Abstract: According to one embodiment, an oscillator includes a first element. The first element includes first and second magnetic layers, and a first nonmagnetic layer. The first magnetic layer includes first and second magnetic films, and a first nonmagnetic film. The second magnetic film is provided between the second magnetic layer and the first magnetic film. The first nonmagnetic layer is provided between the second magnetic film and the second magnetic layer. An orientation of a first magnetization of the first magnetic film has a reverse component of an orientation of a second magnetization of the second magnetic film. A first magnetic field is applied to the first element. The first element is in a first state when a first current flows in the first element. An electrical resistance of the first element in the first state includes first and second electrical resistances repeating alternately.

Abstract: A method of making an atomic vapor source includes positioning a glass base of a vapor cell in a vacuum chamber, providing an alkaline-earth metal in the glass base, and positioning a linear motion feedthrough mechanism adjacent the vacuum chamber in line with the glass base. The method includes sealing and evacuating the vacuum chamber, and positioning, using a linear motion actuator of the linear motion feedthrough mechanism, a glass lid to contact the glass base of the vapor cell to form an optical contact bond therebetween.

Abstract: A vapor cell heating assembly, method, and high temperature optical system including a vapor cell having exterior surfaces; a slide disposed on at least one exterior surface of the vapor cell; a heating element disposed on the at least one exterior surface, the heating element including a frame and a first opening in the frame to pass light through the frame to the at least one exterior surface; and a shell disposed on the vapor cell to hold the slide and heating element to the vapor cell, wherein the shell includes a plurality of structural elements, each structural element disposed on a corresponding exterior surface of the vapor cell and aligned to adjacent structural elements at edges, and wherein each structural element includes a second opening to pass light through the structural element to a respective exterior surface.

Abstract: A data writing method according to an aspect is configured such that a spin-orbit torque-type magnetoresistance effect element includes: a spin-orbit torque wire extending in a first direction; and a functional portion having a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer stacked on one surface of the spin-orbit torque wire in that order from the spin-orbit torque wire, wherein a voltage applied in the first direction of the spin-orbit torque wire is equal to or higher than a critical writing voltage at an environmental temperature and is equal to or lower than a predetermined value.

Abstract: A chip scale vapor cell and millimeter wave atomic clock apparatus are disclosed. The chip scale vapor cell includes a first substrate and a second substrate bonded to the first substrate with a bonding material. A primary hermetic cavity includes a first bottom wall and first sidewalls formed in the first substrate and a first top wall formed by the lower surface of the second substrate. A secondary hermetic cavity includes a second bottom wall and second sidewalls formed in the first substrate and a second top wall formed by the lower surface of the second substrate. The secondary hermetic cavity is separate from the primary hermetic cavity and surrounds the perimeter of the primary hermetic cavity. A gas, which can be a dipolar molecular gas, is sealed in the primary hermetic cavity and the secondary hermetic cavity at a given initial pressure.

Abstract: A quantum interference device (atomic oscillator) includes a light source unit as a coherent light source, a unit that superimposes microwave on the light source unit to generate a side band, an atom cell in which an alkali metal gas is enclosed, and a light receiving unit that detects light transmitted through the atom cell, wherein the light source unit is a surface-emitting laser that outputs a zero-order mode light and a plurality of higher-order mode lights, and a mode filter that cuts the higher-order mode lights is placed between the light source unit and the atom cell.

Abstract: A light-emitting element module includes a light-emitting element that emits light, a base that has a depression portion in which the light-emitting element is accommodated, and a lid that covers an opening of the depression portion and is joined to the base. The lid includes a protrusion portion that protrudes on an opposite side to the base and has a hole through which the light passes and a window that is installed in the protrusion portion to block the hole and transmits the light. A surface of the window on a side of the light-emitting element is inclined with respect to a surface perpendicular to an optical axis of the light.

Abstract: A quantum interference device includes an atom cell module including an atom cell in which alkali metal is encapsulated, a light source that emits light adapted to excite the alkali metal, and a heater that heats the atom cell and the light source, a package that houses the atom cell module, and a controller adapted to control drive of the heater so that the light source becomes at a set temperature, R?(Tv?Tout)/Qv is satisfied, where R [° C./W] is a thermal resistance between the atom cell module and the package, Tv [° C.] is the set temperature, Tout [° C.] is an upper limit value of a usage environmental temperature set to a value lower than the set temperature, Qv [W] is an amount of heat generation of the light source.

Abstract: An atomic oscillator includes: an atomic cell in which an alkali metal is sealed; a light-emitting element that emits light to be radiated to the atomic cell; a light-receiving element that detects the light transmitted through the atomic cell; a first optical element that has light transmittance and is disposed between the atomic cell and the light-emitting element; and a second optical element that has light transmittance and is disposed between the first optical element and the atomic cell. The first optical element reflects the light from the light-emitting element toward the light-emitting element in a first direction inclined with respect to an optical axis of the light. The second optical element reflects the light from the light-emitting element toward the light-emitting element in a second direction inclined in a direction different from the first direction with respect to the optical axis of the light.

Abstract: The present disclosure relates to methods and apparatus for accurately calculating time with a Miniature Atomic Clock along with other components that can receive process and communicate information to enable locating, identifying, and tracking physical Assets and data contained within the Assets. More specifically, the present disclosure presents a Global Resource Locating (GRL) device and service that may be adhered or inserted in the Asset, which may be built in or attached to a second Asset, wherein the device may comprise a receiver and a trilateration mechanism. In some aspects, the Asset may comprise a product, organism, produce, or component of a logistics based operational process and marketing based Asset movement and usage analysis.

Abstract: A sensor cell has a chamber that defines an internal sensor volume for a sensor fluid in a vapor phase. A signal path extends into the internal sensor volume. The sensor cell includes a condensation reservoir for a condensed phase of the sensor fluid, in fluid communication with the internal sensor volume. The signal path is spatially separate from the condensation reservoir. During operation of the sensor cell, some of the sensor fluid may be converted to a vapor phase in the internal sensor volume. During such operation, sensor fluid in the condensed phase is disposed in the condensation reservoir, advantageously out of the signal path, leaving the signal path desirably free of the condensed phase sensor fluid. During periods of non-operation, a significant portion of the sensor fluid may condense from the vapor phase to the condensed phase in the condensation reservoir, advantageously out of the signal path.

Abstract: An atomic oscillator includes at least a gas cell that has metal atoms sealed therein, a coil that is disposed in a vicinity of the gas cell, a first magnetic shield that accommodates the gas cell and the coil therein, a second magnetic shield that accommodates a heater heating the gas cell, a first temperature sensor detecting a temperature of the gas cell, and the first magnetic shield therein, and a temperature adjustment unit and a second temperature sensor that are disposed outside the second magnetic shield.

Abstract: An atomic oscillator includes a plurality of components, the components including a light source that emits excitation light, a gas cell in which an atom to be excited by the excitation light is sealed, and a photodetector that detects the excitation light transmitting through the gas cell; and a main part, wherein a part of the plurality of components are laminated in the main part. In a first component and a second component adjacent to each other of the main part, an electrically conductive film is formed on each of side surfaces of the first component and the second component; bonding patterns that are extended from the respective electrically conductive films and that face each other are formed on respective bonding surfaces facing each other of the first component and the second component; and the bonding patterns that face each other are bonded by a bonding material.

Abstract: Methods and structures useful for magnetoresistive random-access memory (MRAM) are disclosed. The MRAM device has a magnetic tunnel junction stack having a significantly improved performance of the free layer in the magnetic tunnel junction structure. The MRAM device utilizes a STNO, an in-plane polarization magnetic layer, and a perpendicular MTJ.

Abstract: A method of quantum processing using a quantum processor comprising a plurality of Kerr non-linear oscillators (KNOs), each operably drivable by both i) a controllable single-boson drive and ii) a controllable two-boson drive, the method comprising simultaneously controlling a drive frequency and a drive amplitude of the controllable single-boson drives to define a problem and controlling a drive frequency and a drive amplitude of the two-photon drives to define the Hilbert space, including increasing the amplitude of the two-boson drive and reaching both amplitude conditions a) 4 times the amplitude of the two-boson drives being greater than the loss rate, and b) the amplitude of the two-boson drives being greater than the amplitude of the single-boson drive, and maintaining both amplitude conditions a) and b) until a solution to the problem is reached; and reading the solution.

Abstract: A method of operating a cold atom clock to maintain a highly homogeneous microwave field is provided. The method includes: driving a subset of microwave feed lines to excite a microwave field in a resonator, while a power and a phase of at least one microwave feed line in the subset is held constant, and while the power or the phase of at least one other microwave feed line in the subset is changed; measuring a strength of the atomic transition excited by the microwave field; extracting a relative power and a relative phase between or among the subset of microwave feed lines by processing the strength of the atomic transitions excited by the microwave field measured in at least one auxiliary-measurement sequence; and determining if an adjustment to one or more of the microwave feed lines is needed to improve the homogeneity of the microwave field phase and amplitude.

Abstract: A timing signal generation device includes a PLL circuit that synchronizes a first clock signal of an atomic oscillator with a reference timing signal of a GPS receiver, a PLL circuit that synchronizes a second clock signal of an oven-controlled crystal oscillator with the first clock signal, a first count reset unit that enables resetting of a count value of a divider in the PLL circuit when an operation of the PLL circuit is restarted, and a second count reset unit that enables resetting of a count value of a divider in the PLL circuit when the operation of the PLL circuit is restarted.

Abstract: An atomic oscillator includes a base, an atomic cell unit that is disposed on the base, a lid that constitutes an internal space accommodating the atomic cell unit together with the base, and a getter material that is disposed on the base with a gap with respect to the base in the internal space.

Abstract: A surface emitting laser element includes a lower Bragg reflection mirror; an upper Bragg reflection mirror; and a resonator region formed between the lower Bragg reflection mirror and the upper Bragg reflection mirror, and including an active layer. A wavelength adjustment region is formed in the lower Bragg reflection mirror or the upper Bragg reflection mirror, and includes a second phase adjustment layer, a wavelength adjustment layer and a first phase adjustment layer, arranged in this order from a side where the resonator region is formed. An optical thickness of the wavelength adjustment region is approximately (2N+1)×?/4, and the wavelength adjustment layer is formed at a position where an optical distance from an end of the wavelength adjustment region on the side of the resonator region is approximately M×?/2, where ? is a wavelength of emitted light, M and N are positive integers, and M is N or less.

Abstract: A quantum interference device (atomic oscillator) includes: an atom cell that encapsulates an alkali metal; a first light source portion that emits light including a resonance light pair, the resonance light pair being circularly polarized in the same direction and causing the alkali metal to resonate; a second light source portion that emits light including adjustment light, the adjustment light being circularly polarized in a direction opposite to the resonance light pair and causing the alkali metal to resonate; and a light receiving portion that receives the resonance light pair having passed through the atom cell, in which the adjustment light is FM-modulated.

Abstract: A magnetic solid state device is disclosed. The magnetic solid state device includes a substrate and a topological insulator deposited on top of the substrate. The magnetic solid state device also includes a first perpendicular magnetic anisotropy (PMA) bit having a reference PMA layer located on the topological insulator, and a second PMA bit having a free PMA layer located on the topological insulator. A gate contact is utilized to receive various predetermined voltages for controlling the Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions between the reference PMA layer in the first PMA bit and the free PMA layer in the second PMA bit.

Abstract: A light-emitting element module includes: a Peltier device that includes a first substrate, and a second substrate causing a temperature difference from the first substrate, and a power terminal disposed on the first substrate; a light-emitting element that is disposed on a side of the second substrate of the Peltier device and of which temperature is adjusted by the Peltier device; a temperature sensor that is disposed on the side of the second substrate of the Peltier device; a package that includes a base and a lid; a first external electrode that is electrically connected to the power terminal; a second external electrode that is electrically connected to the temperature sensor; and a third external electrode that is electrically connected to the light-emitting element. The third external electrode is disposed between the first and second external electrodes.

Abstract: An atom cell is provided with an internal space including a space formed of a through hole housing gaseous alkali metal, a space formed of a through hole housing a compound as an alkali metal emission material, and a space formed of a through hole housing liquid or solid alkali metal.

Abstract: According to an embodiment, a computing apparatus includes spin torque oscillators, an interaction unit, a variable direct-current supply device, and a measuring unit. The interaction unit controls an interaction between the spin torque oscillators. The variable direct-current supply device supplies a current to induce oscillations of the spin torque oscillators. The measuring unit measures AC signals obtained from the spin torque oscillators.

Abstract: A device for sensing a microwave magnetic field polarization component (B?, B?, B+) of a microwave relative to a static magnetic field B0, comprising a preparation means to prepare atomic vapor (10) comprising thermal atoms in a first hyperfine state, particularly a dark state to applied laser light, which first hyperfine state is split from other hyperfine state due to zero-field hyperfine splitting and/or due to a static magnetic field (B0) generated by preparation means, at least one cell enclosing the thermal atoms (10), the microwave is adapted to drive Rabi oscillations of thermal atoms between first hyperfine state and second hyperfine state, Rabi frequency of Rabi oscillations being proportional to magnetic field polarization component (B?, B?, B+) of the microwave, and imaging means to capture state image of plurality of atoms representing spatial atomic density distribution (Ne) as a function of the Rabi frequency (?i(r)) of Rabi oscillations.

Abstract: A method for generating a CPT resonance, includes applying an electric current to a laser light-emitting element, to emit laser light having at least two wavelengths. The value of a direct current component of the electric current applied to the laser light-emitting element in a first period is greater than an oscillation threshold for the laser light-emitting element, and the value of the direct current component of the electric current applied to the laser light-emitting element in a second period, following the first period, is less than the value of the direct current component of the electric current in the first period. An alkali metal atom is irradiated with the laser light, the laser light generated in the first period and the laser light generated in the second period entering the alkali metal atom repeatedly a plurality of times to generate a Ramsey resonance.

Abstract: Loss tangents in microwave dielectric materials may be modified (increased and/or reduced), particularly at cryogenic temperatures, via application of external magnetic fields. Exemplary electrical devices, such as resonators, filters, amplifiers, mixers, and photonic detectors, configured with dielectric components having applied magnetic fields may achieve improvements in quality factor and/or modifications in loss tangent exceeding two orders of magnitude.

Abstract: An FM-NMOR magnetometer and concomitant magnetometry method comprising providing a linearly-polarized pump beam generator, employing a center wavelength approximately equal to a center wavelength of hyperfine peaks, and employing a modulation amplitude in the range HFS-3×LW to HFS.

Abstract: The invention relates to a process for fabricating a microcell for a caesium atomic micro-clock having an inversion temperature above 80° C., comprising a step of generating a caesium vapor by heating a caesium-containing pellet, the buffer gas used containing neon and helium.

Abstract: A magnetometer comprising: a sensor formed of diamond material and comprising a plurality of spin centers; a microwave source configured to subject the plurality of spin centers to microwave pulses; a light source configured to subject the plurality of spin centers to light pulses; and a detector configured to detect a fluorescent output signal emitted from the plurality of spin centers, wherein the magnetometer is configured to integrate the fluorescent output signal over a signal averaging time and process the fluorescent output signal such that a standard deviation of the fluorescent output signal decreases with the square root of the signal averaging time over a time period which spans at least two orders of magnitude in the signal averaging time to achieve a standard deviation of less than 100 picotesla.

Abstract: An atomic oscillator includes a gas cell into which alkali metal atoms are sealed, a light emitting portion that emits excitation light including a pair of resonance light beams for resonating the alkali metal atoms toward the alkali metal atoms, a coil that is provided to surround an outer circumference of the gas cell with an axis of the excitation light as an axial direction, and a shield case that stores at least the gas cell and the coil and contains a metal material, in which the shield case is constituted by a plurality of tabular portions, and, among the plurality of tabular portions, a main surface of one of two adjacent tabular portions faces a side surface of the other tabular portion.

Abstract: An atomic clock including an ion trap assembly, a C-field coil positioned for generating a first magnetic field in the interrogation region of the ion trap assembly, a compensation coil positioned for generating a second magnetic field in the interrogation region, wherein the combination of the first and second magnetic fields produces an ion number-dependent second order Zeeman shift (Zeeman shift) in the resonance frequency that is opposite in sign to an ion number-dependent second order Doppler shift (Doppler shift) in the resonance frequency, the C-field coil has a radius selected using data indicating how changes in the radius affect an ion-number-dependent shift in the resonance frequency, such that a difference in magnitude between the Doppler shift and the Zeeman shift is controlled or reduced, and the resonance frequency, including the adjustment by the Zeeman shift, is used to obtain the frequency standard.

Abstract: A quantum interference device includes: a gas cell in which metal atoms are sealed; a light emitting unit which emits light to the gas cell; a light receiving unit which receives the light penetrating the gas cell and outputs a light receiving signal; an input unit which inputs the light receiving signal; a light receiving circuit which processes the light receiving signal output from the input unit; a high frequency current generation unit which is arranged with the light emitting unit in a line, and generates high frequency current; and a first output unit which outputs the high frequency current output from the high frequency current generation unit to the light emitting unit, in which the gas cell is disposed between the input unit and the first output unit.

Abstract: A gas cell includes an internal space in which metal atoms and a buffer gas are sealed. The buffer gas includes a gas mixture including nitrogen gas and argon gas. The mole fraction of the argon gas in the gas mixture is equal to or greater than 15% and equal to or less than 40%.

Abstract: Vapor cells and methods for making the same are presented, in which a cell cavity is completely filled with aqueous alkali metal azide solution and the solution is dried at a controlled evaporation rate to substantially maintain edge contact pinning at an interface with the cavity sidewall to promote preferential evaporation in the center and outward capillary flow from an unpinned air-fluid interface toward the sidewall to form crystallized alkali metal material at the sidewall while inhibiting drying of dispersed aqueous solution on a transparent cavity bottom to provide substantially unrestricted passage of light through the cavity for atomic clock and other applications.

Abstract: Various embodiments improve accuracy by increasing the number of atoms engaged in a clock transitions in an optical lattice clock. An exemplary optical lattice clock an embodiment comprises an optical waveguide, an optical path, a laser light source, and a laser cooler. The optical path has a hollow pathway that extends from a first end to a second end while being surrounded with a tubular wall, which is used as a waveguide path. The optical path passes between mirrors and through the pathway. The laser light source supplies to the optical path a pair of lattice lasers (L1 and L2) propagating in opposite directions with each other. The laser cooler supplies cooled atoms that have two levels of electronic states associated with a clock transition to the vicinity of the first end of the optical waveguide.

Abstract: The present invention relates to using spin transfer torque underneath a nanocontact on a magnetic thin film with perpendicular magnetic anisotropy (PMA), provides generation of dissipative magnetic droplet solitons and report on their rich dynamical properties. Micromagnetic simulations identify a wide range of automodulation frequencies including droplet oscillatory motion, droplet “spinning”, and droplet “breather” states. The droplet can be controlled using both current and magnetic fields, and is expected to have applications in spintronics, magnonics, and PMA-based domain-wall devices.

Abstract: Described examples include a millimeter wave atomic clock apparatus, chip scale vapor cell, and fabrication method in which a low pressure dipolar molecule gas is provided in a sealed cavity with a conductive interior surface forming a waveguide. Non-conductive apertures provide electromagnetic entrance to, and exit from, the cavity. Conductive coupling structures formed on an outer surface of the vapor cell near the respective non-conductive apertures couple an electromagnetic field to the interior of the cavity for interrogating the vapor cell using a transceiver circuit at a frequency that maximizes the rotational transition absorption of the dipolar molecule gas in the cavity to provide a reference clock signal for atomic clock or other applications.

Abstract: A gas cell includes an internal space in which metal atoms and a buffer gas are sealed, the buffer gas includes nitrogen gas, and the partial pressure of the nitrogen gas in the internal space is equal to or higher than 30 Torr. The gas cell includes a pair of window portions and a body portion, the length of the internal space along a direction in which the pair of window portions are arranged is equal to or less than 10 mm, and the width of the internal space along a direction perpendicular to the direction in which the pair of window portions are arranged is equal to or less than 10 mm.

Abstract: The invention concerns a micro-machined vapor cell comprising a central silicon element forming a cavity containing vapor cell reactants such as alkali metal or alkali metal azide, buffer gas(es), and/or anti relaxation coating(s); a first and a second glass caps sealing the cavity; and a solenoid arranged to provide a homogeneous magnetic field to said vapor cell. The solenoid is coiled directly on the central silicon element of the vapor cell. This invention is an improvement for the highly miniaturized atomic clocks developments.

Abstract: An atomic oscillator includes a gas cell into which alkali metal atoms are sealed, a light emitting portion that emits excitation light including a pair of resonance light beams for resonating the alkali metal atoms toward the alkali metal atoms, a coil that is provided to surround an outer circumference of the gas cell with an axis of the excitation light as an axial direction, and a shield case that stores at least the gas cell and the coil and contains a metal material, in which the shield case is constituted by a plurality of tabular portions, and, among the plurality of tabular portions, a main surface of one of two adjacent tabular portions faces a side surface of the other tabular portion.

Abstract: Synthetic antiferromagnetic (SAF) and synthetic ferrimagnetic (SyF) free layer structures are disclosed that reduce Ho (for a SAF free layer), increase perpendicular magnetic anisotropy (PMA), and provide higher thermal stability up to at least 400° C. The SAF and SyF structures have a FL1/DL1/spacer/DL2/FL2 configuration wherein FL1 and FL2 are free layers with PMA, the coupling layer induces antiferromagnetic or ferrimagnetic coupling between FL1 and FL2 depending on thickness, and DL1 and DL2 are dusting layers that enhance the coupling between FL1 and FL2. The SAF free layer may be used with a SAF reference layer in STT-MRAM memory elements or in spintronic devices including a spin transfer oscillator. Furthermore, a dual SAF structure is described that may provide further advantages in terms of Ho, PMA, and thermal stability.

Abstract: An atomic cell includes a pair of windows, and a body disposed between the pair of windows and forming an inner space in which alkali metal atoms are sealed along with the pair of windows. The inner space has a longitudinal shape in which a cross-section perpendicular to an arranging direction of the pair of windows extends in a first direction. Further, when a length of the inner space in a second direction perpendicular to the first direction in the cross-section is set to L1, and a length of the inner space in the first direction is set to L2, a relationship of L2/L1?1.1 is satisfied.

Abstract: A quantum interference device includes: a gas cell in which metal atoms are sealed; a light emitting unit which emits light to the gas cell; a light receiving unit which receives the light penetrating the gas cell and outputs a light receiving signal; an input unit which inputs the light receiving signal; a light receiving circuit which processes the light receiving signal output from the input unit; a high frequency current generation unit which is arranged with the light emitting unit in a line, and generates high frequency current; and a first output unit which outputs the high frequency current output from the high frequency current generation unit to the light emitting unit, in which the gas cell is disposed between the input unit and the first output unit.

Abstract: A quantum interference device includes a gas cell into which metal atoms are sealed, a heater that heats the gas cell, a heat transmission portion that is located between the gas cell and the heater, is connected to the gas cell, and transmits heat generated from the heater to the gas cell, and a heat dissipation portion that is connected to the gas cell so as to be spaced apart from the heat transmission portion, and dissipates heat of the gas cell.

Abstract: A gas cell includes an internal space in which metal atoms and a buffer gas are sealed. The buffer gas includes a gas mixture including nitrogen gas and argon gas. The mole fraction of the argon gas in the gas mixture is equal to or greater than 15% and equal to or less than 40%.

Abstract: A light emitting device includes a first semiconductor multilayer film mirror of a first conductivity type, a second semiconductor multilayer film mirror of a second conductivity type that is different from the first conductivity type, an active layer formed between the first semiconductor multilayer film mirror and the second semiconductor multilayer film mirror, a third semiconductor multilayer film mirror of a semi-insulating type formed between the first semiconductor multilayer film mirror and the active layer, and a contact layer of the first conductivity type formed between the third semiconductor multilayer film mirror and the active layer, and the third semiconductor multilayer film mirror is formed of a material having a bandgap energy higher than an energy of light generated in the active layer.

Abstract: An optical module for an atomic oscillator using a quantum interference effect includes a light source part to emit resonant light having two different wavelengths, a gas cell in which an alkali metal atom gas is enclosed and to which the resonant light is irradiated, a light detection part to detect an intensity of the resonant light transmitted through the gas cell, and a gas-flow generation part to generate a flow of the alkali metal atom gas.

Abstract: An atomic oscillator includes: a base; a unit portion including a gas cell, in which alkali metal atoms are filled, and a heater that heats the gas cell; and a wiring line that electrically connects the base and the unit portion to each other and includes a portion having a cross-sectional area of 60 ?m2 or more and 100 ?m2 or less.

Abstract: An optical module for an atomic oscillator using a quantum interference effect includes a first light source unit that emits first resonance light, a gas cell in which an alkali metal atom is sealed, a first light detection unit that detects the intensity of the first resonance light having passed through the gas cell, a determination unit that determines whether or not the first light source unit has failed, a second light source unit that irradiates the gas cell with second resonance light when the determination unit determines that the first light source unit has failed, and a second light detection unit that detects the intensity of the second resonance light having passed through the gas cell, and the optical path length of the first resonance light in the gas cell and the optical path length of the second resonance light in the gas cell are equal to each other.