JP6442969B2 - Quantum interference devices, atomic oscillators, and electronic equipment - Google Patents

Description

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

  As an oscillator having long-term highly accurate oscillation characteristics, an atomic oscillator that oscillates based on energy transition of an alkali metal atom such as rubidium or cesium is known.

  In general, the operating principles of atomic oscillators are broadly divided into methods that use the double resonance phenomenon of light and microwaves, and methods that use the quantum interference effect (CPT: Coherent Population Trapping) of two types of light with different wavelengths. However, since an atomic oscillator using the quantum interference effect can be made smaller than an atomic oscillator using a double resonance phenomenon, it is expected to be mounted on various devices in recent years (for example, see Patent Document 1). ).

  An atomic oscillator using the quantum interference effect includes, for example, as disclosed in Patent Document 1, a gas cell in which a gaseous alkali metal is sealed, and a light source that emits a resonant light pair that resonates the alkali metal in the gas cell. And a photodetector (light receiving unit) for detecting the resonant light pair transmitted through the gas cell. In such an atomic oscillator, when the frequency difference between the two types of resonance light is a specific value, both types of resonance light are transmitted without being absorbed by the alkali metal in the gas cell (EIT) : Electromagnetically Induced Transparency) phenomenon, an EIT signal which is a steep signal generated with the EIT phenomenon is detected by a photodetector, and the EIT signal is used as a reference signal.

  Here, from the viewpoint of improving short-term frequency stability, it is preferable that the EIT signal has a small line width (half-value width) and a high strength. Therefore, for example, in the atomic oscillator according to Patent Document 1, a circularly polarized resonant light pair is used for the purpose of improving the intensity of the EIT signal.

  However, the atomic oscillator according to Patent Document 1 has a problem that the effect is not sufficient.

JP 2014-17824 A

  The objective of this invention is providing the quantum interference apparatus which can improve the intensity | strength of an EIT signal effectively, and providing an atomic oscillator, an electronic device, and a moving body provided with this quantum interference apparatus.

  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 of the present invention includes an atomic cell in which a metal is enclosed,
A first light source unit that emits a first light including a resonant light pair that is circularly polarized in the same direction and resonates the metal;
A second light source unit that emits second light that is circularly polarized in the opposite direction to the resonant light pair and has a line width larger than that of the resonant light pair;
A light receiving unit that receives the resonant light pair that has passed through the atomic cell;
It is characterized by providing.

  According to such a quantum interference device, in addition to the resonant light pair that is circularly polarized in the same direction, the second light that is circularly polarized in the opposite direction to the resonant light pair is irradiated to the metal as the adjustment light. By doing so, the bias in the distribution of the magnetic quantum number due to the resonant light pair can be canceled or relaxed by the adjustment light, and the bias in the distribution of the magnetic quantum number of the metal can be reduced. Therefore, the number of metal atoms having a desired magnetic quantum number that contributes to EIT is increased, and as a result, the effect of improving the intensity of the EIT signal by using a circularly polarized resonant light pair can be remarkably exhibited. it can. Therefore, the intensity of the EIT signal can be effectively improved.

  In addition, since the line width of the adjustment light is larger than that of the resonance light pair, the adjustment light can resonate with metal atoms having a wide velocity distribution. Therefore, even if the center wavelength of the adjustment light is slightly shifted, the adjustment light can be made to resonate with the metal atom at a desired speed. As a result, the frequency control of the adjustment light is not necessary, and the apparatus configuration can be simplified.

[Application Example 2]
In the quantum interference device according to the aspect of the invention, it is preferable that the second light includes resonance light that resonates the metal.
Thereby, distribution of the magnetic quantum number of a metal atom can be adjusted efficiently.

[Application Example 3]
In the quantum interference device of the present invention, the resonant light pair includes a D1 line,
The resonant light preferably includes a D2 line.
Thereby, the intensity | strength of an EIT signal can be improved efficiently.

[Application Example 4]
In the quantum interference device according to the aspect of the invention, it is preferable that the wavelength band of the resonant light pair is outside the wavelength band of the second light.
Thereby, generation | occurrence | production of the unnecessary signal by adjustment light can be reduced.

[Application Example 5]
In the quantum interference device according to the aspect of the invention, it is preferable that the second light source unit includes a light emitting diode for generating the second light.
Thereby, adjustment light having a wide line width can be generated with a relatively simple configuration.

[Application Example 6]
In the quantum interference device according to the aspect of the invention, it is preferable that the second light source unit includes a light source that emits non-polarized light and a polarizer that receives light from the light source.
Thereby, adjustment light having a wide line width can be generated with a relatively simple configuration.

[Application Example 7]
In the quantum interference device of the present invention, the first light source unit includes a first light source that emits light including a linearly polarized light component,
The second light source unit includes a second light source that emits light including a linearly polarized light component,
The first light source unit and the second light source unit preferably have a common λ / 4 wavelength plate through which both light from the first light source and the second light source passes.
Thereby, the apparatus configuration can be simplified.

[Application Example 8]
In the quantum interference device according to the aspect of the invention, it is preferable that the intensity of the second light is smaller than the intensity of the first light in the atomic cell.
Thereby, the deviation of the magnetic quantum number of a metal can be reduced effectively.

[Application Example 9]
In the quantum interference device of the present invention, it is preferable that the optical axes of the first light and the second light intersect each other.
Thereby, the apparatus configuration can be simplified.

[Application Example 10]
In the quantum interference device according to the aspect of the invention, the atomic cell includes a pair of window portions and an internal space in which the metal is enclosed together with the pair of window portions. A torso part comprising,
It is preferable that the second light passes through the body portion and enters the internal space.
Thereby, it can prevent or reduce that a light-receiving part receives adjustment light.

[Application Example 11]
In the quantum interference device according to the aspect of the invention, it is preferable that the first light passage region is in the second light passage region in the atomic cell.
Thereby, the bias of the distribution of the metal magnetic quantum number can be efficiently reduced.

[Application Example 12]
The quantum interference device of the present invention includes a resonant light pair that is circularly polarized in the same direction on a metal, and a resonance that is circularly polarized in the opposite direction to the resonant light pair and has a larger line width than the resonant light pair. Irradiation with light including light respectively adjusts the bias of the magnetic quantum number distribution of the metal and generates a magnetically induced transmission phenomenon.

  According to such a quantum interference device, in addition to the resonant light pair that is circularly polarized in the same direction, the second light that is circularly polarized in the opposite direction to the resonant light pair is irradiated to the metal as the adjustment light. By doing so, the bias in the distribution of the magnetic quantum number due to the resonant light pair can be canceled or relaxed by the adjustment light, and the bias in the distribution of the magnetic quantum number of the metal can be reduced. Therefore, the number of metal atoms having a desired magnetic quantum number that contributes to EIT is increased, and as a result, the effect of improving the intensity of the EIT signal by using a circularly polarized resonant light pair can be remarkably exhibited. it can. Therefore, the intensity of the EIT signal can be effectively improved.

  In addition, since the line width of the adjustment light is larger than that of the resonance light pair, the adjustment light can resonate with metal atoms having a wide velocity distribution. Therefore, even if the center wavelength of the adjustment light is slightly shifted, the adjustment light can be made to resonate with the metal atom at a desired speed. As a result, the frequency control of the adjustment light is not necessary, and the apparatus configuration can be simplified.

[Application Example 13]
The atomic oscillator according to the present invention includes the quantum interference device according to the present invention.

  Accordingly, it is possible to provide an atomic oscillator including a quantum interference device that can effectively improve the intensity of the EIT signal.

[Application Example 14]
An electronic apparatus according to the present invention includes the quantum interference device according to the present invention.

  Thereby, an electronic apparatus provided with the quantum interference apparatus which can improve the intensity | strength of an EIT signal effectively can be provided.

[Application Example 15]
The moving body of the present invention includes the quantum interference device of the present invention.

  Thereby, the moving body which can improve the intensity | strength of an EIT signal effectively can be provided.

1 is a schematic diagram showing an atomic oscillator (quantum interference device) according to a first embodiment of the present invention. It is a figure for demonstrating simply the energy state of an alkali metal atom. It is a graph which shows the relationship between the frequency difference of two light radiate | emitted from a light source part, and the intensity | strength of the light detected by a light-receiving part. It is the schematic for demonstrating the light source part with which the atomic oscillator shown in FIG. 1 is provided. It is a figure for demonstrating the light each radiate | emitted from the 1st light source part of the light source part shown in FIG. 4, and a 2nd light source part. It is a cross-sectional view of the atomic cell shown in FIG. It is a figure which shows an example of the relationship between the energy state of a cesium atom, a resonance light pair (1st resonance light, 2nd resonance light), and adjustment light (3rd resonance light). A diagram showing a magnetic quantum number of the distribution of sodium atoms, (a) represents a diagram showing a distribution of when irradiated with resonant light of sigma ₊ circularly polarized light, (b), the sigma _- a circularly polarized resonant light It is a figure which shows distribution at the time of irradiating. It is a graph which shows distribution of the magnetic quantum number of a cesium atom, (a) is a graph which shows the distribution at the time of irradiating only a resonance light pair, (b) is the case at the time of irradiating a resonance light pair and adjustment light. It is a graph which shows distribution. It is a graph which shows the difference of the EIT signal by the presence or absence of adjustment light. It is a figure for demonstrating the light each radiate | emitted from the 1st light source part of the light source part which concerns on the modification of 1st Embodiment of this invention, and a 2nd light source part. It is the schematic which shows the atomic oscillator (quantum interference apparatus) which concerns on 2nd Embodiment of this invention. It is a figure for demonstrating the light each radiate | emitted from the 1st light source part and 2nd light source part of a light source part shown in FIG. It is a figure which shows schematic structure at the time of using the atomic oscillator of this invention for the positioning system using a GPS satellite. It is a figure which shows an example of the moving body of this invention.

  Hereinafter, a quantum interference device, an atomic oscillator, an electronic device, and a moving body of the present invention will be described in detail based on embodiments shown in the accompanying drawings.

1. Atomic oscillator (quantum interference device)
First, the atomic oscillator of the present invention (the atomic oscillator including the quantum interference device of the present invention) will be described. In the following, an example in which the quantum interference device of the present invention is applied to an atomic oscillator will be described. However, the quantum interference device of the present invention is not limited to this, and may be applied to devices such as magnetic sensors and quantum memories. Is possible.

<First Embodiment>
First, the atomic oscillator according to the first embodiment of the present invention will be briefly described.

  FIG. 1 is a schematic diagram showing an atomic oscillator (quantum interference device) according to a first embodiment of the present invention. FIG. 2 is a diagram for simply explaining the energy state of alkali metal atoms. FIG. 3 is a graph showing the relationship between the frequency difference between the two lights emitted from the light source unit and the intensity of the light detected by the light receiving unit.

  An atomic oscillator 1 shown in FIG. 1 is an atomic oscillator using a quantum interference effect. As shown in FIG. 1, the atomic oscillator 1 includes an atomic cell 2 (gas cell), a light source unit 3, a light receiving unit 4, a heater 5, a temperature sensor 6, a magnetic field generating unit 7, a control unit 8, It is equipped with.

First, the principle of the atomic oscillator 1 will be briefly described.
As shown in FIG. 1, in the atomic oscillator 1, the light source unit 3 emits light LL toward the atomic cell 2, and the light receiving unit 4 detects the light LL transmitted through the atomic cell 2.

  A gaseous alkali metal (metal atom) is enclosed in the atomic cell 2. As shown in FIG. 2, the alkali metal has a three-level energy level composed of two ground levels (a first ground level and a second ground level) and an excited level. Here, the first ground level is an energy state lower than the second ground level.

The light LL emitted from the light source unit 3 includes first resonance light and second resonance light as two types of resonance light having different frequencies. When the gaseous alkali metal as described above is irradiated with the first resonance light and the second resonance light, the difference (ω ₁ −ω) between the frequency ω ₁ of the first resonance light and the frequency ω ₂ of the second resonance light. ₂ ), the light absorptance (light transmittance) of the resonance light 1 and 2 in the alkali metal changes.

The frequency (ω ₁ −ω ₂ ) between the frequency ω ₁ of the first resonant light and the frequency ω ₂ of the second resonant light corresponds to the energy difference ΔE between the first ground level and the second ground level. , The excitation from the first ground level and the second ground level to the excitation level stops. At this time, both the first resonance light and the second resonance light are transmitted without being absorbed by the alkali metal. Such a phenomenon is called a CPT phenomenon or an electromagnetically induced transparency (EIT) phenomenon.

For example, when the light source unit 3 fixes the frequency ω ₁ of the first resonance light and changes the frequency ω ₂ of the second resonance light, the frequency ω ₁ of the first resonance light and the frequency ω _{2 of} the second resonance light are changed. 3 is equal to the frequency ω ₀ corresponding to the energy difference ΔE between the first and second ground levels (ω ₁ −ω ₂ ), the detected intensity of the light receiving unit 4 is shown in FIG. So as to rise steeply. Such a steep signal is detected as an EIT signal. This EIT signal has an eigenvalue determined by the type of alkali metal. Therefore, a highly accurate oscillator can be configured by using such an EIT signal as a reference.

Hereinafter, each part of the atomic oscillator 1 will be briefly described.
[Gas cell]
The atomic cell 2 is filled with gaseous alkali metals such as rubidium, cesium, and sodium. Further, in the atomic cell 2, a rare gas such as argon or neon, or an inert gas such as nitrogen may be sealed together with an alkali metal gas as a buffer gas, if necessary.

  As will be described in detail later, the atomic cell 2 has a body portion having a through-hole and a pair of windows that close the opening of the through-hole of the body portion, thereby enclosing a gaseous alkali metal. An internal space is formed.

[Light emitting part]
The light source unit 3 has a function of emitting the light LL including the first resonance light and the second resonance light, which form the resonance light pair that resonates the alkali metal atoms in the atomic cell 2.

  The light LL emitted from the light source unit 3 includes third resonance light in addition to the first resonance light and the second resonance light.

  The first resonance light is light (probe light) that excites the alkali metal atom in the atomic cell 2 from the first ground level to the excitation level. On the other hand, the second resonance light is light (coupling light) for exciting the alkali metal atom in the atomic cell 2 from the second ground level to the excitation level. Here, the first resonance light and the second resonance light are circularly polarized in the same direction. The third resonance light is “adjustment light” (repump light) for adjusting the magnetic quantum number of the alkali metal in the atomic cell 2. The third resonance light is circularly polarized in the opposite direction to the first resonance light and the second resonance light. Thereby, the magnetic quantum number of the alkali metal atom in the atomic cell 2 can be adjusted. The light source unit 3 will be described in detail later. Note that “circularly polarized light” refers to either the electric field component or the magnetic field component of a light wave, and the vibration direction rotates at the frequency of the light wave in a plane perpendicular to the light traveling direction. , Light whose amplitude is constant regardless of its direction, in other words, light that draws a circle as the vibration of the electric field (or magnetic field) propagates.

[Light receiving section]
The light receiving unit 4 has a function of detecting the intensity of the light LL transmitted through the atomic cell 2 (particularly, a resonance light pair composed of the first resonance light and the second resonance light).

  The light receiving unit 4 is not particularly limited as long as it can detect the intensity of the light LL as described above. For example, a photodetector such as a photodiode that outputs a signal corresponding to the intensity of the received light. (Light receiving element) can be used.

[heater]
The heater 5 (heating unit) has a function of heating the above-described atomic cell 2 (more specifically, an alkali metal in the atomic cell 2). Thereby, the alkali metal in the atomic cell 2 can be maintained in a gaseous state with an appropriate concentration.

  The heater 5 includes, for example, a heating resistor that generates heat when energized. The heating resistor may be provided in contact with the atomic cell 2 or may be provided in non-contact with the atomic cell 2.

More specifically, for example, when the heating resistor is provided in contact with the atomic cell 2, the heating resistor is provided in each of the pair of windows of the atomic cell 2. Thereby, it is possible to prevent condensation of alkali metal atoms on the window portion of the atomic cell 2. As a result, the characteristics (oscillation characteristics) of the atomic oscillator 1 can be made excellent over a long period of time. Such a heating resistor is a material having transparency to the light LL, specifically, for example, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), In ₃ O ₃ , SnO ₂ , Sb-containing SnO _2. Further, it is made of a transparent electrode material such as an oxide such as Al-containing ZnO. Such a heating resistor can be formed using, for example, a chemical vapor deposition method (CVD) such as plasma CVD or thermal CVD, a dry plating method such as vacuum vapor deposition, a sol-gel method, or the like.

  Further, when the heating resistor is provided in a non-contact manner with respect to the atomic cell 2, heat may be transferred from the heating resistor to the atomic cell 2 through a member such as a metal having excellent thermal conductivity, such as ceramic.

  The heater 5 is not limited to the above-described form as long as the atomic cell 2 can be heated, and various heaters can be used. Further, the temperature of the atomic cell 2 may be adjusted using a Peltier element instead of the heater 5 or in combination with the heater 5.

[Temperature sensor]
The temperature sensor 6 has a function of detecting the temperature of the heater 5 or the atomic cell 2.

This temperature sensor 6 is disposed in contact with, for example, the heater 5 or the atomic cell 2.
The temperature sensor 6 is not particularly limited, and various known temperature sensors such as a thermistor and a thermocouple can be used.

[Magnetic field generator]
The magnetic field generator 7 has a function of applying a magnetic field to the alkali metal in the atomic cell 2. Thereby, the gap between a plurality of different energy levels in which the alkali metal atoms in the atomic cell 2 are degenerated can be expanded by Zeeman splitting, and the resolution can be improved. As a result, the accuracy of the oscillation frequency of the atomic oscillator 1 can be increased.

  The magnetic field generation unit 7 may be configured by, for example, a coil wound around the outer periphery of the atomic cell 2 so as to constitute a solenoid type, or the atomic cell 2 so as to constitute a Helmholtz type. It may be composed of a pair of coils provided to face each other.

  The magnetic field generated by the magnetic field generator 7 is a constant magnetic field (DC magnetic field), but an AC magnetic field may be superimposed.

[Control unit]
The control unit 8 has a function of controlling the light source unit 3, the heater 5, and the magnetic field generation unit 7.

  The control unit 8 includes a light source control unit 82 that controls the light source unit 3, a temperature control unit 81 that controls the temperature of the alkali metal in the atomic cell 2, and a magnetic field control unit 83 that controls the magnetic field from the magnetic field generation unit 7. And have.

The light source control unit 82 has a function of controlling the frequencies of the first resonance light and the second resonance light emitted from the light source unit 3 based on the detection result of the light receiving unit 4 described above. More specifically, the light source control unit 82 includes the first resonance light emitted from the light source unit 3 and the frequency difference (ω ₁ −ω ₂ ) described above to be the frequency ω ₀ unique to the alkali metal described above. The frequency of the second resonance light is controlled. The configuration of the light source control unit 82 will be described in detail later.

  Further, the temperature control unit 81 controls energization to the heater 5 based on the detection result of the temperature sensor 6. Thereby, the atomic cell 2 can be maintained within a desired temperature range. For example, the temperature of the atomic cell 2 is adjusted to about 70 ° C. by the heater 5, for example.

The magnetic field control unit 83 controls energization to the magnetic field generation unit 7 so that the magnetic field generated by the magnetic field generation unit 7 is constant.
Such a control unit 8 is provided, for example, on an IC chip mounted on a substrate.
The configuration of the atomic oscillator 1 has been briefly described above.

(Detailed description of the light source)
FIG. 4 is a schematic diagram for explaining a light source unit included in the atomic oscillator shown in FIG. 5 is a diagram for explaining light emitted from the first light source unit and the second light source unit of the light source unit shown in FIG. 4, and FIG. 6 is a cross-sectional view of the atomic cell shown in FIG. It is sectional drawing perpendicular | vertical to the direction where a pair of window part is located in a line.

  As shown in FIG. 4, the light source unit 3 includes a first light source unit 31 that emits the first pair of resonant light LL1 including the first resonant light and the second resonant light as the first light, and adjustment light including the third resonant light. And a second light source unit 32 that emits LL2 as second light.

  The first light source unit 31 includes a first light source 311, a λ / 2 wavelength plate 312, and a λ / 4 wavelength plate 313.

  The first light source 311 has a function of emitting the first light LL1a composed of a resonant light pair that is linearly polarized. The first light source 311 is not particularly limited as long as it can emit light including the first light LL1a. For example, the first light source 311 is a semiconductor laser such as an edge emitting laser or a vertical cavity surface emitting laser (VCSEL). Note that “linearly polarized light” is light in which the vibration plane of electromagnetic waves (light) is in one plane, in other words, light in which the vibration direction of the electric field (or magnetic field) is constant.

  The λ / 2 wavelength plate 312 is a birefringent element that generates a phase difference π (180 °) between orthogonal polarization components. Therefore, the λ / 2 wavelength plate 312 changes the polarization direction of the linearly polarized first light LL1a from the first light source 311 by 90 ° to generate the resonant light pair LL1b. When the first light source 311 is installed in a posture rotated by 90 ° around the optical axis, the linearly polarized light emitted from the first light source 311 is converted into the linearly polarized light emitted from the second light source 321 described later. Since it is orthogonal to the polarization direction, the λ / 2 wavelength plate 312 can be omitted.

  The λ / 4 wavelength plate 313 is a birefringent element that generates a phase difference π / 2 (90 °) between orthogonal polarization components. This λ / 4 wavelength plate 313 has a function of converting the resonant light pair LL1b generated by the λ / 2 wavelength plate 312 from linearly polarized light to circularly polarized light (including elliptically polarized light) resonant light pair LL1. Thereby, the resonant light pair LL1 configured by the first resonant light and the second resonant light described above can be generated.

  On the other hand, the second light source unit 32 includes a second light source 321, a polarizer 322, and a λ / 4 wavelength plate 313 common to the first light source unit 31 described above. Here, it can be said that the λ / 4 wavelength plate 313 is included in the first light source unit 31 as described above, and can be said to be included in the second light source unit 32.

  The second light source 321 has a function of emitting the second light LL2a including the resonance light linearly polarized in the same direction as the first light source 311 described above. In particular, the second light LL2a includes resonance light having a larger line width than the first light LL1a (resonance light pair) from the first light source 311 described above. Thereby, as will be described later, the adjustment light LL2 having a line width larger than that of the resonance light pair LL1 can be generated. The second light source 321 is not particularly limited as long as the second light source 321 can emit light including a linearly polarized light component that is resonance light having a line width larger than that of the first light LL1a. It is a light emitting element such as a semiconductor laser such as a light emitting laser (VCSEL), a light emitting diode (LED), or an organic electroluminescence (organic EL) element.

  Especially, it is preferable that the 2nd light source 321 is what emits non-polarized light, for example, a light emitting diode. That is, it is preferable that the second light source unit 32 generates the adjustment light LL <b> 2 using light from the light emitting diode constituting the second light source 321. Thereby, adjustment light LL2 with a wide line width can be generated with a relatively simple configuration.

  The polarizer 322 receives the second light LL2a from the second light source 321 and passes and extracts the resonance light LL2b including only the linearly polarized light component in a specific direction included in the second light LL2a. The resonant light LL2b is linearly polarized in a direction (orthogonal direction) different from the polarization direction of the resonant light pair LL1b described above.

  As described above, the λ / 4 wavelength plate 313 is a birefringent element that generates a phase difference π / 2 (90 °) between orthogonal polarization components. The λ / 4 wavelength plate 313 has a function of converting the resonance light LL2b generated by the polarizer 322 from linearly polarized light to circularly polarized light (including elliptically polarized light) adjusting light LL2. Thereby, the adjustment light LL2 composed of the third resonance light described above can be generated. Here, the polarization direction (b2 direction shown in FIG. 5) of the linearly polarized resonance light LL2b is different (orthogonal) from the polarization direction (b1 direction shown in FIG. 5) of the linearly polarized resonance light LL1b. Direction). Therefore, by passing the resonant light pair LL1b and the resonant light LL2b through the common λ / 4 wavelength plate 313, the resonant light pair LL1 that is circularly polarized and the resonant light pair LL1 are circularly polarized in the opposite direction. The adjustment light LL2 that is present can be generated. Thus, since the first light source unit 31 and the second light source unit 32 have the common λ / 4 wavelength plate 313 through which both the resonance light pair LL1 and the adjustment light LL2 pass, the first light source unit 31 and the second light source Compared with the case where each unit 32 includes a λ / 4 wavelength plate, the configuration of the apparatus can be simplified.

  In particular, since the adjustment light LL2 is generated using the second light LL2a having a wide line width as described above, the line width is wider than that of the resonance light pair LL1. Thereby, the adjustment light LL2 can be resonated with respect to alkali metal atoms having a wide velocity distribution. Therefore, even if the center wavelength of the adjustment light LL2 is slightly deviated, the adjustment light LL2 can resonate with the alkali metal atom at a desired speed. As a result, the frequency control of the adjustment light LL2, that is, the frequency control of the second light source 321 becomes unnecessary, and the apparatus configuration can be simplified.

  Further, in the second light source unit 32, when a light source that emits non-polarized light is used as the second light source 321, the light from the second light source 321 is incident on the polarizer 322 with a relatively simple configuration. The adjustment light LL2 having a wide line width can be generated.

  The light source unit 3 configured as described above is controlled such that the first light source 311 emits the first resonance light and the second resonance light described above by the light source control unit 82.

  The light source control unit 82 includes a frequency control unit 821, a voltage controlled crystal oscillator 822 (VCXO: Voltage Controlled Crystal Oscillators), and a phase locked loop 823 (PLL: phase locked loop).

  The frequency control unit 821 detects the EIT state in the atomic cell 2 based on the received light intensity of the light receiving unit 4 and outputs a control voltage corresponding to the detection result. Thus, the frequency control unit 821 controls the voltage controlled crystal oscillator 822 so that the light receiving unit 4 detects the EIT signal.

  The voltage controlled crystal oscillator 822 is controlled by the frequency control unit 821 to have a desired oscillation frequency, and oscillates at a frequency of about several MHz to several tens of MHz, for example. The output signal of the voltage controlled crystal oscillator 822 is input to the phase synchronization circuit 823 and also output as the output signal of the atomic oscillator 1.

The phase synchronization circuit 823 multiplies the output signal from the voltage controlled crystal oscillator 822 by frequency. As a result, the phase locked loop 823 oscillates at a frequency that is half the frequency corresponding to the energy difference ΔE between two different ground levels of the alkali metal atom. The signal (high frequency signal) multiplied in this way is input to the first light source 311 of the first light source unit 31 as a drive signal after a DC bias current is superimposed. Thus, the first resonant light and the second resonant light, which are two lights having a frequency difference (ω ₁ −ω ₂ ) of ω ₀ , are modulated by modulating a light emitting element such as a semiconductor laser included in the first light source 311. Can be emitted. Here, the current value of the DC bias current is controlled to a predetermined value by a bias control unit (not shown). Thereby, the center wavelengths of the first resonance light and the second resonance light can be controlled as desired.

  The first light source 311 and the second light source 321 are each adjusted to a predetermined temperature by a temperature adjusting element (a heating resistor, a Peltier element, etc.) not shown. In addition, by adjusting the temperatures of the first light source 311 and the second light source 321, the center wavelengths of the light from the first light source 311 and the second light source 321 can be controlled.

  The resonant light pair LL1 and the adjustment light LL2 from the first light source unit 31 and the second light source unit 32 configured as described above are applied to the atomic cell 2.

  As shown in FIG. 5, the atomic cell 2 includes a body part 21 and a pair of window parts 22 and 23 provided with the body part 21 interposed therebetween. In the atomic cell 2, the body portion 21 is disposed between the pair of window portions 22, 23, and the body space 21 and the pair of window portions 22 are formed in the internal space S in which gaseous alkali metal is sealed. , 23 are formed (configured).

  More specifically, the body portion 21 has a plate shape, and the body portion 21 is formed with a through hole 211 penetrating in the thickness direction of the body portion 21.

  The constituent material of the body portion 21 is not particularly limited, and examples thereof include a glass material, a crystal, a metal material, a resin material, and a silicon material. Among these, any one of a glass material, a crystal, and a silicon material is used. It is preferable to use a silicon material. Thereby, even when the small atomic cell 2 having a width or height of 10 mm or less is formed, the highly accurate body portion 21 can be easily formed by using a microfabrication technique such as etching. it can. In particular, silicon can be finely processed by etching. Therefore, by forming the body part 21 using silicon, the body part 21 can be formed easily and with high accuracy even if the atomic cell 2 is downsized. Moreover, although the window parts 22 and 23 are generally comprised with glass, silicon is excellent in thermal conductivity compared with glass. Therefore, the heat dissipation of the body part 21 can be made excellent. Moreover, when the window parts 22 and 23 are comprised with glass, the trunk | drum 21 and the window parts 22 and 23 can be easily airtightly joined by anodic bonding, and the reliability of the atomic cell 2 was excellent. Can be.

  A window portion 22 is joined to one surface of the body portion 21, and a window portion 23 is joined to the other surface of the body portion 21. Thus, one end opening of the through hole 211 is sealed by the window portion 22, and the other end opening of the through hole 211 is sealed by the window portion 23.

  The joining method of the body part 21 and the window parts 22 and 23 is determined according to these constituent materials and is not particularly limited as long as it can be hermetically joined. For example, joining by an adhesive Although a method, a direct bonding method, an anodic bonding method, a surface activated bonding method, and the like can be used, it is preferable to use a direct bonding method or an anodic bonding method. Thereby, the trunk | drum 21 and the window parts 22 and 23 can be easily airtightly joined, and the reliability of the atomic cell 2 can be made excellent.

  Each window part 22 and 23 joined to the trunk | drum 21 has the transmittance | permeability with respect to the light LL from the light source part 3 mentioned above. One window portion 22 is an incident-side window portion into which the light LL enters the internal space S of the atomic cell 2, and the other window portion 23 emits the light LL from within the internal space S of the atomic cell 2. It is an emission side window part. Each of the window portions 22 and 23 has a plate shape.

  The constituent materials of the window portions 22 and 23 are not particularly limited as long as they have transparency to the light LL as described above, and examples thereof include glass materials and crystal, but glass materials are used. It is preferable. Thereby, the window parts 22 and 23 which have the transparency with respect to excitation light are realizable. In addition, when the body portion 21 is made of silicon, the body portions 21 and the window portion 22 can be easily and airtightly joined by anodic bonding by forming the window portions 22 and 23 using glass. And the reliability of the atomic cell 2 can be improved. Depending on the thickness of the windows 22 and 23 and the intensity of the light LL, the windows 22 and 23 may be made of silicon. Even in this case, the body portion 21 and the window portions 22 and 23 can be directly bonded or anodic bonded.

  Gaseous alkali metals are mainly stored in the internal space S, which is a space in the through hole 211 sealed by the window portions 22 and 23. The gaseous alkali metal accommodated in the internal space S is excited by the light LL. Here, at least a part of the internal space S constitutes a “light passage space” through which the light LL passes. In the present embodiment, the cross section of the internal space S has a circular shape, while the cross section of the light passage space has a similar shape (that is, a circular shape) to the cross section of the internal space S, and the internal space S. It is set to be slightly smaller than the cross section. The cross-sectional shape of the internal space S is not limited to a circle, and may be, for example, a polygon such as a quadrangle or a pentagon, an ellipse, or the like.

  In the atomic cell 2 configured as described above, as shown in FIG. 5, the optical axis a1 of the resonant light pair LL1 is inclined at an inclination angle θ with respect to the optical axis a2 of the adjustment light LL2. It intersects with the optical axis a2 at the intersection P. In FIG. 5, in the atomic cell 2, the optical axis a <b> 1 of the resonant light pair LL <b> 1 is parallel to the axis line a along the direction in which the window portion 22 and the window portion 23 of the atomic cell 2 are aligned, The optical axis a2 of the light LL2 is inclined at an inclination angle θ with respect to the axis a. In FIG. 5, the optical axis a1 coincides with the axis a.

  Here, on the side of the atomic cell 2 where the resonance light pair LL1 and the adjustment light LL2 are emitted, the light receiving unit 4 described above is disposed on the optical axis a1 or an extension thereof, and the resonance light that has passed through the atomic cell 2 is disposed. The pair LL1 is received by the light receiving unit 4, while the optical axis a2 is set so that the light receiving unit 4 does not receive the adjustment light LL2 that has passed through the atomic cell 2. Thereby, it can prevent or reduce that the light-receiving part 4 receives adjustment light LL2.

  In the present embodiment, the adjustment light LL2 that has passed through the atomic cell 2 is incident on an antireflection portion (not shown) so as not to be stray light.

As shown in FIG. 6, in the atomic cell 2, the width W2 of the adjustment light LL2 is larger than the width W1 of the resonance light pair LL1. Thereby, in the atomic cell 2, the passage region of the resonance light pair LL1 is included in the passage region of the adjustment light LL2.
Further, the width W2 of the adjustment light LL2 is smaller than the width W in the atomic cell 2.

  FIG. 7 is a diagram illustrating an example of the relationship between the energy state of the cesium atom, the resonance light pair (first resonance light, second resonance light), and the adjustment light (third resonance light).

For example, when cesium atoms are enclosed in the atomic cell 2, as shown in FIG. 7, D1 is σ ₊ polarized (left circularly polarized) as the first resonant light and the second resonant light (resonant light pair) A D2 line that is σ _- polarized (right circularly polarized) is used as the third resonance light (adjustment light). The first resonant light and the second resonant light may be σ ₋ polarized light, and the third resonant light may be σ ₊ polarized light, or the first resonant light and the second resonant light may be D2 line and the third resonant light. May be the D1 line.

Cesium atom is a kind of alkali metal atoms _has a ground level of _{6S 1/2,} and two excited levels of _{6P 1/2} and _{6P 3/2,} the. Each level of 6S _1/2 , 6P _1/2 , 6P _3/2 has a fine structure divided into a plurality of energy levels. Specifically, the 6S _1/2 level has two ground levels of F = 3 and 4, and the 6P _1/2 level has two excitation levels of F ′ = 3 and 4, The 6P _3/2 level has four excitation levels of F ″ = 2, 3, 4, and 5.

The cesium atom in the first ground level of F = 3 of 6S _1/2 transitions to the excited level of F ″ = 2, 3 and 4 of 6P _3/2 by absorbing the D2 line. However, it is not possible to transition to an excitation level of F ″ = 5. The cesium atom in the second ground level of F = 4 of 6S _1/2 transitions to the excited level of F ″ = 3, 4 or 5 of 6P _3/2 by absorbing the D2 line. However, it is not possible to transition to an excitation level of F ″ = 2. These are based on the transition selection rule when electric dipole transition is assumed. Conversely, a cesium atom in an excited level of F ″ = 3, 4 of 6P _3/2 emits a D2 line, and a ground level of F = 3 or F = 4 of 6S _1/2 ( Either the original ground level or the other ground level), such 6S _1/2 F = 3, 4 two ground levels and 6P _3/2 F ″ = The three levels consisting of any of the three or four excitation levels are called Λ-type three levels because Λ-type transition by absorption and emission of the D2 line is possible. Similarly, three levels consisting of two ground levels of F = 3, 4 of 6S _1/2 and excited levels of F ′ = 3, 4 of 6P _1/2 are also absorbed by the D1 line. Since a Λ-type transition by light emission is possible, a Λ-type three level is formed.

On the other hand, the cesium atom in the excitation level of F ″ = 2 of 6P _3/2 emits the D2 line and is always in the ground level of F = 3 of 6S _1/2 (original ground level). Similarly, the cesium atom in the excited level of F ″ = 5 in 6P _3/2 emits the D2 line, and the F = 4 ground level of 6S _1/2 (the original ground level) ). Therefore, the three levels consisting of two ground levels of 6S _1/2 F = 3 and 4 and 6P _3/2 F = 2 or F = 5 excited levels are Λ due to absorption and emission of the D2 line. Since type transition is impossible, Λ-type three levels are not formed.

Such a cesium atom has a wavelength of D1 line in vacuum of 894.593 nm and a wavelength of D2 line in vacuum of 892.347 nm, which corresponds to a hyperfine splitting frequency of 6S _1/2 (corresponding to ΔE). Frequency) is 9.1926 GHz.

Note that alkali metal atoms other than the cesium atom similarly have two ground levels and an excited level that form a Λ-type three level. Here, the wavelength of the D1 line in vacuum is 589.756 nm, the wavelength of the D2 line in vacuum is 589.158 nm, and the hyperfine splitting frequency of 3S _1/2 is 1.7716 GHz for sodium atoms. It is. The rubidium ( ⁸⁵ Rb) atom has a D1 line wavelength of 7944.979 nm in vacuum, a D2 line wavelength of 780.241 nm in vacuum, and an ultrafine splitting frequency of 5S _1/2. 3.0357 GHz. In addition, the rubidium ( ⁸⁷ Rb) atom has a wavelength of D1 line in a vacuum of 7944.979 nm, a wavelength of D2 line in a vacuum of 780.241 nm, and has a hyperfine splitting frequency of 5S _1/2. 6.8346 GHz.

8A and 8B are diagrams showing the distribution of magnetic quantum numbers of sodium atoms, where FIG. 8A is a diagram showing the distribution when σ ₊ circularly polarized resonance light is irradiated, and FIG. 8B is a diagram showing σ ₋ circularly polarized light. It is a figure which shows distribution at the time of irradiating the resonant light of.

For example, as shown in FIG. 8, a sodium atom, which is a kind of alkali metal atom, has two ground levels and an excited level that form a Λ-type three level, and 3S _1/2 F = 1 The first ground level has three magnetic quantum numbers of m _F1 = −1, 0, 1 and the second ground level of F = 2 of 3S _1/2 is m _F2 = −2, −1. , 0, 1 and 5 and the excitation level of 3P1 / 2 has five magnetic quantum numbers m _{F ′} = −2, −1, 0, 1 and 2.

When a σ ₊ circularly polarized resonant light pair is irradiated onto a sodium atom at the ground level of F = 1 or F = 2, as shown in FIG. 8 (a), the magnetic quantum number increases by one. And excited to the excited level. At this time, the distribution of the sodium atom at the ground level of F = 1 or F = 2 changes to the one with the larger magnetic quantum number.

On the other hand, when a sodium atom at the ground level of F = 1 or F = 2 is irradiated with a σ _- circularly polarized resonant light pair, the magnetic quantum number is reduced by 1 as shown in FIG. According to the law, it is excited to the excitation level. At this time, the distribution of the sodium atom at the ground level of F = 1 or F = 2 changes toward the smaller magnetic quantum number.

  In FIG. 8, for convenience of explanation, the distribution of the magnetic quantum number is shown by taking a sodium atom having a simple structure as an example. However, in other alkali metal atoms, each of the ground level and the excited level is 2F + 1. It has a number of magnetic quantum numbers (magnetic sublevels), and the distribution of the magnetic quantum numbers changes with the selection rule as described above.

  FIG. 9 is a graph showing the distribution of magnetic quantum numbers of cesium atoms, (a) is a graph showing the distribution when only the resonant light pair is irradiated, and (b) is a graph showing the resonant light pair and the adjustment light. It is a graph which shows distribution at the time of irradiation.

When the cesium atom is irradiated with only the resonant light pair LL1, as shown in FIG. 9A, the cesium atom at the first ground level has a small bias in the distribution of the magnetic quantum number m _F3 , but the number thereof is In addition, the distribution of the cesium atoms at the second ground level is greatly biased toward the larger magnetic quantum number _mF4 .

  That is, in the conventional atomic oscillator (for example, the atomic oscillator according to Patent Document 1), all of the resonance light irradiated to the metal is circularly polarized in one direction, and therefore, for example, compared to the case where the resonance light is linearly polarized. Although the strength of the EIT signal can be improved, the effect is not sufficient. This is because all of the resonant light is circularly polarized in one direction, so that the distribution is biased to either the smaller or the larger magnetic quantum number of the metal, and thus the desired magnetism contributing to EIT. This is because the number of quantum metal atoms is reduced.

On the other hand, when the cesium atoms are simultaneously irradiated with both the resonant light pair LL1 and the adjustment light LL2, as shown in FIG. 9B, the cesium atoms in each of the first ground level and the second ground level _Has a relatively small distribution of the magnetic quantum numbers m _F3 and m _F4 , and the number thereof is also relatively large. In particular, the number of cesium atoms with which the magnetic quantum numbers m _F3 and m _F4 = 0 are stable against a magnetic field can be increased. That is, when both the resonant light pair LL1 and the adjustment light LL2 are simultaneously irradiated to the cesium atom, compared with the case where only the resonant light pair LL1 is irradiated to the cesium atom, each of the first ground level and the second ground level In this level, the distribution of magnetic quantum numbers of cesium atoms can be averaged while increasing the number of cesium atoms in each level.

FIG. 10 is a graph showing the difference in EIT signal depending on the presence or absence of adjustment light.
As shown in FIG. 10, when both the resonance light pair LL1 and the adjustment light LL2 are simultaneously irradiated to the cesium atom (repump on), compared to the case where only the resonance light pair LL1 is irradiated to the cesium atom (repump off), The signal intensity of the EIT signal can be increased by about three times while making the full width at half maximum substantially the same.

  The results shown in FIGS. 9 and 10 are obtained by using a polarized resonance light pair (first resonance light, second resonance light) and adjustment light (third resonance light) as shown in FIG. The intensity of the adjustment light (photon flux density) was about half that of the resonant light pair.

  As described above, in the atomic oscillator 1, in addition to the resonant light pair LL1 that is circularly polarized in the same direction, the adjustment light LL2 that is circularly polarized in the opposite direction to the resonant light pair LL1 is used as an alkali metal. By irradiating, the bias of the magnetic quantum number distribution by the resonant light pair LL1 can be canceled or relaxed by the adjustment light LL2, and the bias of the magnetic metal quantum number distribution of the alkali metal can be reduced. For this reason, the number of alkali metal atoms having a desired magnetic quantum number that contributes to EIT is increased, and as a result, the effect of improving the intensity of the EIT signal by using the circularly polarized resonant light pair LL1 is remarkably exhibited. Therefore, the strength of the EIT signal can be effectively improved.

  Moreover, since the line width of the adjustment light LL2 is larger than that of the resonance light pair LL1, the adjustment light LL2 can be resonated with respect to alkali metal atoms having a wide velocity distribution. Therefore, even if the center wavelength of the adjustment light LL2 is slightly deviated, the adjustment light LL2 can resonate with the alkali metal atom at a desired speed. As a result, frequency control of the adjustment light LL2 becomes unnecessary, and the apparatus configuration can be simplified.

  Here, since the adjustment light LL2 resonates the alkali metal, the distribution of the magnetic quantum number of the alkali metal atom can be adjusted efficiently.

  Also, as shown in FIG. 7, when the resonant light pair LL1 is a D1 line and the adjustment light LL2 is a D2 line, the EIT phenomenon is efficiently generated, and as a result, the intensity of the EIT signal is efficiently improved. be able to.

  The wavelength band of the resonant light pair LL1 is preferably outside the wavelength band of the adjustment light LL2. That is, it is preferable that the wavelength band of the resonance light pair LL1 is not included in the wavelength band of the adjustment light LL2. Thereby, generation | occurrence | production of the unnecessary signal by adjustment light LL2 can be reduced.

  Further, the line width of the adjustment light LL2 may be larger than the line width of the resonant light pair LL1, but is preferably 1.5 times or more and 1000 times or less than the line width of the resonant light pair LL1. It is more preferable that it is not less than 100 times and not more than 100 times. Thereby, even if the center wavelength of adjustment light LL2 shifts | deviates somewhat, adjustment light LL2 can be resonated with respect to the alkali metal atom in desired speed.

  Further, the intensity (photon flux density) of the adjustment light LL2 in the atomic cell 2 is smaller than that of the resonance light pair LL1. Thereby, the bias | inclination of the magnetic quantum number of the alkali metal in the atomic cell 2 can be reduced effectively.

  In addition, if the intensity of the adjustment light LL2 is too strong, the distribution of the magnetic quantum number of the alkali metal in the atomic cell 2 may be greatly biased to the side opposite to the bias of the distribution of the magnetic quantum number by the resonant light pair LL1. is there. On the other hand, if the intensity of the adjustment light LL2 is too weak, the bias of the distribution of the magnetic quantum numbers by the resonance light pair LL1 may not be sufficiently canceled or relaxed by the adjustment light LL2.

  From such a viewpoint, when the photon flux density of the resonant light pair LL1 in the atomic cell 2 is D1, and the photon flux density of the adjustment light LL2 in the atomic cell 2 is D2, D2 / D1 is 0.1 or more It is preferably 0.9 or less, more preferably 0.2 or more and 0.7 or less, and further preferably 0.3 or more and 0.5 or less.

  Here, the intensity of the adjustment light LL2 can be adjusted by the dimming rate of the neutral density filter, or can be adjusted by adjusting the drive current of the second light source 321.

  In addition, since the pass region of the resonant light pair LL1 is included in the pass region of the adjustment light LL2 in the atomic cell 2, it is possible to effectively reduce the bias of the magnetic metal quantum number distribution of the alkali metal.

  In the present embodiment, since the optical axes a1 and a2 of the resonance light pair LL1 and the adjustment light LL2 intersect at the intersection P in the atomic cell 2 as described above, the adjustment is performed with the resonance light pair LL1. An optical component for synthesizing the light LL2 is unnecessary, and the apparatus configuration can be simplified.

  Here, the inclination angle θ of the optical axis a1 of the resonant light pair LL1 with respect to the optical axis a2 of the adjustment light LL2 in the atomic cell 2 is preferably 1 ° or more and 30 ° or less, and is 2 ° or more and 10 ° or less. It is more preferable. Thereby, the distribution of the magnetic quantum number by the adjustment light LL2 can be easily adjusted while reducing the size and simplification of the apparatus. On the other hand, when the inclination angle θ is too small, the degree of freedom of installation of the first light source 311 and the second light source 321 becomes extremely small and the apparatus tends to be enlarged. On the other hand, if the inclination angle θ is too large, the second light source unit 32 must be designed in consideration of the Doppler width of alkali metal atoms in the atomic cell 2, and the design tends to be difficult.

(Modification)
FIG. 11 is a diagram for explaining light emitted from the first light source unit and the second light source unit of the light source unit according to the modification of the first embodiment of the present invention.

  In the modification shown in FIG. 11, in the atomic cell 2, the optical axis a1 of the resonant light pair LL1 is inclined at an inclination angle θ1 with respect to the axis a, while the optical axis a2 of the adjustment light LL2 is It is inclined at an inclination angle θ2 to the opposite side of the optical axis a1 with respect to a. Thereby, the structure with high symmetry with respect to the axis line a is realizable.

  Here, also in the modification shown in FIG. 11, the optical axis a1 of the resonant light pair LL1 is inclined with respect to the optical axis a2 of the adjustment light LL2 in the atomic cell 2 as in the example shown in FIG. It is inclined at θ and intersects the optical axis a2 at the intersection P. Therefore, the inclination angle θ is the sum of the inclination angle θ1 and the inclination angle θ2.

  Although FIG. 11 illustrates a case where the inclination angle θ1 and the inclination angle θ2 are equal to each other, the inclination angle θ1 and the inclination angle θ2 may be different from each other.

Second Embodiment
Next, a second embodiment of the present invention will be described.

  FIG. 12 is a schematic view showing an atomic oscillator (quantum interference device) according to the second embodiment of the present invention. FIG. 13 is a diagram for explaining light emitted from the first light source unit and the second light source unit of the light source unit shown in FIG.

  The present embodiment is the same as the first embodiment described above except that the configuration of the second light source unit is different.

  In the following description, the second embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted. 12 and 13, the same reference numerals are given to the same configurations as those in the above-described embodiment.

An atomic oscillator 1A shown in FIG. 12 includes a light source unit 3A.
The light source unit 3A includes a first light source unit 31 that emits the resonant light pair LL1, and a second light source unit 32A that emits the adjustment light LL2.

  The second light source unit 32A is the same as that of the first embodiment described above except that the λ / 4 wavelength plate 313 is omitted and a λ / 4 wavelength plate 323 and a mirror 324 are added between the polarizer 322 and the atomic cell 2. The second light source unit 32 is configured in the same manner. That is, the second light source unit 32 </ b> A includes a second light source 321, a polarizer 322, a λ / 4 wavelength plate 323, and a mirror 324.

  The λ / 4 wavelength plate 323 is a birefringent element that generates a phase difference π / 2 (90 °) between orthogonal polarization components. The λ / 4 wavelength plate 323 has a function of converting the resonance light LL2b generated by the polarizer 322 from linearly polarized light to circularly polarized light (including elliptically polarized light) adjusting light LL2. As described above, the second light source unit 32A includes the λ / 4 wavelength plate 323 that is separate from the λ / 4 wavelength plate 313 of the first light source unit 31, thereby increasing the degree of freedom of installation of the second light source unit 32A. Can do.

  The adjustment light LL2 generated by the λ / 4 wavelength plate 323 is reflected by the mirror 324 and enters the atomic cell 2. Note that the mirror 324 may be omitted. In this case, the second light source 321 and the polarizer 322 may be installed in such a direction that the adjustment light LL2 enters the atomic cell 2.

  In particular, in the present embodiment, as shown in FIG. 13, the adjustment light LL2 enters the internal space S via the body portion 21 of the atomic cell 2. Thereby, it can prevent or reduce that the light-receiving part 4 receives adjustment light LL2. In FIG. 13, the mirror 324 is not shown for convenience of explanation.

  Also according to the second embodiment as described above, the intensity of the EIT signal can be effectively improved.

2. Electronic equipment The atomic oscillator described above can be incorporated into various electronic equipment.

Hereinafter, the electronic apparatus of the present invention will be described.
FIG. 14 is a diagram showing a schematic configuration when the atomic oscillator of the present invention is used in a positioning system using a GPS satellite.

  The positioning system 100 shown in FIG. 14 includes a GPS satellite 200, a base station device 300, and a GPS receiver 400.

The GPS satellite 200 transmits positioning information (GPS signal).
The base station device 300 receives the positioning information from the GPS satellite 200 with high accuracy via, for example, an antenna 301 installed at an electronic reference point (GPS continuous observation station), and the reception device 302 receives the positioning information. And a transmission device 304 that transmits positioning information via the antenna 303.

  Here, the receiving device 302 is an electronic device provided with the above-described atomic oscillator 1 of the present invention as its reference frequency oscillation source. Such a receiving apparatus 302 has excellent reliability. In addition, the positioning information received by the receiving device 302 is transmitted by the transmitting device 304 in real time.

  The GPS receiver 400 includes a satellite receiver 402 that receives positioning information from the GPS satellite 200 via the antenna 401, and a base station receiver 404 that receives positioning information from the base station device 300 via the antenna 403. Prepare.

3. Mobile Object FIG. 15 is a diagram showing an example of the mobile object of the present invention.

  In this figure, a moving body 1500 has a vehicle body 1501 and four wheels 1502, and is configured to rotate the wheels 1502 by a power source (engine) (not shown) provided in the vehicle body 1501. In such a moving body 1500, the atomic oscillator 1 is built.

  Note that the electronic apparatus of the present invention is not limited to the above-described ones. For example, a mobile phone, a digital still camera, an ink jet discharge device (for example, an ink jet printer), a personal computer (a mobile personal computer, a laptop personal computer). , TV, camcorder, video tape recorder, car navigation device, pager, electronic notebook (including communication function), electronic dictionary, calculator, electronic game device, word processor, workstation, video phone, security TV monitor, electronic binoculars POS terminal, medical equipment (eg electronic thermometer, blood pressure monitor, blood glucose meter, electrocardiogram measuring device, ultrasonic diagnostic device, electronic endoscope), fish detector, various measuring equipment, instruments (eg, vehicle, aircraft, ship) Instrumentation) Ito simulator, terrestrial digital broadcasting, cellular base stations, can be applied to the GPS module or the like.

  As described above, the quantum interference device, the atomic oscillator, the electronic device, and the moving body of the present invention have been described based on the illustrated embodiments, but the present invention is not limited to these.

  Moreover, the structure of each part of this invention can be substituted by the thing of the arbitrary structures which exhibit the same function of embodiment mentioned above, and arbitrary structures can also be added. Moreover, you may make it this invention combine arbitrary structures of each embodiment mentioned above.

DESCRIPTION OF SYMBOLS 1 ... Atomic oscillator 1A ... Atomic oscillator 2 ... Atomic cell 3 ... Light source part 3A ... Light source part 4 ... Light receiving part 5 ... Heater 6 ... Temperature sensor 7 ... Magnetic field generation part 8 ... Control part 21 ... Body part 22 ... Window part 23 ... Window part 31 ... First light source part 32 ... Second light source part 32A ... Second light source part 81 ... Temperature control part 82 ... Light source control part 83 ... Magnetic field control unit 100 Positioning system 200 GPS satellite 211 Through-hole 300 Base station device 301 Antenna 302 Reception device 303 Antenna 304 Transmission device 311 First light source 312 Λ / 2 wavelength plate 313 λ / 4 wavelength plate 321 Second light source 322 Polarizer 323 λ / 4 wavelength plate 324 Mirror 400 GPS receiver 401 Antenna 402 Satellite receiver 403 Antenna 404 Ground station receiver 821 ... Frequency controller 822 ... Voltage controlled crystal oscillator 823 ... Phase synchronization circuit 1500 ... Mobile body 1501 ... Car body 1502 ... Wheel a ... Axis line a1 ... Optical axis a2 ... Light Axis LL ... Light LL1 ... Resonant light pair LL1a ... First light LL1b ... Resonant light pair LL2 ... Adjusted light LL2a ... Second light LL2b ... Resonant light P ... Intersection S ... Internal space W ... Width W1 ... Width W2 ... Width ΔE ... Energy difference θ ... Inclination angle θ1 ... Inclination angle θ2 ... Inclination angle ω ₀ ... Frequency ω ₁ ... Frequency ω ₂ ... Frequency

Claims (13)

An atomic cell encapsulating an alkali metal atom ;
A first light source unit that emits a first light including a resonant light pair that is circularly polarized in the same direction and resonates with the alkali metal atom ;
A second light source unit that emits second light that is circularly polarized in the opposite direction to the resonant light pair and has a line width larger than that of the resonant light pair;
A light receiving unit that receives the resonant light pair that has passed through the atomic cell;
A quantum interference device comprising: The second light includes a resonant light to resonate the alkali metal atom, quantum interference device according to claim 1. One of the resonant light pair and the resonant light includes a D1 line,
Wherein one of the resonant light and the resonant light comprises D2 line, quantum interference device according to claim 1 or 2. The wavelength band of the resonant light pair, the second is outside the wavelength band of light, quantum interference device according to any one of claims 1 to 3. The second light source unit, the has a second light-emitting diodes that generate light, quantum interference device according to any one of claims 1 to 4. The quantum interference device according to claim 1 , wherein the second light source unit includes a light source that emits non-polarized light and a polarizer that receives light from the light source. The first light source unit emits light including linearly polarized light component,
The second light source unit emits light including linearly polarized light component,
The light from the light and the second light source section from the first light source unit have a common lambda / 4 wave plate passing through, quantum interference device according to any one of claims 1 to 6. Intensity of the second light is smaller than the intensity of the first light in said atomic cell, quantum interference device according to any one of claims 1 to 7. The first is the optical axis and the optical axis of said second optical light crosses, quantum interference device according to any one of claims 1 to 8. The atomic cell includes a pair of window portions, and a body portion that is disposed between the pair of window portions and forms an internal space in which the metal is sealed together with the pair of window portions; Have
10. The quantum interference device according to claim 1 , wherein the second light passes through the body portion and enters the internal space. 11. 11. The quantum interference device according to claim 1 , wherein in the atomic cell, the first light passage region is included in the second light passage region. 11. It claims 1 to atomic oscillator comprising: a quantum interference device as claimed in any one of 11. An electronic apparatus comprising: a quantum interference device according to any one of claims 1 to 11.

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