1 cm, the magnetic field gradient is 100 G / cm.

[0019] The behavior of the residual magnetic field B when x>>R is B ∝ IR ２ / x ４ Therefore, making the structure of the system finer contributes to reducing the residual magnetic field.

[0020] On the other hand, if the typical size of the coil is D, the current required to create the same magnetic field gradient is 1 / D. ２ Therefore, the power loss is 1 / D ４ In this way, miniaturizing the system structure also contributes to power saving.

[0021] However, to realize a magneto-optical trap (MOT), a distance of about 2 cm is required for laser cooling of atoms, so a method is needed to continuously connect the large volume of the MOT magnetic field with a compact magnetic trap.

[0022] An object of the present invention is to generate a compact quasi-three-dimensional quadrupole magnetic field for realizing MOT and subsequent magnetic trapping, and to reduce the generated stray magnetic field as much as possible.

[0023] To achieve the above object, one embodiment of the present invention provides an atom trapping device for trapping atoms, comprising an atom trapping unit into which an atomic gas beam is incident. The atom trapping unit comprises a plurality of optical elements for forming a laser beam group, and a magnetic field generating unit. The magnetic field generating unit comprises at least two helical coils and a tapered solenoid coil. The helical coils are configured so that they taper and become less densely wound as the atoms move in the guided direction, and the helical coils are arranged opposite each other so that the spacing between them becomes narrower as the atoms move in the guided direction, and the tapered solenoid coil generates a magnetic field that cancels out the component of the magnetic field generated by the helical coil in the direction in which the atoms are guided.

[0024] In an embodiment, the magnetic field generating unit may form a magnetic field distribution that generates a first region of a larger magnetic field gradient that realizes magneto-optical trapping and a second region of a smaller magnetic field gradient in the guiding direction that realizes magnetic field guiding of atoms.

[0025] In one embodiment, the magnetic field distribution may be a quasi-three-dimensional quadrupole field that is a spherical quadrupole field in a first region and a linear quadrupole field with a bias field in a second region.

[0026] In some embodiments, the atom trapping device may include a magnetic trap that traps the guided atoms in a final trapping region.

[0027] In one embodiment, the volume of the first region is 1000 mm ３ The final trapping area volume is 1 mm ３ It may be the following:

[0028] In one embodiment, the strength of the leakage magnetic field from the magnetic field generating unit at a position 2 cm or more away from the magnetic field generating unit may be 1 G or less.

[0029] In an embodiment, the direction in which the atoms are guided may be the direction in which gravity acts.

[0030] In one embodiment, the helical coil and tapered solenoid may be fabricated on a multi-layer PCB board.

[0031] In some embodiments, the magnetic field generator may comprise a baseball coil.

[0032] In one embodiment, the atoms may be strontium atoms.

[0033] In one embodiment, the atoms may be ytterbium atoms.

[0034] Another aspect of the present invention is an atom cooling device, which comprises the atom trap device of the above-described aspect and a Doppler cooling mechanism.

[0035] Yet another aspect of the present invention is a spectroscopic device, which includes the atom cooling device of the above-described aspect and a spectroscopic unit.

[0036] Yet another aspect of the present invention is an optical lattice clock, which comprises a physics package, an optical system, a control device, and a PC. The physics package comprises the atom refrigerator of the aforementioned aspect and a clock transition excitation unit.

[0037] Yet another aspect of the present invention is a quantum computer comprising a physics package, an optical system, a control device, and a PC, wherein the physics package comprises the atom refrigerator of the aforementioned aspect and a clock transition excitation unit corresponding to the operation of the quantum bit.

[0038] Yet another aspect of the present invention is a coil, which is a helical coil configured to taper and become less densely wound as it progresses forward.

[0039] Yet another aspect of the present invention is an atom trapping method. The method is a method for trapping atoms using an atom trapping device equipped with an atom trapping unit, comprising the steps of supplying atoms, magneto-optically trapping the atoms using the atom trapping unit, and magnetically trapping and guiding the atoms using the atom trapping unit. The atom trapping unit includes a plurality of optical elements that form a laser beam group, and a magnetic field generating unit. The magnetic field generating unit includes at least two helical coils and a tapered solenoid coil. The helical coils are configured to taper and become less densely wound as the atoms move in the guiding direction. The helical coils are arranged opposite each other so that the spacing between them becomes narrower as the atoms move in the guiding direction. The tapered solenoid coil generates a magnetic field that cancels out the component of the magnetic field generated by the helical coil in the direction in which the atoms are guided.

[0040] In an embodiment, the magnetic field generating unit may comprise a baseball coil instead of the helical coil and tapered solenoid coil.

[0041] Yet another aspect of the present invention is a method for cooling atoms using an atom cooling device including an atom cooling device and a Doppler cooling mechanism, the method including the steps of supplying atoms, magneto-optically trapping the atoms using an atom trapping unit, magnetically trapping and guiding the atoms using the atom trapping unit, and Doppler cooling the guided atoms using the Doppler cooling mechanism.

[0042] Yet another aspect of the present invention is a spectroscopy method using a spectroscopic device including an atom cooling device and a spectroscopic unit, the method including the steps of supplying atoms, magneto-optically trapping the atoms using the atom trapping unit, magnetically trapping and guiding the atoms using the atom trapping unit, Doppler cooling the guided atoms using a Doppler cooling mechanism, and performing spectroscopy using the spectroscopic unit.

[0043] In an embodiment, the atom cooling device may include a Sisyphos cooling mechanism instead of a Doppler cooling mechanism, and may include a step of Sisyphos-cooling the guided atoms using the Sisyphos cooling mechanism.

[0044] According to the present invention, it is possible to generate a compact quasi-three-dimensional quadrupole magnetic field that realizes MOT and subsequent magnetic trapping while minimizing the leakage magnetic field that is generated.

[0045] 11(a) is a schematic diagram of an anti-Helmholtz coil; 11(b) is a diagram showing the energy levels of strontium atoms; 11(c) is a diagram showing the process flow of an atom trapping method according to an embodiment; 11(d) is a diagram showing an arrangement of two coils whose front ends become thinner toward the direction in which atoms are guided; 11(e) is a schematic diagram of a coil whose winding density decreases toward the front end; 11(f) is a schematic diagram of a tapered solenoid coil; 11(f) is a perspective view of an atom trapping device according to a first embodiment; 11(g) is a perspective view of an atom trapping device according to a first embodiment; 11(g) is a diagram showing the atom trapping device according to the first embodiment as viewed from the -z direction; 11(g) is a diagram showing the atom trapping device according to the first embodiment as viewed from the y direction; 11(b) is a diagram showing the absolute value of the magnetic field strength on the y axis and the resultant force of magnetic and gravitational forces acting on atoms; 11(c) is a diagram showing the contours of the leakage magnetic field generated in the system of FIG. 11(a). 12(a) is the y-z plane at x=0, and FIG. 12(b) is the x-y plane at z=0. FIG. 1 is a schematic diagram of an implementation example of a magnetic field generating unit. FIG. 2 is a schematic diagram of a magnetic field generating unit configured with four multilayer PCB boards. FIG. 3 is a diagram showing a coil wired on a first layer of a multilayer PCB board. FIG. 4 is a schematic diagram of a modified example of a magnetic field generating unit. FIG. 5 is a functional block diagram of an optical lattice clock according to a fourth embodiment. FIG. 6 is a diagram showing a schematic diagram of a third embodiment. FIG. 7 is a diagram showing a schematic diagram of a fourth embodiment.

[0046] The present invention will be described below with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. The same or equivalent components, parts, and processes shown in the drawings are designated by the same reference numerals, and redundant descriptions are omitted where appropriate. The scale and shape of each part shown in the drawings are set for convenience to facilitate explanation and should not be interpreted as limiting unless otherwise specified. Furthermore, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not indicate any order or importance, but are merely used to distinguish one configuration from another. Furthermore, some components that are not important for explaining the embodiments are omitted from the drawings.

[0047] [First embodiment] An atom trapping device will be described in detail below as a first embodiment of the present disclosure. First, the flow of processing executed by the atom trapping device according to the embodiment will be described. The processing performed continuously can be broadly divided into a first step and a second step. In the first step, an atomic gas is generated from solid-state atoms. In the second step, the generated atomic gas is trapped in the MOT region, and the atoms are further magnetically trapped and guided to the final trapping position.

[0048] For example, external forces for guiding neutral atoms belonging to alkaline earth metals include gravity (an external force that is effective when the mass of the atom is finite), magnetic force (an external force that is effective when the magnetic moment of the atom is finite), laser radiation pressure (such as laser radiation pressure used in laser deceleration, magneto-optical trapping (MOT), or optical molasses), and optical dipole force (used in optical dipole force trapping, optical lattices, etc.). Here, we will explain gravity and magnetic force.

[0049] Alkaline earth metal atoms, which have two electrons in their outermost shell, have a spin singlet ground state, where both the angular momentum and the total orbital angular momentum are zero. In this case, it may seem difficult to induce motion in an atomic gas using a magnetic force as an external force. However, the optical pumping that occurs during the laser cooling process allows ３P ２ It is known that atoms in this state can be produced. In the following, this method will be explained using strontium atoms as an example, but this method can also be applied to atoms belonging to Groups 2 and 2b of the periodic table, such as magnesium atoms and calcium atoms, as well as ytterbium atoms.

[0050] Figure 2 shows the energy levels of a strontium atom. Previous research using strontium atoms has shown that ３ P ２ It has been found that the lifetime of atoms in this state is more than 100 seconds (see, for example, Non-Patent Document 5). Also, another study using strontium atoms has shown that atoms can be trapped by magnetic force (see, for example, Non-Patent Document 6). Therefore, atoms in this state have a long lifetime and are considered to be in a metastable state. ３ P ２ Atoms in this state can be moved by gravity.

[0051] 3 shows the process flow of the atom trapping method according to the embodiment. In the embodiment, the following steps S1 to S3 are executed: S1: Supplying slow atoms; S2: Magneto-optical trapping (MOT) using a quasi-three-dimensional quadrupole magnetic field; S3: Magneto-optical guiding using a quasi-three-dimensional quadrupole magnetic field.

[0052] [Principle of Atom Trapping] The principle of atom trapping in the embodiment will be described below. ８８ Here, a three-dimensional coordinate system {x, y, z} is defined. The x-axis, y-axis, and z-axis are perpendicular to each other. ８６ Sr), or odd isotopes with nuclear spin ( ８７ The same procedure can be carried out for Sr).

[0053] The quasi-three-dimensional quadrupole magnetic field shown in steps S2 to S3 has a magnetic field distribution in which the magnetic field gradient in one axial direction is weaker than the magnetic field gradient in the other two axial directions. (a ａｎｉｓｏ =|G ｙ -G ｘ | / |G ｚ |~1,|G ｙ |≪|Gｘ |<|G ｚ |) (a linear quadrupole guide in the middle of a quasi-three-dimensional quadrupole field). ｘ , G ｙ , G ｚ} represents the magnetic field gradient around the zero field position. In the above example, the magnetic field gradient in the y-axis direction is smaller than the magnetic field gradients in the x- and z-axis directions, and the magnetic force in the y-axis direction (F ｙ =-∂U / ∂y) is weaker than the magnetic force in the x and z axis directions.

[0054] In step S2, the above-mentioned quasi-three-dimensional quadrupole magnetic field and １ S ０ - １ P １ By interacting with the 461 nm laser light that resonates between the states, the atoms are subjected to a restoring force and are trapped near the origin, which is the zero magnetic field position. １ P １ From the state １ D ２ Through the state ３ P ２ The metastable state is then relaxed by the optical pumping process. ３ P ２ An atom of the state is generated.

[0055] In step S3, ３ P ２ In the atom of the state, the magnetic quantum number m ｊ Atoms with a value of 1 or 2 are energetically stable in a weak magnetic field and are magnetically trapped near the zero field position of the quasi-three-dimensional quadrupole magnetic field. The magnetic interaction potential U between the atom and the quasi-three-dimensional quadrupole magnetic field ｍａｇ is expressed by the following equation (1) near the zero magnetic field position. g is the g-factor (the state of the atom ３ P ２ In the case of the state, g = 3 / 2), μ Ｂ is the Bohr magneton.

[0056] Also, the magnetic force F acting on the atom ｍａｇ is expressed by the following equation (2).

[0057] Gravity (F = mg) acts on the atom in the y direction. Gravity acts on the atom in the y direction. ｍａｇ If the y component of the magnetic field is larger than the y component, the atoms will move from the zero magnetic field position in the y direction (i.e., the direction in which gravity acts) due to gravity. The magnetic trapping traps the atoms in the final trapping position in the final trapping region. Preferably, the volume of the MOT region (magneto-optical trapping region) is 1000 mm ３ The final trapping area volume is 1 mm ３ The following is the result.

[0058] The atoms used as the sample have a magnetic quantum number m ｊ =2 ８８ In the case of Sr atoms, the gravity coefficient is 9.8 m / s ２ The magnetic force that balances the gravity is obtained by a magnetic field with a magnetic field gradient of 5.2 G / cm. In other words, in order to move atoms on the y-axis from the center of the zero magnetic field by gravity, the magnetic field gradient from the center of the zero magnetic field to the trapping position must be less than 5.2 G / cm. １ S ０ Atoms in this state are cooled and captured in a magneto-optical trap for a period of several milliseconds or more. ３ P ２ To relax the atoms to the axial state and magnetically trap them, a magnetic field gradient of 30 to 100 G / cm is preferred (the spherical quadrupole trap region at both ends of the quasi-three-dimensional quadrupole magnetic field). A highly anisotropic quasi-three-dimensional quadrupole magnetic field can satisfy these conditions.

[0059] Next, we will explain how to generate a highly anisotropic quasi-three-dimensional quadrupole magnetic field for executing steps S1 to S3. As mentioned above, when a quasi-three-dimensional quadrupole magnetic field is generated using a bar magnet, the problem is that the leakage magnetic field from the bar magnet is large. If the deceleration distance D of the atoms is D ~ 10 mm, the MOT region is D ３ ~1000mm ３ Therefore, the quadrupole magnetic field to realize MOT must also have a similar volume. On the other hand, the length d of the region where atoms are magnetically trapped after being laser cooled is about d ~ 1 mm. Therefore, the volume of the quadrupole magnetic field to realize magnetic trapping is d ３ ~1mm３ is.

[0060] The leakage region of the quadrupole magnetic field is approximately the distance between the coils. Therefore, by reducing the magnetic trapping region, the range of the leakage magnetic field can be narrowed. To achieve this, as shown in FIG. 4, two coils 221A and 221B (for example, trapezoidal coils) are formed that taper toward the direction in which the atoms are guided (y-axis direction). The coils 221A and 221B have approximately the same shape and dimensions. Consider arranging the coils 221A and 221B opposite each other so that the distance between them narrows toward the direction in the y-axis direction, forming an anti-Helmholtz coil. In other words, when currents in opposite directions are passed through the coils 221A and 221B arranged in this manner, a quadrupole magnetic field is generated. Referring also to FIG. 11, the final trap position is formed about 3 mm inside the coils from the front ends (y = 70 mm) of the coils 221A and 221B. ＭＴ = 67 mm). This y coordinate is y ＭＴ In addition, the point about 20 mm inside the coil from the rear end (y=0 mm) of the coils 221A and 221B (this y coordinate y ＭＯＴ The MOT region is formed around (y ＭＯＴ =20mm). y=y ＭＴ The volume of the region formed near ３ ~1mm ３ , y=y ＭＯＴ The volume of the region formed near ３ ~1000mm ３ It is expected that by selecting the shape and size of the coils 221A and 221B so that MOT regions and magnetic trapping regions of appropriate sizes can be formed.

[0061] However, in the above configuration, if a uniform current is passed through the coils 221A and 221B, the magnetic field gradient of the guide portion increases unnecessarily.

[0062] To solve this problem, as shown in Figure 5, coil 222 is tapered in the y-axis direction, and is configured so that the coil winding density decreases as the direction increases. That is, coil 222 has a spiral shape. In the example of Figure 5, coil 222 consists of four turns, a, b, c, and d. Two such coils, 222A and 222B, are arranged as shown in Figure 4, 221A and 221B, respectively. By appropriately selecting the coil winding density, the volume of the magnetic guide section and the trapping region can be reduced while maintaining a constant magnetic field gradient.

[0063] When the spiral coil shown in Figure 5 is arranged as shown in Figure 4 and a current is passed through it, the magnetic field gradient in the plane perpendicular to the y-axis can be made constant, but confinement in the y-axis direction occurs, which hinders the movement of atoms and adversely affects measurements in the subsequent stages.

[0064] To solve this problem, a tapered solenoid coil 223 is provided as shown in Fig. 6. This can cancel the confinement in the y-axis direction caused by the spiral coils 223A and 223B, and prevent the movement of atoms from being hindered.

[0065] [Specific Configuration of the Embodiment] An atom trapping device and an atom trapping method according to the embodiment will be described below with reference to Figs. 7 to 10. Fig. 7 is a perspective view of an atom trapping device 10 according to the embodiment. Fig. 8 is a perspective view of the atom trapping device 10. Fig. 9 is a view of the atom trapping device 10 from the -z direction. Fig. 10 is a view of the atom trapping device 10 from the y direction. A three-dimensional coordinate system {x, y, z} is defined. The x-axis, y-axis, and z-axis are mutually orthogonal. The x-direction is the direction in which the atomic beam emitted from the atomic oven travels. The y-direction is the direction in which gravity acts.

[0066] The atom trapping device 10 according to the embodiment includes an atomic oven 12, a Zeeman decelerator 14, and an atom trapping section 16. The atomic oven 12, the Zeeman decelerator 14, and the atom trapping device 10 are installed in an ultra-high vacuum environment. In each figure, fixtures for each module, viewports for inputting and outputting laser light, vacuum exhaust ports, and vacuum exhaust pumps are not shown.

[0067] The atomic oven 12 includes a sample container, a heater, a capillary nozzle, a thermometer, an electrical connector, and a thermal radiation shield. A sample is placed in the sample container. For example, strontium atoms ( ８７ Sr and ８８ Sr) is used as the sample. The sample in the sample container is heated by a heater, causing atoms to evaporate and generate atomic gas. The capillary nozzle is connected to the sample container. The atomic gas passes through the capillary nozzle and is emitted as a directional atomic beam. The thermometer is used to measure the temperature of the sample container. The electrical connector is used to supply power to the heater. The thermal radiation shield is used to shield the heater and sample container from thermal radiation to the outside. A known atomic oven can be used as the atomic oven 12. The atomic beam emitted from the atomic oven 12 proceeds to the downstream Zeeman decelerator 14.

[0068] The Zeeman decelerator 14 includes a bore and a magnetic field generator installed around the bore, and extends in the x-direction. The magnetic field generator includes, for example, a solenoid coil, and generates a magnetic field along the central axis (x-axis) of the bore extending in the x-direction. In this example, the magnetic field generator generates a magnetic field whose strength decreases with increasing distance from the atomic oven 12. Furthermore, a resonant laser beam 14b is irradiated into the bore from the direction opposite to the direction of travel of the atomic beam (-x-direction). The atomic beam emitted from the atomic oven 12 is irradiated into the bore and travels in the x-direction within the bore. The Zeeman decelerator 14 uses the resonant laser beam 14b and the gradient magnetic field generated by the magnetic field generator to decelerate the atomic beam, which has a high initial velocity and is emitted from the atomic oven 12, to a velocity that can be trapped by the downstream atom trap device 10, according to the Zeeman deceleration method. The high-temperature atomic beam travels through the bore toward the atom trap device 10 while being decelerated according to the Zeeman deceleration method. A known Zeeman decelerator can be used as the Zeeman decelerator 14 .

[0069] In the above embodiment, the atomic beam emitted from the atomic oven is decelerated using a Zeeman decelerator. However, the present invention is not limited to this, and if a slow atomic beam is to be supplied, the Zeeman decelerator is not necessary.

[0070] The atom trapping unit 16 includes a vacuum chamber, and forms a trapping region within the vacuum chamber where atoms are trapped. The atomic beam traveling from the Zeeman decelerator 14 to the atom trapping unit 16 is trapped by the atom trapping unit 16. Specifically, the atom trapping unit 16 includes a plurality of optical elements that form the laser beam group 18, and a magnetic field generating unit 22.

[0071] The multiple optical elements include, for example, a light source, mirrors such as a λ / 4 mirror 20, and a beam splitter. Laser beam groups 18 are irradiated from six directions toward the zero magnetic field position for the purpose of applying a restoring force due to radiation pressure to the atoms. The laser beam groups 18 include laser beams traveling in the x direction on the x axis, laser beams traveling in the opposite −x direction, laser beams traveling in the y direction on the y axis, laser beams traveling in the y direction, laser beams traveling in the opposite −y direction, laser beams traveling in the z direction on the z axis, and laser beams traveling in the opposite −z direction. A λ / 4 mirror 20 is installed on the z axis. The laser beam traveling in the −z direction is formed by the laser beam traveling in the z direction and the λ / 4 mirror 20. In other words, the laser beam traveling in the z direction is reflected by the λ / 4 mirror 20, thereby forming a laser beam traveling in the −z direction.

[0072] The magnetic field generating unit 22 will be described with reference to FIGS. 5 to 10. The magnetic field generating unit 22 includes a coil 222A, a coil 222B, and a tapered solenoid coil 223, and generates a quasi-three-dimensional quadrupole magnetic field. The coils 222A and 222B have approximately the same shape and dimensions. The coils 222A and 222B taper toward the direction in which the atoms are guided (the y-axis direction). The coil winding density of the coils 222A and 222B decreases toward the direction in which the atoms are guided (spiral shape). The coils 222A and 222B are arranged opposite each other so that the distance between them decreases toward the direction in which the atoms are guided. The coils 222A and 222B are arranged tapered with respect to the xy plane formed by the x-axis and y-axis. Tapered solenoid coil 223 is sandwiched between coil 222A and coil 222B or disposed outside coil 222A and coil 222B.

[0073] The λ / 4 mirror 20 is installed outside the coil so as not to block the laser light traveling in the x direction, the laser light traveling in the -x direction, the laser light traveling in the y direction, and the laser light traveling in the -y direction. In order to prevent deterioration of the optical characteristics of the λ / 4 mirror 20, it may be fixed at a location other than the light receiving unit (for example, one of the four corners). Furthermore, the λ / 4 mirror 20 may be installed so as not to come into direct contact with the magnetic field generating unit 22.

[0074] Laser light 28 is a narrow-linewidth cooling laser beam emitted from light source 29, and has a wavelength of 2.9 μm. Laser light 28 is emitted in the +y direction on the y axis. As a result, atoms are trapped near position 30 where the magnetic force, gravity, and radiation pressure of laser light 28 are balanced.

[0075] The laser beam 28 may be incident from both the +y-axis direction and the −y-axis direction, and molasses cooling of the atoms may be performed at the balance point between the magnetic force and gravity.

[0076] Figure 11(a) is a plan view of the magnetic field generating unit 22 as seen from the +z direction. Figure 11(b) shows the absolute value of the magnetic field strength on the y axis and the resultant force of the magnetic force and gravity acting on the atoms. The magnetic field on the y axis crosses zero near y = 20 mm, and an MOT region is formed around this. A spherical quadrupole magnetic field is formed in this region. Outside the MOT region (region with a y value greater than that of the MOT region), the magnetic field gradient is weak, forming a magnetic field guide (magnetic trap region) for the atoms. A linear quadrupole magnetic field with a bias magnetic field is formed in this region. In the MOT region ３ P ２ The atoms relaxed to the +y direction are subjected to the combined force of magnetic and gravitational forces. In this system, a potential barrier is set up by the magnetic trap near y = 70 mm, and the final trap position is realized near y = 67 mm.

[0077] Consider the case where a current of 3 A is passed through a coil with a total of 30 turns in the system shown in Figure 11(a). In this case, the magnetic field gradient in the x-axis direction near the MOT position is calculated to be approximately 30 G / cm, and the magnetic field gradient in the y-axis direction is calculated to be approximately 10 G / cm. This shows that MOT can be realized in the system shown in Figure 11(a).

[0078] Figure 12 shows the contours of the stray magnetic field generated by the system shown in Figure 11(a). Figure 12(a) shows the y-z plane at x = 0, and Figure 12(b) shows the x-y plane at z = 0. These figures show magnetic fields up to 10 G in 1 G steps, with fields exceeding 10 G shown in white. In both Figures 12(a) and 12(b), the region indicated by thick hatching at the top (positions 2 cm or more away from the magnetic field generator) has a magnetic field strength of 1 G or less, making it suitable for spectroscopy. In contrast, if a quasi-three-dimensional quadrupole magnetic field is formed using, for example, a bar magnet, a stray magnetic field of approximately 10 G is generated at a position approximately 2 cm away from the bar magnet. This makes spectroscopy difficult. It can be seen that this problem can be solved by this embodiment. Figures 12(a) and 12(b) also show the spherical quadrupole magnetic field that realizes MOT, the linear quadrupole magnetic field with a bias magnetic field that is suitable for magnetically guiding atoms, and the final trapping position of the atoms.

[0079] [Implementation of Magnetic Field Generator] An implementation example of the magnetic field generator of the embodiment will be described below with reference to FIG. 13. In the example of FIG. 13, a spiral coil (e.g., coil 222 shown in FIG. 5) is fabricated using a multilayer PCB substrate. The body, which is sandwiched between two such multilayer PCBs and supports the multilayer PCB substrates, is fabricated using a thermally conductive metal such as Al or Cu. This allows heat generated from the multilayer PCB to be dissipated. Holes are provided in the multilayer PCB substrate and the body to allow the necessary optical paths to pass through.

[0080] As a consideration for mounting, we will consider heat dissipation in multilayer PCB boards. If the width of the current path on the PCB board is constant, the power loss of the PCB board is inversely proportional to the thickness of the copper foil that forms the board. For example, with a commonly used copper foil thickness of 35 μm, the power loss is estimated to be approximately 24 W. If a copper foil thickness of 105 μm is used, the power loss is reduced to approximately 8 W, making it possible to mount the board without any problems with heat dissipation. Furthermore, power consumption can be reduced by increasing the copper foil thickness.

[0081] Figure 14 shows an example of a magnetic field generating unit composed of four multilayer PCB boards A, B, C, and D. The spiral coil is formed on the top and bottom multilayer PCB boards A and C. The tapered solenoid coil is formed on the top and bottom multilayer PCB boards A and C and on the side multilayer PCB boards B and D. Boards A and C are 10-layer PCB boards with nearly identical patterns. Boards B and D are double-sided PCB boards with nearly identical patterns. With this configuration, a 9-turn spiral coil and a 9-turn tapered solenoid coil are formed.

[0082] Table 1 shows the wiring of the coils of the magnetic field generating unit formed of a multilayer (10-layer) PCB board having layers 1 to 10 in order from the bottom layer. Figure 15 shows, as an example, the coils wired on the first layer of this multilayer PCB board.

[0083] [Modification] Figure 16 is a schematic diagram of a modification of the magnetic field generating unit. In the above example, the magnetic field generating unit is configured with a spiral coil and a tapered solenoid coil. Alternatively, the magnetic field generating unit may be configured using a coil shaped as shown in Figure 16. By passing a current through the coil in the direction of the arrows in Figure 16, it is possible to simultaneously form a quadrupole magnetic field and cancel out the magnetic field in the y-axis direction. The coil in Figure 16 is called a "baseball coil" because it resembles the stitching on a baseball.

[0084] The magnetic field generating unit may be configured by combining a helical coil, a tapered solenoid coil, and a baseball coil.

[0085] As described above, according to this embodiment, it is possible to provide an atom trapping device that generates a compact quasi-three-dimensional quadrupole magnetic field that realizes MOT and subsequent magnetic trapping while minimizing the leakage magnetic field that is generated.

[0086] [Second embodiment] A second embodiment of the present disclosure is an atomic cooling device. ３ P ２ Increase the number of atoms in the state as much as possible, ３ P ２It is effective to cool the atoms in this state.

[0087] ３ P ２ As a way to increase the number of atoms in the state, １ S ０ - １ P １ By using the excitation between １ D ２ via the state ３ P ２ There are ways to alleviate the condition.

[0088] Magnetically trapped ３ P ２ To further cool the atoms in the state, an energy difference of 2.9 μm is required. ３ P ２ - ３ D ３ It is conceivable to perform Doppler cooling using excitation between the two. The transition linewidth between these two is extremely narrow at 57 kHz, so that a low cooling temperature of several microkelvins can be achieved (see, for example, Non-Patent Documents 4 and 7). The cooling temperature that can be achieved in a magnetic trap is expressed by the following equation (3): Here, T Ｄ is the theoretical cooling temperature known as the Doppler temperature, and is expressed by the following equation (4): f ０ is the magnetic-gravitational force F ＢＧ and maximum radiation pressure F Ｒ and is expressed by the following equation (5).

[0089] The atom cooling device according to the second embodiment includes the atom trapping device of the above-described embodiment (for example, the atom trapping device 10). The atom cooling device executes the following steps in addition to the processes S1 to S3 of the atom trapping device: S4: ３ P ２ S5: The cooled atoms are guided to a downstream device by an optical lattice or an optical dipole guide. At this time, the atoms may be optically pumped to a third state that is insensitive to magnetic fields.

[0090] ​In step S4, ３ P ２ For an atom in the state, ３ P ２ - ３ D ３ Doppler cooling is performed by irradiating the atoms with a 2.9 μm laser beam that resonates between the states, thereby lowering the temperature of the atoms to a few microkelvins. ３ D ３ An optical lattice potential may be introduced into the state to enhance the cooling efficiency of atoms using the Sisyphus process (see, for example, Non-Patent Document 8).

[0091] In step S5, an optical dipole guide is used to connect the position where the atoms are finally trapped to the input section of the downstream device (where the cooled atoms are input). At this time, the cooled atoms may be guided to the downstream device by optically pumping them into a state insensitive to magnetic fields. For example, the cooled atoms may be moved from the trapped position to the input section of the downstream device using a moving optical lattice technique (see, for example, Patent Document 3). The third state is ３ P ２ State of m ｊ = 0 magnetic sublevel, ３ P ０ Status or １ S ０ It may be in a state.

[0092] According to this embodiment, the magnetically trapped atoms can be cooled effectively.

[0093] In the above embodiment, the magnetically trapped atoms are cooled by Doppler cooling. However, the cooling method is not limited to Doppler cooling. For example, a Sisyphus cooling mechanism may be used instead of the Doppler cooling mechanism.

[0094] Third Embodiment A third embodiment of the present disclosure is a spectrometer. This spectrometer includes the atom cooling device of the above-described embodiment and a spectroscopic unit. The spectroscopic unit is installed in a region where the leakage magnetic field from the magnetic field generating unit 22 is sufficiently weak (for example, a region where the leakage magnetic field is less than 1 G). Atoms cooled by the atom cooling device are guided to the spectroscopic unit and spectroscopically analyzed.

[0095] According to this embodiment, it is possible to provide a spectroscopic device that is compact and capable of performing spectroscopy in an environment with a weak leakage magnetic field.

[0096] The above embodiment is shown in Fig. 18. From the position where the atom is finally trapped, the atom ３ P ２ The moving optical grating is used to extract the light beam from the moving optical grating. １ S ０ - ３ P ０ The spectroscopic laser that excites the clock transition of the atom is incident on the atom. ３ P ０ The atom is optically pumped into a state that defines the beginning of the spectroscopic region. As the atom moves through the spectroscopic region, it interacts with the spectroscopic laser, １ S ０ State and ３ P ０ The optical pump laser 2 evolves into a superposition state with the ３ P ０ The atom in the state ３ P ２ By optically pumping the state, １ S ０ - ３ P ０ The end point of the spectroscopic region is defined by projecting the clock transition of the atomic number measurement laser. ３ P ２ The atom in the state ３ P ２ - ３ D ３ transitions measured by laser-induced fluorescence, ３ P ０ Determine the excitation rate of the state.

[0097] According to this embodiment, laser light and laser-induced fluorescence, which cause an optical shift in the clock transition, are prevented from entering the spectroscopic region, enabling highly accurate spectroscopic measurement. Furthermore, this embodiment realizes spectroscopic measurement without dead time or wasted time.

[0098] The state of the optical pump is arbitrary. For example, the optical pump laser 1 １ S ０ state by optical pump laser 2. ３P ０ The atom in the state ３ P ２ In this case, the atomic number measurement laser is ３ P ２ The atom in the state ３ P ２ - ３ D ３ transitions measured by laser-induced fluorescence, ３ P ０ Determine the excitation rate of the state.

[0099] The spectroscopic laser may be a clock transition laser.

[0100] All of the above-mentioned methods realize time-delay-free Rabi spectroscopy of atoms in the spectroscopic region (longitudinal excitation Rabi spectroscopy), and realize a highly accurate and stable optical lattice clock.

[0101] [Fourth embodiment] A fourth embodiment of the present disclosure is an optical lattice clock. This optical lattice clock includes the atom cooling device of the above-described embodiment.

[0102] 17 is a functional block diagram of an optical lattice clock 200 according to this embodiment. The optical lattice clock 200 comprises a physics package 202, an optical system device 204, a control device 206, and a PC (personal computer) 208. The physics package 202 comprises an atom cooling device 2021 and a clock transition excitation unit 2022. The atom cooling device 2021 is the atom cooling device of the above-described embodiment.

[0103] The physics package 202 is a device that confines a cooled atomic ensemble in an optical lattice and induces a clock transition. The optical system device 204 is a device equipped with optical devices such as a laser light source for atom cooling, a laser light source for atom trapping, a clock transition excitation laser light source, and a laser frequency control device. In addition to sending laser light to the physics package 202, the optical system device 204 excites a clock transition in the physics package 202 using Rabi or Ramsey spectroscopy and then measures the electronic state of the atoms by projection measurement. The optical system device 204 receives the projection measurement signal, converts it into an electrical signal, and performs processing such as feeding it back to the laser light source to match the atomic resonance frequency. The control device 206 is a device that controls the physics package 202 and the optical system device 204. The control device 206 performs, for example, operation control of the physics package 202 and the optical system device 204, and analysis processing such as frequency analysis of the clock transition obtained by measurement. The physics package 202, the optical system device 204, and the control device 206 cooperate with each other to realize the functions of the optical lattice clock 200.

[0104] The PC 208 is a general-purpose computer including a processor and memory. The functions of the PC 208 are realized by software being executed by hardware including the processor and memory. An application program for controlling the optical lattice clock 200 is installed in the PC 208. The PC 208 is connected to the control device 206 and may control not only the control device 206 but also the entire optical lattice clock 200 including the physics package 202 and the optical device 204. The PC 208 also provides a UI (user interface) for the optical lattice clock 200. A user can excite the optical lattice clock 200, measure time, and check results via the PC 208.

[0105] In the physics package 202 , an atomic ensemble cooled by an atom cooling device 2021 is moved to a clock transition spectroscopy region in a clock transition excitation unit 2022 .

[0106] In the clock transition space, atoms are irradiated with laser light with controlled optical frequencies, and the clock transitions (i.e., the atomic resonant transitions that serve as the reference for the clock) are measured with high precision spectroscopy, resulting in the measurement of the unique and invariant frequency of the atom, thereby realizing an accurate atomic clock.

[0107] To improve the accuracy of atomic clocks, it is necessary to eliminate perturbations surrounding the atoms and accurately read out their frequency. Particularly important is the elimination of frequency shifts caused by the Doppler effect due to the thermal motion of atoms. In optical lattice clocks, atoms are confined in an optical lattice created by the interference of laser light in a space sufficiently small compared to the wavelength of the clock laser, thereby quantizing the atomic motion. However, within the optical lattice, the laser light that forms the optical lattice causes the atomic frequency to shift. Therefore, by selecting a specific wavelength and frequency known as the "magic wavelength" or "magic frequency" for the optical lattice light beam, the influence of the optical lattice on the frequency of the atomic clock transition is eliminated.

[0108] The light emitted by the clock transition is received by the optical system 204 and subjected to spectroscopic processing by the control unit 206 to determine the frequency.

[0109] According to this embodiment, a compact optical lattice clock can be provided.

[0110] FIG. 19 shows a schematic diagram of the above embodiment.

[0111] Fifth Embodiment A fifth embodiment of the present disclosure is a quantum computer, which includes the atom cooling device according to the above-described embodiment.

[0112] This quantum computer includes a physics package, an optical system, a control device, and a PC. The physics package includes an atom refrigerator and a clock transition excitation unit. The atom refrigerator is the atom refrigerator of the above-described embodiment. The clock transition excitation unit is configured to correspond to the operation of a quantum bit.

[0113] According to this embodiment, a compact quantum computer with high extensibility of quantum bits can be realized.

[0114] Sixth Embodiment A sixth embodiment of the present disclosure is a coil. This coil is a spiral coil as shown in Fig. 5. That is, this coil is a spiral coil that tapers toward the front and has a sparse winding density toward the front.

[0115] According to this embodiment, a compact quasi-three-dimensional quadrupole magnetic field can be generated to realize MOT and subsequent magnetic trapping.

[0116] Seventh Embodiment The seventh embodiment is an atom trapping method. This is a method for trapping atoms using an atom trapping device including an atomic oven and an atom trapping unit. The method includes the steps of generating an atomic gas using the atomic oven, magneto-optically trapping the atoms using the atom trapping unit, and magnetically trapping and guiding the atoms using the atom trapping unit. The atom trapping unit includes a plurality of optical elements that form a laser beam group and a magnetic field generating unit. The magnetic field generating unit includes at least two helical coils and a tapered solenoid coil. The helical coils are configured to taper and become less densely wound as the atoms move in the guiding direction. The helical coils are arranged opposite each other so that the distance between them becomes narrower as the atoms move in the guiding direction. The tapered solenoid coil generates a magnetic field that cancels out the component of the magnetic field generated by the helical coil in the direction in which the atoms are guided.

[0117] Eighth Embodiment The eighth embodiment is an atom cooling method. This is a method for trapping atoms using an atom cooling device that includes the atom cooling device described in the second embodiment and a Doppler cooling mechanism. This method includes the steps of generating an atomic gas using an atomic oven, magneto-optically trapping the atoms using an atom trapping unit, magnetically trapping and guiding the atoms using the atom trapping unit, and Doppler cooling the guided atoms using the Doppler cooling mechanism.

[0118] Ninth Embodiment The ninth embodiment is a spectroscopy method. This is a method for performing spectroscopy using the atom cooling device described in the second embodiment. This method includes the steps of generating an atomic gas using an atomic oven, magneto-optically trapping atoms using an atom trapping unit, magnetically trapping and guiding the atoms using the atom trapping unit, and Doppler cooling the guided atoms using a Doppler cooling mechanism.

[0119] The present invention has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components and treatment processes, and that such modifications are also within the scope of the present invention.

[0120] When understanding the abstract technical ideas of the embodiments and modifications, the technical ideas should not be interpreted as being limited to the contents of the embodiments and modifications. The above-described embodiments and modifications are merely illustrative examples, and many design modifications, such as changes, additions, and deletions of components, are possible. In the embodiments, the contents in which such design modifications are possible are emphasized by adding the notation "embodiment." However, design modifications are also permitted even in contents without such notation.

[0121] The present invention can be used in atom trapping devices, atom cooling devices, spectroscopic devices, optical lattice clocks, quantum computers, coils, atom trapping methods, atom cooling methods, and spectroscopic methods.

[0122] 10...atom trap device, 12...atom oven, 14...Zeeman decelerator, 14b...laser light for Zeeman deceleration, 16...atom trap section, 18...laser light group, 20...λ / 4 mirror, 28...laser light, 29...light source, 221A...trapezoidal coil, 221B...trapezoidal coil, 222...spiral coil, 222A...spiral coil, 222B...spiral coil, 223...tapered solenoid coil, S1...step of supplying slow atoms, S2...step of performing MOT using a quasi-three-dimensional quadrupole magnetic field, S4...step of performing magnetic guiding using a quasi-three-dimensional quadrupole magnetic field, S4...step of performing Doppler cooling, S5...step of guiding cooled atoms to a subsequent device.

Claims

1. An atomic trap device for trapping atoms, comprising: an atomic trap section into which a beam of atomic gas is incident, wherein the atomic trap section includes a plurality of optical elements that form a laser light group and a magnetic field generation section, the magnetic field generation section includes at least two helical coils and a tapered solenoid coil, the helical coils are configured such that as the atoms travel in the direction in which they are guided, the tips become thinner and the winding density becomes sparser, the helical coils are arranged to face each other such that as the atoms travel in the direction in which they are guided, the distance between them becomes narrower, and the tapered solenoid coil generates a magnetic field that adjusts the component of the magnetic field generated by the helical coils in the direction in which the atoms are guided.

2. The atomic trap device according to claim 1, wherein the magnetic field generation section forms a magnetic field distribution that generates a first region having a larger magnetic field gradient for realizing a magneto-optical trap and a second region having a smaller magnetic field gradient in the guide direction for realizing magnetic field guiding of atoms.

3. The atomic trap device according to claim 2, wherein the magnetic field distribution is a quasi-three-dimensional quadrupole magnetic field that is a spherical quadrupole magnetic field in the first region and a linear quadrupole magnetic field with a bias magnetic field in the second region.

4. The atomic trap device according to claim 3, further comprising a magnetic trap for trapping the guided atoms within a final trap region.

5. The volume of the first region is 1000 mm ３ or more, and the volume of the final trap region is 1 mm ３ or less. The atomic trap device according to claim 4, characterized in that.

6. The atomic trap device according to claim 1, wherein the strength of the leakage magnetic field from the magnetic field generation section at a position more than 2 cm away from the magnetic field generation section is 1 G or less.

7. The atomic trap device according to claim 1, wherein the direction in which the atoms are guided is the direction in which gravity acts.

8. The atomic trap device according to claim 1, wherein the helical coil and the tapered solenoid are formed on a multilayer PCB substrate.

9. The atomic trap device according to claim 1, wherein the magnetic field generation section includes a baseball coil.

10. An atomic cooling device comprising the atomic trap device according to claim 1 and a Doppler cooling mechanism.

11. An atomic cooling device comprising the atomic trap device according to claim 1 and a Sisyphus cooling mechanism.

12. A spectroscopic apparatus comprising the atomic cooling device according to claim 10 or 11 and a spectroscopic unit.

13. An optical lattice clock comprising a physical package, an optical system device, a control device, and a PC, wherein the physical package comprises the atomic cooling device according to claim 10 and a clock transition excitation unit.

14. A quantum computer comprising a physical package, an optical system device, a control device, and a PC, wherein the physical package comprises the atomic cooling device according to claim 10 and a clock transition excitation unit corresponding to the operation of a quantum bit.

15. A helical coil configured such that the tip becomes thinner and the winding density becomes sparser as it progresses forward.

16. A method for trapping atoms using an atomic trap device having an atomic trap unit, the method including: a step of supplying atoms; a step of magneto-optically trapping the atoms using the atomic trap unit; and a step of magnetically trapping and guiding the atoms using the atomic trap unit, wherein the atomic trap unit includes a plurality of optical elements that form a laser beam group and a magnetic field generation unit, the magnetic field generation unit includes at least two helical coils and a tapered solenoid coil, the helical coils are configured such that the tip becomes thinner and the winding density becomes sparser as the atoms are guided in the direction of travel, the helical coils are arranged to face each other such that the distance therebetween becomes narrower as the atoms are guided in the direction of travel, and the tapered solenoid coil generates a magnetic field for adjusting a component of the magnetic field generated by the helical coils in the direction in which the atoms are guided.

17. The atomic trap method according to claim 16, wherein the magnetic field generation unit comprises a baseball coil instead of the helical coils and the tapered solenoid coil.

18. A method for cooling atoms using the atomic cooling device according to claim 10, comprising: a step of supplying atoms; a step of magneto-optically trapping the atoms using the atom trap section; a step of magnetically trapping and guiding the atoms using the atom trap section; and a step of Doppler cooling the guided atoms using the Doppler cooling mechanism.

19. A method for cooling atoms using the atomic cooling device according to claim 11, comprising: a step of supplying atoms; a step of magneto-optically trapping the atoms using the atom trap section; a step of magnetically trapping and guiding the atoms using the atom trap section; and a step of Doppler cooling the guided atoms using the Sisyphus cooling mechanism.

20. A method for spectroscopy using a spectroscopic device comprising the atomic cooling device according to claim 10 and a spectroscopic section, comprising: a step of supplying atoms; a step of magneto-optically trapping the atoms using the atom trap section; a step of magnetically trapping and guiding the atoms using the atom trap section; a step of Doppler cooling the guided atoms using the Doppler cooling mechanism; and a step of performing spectroscopy using the spectroscopic section.

21. A method for spectroscopy using a spectroscopic device comprising the atomic cooling device according to claim 11 and a spectroscopic section, comprising: a step of supplying atoms; a step of magneto-optically trapping the atoms using the atom trap section; a step of magnetically trapping and guiding the atoms using the atom trap section; a step of Doppler cooling the guided atoms using the Sisyphus cooling mechanism; and a step of performing spectroscopy using the spectroscopic section.

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