Inertial sensor

Abstract

To disclose an inertial sensor capable of suppressing decrease in a contrast of an atomic interference of atoms included in an atomic ray due to the fact that a velocity of the atomic ray in a direction of travel has a distribution, a phenomenon occurring when an angular speed and / or acceleration are applied to the inertial sensor.SOLUTION: An inertial sensor 900 includes a dual atomic interferometer. A traveling light standing wave generator 300 of the dual atomic interferometer generates M (3≤M) traveling light standing waves. Each of the M traveling light standing waves is generated by a pair of laser beams that propagates facing each other. The traveling light standing wave generator 300 sets two-photon detuning of the pair of laser beams corresponding to each of N (2≤N<M) traveling light standing waves among the M traveling light standing waves so that a difference between a phase of population of one atomic ray 131c obtained by interference with the M traveling light standing waves and a phase of population of the other atomic ray 131d obtained by interference with the M traveling light standing waves becomes constant.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to an inertial sensor that utilizes atomic interference and can suppress a decrease in the contrast of atomic interference caused by the speed of atoms contained in an atomic beam having a distribution in the direction of propagation of the atomic beam, which occurs when angular velocity and / or acceleration is applied to the inertial sensor. [Background technology]

[0002] In recent years, with the progress of laser technology, research on atom interferometers, inertial sensors that utilize atomic interference, etc. Known examples of atom interferometers include the Mach-Zehnder type atom interferometer and the Ramsey-Bode type atom interferometer (see, for example, Non-Patent Document 1).

[0003] In the basic scheme of the Mach-Zehnder atom interferometer, an atomic beam is irradiated with two traveling optical standing waves, each called a π / 2 pulse, and one traveling optical standing wave, called a π pulse. Due to the interaction between the atomic beam and the traveling optical standing wave, the atomic beam splits into two atomic beams, which then cross each other. As a result, an atomic beam is obtained that corresponds to a superposition of the atomic states corresponding to one of the two atomic beams and the atomic states corresponding to the other of the two atomic beams.

[0004] When an angular velocity is applied to a Mach-Zehnder atom interferometer in a plane containing two atomic beams, for example, a phase difference occurs between the two atomic beams after splitting, and this phase difference is reflected in the probability of existence of an atomic state corresponding to one of the two atomic beams after crossing and the probability of existence of an atomic state corresponding to the other of the two atomic beams. Therefore, the angular velocity can be detected by observing the atomic beam corresponding to the superposition state of the atomic state corresponding to one of the two atomic beams and the atomic state corresponding to the other of the two atomic beams.

[0005] Also known is a double-atom interferometer having a configuration in which a traveling optical standing wave is irradiated onto two atomic beams traveling toward each other (see, for example, Non-Patent Documents 1 and 2). [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] TL Gustavson, P. Bouyer and MA Kasevich, “Precision Rotation Measurements with an Atom Interferometer Gyroscope,” Phys. Rev. Lett.78, 2046-2049, Published 17 March 1997. [Non-Patent Document 2] T. Muller, M. Gilowski, M. Zaiser, T. Wendrich, W. Ertmer, and EM Rasel, “A compact dual atom interferometer gyroscope based on laser-cooled rubidium,” Eur. Phys. J. D 53, 273-281, 2009. Summary of the Invention [Problem to be solved by the invention]

[0007] When the atomic beam is, for example, a thermal atomic beam, the speed of the atoms contained in the atomic beam in the direction of travel of the atomic beam follows the Maxwell-Boltzmann distribution. When the atomic beam is, for example, a cooled atomic beam, it is generally known that the distribution of atomic speeds in the direction of travel of the cooled atomic beam has a full width at half maximum of about 20% of the mode, and for example, when the mode of this distribution is 20 m / s, this distribution has a full width at half maximum of about ±2 m / s.

[0008] The population P of excited atoms in an atomic beam irradiated in this order with a π / 2 pulse, a π pulse, and a π / 2 pulse. eis expressed by equation (1). φ1 is the initial phase of the first π / 2 pulse, φ2 is the initial phase of the π pulse, φ3 is the initial phase of the second π / 2 pulse, and k eff is the effective wave number, Ω is the angular velocity, a is the acceleration, v is the speed of the atoms in the atomic beam in the direction of travel of the atomic beam, and L is the distance between the first π / 2 pulse and the π pulse (= the distance between the second π / 2 pulse and the π pulse).

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[0009] As can be seen from equation (1), when the speed v of the atoms in the atomic beam in the direction of the atomic beam is not the same for all atoms, the various speeds included in the width of the atomic speed distribution are called the population P e Therefore, when an atomic interferometer is subjected to angular velocity and / or acceleration, the cosine functions with different phases cancel each other out, resulting in a decrease in the contrast of the atomic interference.

[0010] Therefore, we disclose an inertial sensor that utilizes atomic interference and can suppress a decrease in the contrast of atomic interference caused by the atoms contained in an atomic beam having a distribution of speeds in the direction of propagation of the atomic beam, which occurs when angular velocity and / or acceleration is applied to the inertial sensor. [Means for solving the problem]

[0011] The technical matters described herein are not intended to explicitly or implicitly limit the invention described in the claims, nor to enable those who benefit from the invention (e.g., the applicant and the right holder) to limit the invention described in the claims, but are merely provided to facilitate understanding of the gist of the invention. The outline of the invention from other perspectives can be understood, for example, from the claims at the time of filing of this patent application. The disclosed inertial sensor includes a dual atom interferometer. The traveling light standing wave generation device of the dual atom interferometer generates M traveling light standing waves. Each of the M traveling light standing waves is generated by a pair of counter-propagating laser beams. The M traveling light standing waves are arranged parallel to each other along the traveling direction of the first atomic beam (in other words, the traveling direction of the second atomic beam), and are arranged in line symmetry with a straight line perpendicular to the traveling direction of the first atomic beam as the axis of symmetry. The traveling light standing wave generation device is such that the difference in phase between the population of one atomic beam obtained by interfering with the M traveling light standing waves in the dual atom interferometer and the population of the other atomic beam obtained by interfering with the M traveling light standing waves in the dual atom interferometer is constant. For the 2-photon detuning δ of the pair of laser beams corresponding to the i-th traveling light standing wave among the M traveling light standing waves i and the 2-photon detuning δ of the pair of laser beams corresponding to the (M - i + 1)-th traveling light standing wave among the M traveling light standing waves M-i+1 are set. δ i = -δ M-i+1 is satisfied. M is a predetermined integer satisfying 3 ≤ M. N is a predetermined integer satisfying 2 ≤ N < M. i represents at least one integer among the [M / 2] integers satisfying 1 ≤ N ≤ [M / 2].

[0012] Furthermore, the traveling light standing wave generation device may set the 2-photon detuning δ of the pair of laser beams corresponding to at least one traveling light standing wave excluding the i-th traveling light standing wave and the (M - i + 1)-th traveling light standing wave among the M traveling light standing waves so as to maintain the extreme value of the contrast of the population of one atomic beam obtained by interfering with the M traveling light standing waves in the dual atom interferometer or to maintain the extreme value of the contrast of the population of the other atomic beam obtained by interfering with the M traveling light standing waves in the dual atom interferometer.

Advantages of the Invention

[0013] According to the inertial sensor of the present disclosure, it is possible to suppress the reduction in the contrast of atom interference caused by the fact that the speeds of the atoms contained in the atomic beam have a distribution in the traveling direction of the atomic beam when an angular velocity and / or an acceleration is applied to the inertial sensor. [Brief description of the drawings]

[0014] [Figure 1] Λ-type three-level system. [Diagram 2] Basic scheme of a Mach-Zehnder atom interferometer. [Diagram 3] Basic scheme of a double atom interferometer. [Figure 4] An example of an inertial sensor configuration. [Diagram 5] 1 shows examples of inertial sensor configurations, (a) a configuration example relating to a first atomic beam, and (b) a configuration example relating to a second atomic beam. [Figure 6] Examples of configurations of atom beam generators. (a) Example of the configuration of an atom beam generator that generates a thermal atomic beam. (b) Example of the configuration of an atom beam generator that generates a cold atomic beam. [Figure 7] An example of controller configuration. [Figure 8] An example of controller configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Prior to describing embodiments of the inertial sensor of the present disclosure, the theory of the inertial sensor of the present disclosure will be described.

[0016] [Traveling light standing wave] Each of the M traveling light standing waves generated by the traveling light standing wave generating device 300 described later is generated by a pair of counter-propagating laser beams. M is a predetermined integer satisfying 3≦M. The electric field vector E(t,r) of the pair of counter-propagating laser beams at time t and position r is expressed as a superposition of plane waves in equation (2). Hereinafter, one of the pair of counter-propagating laser beams is referred to as the "pump laser beam", and the other of the pair of counter-propagating laser beams is referred to as the "Stokes laser beam". E p is the amplitude vector of the pump laser light, and E s is the amplitude vector of the Stokes laser light, and k p is the wave vector of the pump laser light, and k sis the wave vector of the Stokes laser light, and ω p is the angular frequency of the pump laser, and ω s is the angular frequency of the Stokes laser light, and φ p is the initial phase of the pump laser light, and φ s is the initial phase of the Stokes laser light. For convenience of explanation, φ eff Define k by equation (4). eff Define |k eff When | is sufficiently small, a traveling optical standing wave is generated that drifts at a speed sufficiently small compared to the speed of light, c. p / |k p |=-k s / |k s For the sake of simplicity, we will use E p =E s Let us assume that.

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[0017] In a Mach-Zehnder atom interferometer using M traveling optical standing waves, the atomic beam is irradiated in this order with M traveling optical standing waves that are arranged parallel to each other along the traveling direction of the atomic beam and arranged in line symmetry with a straight line perpendicular to the traveling direction of the atomic beam as the axis of symmetry. In particular, when M=3, the optical axis of the π pulse is the axis of line symmetry, and the three traveling optical standing waves (i.e., the first π / 2 pulse, π pulse, and second π / 2 pulse) are arranged at equal intervals L (see Figure 2).

[0018] [Stimulated Raman transitions] Atom interferometers generally use stimulated Raman transitions. The stimulated Raman transitions used in atom interferometers are transitions that couple the first transition between state |g> induced by the pump laser light and virtual state |i> and the second transition between state |e> induced by the Stokes laser light and virtual state |i> in a Λ-type three-level system (see Figure 1). The energy level of state |e> is higher than the energy level of state |g>. The virtual state |i> is separated from state |u> by a detuning Δ. The energy level of state |u> is higher than the energy level of state |e>.

[0019] In a stimulated Raman transition, if the atom's initial state is state |g>, the atom undergoes a stimulated Raman transition by absorbing a photon from the pump laser light. - k p by emitting a photon as stimulated emission of a Stokes laser beam. - k s In other words, the atom gains a momentum of h by transitioning from state |g> to state |e>. - k eff Conversely, the atom gains a recoil momentum of -h by transitioning from state |e> to state |g>. - k eff In this way, since the transition direction and the recoil momentum correspond one-to-one, the state and the recoil momentum can be made to correspond one-to-one. Therefore, state |g> can be expressed as |g,p>, and state |e> as |e,p+h - k eff > can be expressed as - is the Dirac constant (Planck's constant divided by 2π) and (h - is a symbol for use in the text and differs from the conventional symbol), and p is the momentum of the atom in state |g>.

[0020] [Interference between atoms and traveling optical standing waves] When the detuning Δ is large in stimulated Raman transitions, the Λ-type three-level system can be regarded as a two-level system of states |g> and |e>. Here, we consider the interaction between an atom and a pair of laser beams. As mentioned above, the two states of the atom are |g,p>,|e,p+h- k eff >. In this case, the wave function of the atom is expressed by equation (5). In the equation, the Dirac constant is expressed by the conventional symbol.

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[0021] In such a system, atoms exist in states |g,p> and |e,p+h - k eff > between the two-photon Rabi frequency Ω eg (t). And the two-photon detuning δ shown in Figure 1 is Ω eg When ω is sufficiently smaller than (t), the coefficients of the wave function are expressed by equation (6) (see Non-Patent Document 1). In equation (6), t0 is the start time of the interaction, and t1 is the end time of the interaction. The two-photon detuning δ is expressed by equation (7). In equation (7), m is the mass of one atom, and ω eg is the frequency corresponding to the transition between the energy level of state |e> and the energy level of state |g>.

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[0022] When θ=π / 2, the coefficients of the wave function are expressed by Equation (8). When θ=π / 2, the traveling optical standing wave is a π / 2 pulse.

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[0023] When θ=π, the coefficients of the wave function are expressed by Equation (9). When θ=π, the traveling optical standing wave is a π pulse.

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[0024] By the way, when each of a pair of laser beams that generate a traveling optical standing wave is a Gaussian beam, the two-photon Rabi frequency Ω eg(t) is expressed by equation (10), and the interaction time width σ t For σ t =w / (2|v|), where v is the velocity vector of the atoms in the atomic beam in the direction of travel of the atomic beam. w is the width of the traveling light standing wave, specifically, the beam waist of a Gaussian beam (this is, for example, 1 / (e 2 ) width. Therefore, for a π pulse, 0,π =√(π / 2)w π / |v|, that is, π|v|=√(π / 2)w π Ω 0,π holds, and for a π / 2 pulse, 0,π / 2 )=√(π / 2)w π / 2 / |v|, that is, π|v|=2√(π / 2)w π / 2 Ω 0,π / 2 For example, the width of the π pulse is w π is the width of the pulse w π / 2 If we design it so that the Rabi frequency of the π pulse is equal to 0,π is the Rabi frequency of the π / 2 pulse, Ω 0,π / 2 The Rabi frequency is designed to be twice as high as the intensity of the laser light. Since the Rabi frequency is proportional to the intensity of the laser light, the intensity of the pair of laser lights that generates a π pulse is twice as high as the intensity of the pair of laser lights that generates a π / 2 pulse. In general, the speed of atoms contained in an atomic beam has a distribution in the direction of travel of the atomic beam, so for atoms with a certain speed |v0|, the speed is expressed as π|v0|=2√(π / 2)w π Ω 0,π If this is true, then other speeds |v x For atoms with |π|v x |=2√(π / 2)w π Ω 0,πdoes not hold. Therefore, the atomic speed must be specified in advance to design the traveling light standing wave. The designer can freely determine the atomic speed as a premise for designing the traveling light standing wave, but from the viewpoint of the visibility of the observed atomic beam, the mode or average value of the atomic speed distribution in the traveling direction of the atomic beam is usually selected as the atomic speed for designing the traveling light standing wave. Hereinafter, unless otherwise specified, |v| represents the atomic speed included in the vicinity range of the mode including the mode of the atomic speed distribution in the traveling direction of the atomic beam, and v is the velocity vector of the atom. It is to be noted that the traveling light standing wave does not function as a π / 2 pulse or a π pulse for atoms having a speed not included in the vicinity range.

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[0025] Atom interferometers generally have sensitivity to both angular velocity and acceleration. In the following, for simplicity of explanation, we consider the case of M=3. In a Mach-Zehnder type atom interferometer using three traveling optical standing waves, as shown in Figure 2, an atomic beam is irradiated in this order with a first π / 2 pulse, a π pulse, and a second π / 2 pulse, which are arranged at equal intervals L in the traveling direction of the atomic beam. Therefore, the coefficient (c e ,c g ) is expressed by equation (11). In equation (11), δ1 is the two-photon detuning δ of the first π / 2 pulse, δ2 is the two-photon detuning δ of the π pulse, δ3 is the two-photon detuning δ of the second π / 2 pulse, and φ1 is the φ of the first π / 2 pulse. eff and φ2 is the φ of the π pulse. eff and φ3 is the φ of the second π / 2 pulse. eff where α(t) represents the phase shift caused by the angular velocity vector Ω, and β(t) represents the phase shift caused by the acceleration vector a. In equation (11), T = L / |v|. The effective wave vectors k of the three traveling optical standing waves eff (see equation (4)) are the same as each other.

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[0026] If the initial state of the atom is |g,p>, (c e (t0), c g Since (t0))=(0,1), the state of the atoms in the atomic beam irradiated with the first π / 2 pulse, the π pulse, and the second π / 2 pulse in this order is |e,p+h - k eff > Population P e is expressed by equation (12).

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[0027] The population P of the atomic state |g,p> in the atomic beam irradiated in this order by the first π / 2 pulse, π pulse, and second π / 2 pulse is g , P g =1-P e It is expressed as:

[0028] For the sake of convenience, we will refer to Population P below. e The phase of the cosine function in is represented by Φ, the above-mentioned atomic beam is called the "first atomic beam", and the subscript L is added to the symbol for the first atomic beam. When the first atomic beam is irradiated with the first π / 2 pulse, π pulse, and second π / 2 pulse in this order and observed at time t, the population P e,L Phase Φ L is expressed by equation (13). In equation (13), T L =L / |v L |,T det,L =L det,L / |v L | det,L is the distance between the second π / 2 pulse and the photodetector 409a described later. L | is the speed of the atoms contained in the first atomic beam in the traveling direction of the first atomic beam.

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[0029] In equation (13), if we consider the case where the magnitude of the acceleration vector a and the two-photon detuning δ 2 are sufficiently small, equation (13) can be rewritten as equation (14).

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[0030] In equation (14), the population P e,L Phase Φ L is the speed of the atoms in the first atomic beam in the direction of travel of the first atomic beam |v L In order to be independent of |, it is sufficient that δ3 = -δ1 and equation (15) hold. By setting the two-photon detuning δ1 of the first π / 2 pulse to the value of equation (15), setting the two-photon detuning δ2 of the π pulse to a sufficiently small value (ideally δ2 = 0), and setting the two-photon detuning δ3 of the second π / 2 pulse to the value of -δ1, the population P e,L Phase Φ L is expressed by equation (16). Therefore, the population P e,L Phase Φ L is the speed of the atoms in the first atomic beam in the direction of travel of the first atomic beam |v L It can be seen that it is not affected by |.

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[0031] However, since the right-hand side of equation (15) includes the angular velocity vector Ω to be detected, the values ​​of δ1 and δ3 (=-δ1) cannot be set directly. Therefore, we consider controlling the population phase.

[0032] For the purpose of phase control, consider the dual atom interferometer shown in FIG. 3. One of the two atomic beams entering the dual atom interferometer and traveling toward each other is called the first atomic beam, and the other is called the second atomic beam. The above explanation for the first atomic beam is valid as is. By adding the subscript R to the symbol for the second atomic beam, equation (17) is valid for the second atomic beam in the same manner as above. In equation (17), v L / |vL |=-v R / |v R | was used.

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[0033] In equation (17), the population P e,R Phase Φ R is the speed of the atoms in the second atomic beam in the direction of travel of the second atomic beam |v R In order to be independent of |, the population P e,L Phase Φ L As with the above condition for , it is sufficient that δ3 = -δ1 and formula (15) are satisfied. By setting the two-photon detuning δ1 of the first π / 2 pulse to the value of formula (15), setting the two-photon detuning δ2 of the π pulse to a sufficiently small value (ideally δ2 = 0), and setting the two-photon detuning δ3 of the second π / 2 pulse to the value of -δ1, the population P e,R Phase Φ R is expressed by equation (18). Therefore, the population P e,R Phase Φ R is the speed of the atoms in the second atomic beam in the direction of travel of the second atomic beam |v R It can be seen that it is not affected by |.

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[0034] If δ3=-δ1 and equation (15) holds, then from equations (16) and (18), Φ L =Φ R Conversely, under the condition δ3=-δ1, Φ L =Φ R holds true under the condition that δ3=-δ1, equation (15) holds true. In fact, from equations (14) and (17), under the condition that δ3=-δ1, Φ L -Φ R = 0 holds true independently of time and atomic speed only when equation (15) holds true. Under the condition δ3 = -δ1, Φ L =Φ RWhen this is true, the z-direction component of the angular velocity vector Ω is |Ω z | is expressed by equation (19). The z direction is the effective wave vector k eff and perpendicular to the traveling direction of the first atomic beam. In equation (19), the effective wave vector k eff It is considered that the direction of travel of the first atomic beam is perpendicular to that of the second atomic beam.

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[0035] From the above explanation, under the condition δ3=-δ1, Φ L =Φ R By controlling the speed of the atoms in the first atomic beam in the direction of travel of the first atomic beam, |v L |, and the speed of the atoms in the second atomic beam in the direction of travel of the second atomic beam |v R In other words, even if an angular velocity is applied to the inertial sensor, the z-direction component |Ω of the angular velocity vector Ω is not affected by |, and the contrast of atomic interference caused by the atomic speed distribution in the direction of atomic beam travel is not reduced. z It can be seen that | can be detected.

[0036] In the inertial sensor of the present disclosure, under the condition of δ3=-δ1, Φ L =Φ R The control that realizes this is usually feedback control. Under the condition δ3=-δ1, Φ L =Φ R As a feedback control to realize L -Φ R An example of such a frequency shifter is a PID control of the two-photon detuning δ1 (=-δ3) that keeps the frequency constant. The setting of the two-photon detuning δ is realized, for example, by a frequency shifter into which the other laser beam of the pair of laser beams enters. When the frequency shifter is an AOM (acousto-optic modulator), the acoustic signal input to the AOM is controlled. When the frequency shifter is an EOM (electro-optic modulator), the voltage signal input to the EOM is controlled.

[0037] The above description is extended to the case where M is a predetermined integer satisfying 3 ≤ M. Assuming that M traveling light standing waves in the dual-atom interferometer are arranged in ascending order in the traveling direction of one atomic beam, and i represents at least one of [M / 2] integers satisfying 1 ≤ N ≤ [M / 2], the traveling light standing wave generation device makes the difference between the phase of the population of one atomic beam obtained by interfering with M traveling light standing waves in the dual-atom interferometer and the phase of the population of the other atomic beam obtained by interfering with M traveling light standing waves in the dual-atom interferometer constant. The two-photon detuning δ of a pair of laser beams corresponding to the i-th traveling light standing wave among the M traveling light standing waves i and the two-photon detuning δ of a pair of laser beams corresponding to the (M - i + 1)-th traveling light standing wave among the M traveling light standing waves M-i+1 are set. δ i = -δ M-i+1 holds. The symbol [x] is the Gaussian symbol and represents the integer n satisfying n ≤ x < n + 1.

[0038] For example, when M = 4, in order to make the difference between the phase of the population of one atomic beam obtained by interfering with M traveling light standing waves and the phase of the population of the other atomic beam obtained by interfering with M traveling light standing waves constant, (1) The two-photon detuning δ1 of the first traveling light standing wave and the two-photon detuning δ4 of the fourth traveling light standing wave may be controlled (in this case, δ1 = -δ4 holds), or (2) The two-photon detuning δ2 of the second traveling light standing wave and the two-photon detuning δ3 of the third traveling light standing wave may be controlled (in this case, δ2 = -δ3 holds), or (3) The two-photon detuning δ1 of the first traveling light standing wave, the two-photon detuning δ2 of the second traveling light standing wave, the two-photon detuning δ3 of the third traveling light standing wave, and the two-photon detuning δ4 of the fourth traveling light standing wave may be controlled (in this case, δ1 = -δ4, δ2 = -δ3 hold).

[0039] For example, in the case of M=5, the difference between the phase of the population of one atomic beam obtained by interference with M traveling optical standing waves and the phase of the population of the other atomic beam obtained by interference with M traveling optical standing waves is constant. (1) The two-photon detuning δ1 of the first traveling optical standing wave and the two-photon detuning δ5 of the fifth traveling optical standing wave may be controlled (in this case, δ1=-δ5 holds), or (2) The two-photon detuning δ2 of the second traveling optical standing wave and the two-photon detuning δ4 of the fourth traveling optical standing wave may be controlled (in this case, δ2=-δ4 holds), or (3) It is also possible to control the two-photon detuning δ1 of the first traveling optical standing wave, the two-photon detuning δ2 of the second traveling optical standing wave, the two-photon detuning δ4 of the fourth traveling optical standing wave, and the two-photon detuning δ5 of the fifth traveling optical standing wave (in this case, δ1=-δ5, δ2=-δ4).

[0040] In the explanation so far, we have assumed that the magnitude of the acceleration vector a and the two-photon detuning δ2 are sufficiently small, and have ignored the second and third terms of the second equation in equation (13). However, in the following explanation, we consider a case where this assumption does not hold.

[0041] L det,L =L det,R =L det , and the speed of the first atomic beam in the direction of travel |v L and the speed of the atoms in the second atomic beam in the direction of travel of the second atomic beam |v R The distributions of | are the same (i.e., from a statistical point of view, v L =v,v R =-v), the second equation of equation (13) and the second equation of equation (17) are expressed by equations (20) and (21), respectively.

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[0042] From equations (20) and (21), if δ3=-δ1 and equation (15) holds, then Φ L -Φ R=0 holds. In the end, L det,L =L det,R And from a statistical point of view, L =v,v R Even if we can consider that =-v, under the condition δ3=-δ1, Φ L =Φ R By controlling the acceleration vector a and the two-photon detuning δ2, the effects of the speeds are cancelled out in common mode, so that the speed of the atoms in the first atomic beam in the direction of travel of the first atomic beam |v L |(=|v|), and the speed of the atoms in the second atomic beam in the direction of travel of the second atomic beam |v R The z-component |Ω of the angular velocity vector Ω is not affected by |(=|v|) z It can be seen that | can be detected. However, the second and third terms of equations (20) and (21) contribute to a decrease in the contrast of the respective atomic interferences. In other words, when acceleration is applied to the inertial sensor, a decrease in the contrast of the atomic interference caused by the atomic speed distribution in the traveling direction of the atomic beam occurs in each atomic interference. Below, we will explain a method for suppressing the decrease in the contrast of the atomic interference caused by the atomic speed distribution in the traveling direction of the atomic beam, which occurs when acceleration is applied to the inertial sensor.

[0043] When acceleration is applied to the atom interferometer, as is clear from equations (20) and (21), the population phase contains the inverse square of the atomic speed and the inverse of the atomic speed, so it is impossible to completely eliminate the effect of the atomic speed on the population phase. Therefore, we consider reducing the effect of the atomic speed on the population phase.

[0044] In equations (20) and (21), the physically controllable quantities in practice are the two-photon detunings δ1, δ2, and δ3. As described above, δ1 and δ3 are controlled to cancel the influence on the phase of the reciprocal of the speed of the atoms with angular velocity. Therefore, consider controlling the two-photon detuning δ2. Specifically, taking the mode value or average value of the above-described speed distribution as v0, control δ2 such that equation (22) holds. v0 can be known in advance by calculating or measuring the speed distribution.

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[0045] Under the control of δ2 for which equation (22) holds, the phase Φ of the speed v0 + Δv of the atoms in the traveling direction of the atomic beam L and Φ R The influence on each of them is represented by equation (23). However, -v0 ≤ Δv.

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[0046] Therefore, the reduction of the influence on the phase Φ of the speed v0 + Δv of the atoms by the control of δ2 for which equation (22) holds L and Φ R The reduction of the influence on each of them is represented by equation (24).

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[0047] Whether it is a thermal atomic beam or a cooled atomic beam, since |Δv| < v0 in the above-mentioned vicinity range including v0, |Δv| / v0 < 1 in equation (24). That is, by controlling the two-photon detuning δ2 such that equation (22) holds, the influence on the phase Φ of the speed of the atoms with acceleration can be reduced. As the feedback control of the two-photon detuning δ2 to realize equation (22), extreme value control based on the perturbation method of the two-photon detuning δ2 can be exemplified. Specifically, the contrast is represented by η(δ2) as a function of the two-photon detuning δ2, and control such that η(δ2) > η(δ2 ± Δ) holds for a small change in δ2 (that is, δ2 ± Δ) can be exemplified.

[0048] In short, when angular velocity and acceleration are applied to the atomic interferometer, under the condition δ3=-δ1, Φ L =Φ R By controlling the angular velocity to realize L and Φ R By controlling the two-photon detuning δ2 so that the effect of each of these on the acceleration can be eliminated (ideally completely) and equation (22) holds, the phase of the atomic speed accompanied by the acceleration Φ L and Φ R The impact on each of these factors can be reduced.

[0049] <Embodiment> An embodiment of an inertial sensor according to the present disclosure will be described with reference to the drawings. Note that the drawings are for the purpose of understanding the embodiment, and the dimensions of each component shown in the drawings are not accurate.

[0050] An embodiment of the inertial sensor of the present disclosure will now be described. The inertial sensor 900 (see FIGS. 4 and 5) using Mach-Zehnder type atomic interference includes a first atomic beam generating device 100a that continuously generates a first atomic beam 131a, a second atomic beam generating device 100b that continuously generates a second atomic beam 131b, a traveling optical standing wave generating device 300 that generates three traveling optical standing waves, an interference device 200 that obtains a third atomic beam 131c resulting from the interaction between the first atomic beam 131a and the three traveling optical standing waves and a fourth atomic beam 131d resulting from the interaction between the second atomic beam 131b and the three traveling optical standing waves when the first atomic beam 131a and the second atomic beam 131b traveling toward each other enter the interferometer 200, a first observation device 400a that observes the third atomic beam 131c, and a second observation device 400b that observes the fourth atomic beam 131d. In this embodiment, the first atomic beam generation device 100a, the second atomic beam generation device 100b, the interference device 200, the first observation device 400a, and the second observation device 400b are housed in a vacuum container (not shown).

[0051] [Atomic beam generator] The configurations of the first atom beam generator 100a and the second atom beam generator 100b will be described. The configuration of the first atom beam generator 100a does not need to be the same as that of the second atom beam generator 100b. Furthermore, there is no limitation on the configuration that can be adopted as the first atom beam generator 100a or the second atom beam generator 100b. Therefore, here, an example of the configuration of the atom beam generator 100x (x∈{a, b}) will be described without distinguishing between the first atom beam generator 100a and the second atom beam generator 100b.

[0052] An atom beam generator 100x (x∈{a,b}) that continuously generates a thermal atomic beam includes, for example, a heater 100a and a nozzle 1002 that communicates with the heater 1001 (see FIG. 6(a)). The heater 1001 generates gaseous atoms by heating a solid made of a single element with high purity. The gaseous atoms obtained by the heater 1001 exit the atom beam generator 100x (x∈{a,b}) from the heated nozzle 1002 as a thermal atomic beam. See FIG. 1 in Reference 1 for an example of the configuration of such an atom beam generator 100x (x∈{a,b}). (Reference 1) Cvejanovic D and Murray AJ, “Design and characterization of an atomic beam oven for combined laser and electron impact experiments,” Meas. Sci. Tech. 13 1482-1487 (2002).

[0053] The traveling direction of the thermal atomic beam is the direction of extension of a line obtained by connecting the peaks of the density distribution of atoms contained in the thermal atomic beam, and usually coincides with the ejection direction of the nozzle 1002 (i.e., the direction of extension of the central axis of the nozzle 1002). The average speed of the atoms contained in the thermal atomic beam in the traveling direction of the thermal atomic beam is approximately several hundred m / s (Rb: up to 300 m / s, Yb: up to 300 m / s, Ca: up to 600 m / s). The speed of the atoms contained in the thermal atomic beam in the traveling direction of the atomic beam follows the Maxwell-Boltzmann distribution.

[0054] An atom beam generator 100x (x∈{a, b}) that continuously generates a cooled atomic beam includes, for example, a gas atom generator 1003 and a laser cooler 1004 (see FIG. 6(b)).

[0055] The gas atom generator 1003 has a configuration in which a solid sublimes or a liquid evaporates or volatilizes, and generates gas atoms. The solid or liquid is preferably made of a single element of high purity. When strontium or calcium is used, the heater 1001 is required, but when rubidium or cesium is used, the saturated vapor pressure at room temperature (a temperature suitable for human activity) is high (i.e., it is easy to vaporize), so sufficient gas atoms can be obtained without using the heater 1001. The gas atoms (hereinafter simply referred to as atoms) that fill one section of the vacuum vessel are naturally supplied to the laser cooler 1004.

[0056] The laser cooler 1004 may be, for example, a two-dimensional magneto-optical trap (2D-MOT) mechanism including a magnetic field generating coil called hairpin wires and two cooling laser light pairs, or a 2D MOT mechanism having a configuration in which one laser light pair along the zero magnetic field line of a two-dimensional quadrupole magnetic field is added to the 2D-MOT mechanism. + The laser cooler 1004 may include a Zeeman decelerator as necessary. Alternatively, the mechanism disclosed in Reference 2 may be employed as the laser cooler 1004. The laser cooler 1004 generates a cooled atomic beam from a cooled atomic ensemble trapped in space. (Reference document 2) Japanese Patent Application Publication No. 2020-020636

[0057] The direction of travel of an ultracold atomic beam is the direction of the line obtained by connecting the peaks of the density distribution of the atoms contained in the ultracold atomic beam. The average speed of the atoms contained in the ultracold atomic beam in the direction of travel of the ultracold atomic beam is approximately several tens of meters per second. In the case of ultracold atomic beams, the distribution of the atomic speeds in the direction of travel of the ultracold atomic beam generally has a width of about 20% of the mode.

[0058] The individual atoms contained in the first atomic beam 131a are set to the same energy level (energy level of state |g> in this example) by optical pumping, and the individual atoms contained in the second atomic beam 131b are also set to the same energy level (energy level of state |g> in this example) by optical pumping. The first atomic beam 131a and the second atomic beam 131b travel toward each other and enter the interference device 200. In the interference device 200, the first atomic beam 131a passes through the first traveling optical standing wave (π / 2 pulse) 200a, the second traveling optical standing wave (π pulse) 200b, and the third traveling optical standing wave (π / 2 pulse) 200c in this order, and the second atomic beam 131b passes through the third traveling optical standing wave 200c, the second traveling optical standing wave 200b, and the first traveling optical standing wave 200a in this order. In the interference device 200, the first atomic beam 131a interacts with the three traveling optical standing waves 200a, 200b, and 200c to obtain a third atomic beam 131c, and the second atomic beam 131b interacts with the three traveling optical standing waves 200a, 200b, and 200c to obtain a fourth atomic beam 131d.

[0059] [Traveling light standing wave generator] An example of an optical configuration of a traveling optical standing wave generating device 300 that generates three traveling optical standing waves 200a, 200b, and 200c (see FIG. 4) will be described.

[0060] The traveling light standing wave generating device 300 has three optical modulation devices 320a, 320b, and 320c corresponding to the three traveling light standing waves 200a, 200b, and 200c. The optical modulation device 320x (x∈{a, b, c}) includes optical fibers 321x and 324x through which laser light propagates, and a frequency shifter 323x that is connected to the optical fibers 321x and 324x and shifts the frequency of the laser light. The frequency shifter 323x is not limited, but may be, for example, an AOM or an EOM. Hereinafter, the frequency shifter 323x is an AOM.

[0061] Laser light L from laser light source 311 is frequency-shifted by a predetermined frequency by passing through EOM 312. The frequency-shifted laser light L is distributed by optical fiber coupler 313a. One of the two laser lights L output from optical fiber coupler 313a is equally distributed by optical fiber coupler 313c, and the other of the two laser lights L output from optical fiber coupler 313a is equally distributed by optical fiber coupler 313b. One of the two laser lights L output from optical fiber coupler 313b is equally distributed by optical fiber coupler 313d, and the other of the two laser lights L output from optical fiber coupler 313b is equally distributed by optical fiber coupler 313e.

[0062] One of the two laser beams L output from the optical fiber coupler 313c is attenuated by a VOA (Variable Optical Attenuator) 314a, and is then shaped into a desired beam L by a beam shaper 315a, which is composed of, for example, a lens and a collimator. a,1 (For example, a circularly polarized Gaussian beam σ a + The resulting beam L a,1enters the interference device 200. The other of the two laser beams L outputted from the optical fiber coupler 313c is guided to the AOM 323a by the optical fiber 321a, one end of which is connected to the optical fiber coupler 313c by an optical connector (not shown), without crossing the atomic beam. In Fig. 4, the illustration of the middle part of the optical fiber 321a is omitted for ease of viewing.

[0063] One of the two laser beams L output from the optical fiber coupler 313d is attenuated by the VOA 314b, and is then shaped into a desired beam L by a beam shaper 315b, which is composed of, for example, a lens and a collimator. b,1 (For example, a circularly polarized Gaussian beam σ b + The resulting beam L b,1 enters the interference device 200. The other of the two laser beams L outputted from the optical fiber coupler 313d is guided to the AOM 323b by the optical fiber 321b, one end of which is connected to the optical fiber coupler 313d by an optical connector (not shown), without crossing the atomic beam. In Fig. 4, for ease of viewing, the illustration of the middle part of the optical fiber 321b is omitted.

[0064] One of the two laser beams L output from the optical fiber coupler 313e is attenuated by the VOA 314c, and then is converted into a desired beam L by a beam shaper 315c, which is composed of, for example, a lens and a collimator. c,1 (For example, a circularly polarized Gaussian beam σ c + The resulting beam L c,1 enters the interference device 200. The other of the two laser beams L outputted from the optical fiber coupler 313e is guided to the AOM 323c by an optical fiber 321c, one end of which is connected to the optical fiber coupler 313e by an optical connector (not shown), without crossing the atomic beam. In Fig. 4, for ease of viewing, the illustration of the middle part of the optical fiber 321c is omitted.

[0065] The other end of the optical fiber 321x (x∈{a, b, c}) is connected to the AOM 323x by an optical connector, and the laser light L enters the AOM 323x. The frequency of the laser light L is shifted by the AOM 323x. The amount of shift is determined by the input signal frequency f x It is determined by the input signal frequency f x An acoustic signal S x is generated by a controller 500, which will be described later. As a result, the laser light L is phase-modulated. One end of the optical fiber 324x is connected to the AOM 323x by an optical connector, and the laser light L emitted from the AOM 323x enters the optical fiber 324x. The laser light L exits from an optical connector attached to the other end of the optical fiber 324x, and is shaped into a desired beam L by a beam shaper 316x, which is composed of, for example, a lens and a collimator. x,2 (For example, a circularly polarized Gaussian beam σ x + The resulting beam L x,2 enters the interference device 200.

[0066] As a result, the laser light L that has not passed through the optical modulator 320x x,1 and the laser light L via the optical modulator 320x. x,2 propagate in the opposite direction through free space, resulting in a traveling optical standing wave 200x (x∈{a,b,c}).

[0067] [Interference Device] In the atomic interference system in the interference device 200, as described above, the transition between two levels of atoms due to light irradiation is utilized. Therefore, in order to avoid decoherence due to spontaneous emission, a transition between two levels with a long life is generally utilized. For example, when the atomic beam is an alkali metal atomic beam, stimulated Raman transition between two levels included in the hyperfine structure of the ground state is utilized. In the hyperfine structure, the state of the lowest energy level is |g>, and the state of an energy level higher than |g> is |e>. As described above, stimulated Raman transition between two levels is realized by a traveling optical standing wave formed by the opposing irradiation of a pair of laser beams whose difference frequency is approximately equal to the resonance frequency between the states |g> and |e>.

[0068] The following describes the atomic interference using the two-photon Raman process by the traveling light standing wave. The interaction between the first atomic beam 131a and the three traveling light standing waves will be described. Except when referring to the second atomic beam 131b, the following description of the interaction between the second atomic beam 131b and the three traveling light standing waves can be explained by simply replacing "the first atomic beam 131a" with "the second atomic beam 131b", "the first traveling light standing wave 200a" with "the third traveling light standing wave 200c", "the third traveling light standing wave 200c" with "the first traveling light standing wave 200a", and "the third atomic beam 131c" with "the fourth atomic beam 131d".

[0069] When the first atomic beam 131a passes through the first traveling optical standing wave 200a, the states of the individual atoms in the initial state |g, p> change to |g, p> and |e, p+h - k eff > (In Fig. 5, p0=p, p1=p+h - k eff The probability of existence of |g,p> immediately after passing through the first traveling light standing wave 200a and |e,p+h - k eff > has a 1:1 ratio. The atom converts |g,p> to |e,p+h> through the absorption and emission of two photons traveling in opposite directions. - k eff > gains the momentum of two photons when transitioning to state |e,p+h - k eff The direction of motion of atoms in the state |g,p> is shifted from the direction of motion of atoms in the state |e,p+h>. In other words, when the first atomic beam 131a passes through the first traveling optical standing wave 200a, the first atomic beam 131a is divided into an atomic beam consisting of atoms in the state |g,p> and an atomic beam consisting of atoms in the state |e,p+h> in a 1:1 ratio. - k eff The first traveling optical standing wave 200a functions as a splitter for the first atomic beam 131a and as a combiner (to be described later) for the second atomic beam 131b.

[0070] After the splitting, an atomic line consisting of atoms in state |g,p> and an atom in state |e,p+h - k eff The atomic beam consisting of atoms in state |g,p> passes through the second traveling optical standing wave 200b. By passing through the second traveling optical standing wave 200b, the atomic beam consisting of atoms in state |e,p+h> - k eff > atoms in the state |e,p+h - k eff The atomic beam consisting of atoms in state |g,p> is inverted to an atomic beam consisting of atoms in state |e,p+h>. - k eff As described above, the direction of travel of the atom that has transitioned to state |g,p> is shifted from the direction of motion of the atom in state |e,p+h>. As a result, after passing through the second traveling optical standing wave 200b, - k eff The direction of travel of the atomic beam consisting of atoms of |e,p+h after passing through the first traveling optical standing wave 200a is - k eff > atoms travel in the direction parallel to the direction of travel of the atomic beam. In the latter case, the atoms absorb and emit two photons traveling in opposite directions, - k eff In the transition from |e,p> to |g,p>, the momentum lost is the same as the momentum gained from the two photons. That is, |e,p+h - k eff The direction of motion of the atom that transitioned from |g,p> to |e,p+h - k eff The direction of motion of the atoms in state |g,p> after passing through the second traveling optical standing wave 200b is shifted from the direction of motion of the atoms in state |g,p> after passing through the first traveling optical standing wave 200a. As a result, the direction of motion of the atomic beam made up of atoms in state |g,p> after passing through the second traveling optical standing wave 200b becomes parallel to the direction of motion of the atomic beam made up of atoms in state |g,p> after passing through the first traveling optical standing wave 200a. The second traveling optical standing wave 200b functions as a mirror for the atomic beam.

[0071] After inversion, an atomic line consisting of atoms in state |g,p> and in state |e,p+h - k effThe atomic beam consisting of atoms in state |g,p> passes through the third traveling optical standing wave 200c. The atomic beam consisting of atoms in state |g,p> and state |e,p+h - k eff The |g,p> and |e,p+h> of each atom included in the intersection region with the atomic line of atoms of - k eff An atomic beam corresponding to the superposition state of the first atomic beam 131a and the second atomic beam 131b is obtained by the interference device 200. One of these atomic beams is the third atomic beam 131c. The third traveling optical standing wave 200c functions as a combiner for the first atomic beam 131a and as the above-mentioned splitter for the second atomic beam 131b.

[0072] Next, the first observation device 400a and the second observation device 400b will be described. The configuration of the first observation device 400a does not need to be the same as that of the second observation device 400b. Furthermore, there is no limitation to the configuration that can be adopted as the first observation device 400a or the second observation device 400b. Therefore, only the first observation device 400a will be described here. The explanation of the second observation device 400b can be obtained by simply replacing the "third atomic beam 131c" in the following description of the first observation device 400a with the "fourth atomic beam 131d", the "probe light 408a" with the "probe light 408b", the "photodetector 409a" with the "photodetector 409b", and the "third traveling light standing wave 200c" with the "first traveling light standing wave 200a". The first observation device 400a irradiates the third atomic beam 131c from the interference device 200 with a probe light 408a to observe, for example, the state |e,p+h - k eff The fluorescence from the atom in state |e,p+h is detected by the photodetector 409a. The detection signal from the photodetector 409a is - k eff The photodetector 409a may be a photomultiplier tube, a fluorescent photodetector, or the like. Alternatively, when a channeltron is used as the photodetector 409a, the atomic beam in one of the two paths after passing through the third traveling optical standing wave 200c may be ionized by a laser or the like instead of the probe light, and the ions may be detected by the channeltron.

[0073] The controller 500 will be described with reference to Fig. 7. The controller 500 included in the inertial sensor 900 of the embodiment includes a first phase detector 501a, a second phase detector 501b, a reference signal generator 502, a phase difference detector 503, and an AOM controller 504.

[0074] The first phase detector 501a includes a high-pass filter (not shown), a multiplier (not shown), and a low-pass filter (not shown). The high-pass filter of the first phase detector 501a multiplies the state |e,p+h observed by the photodetector 409a by - k eff > removes the DC component from the detection signal representing the atomic population. The multiplier of the first phase detector 501a multiplies the output signal of the high-pass filter of the first phase detector 501a by a reference signal sin(2δ2t) generated by the reference signal generator 502. The low-pass filter of the first phase detector 501a extracts the DC component from the output signal of the multiplier of the first phase detector 501a.

[0075] The second phase detector 501b includes a high-pass filter (not shown), a multiplier (not shown), and a low-pass filter (not shown). The high-pass filter of the second phase detector 501b multiplies the state |e,p+h observed by the photodetector 409b by - k eff > removes the DC component from the detection signal representing the atomic population. The multiplier of the second phase detector 501b multiplies the output signal of the high-pass filter of the second phase detector 501b by the reference signal sin(2δ2t) generated by the reference signal generator 502. The low-pass filter of the second phase detector 501b extracts the DC component from the output signal of the multiplier of the second phase detector 501b.

[0076] The phase difference detector 503 obtains a difference signal (phase difference) between the output signal of the first phase detector 501a and the output signal of the second phase detector 501b.

[0077] The AOM controller 504 calculates the frequency ω using δ when the output signal of the phase difference detector 503 becomes zero.eg +δ1 for the acoustic signal S a and generates a frequency ω eg +δ2 b , and the frequency ω is calculated using δ1 when the output signal of the phase difference detector 503 becomes zero. eg -δ1, an acoustic signal S c (see equation (7)). The AOM controller 504 generates the acoustic signal S a is provided to the AOM 323a, and the AOM controller 504 generates an acoustic signal S b is provided to the AOM 323b, and the AOM controller 504 generates an acoustic signal S c is given to AOM323c.

[0078] z-component of angular velocity vector Ω|Ω z | is obtained by equation (19) using δ1 when the output signal of phase difference detector 503 becomes zero.

[0079] As described above, when controlling δ2 so that equation (22) holds, the controller 500 further includes an amplitude detector 505 as shown in Fig. 8. The amplitude detector 505 detects the state |e,p+h observed by the photodetector 409a by a high-pass filter (not shown). - k eff The amplitude detector 505 detects the amplitude of the detection signal from which the DC component has been removed by using a high-pass filter (not shown) to detect the state |e,p+h observed by the photodetector 409b. - k eff A DC component may be removed from the detection signal representing the atomic population of >, and the amplitude of the detection signal from which the DC component has been removed may be detected.

[0080] The AOM controller 504 controls the above-mentioned acoustic signal S a and S. c In addition, the frequency ω is set to ω using δ2, which keeps the extreme value of the output signal of the amplitude detector 505 (i.e., the amplitude of the population). eg +δ2 band further controls the reference signal generator 502 to output a reference signal sin(2δ2t).

[0081] <Modification> For example, the inertial sensor of the above embodiment utilizes Mach-Zehnder type atomic interference using three traveling optical standing waves, but Mach-Zehnder type atomic interference using four or more traveling optical standing waves can be utilized. For information on Mach-Zehnder type atomic interference using four or more traveling optical standing waves, see Reference 2. (Reference 2) Takatoshi Aoki et al., “High-finesse atomic multiple-beam interferometer comprised of copropagating stimulated Raman-pulse fields,” Phys. Rev. A 63, 063611 (2001) - Published 16 May 2001.

[0082] Furthermore, the atomic interference used by the inertial sensor is not limited to Mach-Zehnder type atomic interference, but may be, for example, Ramsey-Bode type atomic interference.

[0083] <Addendum> Although the invention has been described with reference to exemplary embodiments, those skilled in the art will recognize that various changes can be made and elements thereof substituted with equivalents without departing from the scope of the invention. In addition, many modifications can be made to adapt a particular system, device, or component thereof to the teachings of the invention without departing from the essential scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

[0084] Furthermore, the use of terms such as "first", "second", etc., does not indicate any order or importance, except for the order of the M traveling optical standing waves, and terms such as "first", "second", etc., are used to distinguish elements. The terms used herein are for the purpose of describing the embodiments and are not intended to limit the invention in any way. The term "comprises" and its conjugations, when used in this specification and / or the appended claims, discloses the presence of the mentioned features, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The term "and / or" includes any and all combinations of one or more of the associated listed elements, if any. In the claims and the specification, unless otherwise stated, the terms "connected", "coupled", "joined", "connected", or all of their synonyms, and all of their conjugations, do not necessarily negate the presence of one or more intermediate elements between two elements that are, for example, "connected" or "coupled" to each other or "connected" to each other.

[0085] Unless otherwise specified, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. Furthermore, terms such as those defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant art and this disclosure, and should not be interpreted ideally or excessively formally unless explicitly defined.

[0086] It will be understood that in the description of the present invention, many techniques and steps are disclosed. Each of these has separate advantages and each can be used in combination with one or more, or in some cases all, of the other disclosed techniques. Thus, to avoid cluttering, this specification refrains from describing every possible combination of individual techniques or steps. Nevertheless, the specification and claims should be read with the understanding that such combinations are fully within the scope of the present invention and claims.

[0087] The corresponding structure, materials, acts, and equivalents of all functional elements combined with means or steps in the following claims are intended to include the structures, materials, or acts, if any, for performing the function in combination with other claimed elements.

[0088] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Various modifications and variations are permitted within the scope of the present invention. The selected and described embodiments are intended to illustrate the principles of the present invention and its practical application. The present invention is used in various embodiments with various modifications and variations, and the various modifications and variations are determined according to the expected use. All such modifications and variations are intended to be included within the scope of the present invention as defined by the appended claims, and are intended to be accorded the same protection when interpreted in accordance with the breadth that is fairly, legally and equitably entitled thereto. [Explanation of symbols]

[0089] 100a First atomic beam generating device 100b Second atomic beam generating device 1001 Heater 1002 Nozzle 1003 Gas Atom Generator 1004 Laser Cooler 131a First Atomic Beam 131b Second Atomic Beam 131c The third atomic beam 131d The fourth atomic ray 200 Interference Device 200a First traveling optical standing wave 200b Second traveling optical standing wave 200c Third traveling light standing wave 300 Traveling light standing wave generator 311 Laser Light Source 312 EOM 313a Fiber Optic Coupler 313b Fiber Optic Coupler 313c Fiber Optic Coupler 313d Fiber Optic Coupler 313e Fiber Optic Coupler 314a VOA 314b VOA 314c VOA 315a Beam Shaper 315b Beam Shaper 315c Beam Shaper 316a Beam Shaper 316b Beam Shaper 316c Beam Shaper 320a Optical Modulation Device 320b Optical Modulation Device 320c Optical Modulation Device 321a Optical Fiber 321b Optical Fiber 321c Fiber Optic 323a Frequency Shifter 323b Frequency Shifter 323c Frequency Shifter 324a Optical Fiber 324b Optical Fiber 324c Fiber Optic 400a First Observation Device 400b Second Observation Device 408a Probe light 408b Probe light 409a Photodetector 409b Photodetector 500 Controller 501a First Phase Detector 501b Second Phase Detector 502 Reference signal generator 503 Phase difference detector 504 AOM controller 505 Amplitude Detector 900 Inertial Sensor

Claims

1. An inertial sensor, a first atom beam generating device for continuously generating a first atomic beam; a second atom beam generating device for continuously generating a second atomic beam; a traveling optical standing wave generating device that generates M traveling optical standing waves generated by a pair of laser beams that propagate in opposite directions, where M is a predetermined integer that satisfies 3≦M; an interference device into which the first atomic beam and the second atomic beam traveling toward each other enter and obtain a third atomic beam resulting from interaction between the first atomic beam and the M traveling optical standing waves, and a fourth atomic beam resulting from interaction between the second atomic beam and the M traveling optical standing waves; a first observation device for observing the third atomic beam; a second observation device for observing the fourth atomic beam; Including, the M traveling optical standing waves are arranged parallel to one another along the traveling direction of the first atomic beam, and are arranged in line symmetry with a straight line perpendicular to the traveling direction of the first atomic beam as an axis of symmetry; Let N be a predetermined integer satisfying 2≦N<M, [ ] be a Gaussian symbol, and i be at least one integer among [M / 2] integers satisfying 1≦N≦[M / 2]. The traveling optical standing wave generating device calculates a two-photon detuning δ of the pair of laser beams corresponding to the i-th traveling optical standing wave among the M traveling optical standing waves so that a difference between a population phase of the third atomic beam and a population phase of the fourth atomic beam is constant. i and a two-photon detuning δ of the pair of laser beams corresponding to the M-i+1-th traveling optical standing wave among the M traveling optical standing waves. M-i+1 Set δ i = -δ M-i+1 is 1. An inertial sensor comprising:

2. 2. The inertial sensor according to claim 1, The traveling light standing wave generating device sets a two-photon detuning δ of the pair of laser beams corresponding to at least one traveling light standing wave, excluding the i-th traveling light standing wave and the M-i+1-th traveling light standing wave, among the M traveling light standing waves, so as to maintain an extreme value of the population contrast of the third atomic beam or to maintain an extreme value of the population contrast of the fourth atomic beam.

1. An inertial sensor comprising:

3. 3. The inertial sensor according to claim 2, a distance between an M-th traveling light standing wave of the M traveling light standing waves and the first observation device is equal to a distance between a first traveling light standing wave of the M traveling light standing waves and the second observation device, and a speed distribution of the first atomic beam in the traveling direction and a speed distribution of atoms contained in the second atomic beam in the traveling direction of the second atomic beam are equal to each other.

1. An inertial sensor comprising:

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