JP2015041892A - Quantum interference device, atomic oscillator, electronic apparatus and moving body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quantum interference device equipped with a warming means for suppressing generation of a magnetic field, and also to provide an atomic oscillator.SOLUTION: A quantum interference device includes: a housing; a container whose at least a part is surrounded by the housing; metal atoms housed in the container; a light emission part which irradiates light containing resonance light generating electromagnetic induction transparent phenomenon in the metal atoms; a light detection part which detects the light transmitting through the metal atoms; a magnetic field generation part which generates a magnetic field in the container; and a heat medium. This device has a circulation mechanism for circulating the heat medium.

Description

  The present invention relates to a quantum interference device, an atomic oscillator equipped with the quantum interference device, an electronic device equipped with the atomic oscillator, and a moving object.

In recent years, with the advancement of digital networks such as mobile communication networks such as mobile phones and television broadcasting networks, high precision and high accuracy as reference clock sources used to generate clock signals for transmission devices and reference frequencies for broadcasting stations, etc. A stable oscillator is indispensable. As such an oscillator, an atomic oscillator having high oscillation frequency accuracy and stability is often used. Atomic oscillators are required to have higher oscillating frequency accuracy and stability with higher frequency and higher performance of communication equipment.
In response to this demand for high accuracy and high stability, Patent Document 1 discloses that a Peltier element is provided on the light transmission surface of a gas cell of a quantum interference device constituting an atomic oscillator to heat metal atoms accommodated in the gas cell. An atomic oscillator having a structure that maintains the partial pressure of metal atoms in the gas cell is disclosed.

JP 2007-335937 A

In the atomic oscillator described above, since the partial pressure of the metal atoms in the gas cell is maintained, the electromagnetically induced transparency phenomenon that occurs when light passes through the vapor of the metal atoms contained in the gas cell is stably generated. Can be made.
However, in the above-described atomic oscillator, a magnetic field is generated around the Peltier element, which is a metal atom heating means provided in the holding member of the gas cell. In the atomic oscillator, the degeneration of the electron energy level of metal atoms and the transition energy change due to the magnetic field generated by the heating means, so there is a risk that the frequency in the electromagnetically induced transparency phenomenon of light transmitted through the gas cell may change. . In addition, since energization to the Peltier element as a heating means changes according to the environmental temperature in which the gas cell is provided, the magnetic field generated according to the energization also changes, and the magnetic field applied to the metal atoms in the gas cell also changes. However, the frequency in the magnetically induced transparency phenomenon is a factor that fluctuates.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
The quantum interference device according to this application example includes a housing, a container at least partially surrounded by the housing, a metal atom contained in the container, and a resonance that generates an electromagnetically induced transparency phenomenon in the metal atom. A circulation mechanism that circulates a heat medium, including a light emitting part that emits light including light, a light detection part that detects light transmitted through metal atoms, a magnetic field generation part that generates a magnetic field in a container, and a heat medium It is characterized by having.

According to such a quantum interference device, by heating and cooling the container with a heat medium, the metal atoms contained in the container are maintained at a desired temperature and the partial pressure of the metal atoms in the container is maintained. be able to. Further, the heating with the heat medium suppresses the generation of a magnetic field as compared with the heating with a resistor using, for example, an ITO film. That is, since no current is supplied to the heat medium, generation of a magnetic field from the heat medium can be suppressed.
Therefore, by suppressing the influence on the magnetic field generated in the container by the magnetic field generator, and suppressing the fluctuation of the magnetic field in the container, the degeneracy of the electron energy level and the transition energy of the metal atoms contained in the container are reduced. It can suppress changing. Therefore, it is possible to suppress a frequency shift that causes an electromagnetically induced transparency phenomenon in which light including resonance light irradiated to a metal atom is transmitted without being absorbed by the metal atom.

[Application Example 2]
In the quantum interference device according to the application example described above, it is preferable that the circulation mechanism is provided with a temperature control unit, and the temperature of the heat medium is adjusted by the temperature control unit and the temperature of the container is adjusted by the temperature-adjusted heat medium. .

  According to such a quantum interference device, since the temperature control unit is provided in the circulation mechanism for circulating the heat medium, the temperature range for heating and cooling the container can be expanded. Moreover, while maintaining the metal atom accommodated in the container at a desired temperature, the partial pressure of the metal atom in the container can be further stabilized.

[Application Example 3]
In the quantum interference device according to the application example described above, it is preferable that a flow path is provided between the circulation mechanism and the housing.

  According to such a quantum interference device, the circulation mechanism can be connected to the housing via the flow path portion. Therefore, the degree of freedom of arrangement of the components of the quantum interference device such as the circulation mechanism can be increased, and the fluctuation of the magnetic field generated in the container by the arrangement of the components can be further suppressed.

[Application Example 4]
In the quantum interference device according to the application example described above, it is preferable that the circulation mechanism is provided with a heat source unit, and heat generated from the quantum interference device is used as at least a part of the heat source of the heat source unit.

  According to such a quantum interference device, the heat source unit provided in the circulation mechanism uses energy generated from the components of the quantum interference device as a part of the heat source, so that energy such as electric power consumed by the quantum interference device is obtained. Can be reduced.

[Application Example 5]
In the quantum interference device according to the application example described above, it is preferable that the circulation unit includes a MEMS structure.

  According to such a quantum interference device, since the circulation unit is configured by the MEMS structure, generation of a magnetic field can be suppressed as compared with a case where the circulation unit is configured including a motor or the like. Therefore, the fluctuation | variation of the magnetic field generated in a container can further be suppressed.

[Application Example 6]
The atomic oscillator according to this application example includes a housing, a container at least partially surrounded by the housing, metal atoms contained in the container, and resonant light that generates an electromagnetically induced transparency phenomenon in the metal atoms. Provided in a space between the housing and the container, a light detection unit that detects light transmitted through the metal atoms, a light detection unit that detects light transmitted through the metal atoms, a magnetic field generation unit that generates a magnetic field in the container It includes a quantum interference device including a heat medium and a circulation mechanism for circulating the heat medium.

According to such an atomic oscillator, the heating medium provided in the gap between the casing and the container keeps the metal atoms contained in the container at a desired temperature by heating and cooling the container, The partial pressure of metal atoms in the container can be maintained. Further, the heating with the heat medium suppresses the generation of a magnetic field as compared with the heating with a resistor using, for example, an ITO film. That is, since no current is supplied to the heat medium, generation of a magnetic field from the heat medium can be suppressed.
Therefore, by suppressing the influence on the magnetic field generated in the container by the magnetic field generator, and suppressing the fluctuation of the magnetic field in the container, the degeneracy of the electron energy level and the transition energy of the metal atoms contained in the container Can be prevented from changing. In addition, it is possible to suppress a frequency shift that causes an electromagnetically induced transparency phenomenon in which light including resonance light irradiated to a metal atom is transmitted without being absorbed by the metal atom.
Therefore, it is possible to obtain an atomic oscillator that can oscillate a highly accurate signal based on the signal in which the frequency shift of the signal obtained by the electromagnetically induced transparency phenomenon is suppressed.

[Application Example 7]
An electronic apparatus according to this application example includes the above-described atomic oscillator.

  According to such an electronic device, by providing the above-described atomic oscillator, the electronic device can be operated based on a highly accurate oscillation signal. Therefore, the reliability of the electronic device can be increased.

[Application Example 8]
The moving body according to this application example includes the above-described atomic oscillator.

  According to such a moving body, by providing the above-described atomic oscillator, the moving body can be operated based on a highly accurate oscillation signal. Therefore, the reliability of the electronic device can be increased.

The block diagram which shows typically the quantum interference apparatus which concerns on 1st Embodiment. The figure which shows typically the structure of the gas cell with which the quantum interference apparatus which concerns on 1st Embodiment was equipped. The figure explaining the excitation level of the alkali metal atom with which the quantum interference apparatus which concerns on 1st Embodiment was equipped. The figure explaining the energy level of the alkali metal atom with which the quantum interference apparatus which concerns on 1st Embodiment was equipped, and the electromagnetic induction transparency phenomenon. The block diagram which shows typically the structure of the atomic oscillator which concerns on 2nd Embodiment. FIG. 3 is a diagram schematically showing a personal computer as an electronic apparatus according to an example. FIG. 3 is a diagram schematically illustrating a mobile phone as an electronic apparatus according to an example. The figure which shows typically the digital still camera as an electronic device which concerns on an Example. The figure which shows typically the motor vehicle as a moving body which concerns on an Example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure shown below, the size and ratio of each component may be described differently from the actual component in order to make each component large enough to be recognized on the drawing. is there.

[First Embodiment]
The quantum interference device according to the first embodiment will be described with reference to FIGS.
FIG. 1 is a block diagram schematically illustrating the quantum interference device according to the first embodiment. FIG. 2 is a diagram schematically showing the structure of the gas cell provided in the quantum interference device. FIG. 3 is a diagram for explaining the excitation levels of alkali metal atoms provided in the quantum interference device. FIG. 4 is a diagram for explaining the energy levels of the alkali metal atoms and the electromagnetically induced transparency phenomenon provided in the quantum interference device.

<Configuration of Quantum Interference Device 100>
A quantum interference device 100 of this embodiment shown in FIG. 1 includes a light emitting unit 10, a gas cell 11, a light detecting unit 12, a magnetic field generating unit 13, and a circulation mechanism 14. The gas cell 11 is provided with a container 11a in which alkali metal atoms M (see FIG. 2), which are examples of metal atoms, are disposed, and a casing 11c so as to surround at least a part of the container 11a. A heat medium 11d is disposed in a gap between the container 11a and the housing 11c. In addition, the quantum interference device 100 includes a circulation mechanism 14 that circulates the heat medium 11d, a gas cell 11 and the circulation mechanism 14 that are separated from each other, and a flow path portion 15 that serves as a conduit for the heat medium 11d. It can be configured to include. Note that the quantum interference device 100 according to the present embodiment may have a configuration in which some of the components (each unit) in FIG. 1 are omitted or changed as appropriate, or other components are added. For convenience of explanation, FIG. 1 shows an atomic oscillator 200, which will be described later, and some of its components. Hereinafter, the quantum interference device 100 will be described in detail.

(Light emitting part 10)
The light emitting unit 10 emits and emits excitation light LL (a pair of resonance light L1 and resonance light L2) that is transmitted through the gas cell 11 and received by the light detection unit 12. The light emitting unit 10 can use a semiconductor laser as an example of the light source. As the semiconductor laser, for example, a surface emitting laser such as a vertical cavity surface emitting laser (VCSEL) or an edge emitting laser can be used. The excitation light LL emitted toward the light emitting unit 10 passes through various filters (not shown) and enters the gas cell 11.

(Gas cell 11)
The gas cell 11 includes an alkali metal atom M (for example, sodium (Na) atom, rubidium (Rb) atom, cesium (Cs) atom, etc.) and a buffer gas (for example, neon (Ne), argon (Ar) in the container 11a. Or a mixed gas containing these). Part of the excitation light LL that has entered the gas cell 11 passes through the gas cell 11 and enters the light detection unit 12. FIG. 2 schematically shows the structure of the gas cell 11. FIG. 2A is a perspective view schematically showing the gas cell 11. FIG. 2B is a cross section of the gas cell 11 as seen from the direction of the arrow in the line segment AA ′ shown in FIG. 2A, and is viewed from the direction coaxial with the optical axis of the excitation light LL incident on the gas cell 11. 2 shows a cross section of the gas cell 11. Moreover, FIG.2 (c) shows typically the side cross section of the gas cell 11 seen from the direction of the arrow in line segment CC 'shown to Fig.2 (a). FIG. 2C schematically shows a side cross section viewed from a direction parallel to the optical axis of the excitation light LL incident on the gas cell 11.
As shown in FIG. 2, the gas cell 11 is provided with a casing 11c so as to surround the container 11a, and a heat medium 11d is disposed in a gap between the container 11a and the casing 11c.
The material which comprises the container 11a and the housing | casing 11c is not specifically limited. In the present embodiment, as an example, as shown in FIG. 2B, a silicon substrate can be used for the wall 11w of the container 11a and the casing 11c, and a glass substrate can be used for the lid (lid) 11L. . Moreover, the flow path part 15 used as the pipe line of the heat medium 11d can be connected to the lid part 11L. As a result, the excitation light LL incident on the gas cell 11 can enter the container 11a from the lid portion 11L, pass through the gas cell 11, and allow the excitation light LL to enter the light detection unit 12. .

  The heat medium 11d is not particularly limited. It is preferable that the usable pressure of the heat medium 11d is appropriate, the heat capacity per unit volume (latent heat) is large, nonflammable and non-erodible. The heat medium 11d is preferably a nonmagnetic material. As an example of the heat medium 11d, hydrofluorocarbon (HFC), perfluorocarbon (PFC), oil, water, or the like can be used.

(Photodetection unit 12)
Returning to the block diagram of the quantum interference device 100 in FIG. 1, the light detection unit 12 will be described.
The light detection unit 12 detects the excitation light LL transmitted through the gas cell 11 and outputs a signal corresponding to the detected light intensity. As an example, the light detection unit 12 can use a photodiode (PD) that outputs a signal corresponding to the intensity of received light. An output signal of the light detection unit 12 is input to a detection circuit unit 21 and a detection circuit unit 26 that constitute an atomic oscillator 200 described later.

(Magnetic field generator 13)
The magnetic field generator 13 generates a magnetic field in at least a part of the inside of the container 11a in which the alkali metal atom M is accommodated. The magnetic field generator 13 can be configured to include a coil, for example, and can be configured by adjusting the position and shape of the coil (for example, the direction in which the coil is wound, the number of turns, the diameter, etc.), the magnitude and direction of the current, and the like. A magnetic field can be generated.

When a magnetic field is applied to the container 11a, each energy level of the alkali metal atom M accommodated in the container 11a is split into 2F + 1 pieces (Zeeman splitting). For example, in the case of a cesium atom, as shown in FIG. 3A, the ground level of 6S _1/2 and F = 3 and the excited level of 6P _3/2 and F ′ = 3 are represented by the magnetic quantum number mF = It splits into seven levels corresponding to 0, ± 1, ± 2, ± 3, and the 6S _1/2 , F ′ = 4 ground level and 6P _3/2 , F = 4 excited level are magnetic The quantum number is divided into nine levels corresponding to mF = 0, ± 1, ± 2, ± 3, ± 4.
When σ + circularly polarized light is incident on a cesium atom (alkali metal atom M), excitation is performed according to the selection rule of ΔmF = + 1. For example, 6S _1/2 , F = 3,4 ground levels and 6P _3/2 , F Between the excited levels of '= 4, seven Λ-type three levels are formed.
Therefore, in this state, when the frequency difference between the two light waves is swept, seven EIT signals are observed as shown in FIG. The EIT signal is a Λ-type three-level formed between an mF = 0 ground level of 6S _1/2 , F = 3,4, and an excitation level of 6P _3/2 , F ′ = 4, mF = + 1. The strength corresponding to the position is the highest. Therefore, it is useful to control the frequency difference between the resonant light L1 and the resonant light L2 so as to generate this EIT signal.

(Circulation mechanism 14)
Returning to the block diagram of the quantum interference device 100 of FIG. 1, the circulation mechanism 14 will be described.
The circulation mechanism 14 circulates the heat medium 11 d disposed in the gas cell 11. The circulation mechanism 14 keeps the container 11a warm by circulating the heat medium 11d.
The circulation mechanism 14 is disposed integrally with or connected to the gas cell 11. The circulation mechanism 14 can keep the container 11a warm by convection of the heat medium 11d.
Further, the circulation mechanism 14 can be disposed apart from the gas cell 11 by providing a flow path portion 15 serving as a conduit for the heat medium 11 d between the circulation mechanism 14 and the gas cell 11. By separating the gas cell 11 and the circulation mechanism 14 via the flow path unit 15, the degree of freedom of arrangement of each component of the quantum interference device 100 can be increased.

Further, the circulation mechanism 14 may be provided with a temperature adjustment unit 14a that adjusts the temperature of the heat medium 11d.
For example, the temperature control unit 14a is provided with a heat radiating unit (not shown) and a three-way valve (not shown). When the heat medium 11d exceeds a predetermined temperature, the heat medium 11d is circulated to the heat radiating part to radiate heat. It is possible to suppress an excessive temperature rise of the heat medium 11d and the container 11a.

  Further, the circulation mechanism 14 can be provided with a heat source part 14b for heating and cooling the heat medium 11d in addition to the temperature control part 14a. By providing the heat source part 14b, cooling when the temperature of the heat medium 11d and the container 11a rises and heating when the temperature of the heat medium 11d and the container 11a is lowered can be performed. The heat source of the heat source unit 14b is not particularly limited. As an example of the heat source of the heat source unit 14b, a Peltier element can be used for cooling, and a resistance element can be used for heating. Moreover, it can be used as a heating heat source by absorbing the heat generated from the light emitting part 10 with the heat medium 11d. In addition, when providing the temperature control part 14a in the circulation mechanism 14, it is preferable to provide the flow-path part 15 between the circulation mechanism 14 and the housing | casing 11c. By providing the flow path portion 15 and disposing the temperature adjustment portion 14a away from the housing 11c, it is possible to make the gas cell 11 less likely to be affected by the magnetic field generated in the temperature adjustment portion 14a.

  Furthermore, the circulation mechanism 14 can be provided with a circulation part 14c. The circulation part 14c conveys the heat medium 11d, and as an example, a pump composed of a MEMS movable structure can be used. By providing the circulation part 14c, the heat medium 11d can be efficiently circulated, and the latent heat distribution of the heat medium 11d can be made uniform to efficiently retain and warm the container 11a.

  Here, most of the alkali metal atoms M are in a liquefied state at room temperature (20 to 30 degrees). The quantum interference device 100 evaporates the alkali metal M by heating, and detects (detects) a change in the excitation light LL caused by the excitation light LL being transmitted through the vaporized alkali metal atom M. We are using.

  More specifically, as shown in FIG. 4A, the alkali metal atom M has a three-level energy level, and two ground states (ground states α and β) having different energy levels. And an excited state. Here, the ground state α is an energy state lower than the ground state β. When the vaporized alkali metal atom M is irradiated with excitation light LL (first resonance light L1 and second resonance light L2) having different frequencies, the frequency ω1 of the first resonance light L1 and the second resonance light L2 are emitted. The optical absorptance (light transmittance) of the first resonance light 1L1 and the second resonance light L2 in the alkali metal atom M changes according to the difference (ω1-ω2) from the frequency ω2.

  When the difference (ω1−ω2) between the frequency ω1 of the first resonant light L1 and the frequency ω2 of the second resonant light L2 matches the frequency corresponding to the energy difference between the ground state α and the ground state β, The excitation from the states α and β to the excited state stops. At this time, both the first resonance light L1 and the second resonance light L2 are transmitted without being absorbed by the alkali metal atom M. Such a phenomenon is called a CPT phenomenon or an electromagnetically induced transparency (EIT) phenomenon.

  The light emitting unit 10 emits the first resonance light L1 and the second resonance light L2 having different frequencies described above toward the gas cell 11. For example, when the light emitting unit 10 fixes the frequency ω1 of the first resonance light L1 and changes the frequency ω2 of the second resonance light L2, the frequency ω1 of the first resonance light L1 and the frequency of the second resonance light L2 are changed. When the difference (ω1−ω2) from ω2 coincides with the frequency ω0 corresponding to the energy difference between the ground state α and the ground state β, the detection intensity S of the light detection unit 12 is as shown in FIG. It rises steeply. Such a steep signal is detected as an EIT signal. This EIT signal has an eigenvalue determined by the type of alkali metal atom M, and a highly accurate oscillation signal can be obtained by detecting the EIT signal with an atomic oscillator 200 described later.

  In the above-described quantum interference device 100, it is required to warm the alkali metal M disposed in the container 11a of the gas cell 11 and keep it vaporized. If the ratio between the buffer gas in the container 11a and the vaporized alkali metal atom M is different, the characteristics of the EIT signal described above change. Therefore, the state in which the alkali metal atom M is vaporized so as to be saturated in the container 11a is maintained by heating the container 11a with the heating medium 11d and indirectly heating the alkali metal atom M. Can do.

According to the first embodiment described above, the following effects can be obtained.
According to such a quantum interference device 100, the container 11a is accommodated in the container 11a by heating and cooling the container 11a by the heat medium 11d provided in the gap between the casing 11c of the gas cell 11 and the container 11a. While maintaining the alkali metal atom M at a desired temperature, the partial pressure of the alkali metal atom M in the container 11a can be maintained. Moreover, the heating of the container 11a by the heat medium 11d suppresses the magnetic field generated from the heat medium 11d. In other words, since the heating medium 11d is not energized, the magnetic field generated from the heating medium 11d can be suppressed.
Accordingly, by suppressing the influence on the magnetic field generated in the container 11a by the magnetic field generator 13, and suppressing the fluctuation of the magnetic field in the container 11a, the electron energy level of the alkali metal atom M accommodated in the container 11a is reduced. It is possible to suppress the degeneration of the position and the change of the transition energy. Therefore, it is possible to obtain the quantum interference device 100 in which the frequency shift in which the electromagnetically induced transparency phenomenon in which the excitation light LL including the resonance light irradiated to the alkali metal atom M is transmitted without being absorbed by the alkali metal atom M is suppressed is obtained. it can.

[Second Embodiment]
An atomic oscillator according to the second embodiment will be described with reference to FIG.
FIG. 5 is a block diagram showing the structure of the atomic oscillator according to the second embodiment. An atomic oscillator 200 according to the second embodiment includes the quantum interference device 100 described above in the first embodiment. Hereinafter, the atomic oscillator 200 on which the quantum interference device 100 is mounted will be described.

<Structure of the atomic oscillator 200>
An atomic oscillator 200 shown in FIG. 5 is equipped with the above-described quantum interference device 100 and uses the quantum interference effect.
As shown in FIG. 5, the atomic oscillator 200 includes a quantum interference device 100, a detection circuit unit 21, a voltage controlled crystal oscillation (VCXO) unit 22, a modulation circuit unit 23, a low frequency oscillation unit 24, a frequency conversion circuit unit 25, The detection circuit unit 26, the modulation circuit unit 27, the low frequency oscillation unit 28, the drive circuit unit 29, the magnetic field setting circuit unit 30, the bias setting circuit unit 31, the memory unit 32, and the frequency conversion circuit unit 33 are configured. . Note that the atomic oscillator 200 of the present embodiment may have a configuration in which some of the components (each unit) in FIG. 5 are omitted or changed as appropriate, or other components are added.

(Quantum interference device 100)
The atomic oscillator 200 is provided with the light emitting unit 10, the gas cell 11, the light detecting unit 12, the magnetic field generating unit 13, the circulation mechanism 14, and the flow path unit 15 described above in the first embodiment. In the light emitting unit 10, the bias current of the light source is set by the drive circuit unit 29 described later. The output signal from the light detection unit 12 is detected by detection circuit units 21 and 26 described later. The magnetic field generation unit 13 is set with the strength of the magnetic field generated by the magnetic field setting circuit unit 30 described later.
Since each component is the same as that of the first embodiment, description thereof is omitted.

(Detection circuit unit 21)
The detection circuit unit 21 detects the output signal of the light detection unit 12 using the oscillation signal of the low-frequency oscillation unit 24 that oscillates at a low frequency of about several Hz to several hundreds of Hz. Then, the oscillation frequency of the voltage controlled crystal oscillation unit (VCXO) 22 is adjusted according to the magnitude of the output signal of the detection circuit unit 21. The voltage controlled crystal oscillation unit (VCXO) 22 oscillates at, for example, about several MHz to several tens of MHz.

(Modulation circuit section 23)
In order to enable detection by the detection circuit unit 21, the modulation circuit unit 23 uses the oscillation signal of the low-frequency oscillation unit 24 (the same signal as the oscillation signal supplied to the detection circuit unit 21) as a modulation signal, and voltage-controlled crystal oscillation The output signal of the unit (VCXO) 22 is modulated. The modulation circuit unit 23 can be composed of a frequency mixer (mixer), a frequency modulation (FM) circuit, an amplitude modulation (AM) circuit, and the like according to the modulation method.

(Frequency conversion circuit unit 25)
The frequency conversion circuit unit 25 converts the frequency of the output signal of the modulation circuit unit 23 and outputs the converted signal to the drive circuit unit 29. For example, a PLL (Phase Locked Loop) circuit can be used as the frequency conversion circuit unit 25.

(Detection circuit unit 26)
The detection circuit unit 21 detects the output signal of the light detection unit 12 using the oscillation signal of the low frequency oscillation unit 28 that oscillates at a low frequency of about several Hz to several hundred Hz.

(Modulation circuit section 27)
The modulation circuit unit 27 uses the oscillation signal of the low-frequency oscillation unit 28 (the same signal as the oscillation signal supplied to the detection circuit unit 26) as a modulation signal to enable detection by the detection circuit unit 26. The output signal is modulated and output to the drive circuit unit 29. The modulation circuit unit 27 can be configured by a frequency mixer (mixer), a frequency modulation (FM) circuit, an amplitude modulation (AM) circuit, or the like according to the modulation method.

(Magnetic field setting circuit 30)
The magnetic field setting circuit unit 30 performs a process of setting the strength of the magnetic field generated by the magnetic field generation unit 13 constituting the quantum interference device 100 according to the setting information stored in the memory unit 32. For example, the magnetic field generation unit 13 is configured by a coil, and the magnetic field setting circuit unit 30 can set the amount of current flowing through the coil according to the setting information stored in the memory unit 32.

(Bias setting circuit unit 31)
The bias setting circuit unit 31 supplies a bias current (a center wavelength of light generated by a semiconductor laser as a light source) to the light emitting unit 10 according to setting information stored in the memory unit 32 via the drive circuit unit 29. Perform the setting process.

(Memory unit 32)
The memory unit 32 is a non-volatile memory, and stores setting information on the intensity of the magnetic field generated by the magnetic field generation unit 13 and setting information on the bias current of the light emitting unit 10. As the memory unit 32, for example, a flash memory such as a MONOS (Metal-Oxide-Nitride-Oxide-Silicon) memory, an EEPROM (Electrically Erasable Programmable Read-Only Memory), or the like can be used.

(Drive circuit unit 29)
The drive circuit unit 29 sets the bias current of the light source of the light emitting unit 10, adjusts the bias current according to the output signal of the modulation circuit unit 27, and supplies the bias current to the light emitting unit 10. That is, a feedback loop (first feedback) that passes through the light emitting unit 10, the gas cell 11, and the photodetecting unit 12, the detection circuit unit 21, the modulation circuit unit 27, and the drive circuit unit 29 constituting the quantum interference device 100. The center wavelength λ ₀ (center frequency f ₀ ) of the light generated by the light emitting unit 10 is adjusted by the loop.

Further, the drive circuit unit 29 superimposes the current (modulation current) of the output frequency component (modulation frequency f _m ) of the frequency conversion circuit unit 25 on the bias current and supplies the superimposed current to the light emitting unit 10. The light emitting unit 10 is subjected to frequency modulation on the light source of the light emitting unit 10 by this modulation current, and with the light having the center frequency f ₀ (center wavelength λ ₀ ), the frequency f _{0 is} shifted by f _{m on} both sides thereof. ± f _m, f ₀ to generate the excitation light LL of ± 2f _m (first resonant light L1 and the second resonant light L2).

The drive circuit unit 29 includes a light emitting unit 10, a gas cell 11, and a light detection unit 12 that constitute the quantum interference device 100, a detection circuit unit 21, a voltage controlled crystal oscillation unit (VCXO) 22, a modulation circuit unit 23, a frequency converter circuit 25, by a feedback loop through a driving circuit portion 29 (second feedback loop), the frequency f ₀ + f _m of the excitation light LL (first resonant light L1) and the frequency f ₀ -f _m of the excitation light LL ( The second resonance light L2) is adjusted to be a resonance light pair (first resonance light L1 and second resonance light L2) that causes an EIT phenomenon in the alkali metal atom M sealed in the container 11a of the gas cell 11. .

For example, the modulation frequency f _m is feedback controlled by the above-described second feedback loop so that the alkali metal atom M having the ground level of the magnetic quantum number mF = 0 causes the EIT phenomenon.
Specifically, the second feedback loop, the excitation light LL frequency f ₀ + f _m is a first-order sideband (first resonant light L1), the frequency f ₀ -f _m of the excitation light LL (second The frequency difference (= 2f _m ) of the resonant light L2) is exactly matched with the frequency ω ₁₂ corresponding to the energy difference ΔE ₁₂ between the two ground levels of the magnetic quantum number mf = 0 of the alkali metal atom M. Feedback control is applied. For example, when the alkali metal atom M is a cesium atom, ω ₁₂ is 9.192631770 GHz + ΔHz (Δ is a frequency represented by a quadratic function of the magnetic field strength), and thus the modulation frequency f _m is 4.596315585 GHz + Δ / 2 Hz. Match exactly.

  In this way, by using the EIT phenomenon of the alkali metal atom M, the output signal of the frequency conversion circuit unit 25 and the output signal of the voltage controlled crystal oscillation unit (VCXO) 22 included in the second feedback loop are respectively obtained. It can be stabilized at a predetermined frequency.

(Frequency conversion circuit unit 33)
The frequency conversion circuit unit 33 converts the output signal of the voltage controlled crystal oscillation unit (VCXO) 22 to generate a clock signal having a desired frequency (for example, 10.000 MHz). For example, a DDS (Direct Digital Synthesizer) can be used for the frequency conversion circuit unit 33. The atomic oscillator 200 can obtain a highly accurate clock signal by outputting the clock signal to the outside.

According to the second embodiment described above, the following effects can be obtained.
According to such an atomic oscillator 200, the alkali contained in the container 11a by heating and cooling the container 11a by the heat medium 11d provided in the gap between the casing 11c of the gas cell 11 and the container 11a. A quantum interference device 100 capable of maintaining the metal atom M at a desired temperature and maintaining the partial pressure of the alkali metal atom M in the container 11a is mounted.
Moreover, the heating of the container 11a by the heat medium 11d suppresses the magnetic field generated from the heat medium 11d. In other words, since the heating medium 11d is not energized, the quantum interference device 100 that can suppress the magnetic field generated from the heating medium 11d is mounted.
Accordingly, by suppressing the influence on the magnetic field generated in the container 11a by the magnetic field generator 13, and suppressing the fluctuation of the magnetic field in the container 11a, the electron energy level of the alkali metal atom M accommodated in the container 11a is reduced. It is possible to suppress the degeneration of the position and the change of the transition energy. Therefore, the atomic oscillator 200 oscillates based on a signal in which the frequency shift that causes the electromagnetically induced transparency phenomenon in which the excitation light LL including the resonance light irradiated to the alkali metal atom M is transmitted without being absorbed by the alkali metal atom M is suppressed. can do.

(Example)
An example in which the atomic oscillator 200 using the quantum interference device 100 according to the embodiment of the present invention is applied will be described with reference to FIGS.

[Electronics]
An electronic apparatus to which an atomic oscillator 200 according to an embodiment of the present invention is applied will be described with reference to FIGS.

  FIG. 6 is a perspective view schematically illustrating a configuration of a laptop (or mobile) personal computer as an electronic apparatus including the atomic oscillator 200 according to an embodiment of the present invention. In this figure, a laptop personal computer 1100 includes a main body portion 1104 provided with a keyboard 1102 and a display unit 1106 provided with a display portion 1008. The display unit 1106 has a hinge structure portion with respect to the main body portion 1104. It is supported so that rotation is possible. In such a laptop personal computer 1100, an atomic oscillator 200 used as a clock signal for the operation of the laptop personal computer 1100 is mounted. Since such an atomic oscillator 200 oscillates based on a signal in which the frequency shift of the signal obtained by the electromagnetically induced transparency phenomenon is suppressed in the quantum interference device 100 constituting the atomic oscillator 200, it oscillates a highly accurate signal. be able to. Therefore, a highly reliable laptop personal computer 1100 can be obtained by mounting the atomic oscillator 200 described above.

  FIG. 7 is a perspective view schematically showing a configuration of a mobile phone (including PHS) as an electronic apparatus including the atomic oscillator 200 according to the embodiment of the present invention. In this figure, a cellular phone 1200 includes a plurality of operation buttons 1202, an earpiece 1204, and a mouthpiece 1206, and a display unit 1208 is disposed between the operation buttons 1202 and the earpiece 1204. In such a cellular phone 1200, an atomic oscillator 200 is mounted as an oscillator of a clock signal that is a reference for communication and operation of the cellular phone 1200. Since such an atomic oscillator 200 oscillates based on a signal in which the frequency shift of the signal obtained by the electromagnetically induced transparency phenomenon is suppressed in the quantum interference device 100 constituting the atomic oscillator 200, it oscillates a highly accurate signal. be able to. Therefore, a highly accurate signal can be oscillated. Therefore, by mounting the above-described atomic oscillator 200, a highly reliable mobile phone 1200 can be obtained.

FIG. 8 is a perspective view schematically illustrating a configuration of a digital still camera as an electronic apparatus including the atomic oscillator 200 according to the embodiment of the present invention. In this figure, connection with an external device is also simply shown. Here, an ordinary camera sensitizes a silver halide photographic film with a light image of a subject, whereas a digital still camera 1300 photoelectrically converts a light image of a subject with an image sensor such as a CCD (Charge Coupled Device). An imaging signal (image signal) is generated.
A display unit 1308 is provided on the back of a case (body) 1302 in the digital still camera 1300, and is configured to perform display based on an imaging signal from the CCD. The display unit 1308 displays an object as an electronic image. Functions as a viewfinder. A light receiving unit 1304 including an optical lens (imaging optical system), a CCD, and the like is provided on the front side (the back side in the drawing) of the case 1302.
When the photographer confirms the subject image displayed on the display unit 1308 and presses the shutter button 1306, the CCD image pickup signal at that time is transferred and stored in the memory 1310. In the digital still camera 1300, a video signal output terminal 1312 and an input / output terminal 1314 for data communication are provided on the side surface of the case 1302. As shown in the drawing, a liquid crystal display 1430 is connected to the video signal output terminal 1312 and a personal computer 1440 is connected to the input / output terminal 1314 for data communication as necessary. Further, the imaging signal stored in the memory 1310 is output to the liquid crystal display 1430 or the personal computer 1440 by a predetermined operation. Such a digital still camera 1300 is equipped with an atomic oscillator 200 serving as a clock signal for the operation. Since such an atomic oscillator 200 oscillates based on a signal in which the frequency shift of the signal obtained by the electromagnetically induced transparency phenomenon is suppressed in the quantum interference device 100 constituting the atomic oscillator 200, it oscillates a highly accurate signal. be able to. Therefore, a highly accurate signal can be oscillated. Therefore, a highly reliable digital still camera 1300 can be obtained by mounting the atomic oscillator 200 described above.

  In addition to the laptop personal computer (mobile personal computer) in FIG. 6, the mobile phone in FIG. 7, and the digital still camera in FIG. Dispenser (eg inkjet printer), TV, video camera, video tape recorder, car navigation device, pager, electronic notebook (including communication function), electronic dictionary, calculator, electronic game device, word processor, workstation, video phone , Crime prevention TV monitor, electronic binoculars, POS terminal, medical equipment (for example, electronic thermometer, blood pressure monitor, blood glucose meter, electrocardiogram measuring device, ultrasonic diagnostic device, electronic endoscope), fish detector, various measuring devices, instruments (Eg, vehicle, aircraft, ship instrumentation), hula It can be applied to electronic devices of the door simulator like.

[Moving object]
FIG. 9 is a perspective view schematically showing an automobile as an example of a moving body. An atomic oscillator 200 that functions as an acceleration sensor is mounted on various control units of an automobile 1500. For example, as shown in the figure, an automobile 1500 as a moving body includes an electronic control unit (ECU: engine control unit) 1508 that incorporates a sensor that detects the acceleration of the automobile 1500 and controls the output of the engine. 1507. Since the atomic oscillator 200 capable of obtaining a high-accuracy clock signal is mounted on the electronic control unit 1508, the engine output control appropriate for the attitude of the vehicle body 1507 is executed with high accuracy and the consumption of fuel and the like is suppressed. It is possible to obtain an automobile 1500 as a typical mobile body.
In addition, the atomic oscillator 200 can be widely applied to a vehicle body attitude control unit, an anti-lock brake system (ABS), an air bag, and a tire pressure monitoring system (TPMS).

  DESCRIPTION OF SYMBOLS 10 ... Light emission part, 11 ... Gas cell, 11a ... Container, 11c ... Case, 11d ... Heat medium, 12 ... Light detection part, 13 ... Magnetic field generation part, 14 ... Circulation mechanism, 14a ... Temperature control part, 14b ... Heat source , 14c... Circulator, 15. Flow path section, 21... Detection circuit section, 22... Voltage control crystal oscillation section, 23... Modulation circuit section, 24. Circuit part 27 ... Modulation circuit part 28 ... Low frequency oscillation part 29 ... Drive circuit part 30 ... Magnetic field setting circuit part 31 ... Bias setting circuit part 32 ... Memory part 33 ... Frequency conversion circuit part 100 ... Quantum interference device, 200 ... atomic oscillator, 1100 ... laptop personal computer, 1200 ... mobile phone, 1300 ... digital still camera, 1500 ... automobile.

Claims (8)

A housing,
A container at least partially surrounded by the housing;
Metal atoms contained in the container;
A light emitting part for irradiating the metal atom with light including resonance light that generates electromagnetically induced transparency phenomenon;
A light detection unit for detecting the light transmitted through the metal atom;
A magnetic field generator for generating a magnetic field in the container;
With a heating medium,
A quantum interference device having a circulation mechanism for circulating the heat medium.   The temperature adjusting unit is provided in the circulation mechanism, and the temperature of the heating medium is adjusted by the temperature adjusting unit, and the temperature of the container is adjusted by the temperature-adjusted heating medium. The quantum interference device according to 1.   The quantum interference device according to claim 1, wherein a flow path is provided between the circulation mechanism and the housing.   The heat source unit is provided in the circulation mechanism, and heat generated from the quantum interference device is used as at least a part of the heat source of the heat source unit. Quantum interference device.   The quantum interference device according to any one of claims 1 to 4, wherein the circulation unit is configured by a MEMS structure. A housing,
A container at least partially surrounded by the housing;
Metal atoms contained in the container;
A light emitting portion for irradiating the metal atom with light including resonance light that generates electromagnetically induced permeation phenomenon;
A light detection unit for detecting the light transmitted through the metal atom;
A magnetic field generator for generating a magnetic field in the container;
A heat medium provided in a space between the housing and the container;
An atomic oscillator comprising: a quantum interference device including a circulation mechanism for circulating the heat medium.   An electronic apparatus comprising the atomic oscillator according to claim 6.   A moving body comprising the atomic oscillator according to claim 6.

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