JP2014192799A - Atomic oscillator, electronic apparatus and mobile body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an atomic oscillator that has an excellent frequency-temperature characteristic in a simple configuration, and provide a reliable electronic apparatus and mobile body that include the atomic oscillator.SOLUTION: An atomic oscillator 1 includes: a gas cell 2 filled with metal atoms; a light emission section 3 for emitting light for exciting the metal atoms; a light detection section 5 for detecting light transmitted through the metal atoms; and a heater 6 for generating heat to heat the gas cell 2 on energization with a flow of current in a direction to reduce a fluctuation range of frequency in a frequency-temperature characteristic.

Description

  The present invention relates to 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. Is done.

In any of these types of atomic oscillators, for example, as disclosed in Patent Document 1, a gas cell in which an alkali metal is sealed together with a buffer gas, and a light emitting unit that emits light that excites the alkali metal in the gas cell. And a light detection unit that detects light transmitted through the gas cell, and a heater that heats the gas cell.
In such an atomic oscillator, the current supplied to the heater is normally controlled so that the temperature in the gas cell is constant.

In the conventional atomic oscillator, when the current flowing through the heater fluctuates as the outside air temperature changes, the strength of the magnetic field in the gas cell fluctuates due to the fluctuation of the magnetic field generated from the heater, and the ground level of the alkali metal atoms in the gas cell. The frequency corresponding to the energy difference between them fluctuates.
Such frequency fluctuation affects the frequency temperature characteristics of the atomic oscillator (change in oscillation frequency with respect to temperature change).

Therefore, it is conceivable to reduce fluctuations in the strength of the magnetic field in the gas cell.
However, in addition to the above-described change in the magnetic field strength in the gas cell, the type and amount of buffer gas in the gas cell, the temperature characteristics of the circuits constituting the atomic oscillator, etc. also affect the frequency temperature characteristics of the atomic oscillator. . Therefore, the frequency fluctuation range of the frequency temperature characteristic of the atomic oscillator cannot be reduced by simply reducing the fluctuation of the magnetic field strength in the gas cell.
In particular, in recent years, with the miniaturization of atomic oscillators, each part constituting the atomic oscillator is easily affected by changes in the outside air temperature, the type and amount of buffer gas in the gas cell, the temperature characteristics of the circuit constituting the atomic oscillator, etc. Therefore, it is difficult to reduce the frequency fluctuation range of the frequency temperature characteristic of the atomic oscillator.

US Pat. No. 6,320,472

  An object of the present invention is to provide an atomic oscillator having an excellent frequency-temperature characteristic with a simple configuration, and to provide an electronic apparatus and a moving body having such an atomic oscillator and having excellent reliability.

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 atomic oscillator of this application example includes a gas cell in which metal atoms are enclosed,
A light emitting portion that emits light that excites the metal atoms;
A light detection unit for detecting the light that has passed through the metal atom;
A heating unit for heating the gas cell;
A magnetic field generation unit that is electrically connected in series with the heating unit and generates a magnetic field;
It is characterized by providing.
According to such an atomic oscillator, the intensity of the magnetic field of the magnetic field generator varies with a temperature change, so that the intensity change accompanying the temperature change of the magnetic field can be used for adjusting the frequency temperature characteristics of the atomic oscillator. . In addition, since the wiring for energizing the heating unit can be effectively used as the magnetic field generation unit, the configuration can be simplified.

[Application Example 2]
In the atomic oscillator of this application example, it is preferable that the heating unit is energized in a direction in which the frequency fluctuation range in the frequency-temperature characteristic is reduced.
Thereby, the frequency change of the atomic oscillator can be made excellent by effectively utilizing the intensity change accompanying the temperature change of the magnetic field generated from the heating unit for adjusting the frequency temperature characteristic of the atomic oscillator. Therefore, it is possible to provide an atomic oscillator having an excellent frequency temperature characteristic with a simple configuration.

[Application Example 3]
In the atomic oscillator of this application example, the gas cell has a pair of windows that pass the light,
The heating portions are respectively disposed on the pair of window portions,
It is preferable that the magnetic fields generated from the pair of heating units weaken each other in the gas cell.
Thereby, it can prevent that a metal atom condenses on the window part of a gas cell. As a result, the characteristics of the atomic oscillator can be improved over a long period of time. Further, in such a configuration in which the heating unit is provided in the window portion of the gas cell, the distance between the heating unit and the wiring for energizing the heating unit and the metal atom in the gas cell is short. Therefore, the metal atoms in the gas cell are easily affected by the magnetic field generated from the heating unit and the wiring by energization. That is, the influence of the change in the strength of the magnetic field generated from the heating unit on the frequency temperature characteristics of the atomic oscillator is large. Therefore, the magnetic field generated from the heating unit can be efficiently used for adjusting the frequency temperature characteristics.

  In addition, since the magnetic fields generated from the pair of heating units weaken each other in the gas cell, the width of the intensity change accompanying the temperature change of the magnetic field generated from the heating unit can be reduced. Therefore, the adjustment width (adjustment amount) of the frequency temperature characteristic of the atomic oscillator due to the magnetic field generated from the heating unit can be reduced. Therefore, when the frequency fluctuation range of the frequency temperature characteristic due to factors other than the fluctuation of the magnetic field strength acting on the alkali metal in the gas cell is small, the frequency fluctuation range of the frequency temperature characteristic of the atomic oscillator can be reduced.

[Application Example 4]
In the atomic oscillator of this application example, it is preferable that the magnetic field generation unit includes a coil.
Thereby, the magnetic field of a magnetic field generation part can be enlarged. Therefore, the adjustment range of the frequency temperature characteristic of the atomic oscillator by such a magnetic field can be increased.
[Application Example 5]
The atomic oscillator of this application example includes a Zeeman splitting magnetic field generator that generates a Zeeman splitting magnetic field of the metal,
It is preferable that the direction of the magnetic field generated by the magnetic field generator includes a direction component parallel to the direction of the magnetic field causing the Zeeman split in the gas cell.
Thereby, the frequency accuracy of a quantum interference device can be raised. In addition, the adjustment range of the frequency temperature characteristic of the atomic oscillator by the magnetic field of the magnetic field generator can be increased.

[Application Example 6]
In the atomic oscillator of this application example, it is preferable that the magnetic field causing the Zeeman splitting and the magnetic field generated by the heating unit strengthen each other in the gas cell.
Thereby, the width | variety of the intensity | strength change accompanying the temperature change of the magnetic field generated from a heating part and the magnetic field of a magnetic field generation | occurrence | production part can be enlarged. Therefore, the adjustment width (adjustment amount) of the frequency temperature characteristic of the atomic oscillator by the magnetic field generated from the heating unit and the magnetic field of the magnetic field generation unit can be increased. Therefore, when the frequency fluctuation range of the frequency temperature characteristic due to factors other than the fluctuation of the magnetic field strength acting on the alkali metal in the gas cell is large, the frequency fluctuation range of the frequency temperature characteristic of the atomic oscillator can be reduced.

[Application Example 7]
In the atomic oscillator of this application example, it is preferable that the magnetic field causing the Zeeman splitting and the magnetic field generated by the heating unit weaken each other in the gas cell.
Thereby, the width | variety of the intensity | strength change accompanying the temperature change of the magnetic field produced from a heating part and the magnetic field of a magnetic field generation | occurrence | production part can be made small. Therefore, the adjustment width (adjustment amount) of the frequency temperature characteristic of the atomic oscillator by the magnetic field generated from the heating unit and the magnetic field of the magnetic field generation unit can be reduced. Therefore, when the frequency fluctuation range of the frequency temperature characteristic due to factors other than the fluctuation of the magnetic field strength acting on the alkali metal in the gas cell is small, the frequency fluctuation range of the frequency temperature characteristic of the atomic oscillator can be reduced.

[Application Example 8]
An electronic apparatus according to this application example includes the atomic oscillator according to this application example.
Thereby, an electronic device with excellent reliability can be provided.
[Application Example 9]
The moving body of this application example includes the atomic oscillator of this application example.
Thereby, the moving body excellent in reliability 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 the energy state of the alkali metal in the gas cell of the atomic oscillator shown in FIG. 2 is a graph showing the relationship between the frequency difference between two lights from a light emitting part and the detection intensity at the light detecting part for the light emitting part and the light detecting part of the atomic oscillator shown in FIG. 1. It is a longitudinal cross-sectional view which shows the gas cell of the atomic oscillator shown in FIG. 1, a heater, a 1st magnetic field generation part, and a 2nd magnetic field generation part. It is a cross-sectional view which shows the gas cell of the atomic oscillator shown in FIG. 1, a heater, a 1st magnetic field generation part, and a 2nd magnetic field generation part. It is a figure for demonstrating the magnetic field (magnetic field at the time of flowing the electric current of a 1st direction through a heater) from the heater shown in FIG. 5, a 1st magnetic field generation part, and a 2nd magnetic field generation part. It is a figure for demonstrating the magnetic field (magnetic field at the time of flowing the electric current of a 2nd direction through a heater) from the heater shown in FIG. 5, a 1st magnetic field generation part, and a 2nd magnetic field generation part. (A) is a graph which shows the relationship between external temperature and heater electric current, (b) is a graph which shows the relationship between external temperature and the magnetic field intensity in a gas cell. It is a graph which shows the relationship between the magnetic field intensity in a gas cell, and the frequency difference of the two lights from a light-projection part. It is a graph which shows the relationship between external temperature and the frequency difference of the two lights from a light-projection part. It is a figure which shows an example of the frequency temperature characteristic of the atomic oscillator shown in FIG. It is a figure which shows the other example of the frequency temperature characteristic of the atomic oscillator shown in FIG. FIG. 6 is a diagram for explaining a first modification of the atomic oscillator shown in FIG. 1. FIG. 6 is a diagram for explaining a second modification of the atomic oscillator shown in FIG. 1. FIG. 6 is a diagram for explaining a third modification of the atomic oscillator shown in FIG. 1. It is a longitudinal cross-sectional view which shows the gas cell, heater, 1st magnetic field generation part, and 2nd magnetic field generation part of the atomic oscillator which concern on 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which shows the gas cell, heater, 1st magnetic field generation part, and 2nd magnetic field generation part of the atomic oscillator which concern on 3rd Embodiment of this invention. It is a figure for demonstrating the magnetic field (magnetic field at the time of flowing the electric current of a 1st direction through a heater) from the heater shown in FIG. 17, a 1st magnetic field generation part, and a 2nd magnetic field generation part. It is a figure for demonstrating the modification of the atomic oscillator shown in FIG. It is a figure which shows schematic structure at the time of using the electronic device of this invention for the positioning system using a GPS satellite. It is a schematic block diagram which shows an example of the clock transmission system using the atomic oscillator of this invention. It is a figure which shows an example of the moving body of this invention.

Hereinafter, an atomic oscillator, an electronic apparatus, and a moving body of the present invention will be described in detail based on embodiments shown in the accompanying drawings.
1. Atomic Oscillator First, the atomic oscillator of the present invention will be described.
<First Embodiment>
FIG. 1 is a schematic diagram showing an atomic oscillator (quantum interference device) according to a first embodiment of the present invention. 2 is a diagram for explaining the energy state of the alkali metal in the gas cell of the atomic oscillator shown in FIG. 1, and FIG. 3 shows the light emission for the light emitting part and the light detecting part of the atomic oscillator shown in FIG. It is a graph which shows the relationship between the frequency difference of the two lights from a part, and the detection intensity in a photon detection part. 4 is a longitudinal sectional view showing the gas cell, heater, first magnetic field generator and second magnetic field generator of the atomic oscillator shown in FIG. 1, and FIG. 5 is a gas cell of the atomic oscillator shown in FIG. It is a cross-sectional view showing a first magnetic field generator and a second magnetic field generator.

4 to 7, for convenience of explanation, the X axis, the Y axis, and the Z axis are illustrated as three axes orthogonal to each other, and the tip side of each illustrated arrow is indicated by “+ (plus)”. ", The base end side is"-(minus) ". Hereinafter, for convenience of explanation, a direction parallel to the X axis is referred to as an “X axis direction”, a direction parallel to the Y axis is referred to as a “Y axis direction”, and a direction parallel to the Z axis is referred to as a “Z axis direction”.
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 a gas cell 2, a light emitting unit 3, optical components 41, 42, 43, 44, a light detecting unit 5, a heater 6, a temperature sensor 7, 1 magnetic field generation part 8 (Zeeman splitting magnetic field generation part), 2nd magnetic field generation part 9 (magnetic field generation part), and control part 10 are provided.
In addition, the atomic oscillator 1 includes a shield 20 (see FIGS. 4 and 5).

First, the principle of the atomic oscillator 1 will be briefly described.
In the atomic oscillator 1, gaseous alkali metal (metal atom) such as rubidium, cesium, or sodium is enclosed in the gas cell 2.
As shown in FIG. 2, the alkali metal has a three-level energy level, and has three ground states (ground states 1 and 2) having different energy levels and an excited state. Can take. Here, the ground state 1 is a lower energy state than the ground state 2.

When two types of resonant lights 1 and 2 having different frequencies are irradiated onto such a gaseous alkali metal, the above-described gaseous alkali metal is irradiated with the frequency ω 1 of the resonant light 1 and the frequency ω 2 of the resonant light 2. In accordance with the difference (ω1-ω2), the light absorptivity (light transmittance) of the resonance lights 1 and 2 in the alkali metal changes.
When the difference (ω1−ω2) between the frequency ω1 of the resonant light 1 and the frequency ω2 of the resonant light 2 matches the frequency corresponding to the energy difference between the ground state 1 and the ground state 2, the ground states 1 and 2 Each excitation to the excited state stops. At this time, both the resonant lights 1 and 2 are transmitted without being absorbed by the alkali metal. Such a phenomenon is called a CPT phenomenon or an electromagnetically induced transparency (EIT) phenomenon.
The light emitting unit 3 emits two types of light (resonant light 1 and resonant light 2) having different frequencies as described above toward the gas cell 2.

Here, for example, when the frequency ω1 of the resonant light 1 is fixed and the frequency ω2 of the resonant light 2 is changed, the difference (ω1−ω2) between the frequency ω1 of the resonant light 1 and the frequency ω2 of the resonant light 2 is obtained. When the frequency ω 0 corresponding to the energy difference between the ground state 1 and the ground state 2 coincides with the frequency ω 0, the detection intensity of the light detection unit 5 increases sharply as shown in FIG. Such a steep signal is called an EIT signal. This EIT signal has an eigenvalue determined by the type of alkali metal. Therefore, by using such an EIT signal as a reference, a highly accurate oscillator can be realized.
Further, the above-described frequency ω0 varies depending on the strength of the magnetic field acting on the alkali metal (see FIG. 9). This point will be described in detail later together with the frequency temperature characteristics of the atomic oscillator 1 described later.

Hereinafter, each part of the atomic oscillator 1 will be described in detail sequentially.
[Gas cell]
The gas cell 2 is filled with gaseous alkali metals such as rubidium, cesium and sodium.
As shown in FIG. 4, the gas cell 2 includes a main body portion 21 having a columnar through hole, and a pair of window portions 22 and 23 that block both openings of the through hole. Thereby, the internal space S in which the alkali metal as described above is enclosed is formed.

Here, each window part 22 and 23 of the gas cell 2 has the permeability | transmittance with respect to the excitation light from the light-projection part 3 mentioned above. One window portion 22 is an incident-side window portion into which the excitation light LL enters the gas cell 2, and the other window portion 23 is an emission-side window portion from which the excitation light LL is emitted from the gas cell 2.
Further, each of the window portions 22 and 23 has a plate shape, and is installed so that its plate surface is perpendicular to the axis a of the excitation light LL.

The material constituting the window portions 22 and 23 of the gas cell 2 is not particularly limited as long as it has transparency to the excitation light as described above, and examples thereof include a glass material and crystal.
Moreover, the material which comprises the main-body part 21 of the gas cell 2 is not specifically limited, A metal material, a resin material, etc. may be sufficient and a glass material, a crystal | crystallization, etc. may be sufficient like the window parts 22 and 23. FIG.

The window portions 22 and 23 are airtightly joined to the main body portion 21. Thereby, the internal space S of the gas cell 2 can be made into an airtight space.
The joining method of the main body 21 and the window parts 22 and 23 of the gas cell 2 is determined according to these constituent materials, and is not particularly limited. For example, a joining method using an adhesive, a direct joining method, an anode A bonding method or the like can be used.
Further, the temperature of the gas cell 2 is adjusted to, for example, about 70 ° C. by the heater 6.

[light source]
The light emitting unit 3 has a function of emitting excitation light LL that excites alkali metal atoms in the gas cell 2.
More specifically, the light emitting unit 3 emits two types of light (resonant light 1 and resonant light 2) having different frequencies as described above as the excitation light LL.

The resonant light 1 can excite the alkali metal in the gas cell 2 from the ground state 1 to the excited state. On the other hand, the resonance light 2 can excite the alkali metal in the gas cell 2 from the ground state 2 to the excited state.
Further, the axis a of the excitation light LL is parallel to the Y-axis direction in the gas cell 2.
The light emitting unit 3 is not particularly limited as long as it can emit the excitation light as described above. For example, a semiconductor laser such as a vertical cavity surface emitting laser (VCSEL) can be used.
Such a light emission part 3 is connected to the excitation light control part 12 of the control part 10 mentioned later, and is drive-controlled based on the detection result of the light detection part 5 (refer FIG. 1).
In addition, the temperature of the light emitting unit 3 is adjusted to, for example, about 30 ° C. by a temperature adjusting element (a heating resistor, a Peltier element, etc.) (not shown).

[Optical parts]
The plurality of optical components 41, 42, 43, and 44 are respectively provided on the axis a of the excitation light LL between the light emitting unit 3 and the gas cell 2 described above.
Further, the optical component 41, the optical component 42, the optical component 43, and the optical component 44 are arranged in this order from the light emitting portion 3 side to the gas cell 2 side.

The optical component 41 is a lens. Thereby, the excitation light LL can be irradiated to the gas cell 2 without waste.
The optical component 41 has a function of making the excitation light LL a parallel light. Thereby, it is possible to easily and reliably prevent the excitation light LL from being reflected by the inner wall of the gas cell 2. For this reason, resonance of excitation light in the gas cell 2 is preferably generated, and as a result, the oscillation characteristics of the atomic oscillator 1 can be enhanced.

The optical component 42 is a polarizing plate. Thereby, the polarization of the excitation light LL from the light emitting part 3 can be adjusted in a predetermined direction.
The optical component 43 is a neutral density filter (ND filter). Thereby, the intensity of the excitation light LL incident on the gas cell 2 can be adjusted (decreased). Therefore, even when the output of the light emitting unit 3 is large, the excitation light incident on the gas cell 2 can be set to a desired light amount. In the present embodiment, the optical component 43 adjusts the intensity of the excitation light LL having polarized light in a predetermined direction that has passed through the optical component 42 described above.
The optical component 44 is a λ / 4 wavelength plate. Thereby, the excitation light LL from the light emitting unit 3 can be converted from linearly polarized light into circularly polarized light (right circularly polarized light or left circularly polarized light).

  As will be described later, in the state where the alkali metal atoms in the gas cell 2 are Zeeman split by the magnetic field of the first magnetic field generator 8, if the alkali metal atoms are irradiated with linearly polarized excitation light, the mutual excitation light and alkali metal atoms are Due to the action, the alkali metal atoms are present evenly dispersed in a plurality of Zeeman split levels. As a result, the number of alkali metal atoms at a desired energy level is relatively small with respect to the number of alkali metal atoms at other energy levels, so that the number of atoms that develop a desired EIT phenomenon is reduced and desired. As a result, the oscillation characteristics of the atomic oscillator 1 are deteriorated.

  On the other hand, when the alkali metal atoms are irradiated with circularly polarized excitation light in a state where the alkali metal atoms in the gas cell 2 are Zeeman split by the magnetic field of the first magnetic field generator 8 as described later, the excitation light and the alkali metal atoms The number of alkali metal atoms at the desired energy level is relatively higher than the number of alkali metal atoms at other energy levels among the multiple levels where the alkali metal atoms are Zeeman split due to the interaction with can do. Therefore, the number of atoms that develop the desired EIT phenomenon increases, and the intensity of the desired EIT signal increases, and as a result, the oscillation characteristics of the atomic oscillator 1 can be improved.

[Photodetection section]
The light detection unit 5 has a function of detecting the intensity of the excitation light LL (resonance light 1 and 2) transmitted through the gas cell 2.
The photodetector 5 is not particularly limited as long as it can detect the excitation light as described above. For example, a photodetector (light receiving element) such as a solar cell or a photodiode can be used.
Such a light detection unit 5 is connected to an excitation light control unit 12 of the control unit 10 described later (see FIG. 1).

[heater]
The heater 6 (heating unit) has a function of heating the above-described gas cell 2 (more specifically, an alkali metal in the gas cell 2). Thereby, the alkali metal in the gas cell 2 can be maintained in a gaseous state with an appropriate concentration.
The heater 6 generates heat when energized (direct current), and includes heating resistors 61 and 62 provided on the outer surface of the gas cell 2 as shown in FIG.

Here, the heating resistor 61 is provided on the window portion 22 (incident side window portion) of the gas cell 2, and the heating resistor 62 is provided on the window portion 23 (outgoing side window portion) of the gas cell 2. By disposing the heating resistors 61 and 62 in the window portions 22 and 23, it is possible to prevent alkali metal atoms from condensing on the window portions 22 and 23 of the gas cell 2. As a result, the characteristics (oscillation characteristics) of the atomic oscillator 1 can be made excellent over a long period of time.
Thereby, it is possible to prevent the alkali metal atoms from condensing on the windows 22 and 23. As a result, excellent oscillation characteristics can be exhibited over a long period of time.

Such heating resistors 61 and 62 are made of a material having transparency to excitation light, specifically, for example, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), In ₃ O ₃ , SnO ₂ , Sb. formed of a transparent electrode material such as an oxide, such as containing _SnO 2, Al-containing ZnO.
The heating resistors 61 and 62 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 deposition, a sol-gel method, or the like.

  As will be described in detail later, such a heater 6 generates a magnetic field when it generates heat when energized. However, since this magnetic field changes with a change in the outside air temperature, it acts on the alkali metal in the gas cell 2. This causes a change in the strength of the magnetic field. As will be described in detail later, when the magnetic field strength in the gas cell 2 (that is, the strength of the magnetic field acting on the alkali metal) fluctuates, the frequency difference ω0 of the excitation light LL that causes the EIT signal to fluctuate, and the frequency of the atomic oscillator 1 Affects temperature characteristics.

  In particular, in the configuration in which the heating resistors 61 and 62 are provided in the windows 22 and 23 of the gas cell 2 as described above, wiring for energizing the heating resistors 61 and 62 and the heating resistors 61 and 62 ( The distance between the second magnetic field generator 9 and the alkali metal atom in the gas cell 2 is short. Therefore, the metal atoms in the gas cell 2 are easily affected by the magnetic field generated from the heating resistors 61 and 62 and the wiring due to energization. That is, the influence of the change in the strength of the magnetic field generated from the heater 6 on the frequency temperature characteristic of the atomic oscillator 1 is large. Therefore, the magnetic field generated from the heater 6 can be efficiently used for adjusting the frequency temperature characteristics.

Therefore, the direction (direction) of the current flowing through the heater 6 is a direction in which the fluctuation range of the frequency in the frequency temperature characteristic is reduced. The direction of the current flowing through the heater 6 and the action of the magnetic field from the heater 6 will be described in detail later together with the frequency temperature characteristics of the atomic oscillator 1 described later.
The heater 6 is not particularly limited as long as it can heat the gas cell 2, and may be non-contact with the gas cell 2. Further, the gas cell 2 may be heated using a Peltier element instead of the heater 6 or in combination with the heater 6.
Such a heater 6 is electrically connected to a temperature control unit 11 of the control unit 10 described later and energized (see FIG. 1). The heater 6 is electrically connected in series to the second magnetic field generator 9.

[Temperature sensor]
The temperature sensor 7 detects the temperature of the heater 6 or the gas cell 2. Based on the detection result of the temperature sensor 7, the amount of heat generated by the heater 6 is controlled. Thereby, the alkali metal atom in the gas cell 2 can be maintained at a desired temperature.
The installation position of the temperature sensor 7 is not particularly limited, and may be on the heater 6 or on the outer surface of the gas cell 2, for example.
The temperature sensor 7 is not particularly limited, and various known temperature sensors such as a thermistor and a thermocouple can be used.
Such a temperature sensor 7 is electrically connected to a temperature control unit 11 of the control unit 10 to be described later via a wiring (not shown) (see FIG. 1).

[First magnetic field generator (Zeeman splitting magnetic field generator)]
The first magnetic field generator 8 has a function of generating a first magnetic field (hereinafter also simply referred to as “first magnetic field”) that causes Zeeman splitting of a plurality of energy levels of the alkali metal degenerated in the gas cell 2. Thereby, by Zeeman splitting, the gap between different energy levels in which the alkali metal is degenerated can be widened to improve the resolution. As a result, the accuracy of the oscillation frequency of the atomic oscillator 1 can be increased. Further, by appropriately setting the intensity of the first magnetic field, the adjustment width (adjustment amount) of the frequency temperature characteristic of the atomic oscillator 1 by the magnetic field generated from the heater 6 and the second magnetic field generation unit 9 as described later can be increased. it can.

Here, the direction of the first magnetic field in the gas cell 2 is along a direction perpendicular to the axis a of the excitation light LL (specifically, the X-axis direction).
As shown in FIGS. 4 and 5, the first magnetic field generator 8 has a pair of coils 81 and 82 (first coils) arranged side by side in the X-axis direction.
The pair of coils 81 and 82 constitutes a Helmholtz coil arranged so as to sandwich the gas cell 2. As a result, a uniform first magnetic field can be generated between the pair of coils 81 and 82. Therefore, a uniform first magnetic field can be generated in the gas cell 2. Further, the optical path of the excitation light LL can be set so as to penetrate between the pair of coils 81 and 82 constituting the Helmholtz coil in the Z-axis direction.

In the present embodiment, the pair of coils 81 and 82 each have an annular shape. The pair of coils 81 and 82 are arranged concentrically and supported by a support member (not shown) so that their central axes pass through the center of the gas cell 2. The pair of coils 81 and 82 have the same diameter.
Each of the coils 81 and 82 is not limited to an annular shape, and may be a square annular shape, for example.

Such a pair of coils 81 and 82 is electrically connected to a power source (not shown), and generates a first magnetic field when energized.
The first magnetic field generated by the first magnetic field generator 8 is a constant magnetic field (DC magnetic field), but an alternating magnetic field may be superimposed thereon.
Further, the strength of the first magnetic field in the gas cell 2 can be appropriately set according to the position, shape, size, number of turns, resistance value of the coils 81, 82, the magnitude of the current flowing through the coils 81, 82, and the like.
Such a 1st magnetic field generation part 8 is electrically connected to the magnetic field control part 13 of the control part 10 mentioned later, and energization is controlled (refer FIG. 1).

[Second magnetic field generator (magnetic field generator)]
The second magnetic field generator 9 is electrically connected in series to the heater 6 and has a function of generating a second magnetic field (hereinafter, also simply referred to as “second magnetic field”) that acts in the gas cell 2. Thereby, since the intensity of the second magnetic field varies with the temperature change, the intensity change accompanying the temperature change of the second magnetic field can be used for adjusting the frequency temperature characteristic of the atomic oscillator 1. In addition, since the wiring for energizing the heater 6 can be effectively used as the second magnetic field generator 9, the configuration can be simplified.

Here, the direction of the second magnetic field in the gas cell 2 is along a direction perpendicular to the axis a of the excitation light LL (specifically, the X-axis direction).
As shown in FIGS. 4 and 5, the second magnetic field generation unit 9 includes a pair of coils 91 and 92 (second coils) arranged side by side in the X-axis direction. Thereby, a 2nd magnetic field can be enlarged. Therefore, the adjustment range of the frequency temperature characteristic of the atomic oscillator 1 by the second magnetic field can be increased.

  The pair of coils 91 and 92 constitutes a Helmholtz coil disposed so as to sandwich the gas cell 2. As a result, a uniform second magnetic field can be generated between the pair of coils 91 and 92. Therefore, a uniform second magnetic field can be generated in the gas cell 2. Further, the optical path of the excitation light LL can be set so as to penetrate between the pair of coils 91 and 92 constituting the Helmholtz coil in the Z-axis direction.

The pair of coils 91 and 92 is disposed between the pair of coils 81 and 82 described above. Thereby, the magnetic field generated from the pair of coils 91 and 92 can be efficiently applied to the alkali metal in the gas cell 2. Further, the wiring between the coils 91 and 92 and the heater 6 can be shortened, and generation of a magnetic field having an unnecessary direction component due to the wiring can be suppressed.
In the present embodiment, each of the pair of coils 91 and 92 has an annular shape. The pair of coils 91 and 92 are arranged concentrically and supported by a support member (not shown) so that their central axes pass through the center of the gas cell 2. The pair of coils 91 and 92 have the same diameter.

Each of the coils 91 and 92 is not limited to an annular shape, and may be a square annular shape, for example.
Such a pair of coils 91 and 92 is electrically connected to a power source (not shown) while being electrically connected in series to the heater 6, and generates a second magnetic field when energized.
Here, since the second magnetic field generation unit 9 is subjected to energization control common to the heater 6, the magnetic field (second magnetic field) generated by the second magnetic field generation unit 9 is a DC magnetic field. Further, the intensity of the second magnetic field changes according to the amount of current supplied to the heater 6. The direction of the current flowing through the second magnetic field generation unit 9 and the action of the magnetic field from the second magnetic field generation unit 9 will be described later together with the description of the frequency temperature characteristics of the atomic oscillator 1 described later.

Further, the intensity of the second magnetic field in the gas cell 2 can be appropriately set according to the position, shape, size, number of turns, resistance value, and the like of the coils 91 and 92. Moreover, since the coils 91 and 92 are each provided in the middle of the wiring for energizing the heater 6, they can be formed using such wiring.
Such a 2nd magnetic field generation part 9 is electrically connected to the temperature control part 11 of the control part 10 mentioned later, and electricity supply control is carried out (refer FIG. 1).

[shield]
The shield 20 is provided so as to surround the gas cell 2, the heater 6, the first magnetic field generation unit 8, and the second magnetic field generation unit 9 described above, and has a magnetic shielding property. Thereby, it is possible to prevent magnetic fields other than the magnetic field from the heater 6, the first magnetic field, and the second magnetic field from acting on the alkali metal atoms in the gas cell 2. Therefore, the adjustment of the frequency temperature characteristics by the magnetic field from the heater 6 and the second magnetic field becomes easier.

In the present embodiment, the shield 20 has a cylindrical shape.
The shield 20 may also serve as a casing that houses the gas cell 2, the heater 6, the first magnetic field generator 8, and the second magnetic field generator 9.
As a constituent material of the shield 20, any material having magnetic shielding properties may be used. For example, a ferromagnetic material such as iron, cobalt, or nickel can be used.

[Control unit]
The control unit 10 illustrated in FIG. 1 has a function of controlling the light emitting unit 3, the heater 6, the first magnetic field generation unit 8, and the second magnetic field generation unit 9.
The control unit 10 includes an excitation light control unit 12 that controls the frequencies of the resonant lights 1 and 2 of the light emitting unit 3, a temperature control unit 11 that controls the temperature of the alkali metal in the gas cell 2, and a first magnetic field generation unit. And a magnetic field control unit 13 for controlling the second magnetic field from 8.

  The excitation light control unit 12 controls the frequencies of the resonant lights 1 and 2 emitted from the light emitting unit 3 based on the detection result of the light detecting unit 5 described above. More specifically, the excitation light control unit 12 is emitted from the light emission unit 3 so that (ω1-ω2) detected by the light detection unit 5 described above becomes the frequency ω0 specific to the alkali metal described above. The frequency of the resonant lights 1 and 2 is controlled. In addition, the excitation light control unit 12 controls the center frequency of the resonant lights 1 and 2 emitted from the light emitting unit 3.

Although not shown, the excitation light control unit 12 includes a voltage controlled crystal oscillator (oscillation circuit), and the oscillation frequency of the voltage controlled crystal oscillator is synchronized and adjusted based on the detection result of the light detection unit 5. While being output as an output signal of the atomic oscillator 1.
Further, the temperature control unit 11 controls energization to the heater 6 based on the detection result of the temperature sensor 7. Thereby, the gas cell 2 can be maintained within a desired temperature range.

Here, since the second magnetic field generation unit 9 is electrically connected in series to the heater 6, the temperature control unit 11 supplies the second magnetic field generation unit 9 to the second magnetic field generation unit 9 based on the detection result of the temperature sensor 7. It also controls energization. Therefore, the energization amount to the second magnetic field generation unit 9 changes according to the energization amount to the heater 6.
The magnetic field controller 13 controls energization of the first magnetic field generator 8 (coils 81 and 82) so that the first magnetic field generated by the first magnetic field generator 8 is constant.

The magnetic field controller 13 controls energization to the second magnetic field generator 9 (coils 91 and 92). Here, the magnetic field control unit 13 may control the magnetic field generated by the second magnetic field generation unit 9 to be constant, or the magnetic field generated by the second magnetic field generation unit 9 may be set to an energization amount to the heater 6. You may control so that it may change according to it.
Such a control unit 10 is provided, for example, on an IC chip mounted on a substrate.

(Frequency temperature characteristics of atomic oscillator)
Here, the frequency-temperature characteristic of the atomic oscillator 1 described above will be described with reference to FIGS.
FIG. 6 is a diagram for explaining the magnetic fields from the heater, the first magnetic field generation unit, and the second magnetic field generation unit shown in FIG. 5 (magnetic field when a current in the first direction flows through the heater), and FIG. It is a figure for demonstrating the magnetic field (magnetic field at the time of flowing the electric current of a 2nd direction through a heater) from the heater shown in FIG. 5, a 1st magnetic field generation part, and a 2nd magnetic field generation part. FIG. 8A is a graph showing the relationship between the outside air temperature and the heater current, and FIG. 8B is a graph showing the relationship between the outside air temperature and the magnetic field strength in the gas cell. FIG. 9 is a graph showing the relationship between the magnetic field intensity in the gas cell and the frequency difference between the two lights from the light emitting part, and FIG. 10 is the relationship between the outside temperature and the frequency difference between the two lights from the light emitting part. It is a graph which shows a relationship. 11 is a diagram showing an example of the frequency temperature characteristic of the atomic oscillator shown in FIG. 1, and FIG. 12 is a diagram showing another example of the frequency temperature characteristic of the atomic oscillator shown in FIG.

As described above, the direction (direction) of the current flowing through the heater 6 is a direction in which the frequency fluctuation range in the frequency temperature characteristic of the atomic oscillator 1 (change in oscillation frequency (frequency of output signal) with respect to temperature change) becomes smaller. ing.
The frequency-temperature characteristic of the atomic oscillator 1 (hereinafter, also simply referred to as “frequency-temperature characteristic”) is determined by the influence of the temperature characteristics of each part constituting the atomic oscillator 1.

Among the temperature characteristics of each part constituting the atomic oscillator 1, there is a temperature characteristic of the frequency difference ω 0 of the excitation light LL in which the alkali metal in the gas cell 2 causes the EIT phenomenon, which affects the frequency temperature characteristic. In addition, the temperature characteristics of a circuit (for example, a circuit constituting the control unit 10) included in the atomic oscillator 1 also affects the frequency temperature characteristics.
The temperature characteristic of the frequency difference ω0 varies depending on, for example, the type and amount of the buffer gas enclosed in the gas cell 2 together with the alkali metal.

More specifically, the temperature characteristic of the frequency difference ω0 due to the type and amount of the buffer gas is, for example, positive when the temperature increases when neon (Ne) is sealed as the buffer gas in the gas cell 2. When the gas cell 2 is filled with only argon (Ar) as a buffer gas, the gas cell 2 has a negative slope with respect to an increase in temperature.
Theoretically, neon (Ne) and argon (Ar) are blended at an appropriate ratio and sealed in the gas cell 2, so that the temperature characteristic of the frequency difference ω0 caused by the type and amount of the buffer gas can be expressed as temperature. Can flatten against increase.

However, in actuality, due to an error in the amount of buffer gas sealed in the gas cell 2, the temperature characteristic of the frequency difference ω0 caused by the type and amount of buffer gas has a slight inclination with respect to the increase in temperature. Become.
Also, the temperature characteristics of the circuit included in the atomic oscillator 1 have a positive or negative slope with respect to the temperature increase.

By the way, when the intensity of the magnetic field acting on the alkali metal in the gas cell 2 varies, the frequency difference ω0 varies. Specifically, as shown in FIG. 9, the frequency difference ω0 is minimized when the magnetic field strength in the gas cell 2 becomes zero, and increases in a quadratic function as the absolute value of the magnetic field strength increases. To do.
Therefore, the temperature characteristic of the frequency difference ω0 can be adjusted by changing the intensity of the magnetic field in the gas cell 2 in accordance with the temperature change (change in the outside air temperature).

On the other hand, as described above, the magnetic fields from the heater 6 and the second magnetic field generator 9 change according to the outside air temperature.
Therefore, in the atomic oscillator 1, the intensity change accompanying the temperature change of the magnetic field generated from the heater 6 and the second magnetic field generator 9 is effectively used for adjusting the frequency temperature characteristic. Thereby, the atomic oscillator 1 having excellent frequency temperature characteristics can be realized with a simple configuration.

Hereinafter, the adjustment of the frequency temperature characteristic will be described.
As described above, the stationary magnetic field generated from the first magnetic field generator 8 and the variable magnetic field generated from the heater 6 and the second magnetic field generator 9 act in the gas cell 2.
The polarity of the first magnetic field generator 8 is set so that currents in the directions d13 and d14 shown in FIGS.

Here, the directions d13 and d14 are counterclockwise directions when viewed from the + X side.
Therefore, the direction of the first magnetic field, which is a stationary magnetic field generated from the first magnetic field generator 8, is the + X direction in the gas cell 2. Hereinafter, the first magnetic field in the gas cell 2 is referred to as “first magnetic field G1”.

On the other hand, the heater 6 has directions d11 and d12 (first direction) of current flowing in the heating resistors 61 and 62 shown in FIG. 6 and directions d21 and d22 (current directions) flowing in the heating resistors 61 and 62 shown in FIG. The polarity is set so that the current flows in the direction in which the frequency fluctuation range in the frequency temperature characteristic becomes smaller in the second direction (the second direction opposite to the first direction).
Here, as shown in FIG. 6, in the second magnetic field generation unit 9, when currents in the directions d11 and d12 flow through the heating resistors 61 and 62, currents in the directions d15 and d16 flow through the coils 91 and 92. As shown in FIG. 7, when currents in the directions d21 and d22 are passed through the heating resistors 61 and 62, currents in directions d25 and d26 that are opposite to the directions d15 and d16 flow through the coils 91 and 92, respectively.

Hereinafter, a first state in which currents in the directions d11 and d12 are passed through the heating resistors 61 and 62 (hereinafter simply referred to as “first state”), and a current in the directions d21 and d22 are passed through the heating resistors 61 and 62, respectively. Two states (hereinafter also simply referred to as “second state”) will be described respectively.
(First state)
In the first state, as shown in FIG. 6, a current flows through the heating resistor 61 in the direction d11 that is the + Y direction. On the other hand, a current flows through the heating resistor 62 in the direction d12 that is the −Y direction, that is, in the direction opposite to the direction d11 of the current flowing through the heating resistor 61.

The direction of the magnetic field generated from the heater 6 is the + X direction in the gas cell 2. That is, the direction of the magnetic field generated from the heater 6 is the same direction (the same direction) as the direction of the first magnetic field G 1 described above in the gas cell 2. Hereinafter, the magnetic field from the heater 6 in the gas cell 2 is referred to as “magnetic field G2”.
In the first state, as shown in FIG. 6, current flows through the coils 91 and 92 in the counterclockwise directions d15 and d16 when viewed from the + X side.

Therefore, in the first state, the direction of the second magnetic field, which is a variable magnetic field generated from the second magnetic field generator 9, is the + X direction in the gas cell 2. That is, the direction of the second magnetic field is the same direction (same direction) as the direction of the first magnetic field G1 and the magnetic field G2 described above in the gas cell 2. Hereinafter, the second magnetic field in the gas cell 2 is referred to as “second magnetic field G3”.
For this reason, in the first state, the magnetic field G (hereinafter simply referred to simply as the sum of the first magnetic field G1, the magnetic field G2 from the heater 6 and the second magnetic field G3) is added to the alkali metal atoms in the gas cell 2. "Magnetic field G") acts.

Here, the energization amount to the heater 6 changes as the outside air temperature changes. Specifically, as shown in FIG. 8 (a), when the outside air temperature is increased from T ₁ to T _2, the current flowing through the heater 6 is decreased. Therefore, as shown in FIG. 8B, when the outside air temperature rises from T ₁ to T ₂ , the strengths of the magnetic field G 2 and the second magnetic field G 3 also decrease, and accordingly, the strength of the magnetic field G changes from H _4. reduced to H _3.

(Second state)
In the second state, as shown in FIG. 7, a current flows through the heating resistor 61 in the direction d21 that is the −Y direction. On the other hand, the current flows through the heating resistor 62 in the direction d22 that is the + Y direction, that is, in the direction opposite to the direction d21 of the current flowing through the heating resistor 61.
Further, the direction of the magnetic field G <b> 2 generated from the heater 6 is the −X direction in the gas cell 2. That is, the direction of the magnetic field G2 generated from the heater 6 is the opposite direction (opposite direction) to the direction of the first magnetic field G1 described above in the gas cell 2.

Further, in the first state, as shown in FIG. 7, when the coils 91 and 92 are viewed from the + X side, current flows in the clockwise directions d25 and d26.
Therefore, in the second state, the direction of the second magnetic field G3, which is a variable magnetic field generated from the second magnetic field generation unit 9, is the −X direction in the gas cell 2. That is, the direction of the second magnetic field G3 is opposite to the direction of the first magnetic field G1 described above (opposite direction) in the gas cell 2.

For this reason, in the second state, a magnetic field G having a strength obtained by subtracting the magnetic field G2 from the heater 6 and the second magnetic field G3 from the first magnetic field G1 acts on the alkali metal atoms in the gas cell 2.
Here, as shown in FIG. 8 (b), when the outside air temperature is increased from _{T 1} to _{T 2,} the strength of the magnetic field G2 and the second magnetic field G3 decreases, the strength of the magnetic field G is _{H 2} from _{H 1} To increase.

Thus, in the first state, the magnetic field G decreases as the outside air temperature increases, whereas in the second state, the magnetic field G increases as the outside air temperature increases.
When the outside air temperature rises from T ₁ to T ₂ , as shown in FIG. 9, in the first state, the frequency difference ω ₀ is, for example, f ₄ due to the decrease in the intensity of the magnetic field G from H ₄ to H ₃ . reduced to _{f 3} from. On the other hand, in the second state, the frequency difference ω ₀ increases from, for example, f ₁ to f ₂ due to the increase in the intensity of the magnetic field G from H ₁ to H ₂ .

That is, as shown in FIG. 10, in the first state, when the outside air temperature increases from T ₁ to T ₂ , the frequency difference ω ₀ decreases linearly from, for example, f ₄ to f ₃ . On the other hand, in the second state, when the outside air temperature rises from T ₁ to T ₂ , the frequency difference ω ₀ increases linearly from, for example, f ₁ to f ₂ .
Thus, the temperature characteristic of the frequency difference ω ₀ varies depending on the difference in the direction of the current flowing through the heater 6 and the second magnetic field generator 9.

Therefore, the frequency temperature characteristic can be easily adjusted by selecting one of the first state and the second state described above.
In particular, in the atomic oscillator 1, the direction of the second magnetic field is along the direction parallel to the direction of the first magnetic field in the gas cell 2. Thereby, the adjustment range of the frequency temperature characteristic of the atomic oscillator 1 by the second magnetic field can be increased.

If the direction of the second magnetic field includes a direction component parallel to the direction of the first magnetic field in the gas cell 2, the frequency temperature characteristics of the atomic oscillator 1 can be effectively adjusted by the second magnetic field. it can.
In the present embodiment, the magnetic field generated from the heating resistor 61 between the heating resistor 61 and the heating resistor 62 by changing the direction of the current flowing through the heating resistors 61 and 62 in the opposite direction, The magnetic field generated from the heating resistor 62 strengthens each other.

  That is, the magnetic fields generated from the pair of heating resistors 61 and 62 reinforce each other in the gas cell 2. Thereby, the width | variety of the intensity | strength change accompanying the temperature change of the magnetic field produced from the heater 6 can be enlarged. Therefore, the adjustment range (adjustment amount) of the frequency temperature characteristic of the atomic oscillator 1 by the magnetic field generated from the heater 6 can be increased. Therefore, when the frequency fluctuation range of the frequency temperature characteristic due to factors other than the fluctuation of the magnetic field strength acting on the alkali metal in the gas cell 2 is large, the frequency fluctuation range of the frequency temperature characteristic of the atomic oscillator 1 can be reduced. it can.

  Further, the second magnetic field and the magnetic field generated from the heater 6 reinforce each other in the gas cell 2. Thereby, the width | variety of the intensity | strength change accompanying the temperature change of the magnetic field produced from the heater 6 and a 2nd magnetic field can be enlarged. Therefore, the adjustment width (adjustment amount) of the frequency temperature characteristic of the atomic oscillator 1 by the magnetic field generated from the heater 6 and the second magnetic field can be increased. Therefore, when the frequency fluctuation range of the frequency temperature characteristic due to factors other than the fluctuation of the magnetic field strength acting on the alkali metal in the gas cell 2 is large, the frequency fluctuation range of the frequency temperature characteristic of the atomic oscillator 1 can be reduced. it can.

The manufacturing method of the atomic oscillator 1 configured as described above includes a frequency temperature characteristic adjusting step.
In the adjusting process of the frequency temperature characteristic, first, the respective parts constituting the atomic oscillator 1 described above are respectively arranged at predetermined positions.
Next, frequency temperature characteristics in each of the first state and the second state described above are measured.

  Based on the result of the measurement, the frequency of the frequency-temperature characteristic in the first direction (current direction (direction) in the first state) and the second direction (current direction (direction) in the second state). The direction in which the fluctuation range becomes smaller is selected, and the polarities of the heater 6 and the second magnetic field generation unit 9 are set to the polarities that become the selected direction.

  For example, when the frequency fluctuation range of the frequency temperature characteristic due to factors other than the fluctuation of the magnetic field strength acting on the alkali metal in the gas cell 2 is zero (the frequency does not vary even when the outside air temperature rises), FIG. As shown in FIG. 8, the influence of the temperature characteristic (see FIG. 10) of the frequency difference ω0 described above appears directly. Therefore, the frequency fluctuation range of the frequency temperature characteristic in the second state is smaller than the frequency fluctuation range of the frequency temperature characteristic in the first state. Therefore, in this case, the polarities of the heater 6 and the second magnetic field generator 9 are set to the polarities in the second direction.

  Further, when the slope of the frequency temperature characteristic due to factors other than the fluctuation of the magnetic field strength acting on the alkali metal in the gas cell 2 is negative (the frequency decreases as the outside air temperature increases), FIG. ), The frequency fluctuation range of the frequency temperature characteristic in the second state is smaller than the frequency fluctuation range of the frequency temperature characteristic in the first state. That is, in this case, the frequency temperature characteristic is deteriorated by the influence of the magnetic field from the heater 6 and the second magnetic field generator 9 in the first state, but the magnetic field from the heater 6 and the second magnetic field generator 9 in the second state. Improved by influence. Therefore, also in this case, the polarities of the heater 6 and the second magnetic field generator 9 are set to the polarities in the second direction.

  Further, when the slope of the frequency temperature characteristic due to factors other than the fluctuation of the magnetic field strength acting on the alkali metal in the gas cell 2 is positive (the frequency increases as the outside air temperature increases), FIG. As shown in FIG. 4, the frequency fluctuation range of the frequency temperature characteristic in the first state may be smaller than the frequency fluctuation range of the frequency temperature characteristic in the second state. In other words, in this case, the frequency-temperature characteristic is deteriorated due to the influence of the magnetic field from the heater 6 and the second magnetic field generation unit 9 in the second state, but in the first state, the frequency magnetic characteristic from the heater 6 and the second magnetic field generation unit 9 is reduced. Improved by influence. Therefore, in this case, the polarities of the heater 6 and the second magnetic field generator 9 are set to the polarities in the first direction.

According to the atomic oscillator 1 of the present embodiment as described above, the intensity change accompanying the temperature change of the magnetic field generated from the heater 6 and the second magnetic field generation unit 9 is effectively used for adjusting the frequency temperature characteristic of the atomic oscillator 1. The frequency temperature characteristics of the atomic oscillator 1 can be made excellent. Therefore, it is possible to provide the atomic oscillator 1 having an excellent frequency temperature characteristic with a simple configuration.
In addition, the combination of the direction of the electric current sent through the heating resistors 61 and 62 and the coils 91 and 92 is not limited to that described above, and may be, for example, the following first to third modifications.

(Modification 1)
FIG. 13 is a diagram for explaining a first modification of the atomic oscillator shown in FIG.
In the first modification of the first embodiment, in the first state, as shown in FIG. 13, when the coils 91 and 92 are viewed from the + X side, current flows in the clockwise directions d15 and d16.
Therefore, in the first state of the first modification, the direction of the second magnetic field, which is the variable magnetic field generated from the second magnetic field generation unit 9, is the −X direction in the gas cell 2. That is, the direction of the second magnetic field is the opposite direction (opposite direction) to the direction of the first magnetic field G1 and the magnetic field G2 described above in the gas cell 2.
For this reason, in the first state of the first modification, the strength of the second magnetic field G3 is determined from the strength obtained by adding the first magnetic field G1 and the magnetic field G2 from the heater 6 to the alkali metal atoms in the gas cell 2. The magnetic field G having the subtracted strength acts.

  In the first modification, the second magnetic field and the magnetic field generated from the heater 6 weaken each other in the gas cell 2. Thereby, the width | variety of the intensity | strength change accompanying the temperature change of the magnetic field produced from the heater 6 and a 2nd magnetic field can be made small. Therefore, the adjustment width (adjustment amount) of the frequency temperature characteristic of the atomic oscillator 1 by the magnetic field generated from the heater 6 and the second magnetic field can be reduced. Therefore, when the frequency fluctuation range of the frequency temperature characteristic due to factors other than the fluctuation of the magnetic field strength acting on the alkali metal in the gas cell 2 is small, the frequency fluctuation range of the frequency temperature characteristic of the atomic oscillator 1 can be reduced. it can.

(Modification 2)
FIG. 14 is a diagram for explaining a second modification of the atomic oscillator shown in FIG.
In the second modification of the first embodiment, in the first state, as shown in FIG. 14, a current flows through the heating resistor 61 in the direction d11 that is the + Y direction. On the other hand, the current flows through the heating resistor 62 in the direction d12 that is the + Y direction, that is, in the same direction as the direction d11 of the current flowing through the heating resistor 61.

In the second modification, the magnetic fields generated from the pair of heating resistors 61 and 62 weaken each other in the gas cell 2. Thereby, the width | variety of the intensity | strength change accompanying the temperature change of the magnetic field produced from the heater 6 can be made small. Therefore, the adjustment width (adjustment amount) of the frequency temperature characteristic of the atomic oscillator 1 by the magnetic field generated from the heater 6 can be reduced. Therefore, when the frequency fluctuation range of the frequency temperature characteristic due to factors other than the fluctuation of the magnetic field strength acting on the alkali metal in the gas cell 2 is small, the frequency fluctuation range of the frequency temperature characteristic of the atomic oscillator 1 can be reduced. it can.
FIG. 14 illustrates a case where the magnetic fields generated from the pair of heating resistors 61 and 62 are canceled out in the gas cell 2. In this case, in the first state of the modification 2, the alkali metal in the gas cell 2 is illustrated. A magnetic field G having a strength obtained by adding the first magnetic field G1 and the second magnetic field G3 acts on the atoms.

(Modification 3)
FIG. 15 is a diagram for explaining a third modification of the atomic oscillator shown in FIG.
In Modification 3 of the first embodiment, in the first state, as shown in FIG. 15, when viewed from the + X side, a current flows through the coil 91 in the clockwise direction d <b> 15. A current flows in the counterclockwise direction d16.

Therefore, in the first state of the third modification, the magnetic fields generated from the pair of coils 91 and 92 weaken each other in the gas cell 2. Thereby, the width | variety of the intensity | strength change accompanying the temperature change of the magnetic field produced from the heater 6 can be made small.
FIG. 15 shows a case where the magnetic fields generated from the pair of coils 91 and 92 cancel each other in the gas cell 2. In this case, in the first state of the modification 3, the alkali metal atoms in the gas cell 2 are On the other hand, a magnetic field G having a strength obtained by adding the first magnetic field G1 and the magnetic field G2 from the heater 6 acts.

Second Embodiment
Next, a second embodiment of the present invention will be described.
FIG. 16 is a longitudinal sectional view showing a gas cell, a heater, a first magnetic field generator, and a second magnetic field generator of an atomic oscillator according to the second embodiment of the present invention.
The atomic oscillator according to the present embodiment is the same as the atomic oscillator according to the first embodiment described above except that the arrangement of the first magnetic field generator and the second magnetic field generator is different.

In the following description, the atomic oscillator according to the second embodiment will be described with a focus on differences from the first embodiment, and description of similar matters will be omitted. In FIG. 16, the same reference numerals are given to the same configurations as those in the above-described embodiment.
An atomic oscillator 1A shown in FIG. 16 includes a first magnetic field generator 8A and a second magnetic field generator 9A.

The first magnetic field generator 8A generates a first magnetic field in a direction along the direction parallel to the axis a of the excitation light LL (specifically, the Y-axis direction) in the gas cell 2. Thereby, the quantum interference effect can be suitably generated in the gas cell 2.
The first magnetic field generator 8A includes a pair of coils 81A and 82A (first coils) arranged side by side in the Y-axis direction.

The pair of coils 81 </ b> A and 82 </ b> A constitutes a Helmholtz coil disposed so as to sandwich the gas cell 2. Thereby, a uniform first magnetic field can be generated in the gas cell 2. Further, the optical path of the excitation light LL can be set so as to penetrate the inside of each of the coils 81A and 82A in the Z-axis direction.
Similarly, the second magnetic field generator 9A includes a pair of coils 91A and 92A (second coils) arranged side by side in the Y-axis direction.

The pair of coils 91 </ b> A and 92 </ b> A constitute a Helmholtz coil arranged so as to sandwich the gas cell 2. Thereby, a uniform second magnetic field can be generated in the gas cell 2. Further, the optical path of the excitation light LL can be set so as to penetrate the inside of each of the coils 91A and 92A in the Z-axis direction.
The atomic oscillator 1A according to the second embodiment as described above can also exhibit excellent frequency temperature characteristics with a simple configuration.

<Third Embodiment>
Next, a third embodiment of the present invention will be described.
17 is a longitudinal sectional view showing a gas cell, a heater, a first magnetic field generator and a second magnetic field generator of an atomic oscillator according to a third embodiment of the present invention, and FIG. 18 is a heater and a first magnetic field shown in FIG. It is a figure for demonstrating the magnetic field (magnetic field at the time of flowing the electric current of a 1st direction through a heater) from a generation part and a 2nd magnetic field generation part.
The atomic oscillator according to the present embodiment is the same as the atomic oscillator according to the first embodiment described above except that the configuration of the second magnetic field generator is different.

In the following description, the atomic oscillator according to the second embodiment will be described with a focus on differences from the first embodiment, and description of similar matters will be omitted. In FIG. 17 and FIG. 18, the same reference numerals are given to the same configurations as those of the above-described embodiment.
An atomic oscillator 1B illustrated in FIG. 17 includes a second magnetic field generation unit 9B.
The second magnetic field generator 9B generates a first magnetic field including a component in a direction parallel to the axis a of the excitation light LL (specifically, the X-axis direction) in the gas cell 2.
The second magnetic field generator 9 </ b> B includes a pair of wirings 93 and 94 that are electrically connected to the heating resistor 61, and a pair of wirings 95 and 96 that are electrically connected to the heating resistor 62.

Hereinafter, the pair of wirings 93 and 94 will be described. Note that the pair of wirings 95 and 96 are the same as the pair of wirings 93 and 94, and thus description thereof is omitted.
As shown in FIG. 18, the wiring 93 is connected to the + Y side end of the heating resistor 61, and the wiring 94 is connected to the −Y side end of the heating resistor 61.
Further, the wirings 93 and 94 respectively extend along the Y-axis direction when viewed from the −Z side. In the first state, the current flows through the wirings 93 and 94 in the directions d15 and d16 (the same direction as the direction d11 of the current flowing through the heating resistor 61) that is the + Y direction when viewed from the −Z side.
Therefore, in the first state, the direction of the second magnetic field, which is a fluctuating magnetic field generated from the second magnetic field generation unit 9B, includes a direction component in the + X direction in the gas cell 2.

Also in such an atomic oscillator 1B, the temperature characteristics of the frequency difference ω ₀ differ depending on the difference in the direction of the current flowing through the heater 6 and the second magnetic field generator 9B. Therefore, the frequency temperature characteristic can be easily adjusted by selecting one of the two current directions.
The atomic oscillator 1B according to the third embodiment as described above can also exhibit excellent frequency temperature characteristics with a simple configuration.

(Modification)
FIG. 19 is a diagram for explaining a modification of the atomic oscillator shown in FIG.
In the modification of the third embodiment, each of the wires 93 and 94 has a portion extending along the Y-axis direction at one end in the X-axis direction of the heating resistor 61 when viewed from the −Z side. . In the first state, the current flows through the wirings 93 and 94 in the directions d15 and d16 (the direction opposite to the direction d11 of the current flowing in the heating resistor 61) which is the −Y direction when viewed from the −Z side.

Therefore, in the first state of this modification, the direction of the second magnetic field, which is a fluctuating magnetic field generated from the second magnetic field generator 9B, includes a direction component in the −X direction in the gas cell 2.
For this reason, in the first state of this modification, the strength of the second magnetic field G3 is determined from the strength obtained by adding the first magnetic field G1 and the magnetic field G2 from the heater 6 to the alkali metal atoms in the gas cell 2. The magnetic field G having the subtracted strength acts.

2. Electronic equipment The atomic oscillator described above can be incorporated into various electronic equipment. Such an electronic device has excellent reliability.
Hereinafter, the electronic apparatus of the present invention will be described.
FIG. 20 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. 20 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.

FIG. 21 is a schematic configuration diagram showing an example of a clock transmission system using the atomic oscillator of the present invention.
A clock transmission system 500 shown in FIG. 21 matches the clocks of the respective devices in the time division multiplexing network, and has a redundant configuration of N (Normal) system and E (Emergency) system.

The clock transmission system 500 includes a clock supply device (CSM: Clock Supply Module) 501 and an SDH (Synchronous Digital Hierarchy) device 502 of station A (upper (N system)), and a clock of station B (upper (E system)). A supply device 503 and an SDH device 504, and a clock supply device 505 and SDH devices 506 and 507 of a station C (lower level) are provided.
The clock supply device 501 has an atomic oscillator 1 and generates an N-system clock signal. The atomic oscillator 1 in the clock supply device 501 generates a clock signal in synchronization with higher-precision clock signals from master clocks 508 and 509 including an atomic oscillator using cesium.

The SDH device 502 transmits and receives the main signal based on the clock signal from the clock supply device 501, superimposes the N-system clock signal on the main signal, and transmits it to the lower clock supply device 505.
The clock supply device 503 includes the atomic oscillator 1 and generates an E-system clock signal. The atomic oscillator 1 in the clock supply device 503 generates a clock signal in synchronization with higher-precision clock signals from master clocks 508 and 509 including an atomic oscillator using cesium.

The SDH device 504 transmits and receives the main signal based on the clock signal from the clock supply device 503, superimposes the E-system clock signal on the main signal, and transmits it to the lower clock supply device 505.
The clock supply device 505 receives the clock signals from the clock supply devices 501 and 503, and generates a clock signal in synchronization with the received clock signals.

Here, the clock supply device 505 normally generates a clock signal in synchronization with the N-system clock signal from the clock supply device 501. When an abnormality occurs in the N system, the clock supply device 505 generates a clock signal in synchronization with the E system clock signal from the clock supply device 503. By switching from the N system to the E system in this way, stable clock supply can be ensured and the reliability of the clock path network can be improved.
The SDH device 506 transmits and receives the main signal based on the clock signal from the clock supply device 505. Similarly, the SDH device 507 transmits and receives the main signal based on the clock signal from the clock supply device 505. As a result, the C station apparatus can be synchronized with the A station or B station apparatus.

3. Mobile Object FIG. 22 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.
According to such a moving body, excellent reliability can be exhibited.

The electronic device including the atomic oscillator of the present invention is not limited to the above-described ones. For example, a mobile phone, a digital still camera, an ink jet type ejection device (for example, an ink jet printer), a personal computer (mobile personal computer, laptop) Type personal computer), TV, camcorder, video tape recorder, car navigation device, pager, electronic notebook (including communication functions), electronic dictionary, calculator, electronic game device, word processor, workstation, video phone, crime prevention TV Monitors, electronic binoculars, POS terminals, medical devices (for example, electronic thermometers, blood pressure meters, blood glucose meters, electrocardiogram measuring devices, ultrasonic diagnostic devices, electronic endoscopes), fish detectors, various measuring devices, instruments (for example, vehicles) ,aircraft, Instruments of 舶), can be applied to a flight simulator or the like.
As described above, 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.
In the above-described embodiment, the direction of the current flowing through the first magnetic field generation unit is the same in the first state and the second state, but the direction of the current flowing through the first magnetic field generation unit is the same as that in the first state and the second state. It is good also as an opposite direction in two states.

  In the above-described embodiment, the case where the first magnetic field generation unit is configured by using the Helmholtz type coil has been described as an example. However, the first magnetic field generation unit is not limited to this, and for example, a solenoid type coil is used. May be configured. In this case, for example, a coil wound along the inner peripheral surface of the shield of the first embodiment may be disposed, and the gas cell and the second magnetic field generator may be disposed inside the coil.

  DESCRIPTION OF SYMBOLS 1 ...... Atomic oscillator 1A ... Atomic oscillator 1B ... Atomic oscillator 2 ... Gas cell 3 ... Light emission part 5 ... Light detection part 6 ... Heater 7 ... Temperature sensor 8 ... First magnetic field generation part (Zeeman Magnetic field generator for splitting) 8A ... 1st magnetic field generator (magnetic field generator for Zeeman splitting) 9 ... 2nd magnetic field generator (magnetic field generator) 9A ... 2nd magnetic field generator (magnetic field generator) 9B ... 2nd magnetic field generation unit (magnetic field generation unit) 10 Control unit 11 Temperature control unit 12 Excitation light control unit 13 Magnetic field control unit 20 Shield 21 Main unit 22 Window unit 23 ... Window part 41 ... Optical part 42 ... Optical part 43 ... Optical part 44 ... Optical part 61 ... Heating resistor 62 ... Heating resistor 81 ... Coil 82 ... Coil 81A ... Coil 82A ... Coil 91 92 ... coil 91A ... coil 92A ... coil 93 ... wiring 94 ... wiring 95 ... wiring 96 ... wiring 100 ... positioning system 200 ... satellite 300 ... base station device 301 ... antenna 302 ... ...... Receiver 303 ... Antenna 304 ... Transmitter 400 ... Receiver 401 ... Antenna 402 ... Satellite receiver 403 ... Antenna 404 ... Base station receiver 500 ... Clock transmission system 501 ... Clock supply device 502 ... SDH device 503 ... Clock supply device 504 ... SDH device 505 ... Clock supply device 506 ... SDH device 507 ... SDH device 508 ... Master clock 1500 ... Moving body 1501 ... Car body 1502 ... Wheel a ... axis d11 ... direction (first direction) d 2 ... Direction (first direction) d13 ... Direction d14 ... Direction d15 ... Direction (first direction) d16 ... Direction (first direction) d21 ... Direction (second direction) d22 ... Direction (first) 2 direction) d23 ... direction d24 ... direction d25 ... direction (second direction) d26 ... direction (second direction) G ... magnetic field G1 ... first magnetic field G2 ... magnetic field G3 ... second magnetic field LL ... Excitation light S ... Internal space

Claims (9)

A gas cell in which metal atoms are enclosed;
A light emitting portion that emits light that excites the metal atoms;
A light detection unit for detecting the light that has passed through the metal atom;
A heating unit for heating the gas cell;
A magnetic field generation unit that is electrically connected in series with the heating unit and generates a magnetic field;
An atomic oscillator comprising:   2. The atomic oscillator according to claim 1, wherein the heating unit is energized in a direction in which a frequency fluctuation range in a frequency-temperature characteristic is reduced. The gas cell has a pair of windows that pass the light,
The heating portions are respectively disposed on the pair of window portions,
The atomic oscillator according to claim 1, wherein magnetic fields generated from the pair of heating units weaken each other in the gas cell.   The atomic oscillator according to any one of claims 1 to 3, wherein the magnetic field generation unit includes a coil. A Zeeman splitting magnetic field generator for generating a magnetic field for splitting the metal with Zeeman splitting,
5. The atom according to claim 1, wherein a direction of a magnetic field generated by the magnetic field generation unit includes a direction component parallel to a direction of the magnetic field causing the Zeeman split in the gas cell. Oscillator.   The atomic oscillator according to claim 5, wherein the magnetic field causing the Zeeman splitting and the magnetic field generated by the heating unit mutually strengthen in the gas cell.   The atomic oscillator according to claim 5, wherein the magnetic field causing the Zeeman splitting and the magnetic field generated by the heating unit weaken each other in the gas cell.   An electronic apparatus comprising the atomic oscillator according to claim 1.   A moving body comprising the atomic oscillator according to claim 1.

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