Atomic oscillator

Abstract

To improve the stability of the resonant frequency in an atomic oscillator, which has been difficult to achieve.SOLUTION: An atomic oscillator 100 according to the present disclosure includes a gas cell 101, a light generating unit 102 that irradiates the gas cell with irradiation light, a light detecting unit 103 that detects transmitted light that has passed through the gas cell, a control unit 104 that controls the oscillation frequency of an oscillation signal that is output to the outside on the basis of a resonance frequency that is determined on the basis of the amount of the detected transmitted light, and a temperature adjusting unit 105 that adjusts the temperatures of the gas cell and the light generating unit, respectively. The temperature adjusting unit 105 adjusts the temperatures of the gas cell and the light generating unit to prescribed temperatures of the gas cell and the light generating unit, the prescribed temperatures being set on the basis of the relationship between the temperatures of the gas cell and the light generating unit and the resonance frequency, such that the amount of change in the resonance frequency when both the temperatures of the gas cell and the light generating unit fluctuate is smaller than the amount of change in the resonance frequency when either the temperature of the gas cell or the light generating unit fluctuates.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to atomic oscillators. [Background technology]

[0002] Atomic oscillators that oscillate based on the energy transition of alkali metal atoms are known as oscillators with long-term, highly accurate oscillation characteristics. In atomic oscillators, the resonant frequency is determined by detecting the amount of light transmitted through the atoms. The oscillation frequency is controlled based on this. In atomic oscillators, temperature fluctuations in the light source and the gas cell containing the atoms can impair the frequency stability of the resonant frequency. For this reason, Patent Document 1 describes maintaining constant temperatures for the light source and the gas cell. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-065148 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in an atomic oscillator, it is difficult to control the temperatures of the light source and the gas cell to keep them constant. For example, if the temperature changes in a short period of time, it is difficult to control the temperatures of the light source and the gas cell to keep them constant in response to such temperature changes. This causes a problem in that it is difficult to improve the stability of the resonant frequency in the atomic oscillator.

[0005] An object of the present disclosure is to solve the above-mentioned problem that it is difficult to improve the stability of the resonant frequency in an atomic oscillator. [Means for solving the problem]

[0006] An atomic oscillator according to one aspect of the present invention includes: a gas cell in which alkali metal atoms are sealed; a light generating unit that irradiates the gas cell with irradiation light having at least two different frequency components; a light detection unit that detects transmitted light that has passed through the gas cell; a control unit that determines a resonance frequency based on the detected amount of transmitted light and controls an oscillation frequency of an oscillation signal that is output to the outside based on the determined resonance frequency; a temperature adjusting unit that adjusts the temperatures of the gas cell and the light generating unit; Equipped with the temperature adjusting unit adjusts the temperature of the gas cell and the temperature of the light generating unit to set temperatures of the gas cell and the light generating unit, respectively, based on the relationship between the temperature and the resonance frequency in the gas cell and the light generating unit, such that a fluctuation amount of the resonance frequency when both the temperatures of the gas cell and the light generating unit fluctuate is smaller than a fluctuation amount of the resonance frequency when either the temperature of the gas cell or the light generating unit fluctuates. The structure is as follows. Furthermore, a control method according to one aspect of the present invention includes: a gas cell in which alkali metal atoms are sealed; a light generating unit that irradiates the gas cell with irradiation light having at least two different frequency components; a light detection unit that detects transmitted light that has passed through the gas cell; A control method for an atomic oscillator comprising: determining a resonance frequency based on the detected amount of transmitted light; based on the relationship between the temperature and the resonant frequency in each of the gas cell and the light generating unit, the temperature of the gas cell and the temperature of the light generating unit are controlled to be adjusted to the set temperature of the gas cell and the set temperature of the light generating unit, which are set so that the amount of change in the resonant frequency when both the temperatures of the gas cell and the light generating unit change is smaller than the amount of change in the resonant frequency when either the temperature of the gas cell or the temperature of the light generating unit changes; The structure is as follows. [Effects of the Invention]

[0007] With the above-described configuration, the present disclosure can improve the stability of the resonant frequency in the atomic oscillator. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing the configuration of an atomic oscillator according to the present disclosure. [Figure 2] FIG. 10 is a diagram illustrating a process performed by an atomic oscillator. [Figure 3] FIG. 10 is a diagram illustrating a process performed by an atomic oscillator. [Figure 4] FIG. 10 is a diagram illustrating a process performed by an atomic oscillator. [Figure 5] 10 is a flowchart showing a processing operation by the atomic oscillator. [Figure 6] FIG. 1 is a block diagram showing the configuration of an atomic oscillator according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Embodiment 1> A first embodiment of the present disclosure will be described with reference to the drawings, which may be relevant to any embodiment.

[0010] [composition] First, we will provide an overview of atomic oscillators. An atomic oscillator is a device that uses atomic gases, such as alkali metal atoms, to achieve stable frequency oscillation. An atomic oscillator has a gas cell containing the atomic gas. By irradiating the gas cell with light containing at least two different frequencies and measuring the transmitted light, the quantum interference effect (called CPT (Coherent Population Trapping) resonance) that occurs when the transition frequency between specific quantum states of the atomic gas matches the difference frequency of the irradiated light can be detected as fluctuations in the amount of transmitted light. Figure 2 shows the CPT resonance that appears in the transmitted light spectrum. For example, if the transmitted light spectrum is measured while sweeping the difference frequency of the irradiated light and detecting the transmitted light of cesium atoms, the amount of transmitted light reaches a peak when the difference frequency matches the transition frequency between specific quantum states, as shown in Figure 2(2-1), and CPT resonance is detected. The difference frequency of the irradiated light at this time is called the resonant frequency. By detecting the resonant frequency of the CPT resonance and controlling the difference frequency of the irradiated light to match the transition frequency between specific quantum states, a high-precision atomic oscillator utilizing the quantum interference effect can be realized. In the atomic oscillator using the CPT method described above, the resonant frequency of the CPT resonance is used as the reference for the oscillation frequency.

[0011] The transmitted light spectrum is expressed as a Lorentzian function centered on the transition frequency between quantum states. The point where the transmitted light amount is maximized is generally defined as the resonant frequency of the CPT resonance and used as the reference for the oscillation frequency. As an example, by sweeping the difference frequency of the light irradiated at the start of the atomic oscillator, an error signal of the transmitted light spectrum, as shown in the schematic diagram in Figure 2(2-2), can be obtained. The zero-crossing point of the error signal can be used as the resonant frequency and used as the reference for the oscillation frequency. The error signal of the transmitted light spectrum can be obtained, for example, by modulating the difference frequency with a reference frequency whose period is shorter than the sweep period of the difference frequency when sweeping the difference frequency of the irradiated light, and then locking in the detected transmitted light amount with the reference frequency.

[0012] The amount of change in the error signal at the zero-cross point, which is the resonance frequency, i.e., the ratio of the amount of change in the error signal to the amount of deviation between the difference frequency and the resonance frequency, is called the zero-point slope. When monitoring the error signal, the greater the absolute value of the zero-point slope, the higher the detection sensitivity of the difference between the difference frequency and the resonance frequency.

[0013] In the atomic oscillator, after detecting the resonant frequency by the zero crossing point as described above as an initialization process, the zero crossing point is constantly monitored, and the amount of deviation from the zero crossing point is fed back to the control signal of the oscillator, thereby increasing the stability of the output frequency.

[0014] Next, the configuration of the atomic oscillator in this embodiment will be described. As shown in Fig. 1, the atomic oscillator includes a light generating unit 1, a magnetic field applying device 2, a gas cell 3 in which alkali metal atoms or the like are sealed in a gaseous state, a light detecting unit 4, a control device 5, and an oscillation device 6. Here, the control device 5 is configured as an information processing device including a calculation device and a storage device. As shown in Fig. 1, the control device 5 includes a frequency control unit 51 and a temperature control unit 52 that are constructed by the calculation device executing a program. Of these, at least the gas cell 3 and the light generating unit 4 are housed in a single housing (not shown).

[0015] The light generating unit 1 generates light having at least two different frequencies. The irradiated light generated by the light generating unit 1 is irradiated onto the gas cell 3, and the transmitted light that passes through the gas cell 3 reaches the light detecting unit 4, where it is detected, converted into an electrical signal, etc., and sent to the control unit 5. The light generating unit 1 is configured to control the wavelength of the generated light, the intensity of the light for each frequency component, and the difference frequency based on a control signal from the control unit 5, as will be described later.

[0016] The irradiated light generated by the light generating unit 1 has at least two different frequency components. The light generated by the light generating unit 1 may have three or more different frequency components, but the difference frequency between two of these frequency components is approximately equal to the transition frequency between specific quantum states that form the CPT resonance of the alkali metal atom. For example, the light generated by the light generating unit 1 is realized by generating sidebands by modulating single-wavelength light emitted from a semiconductor laser or the like with a frequency approximately equal to the transition frequency of the alkali metal atom or 1 / N times the frequency, where N is an integer. In this case, the difference frequency is controlled by a mechanism that controls the modulation frequency. Alternatively, the light generated by the light generating unit 1 can be realized by combining two single-wavelength light beams emitted from two semiconductor lasers or the like that have a mechanism for controlling the difference frequency.

[0017] Specifically, in this embodiment, the light generating unit 1 is configured to include a vertical cavity surface emitting laser (VCSEL) as a light source element that generates excitation light of a single wavelength, and two excitation lights are generated by frequency modulation of this excitation light of a single wavelength. The VCSEL, which is the light source element, is equipped with a light source temperature regulator (temperature regulator) that regulates its own temperature. The light source temperature regulator regulates the temperature of the VCSEL to a set temperature in response to a control command from a temperature control unit 52 that specifies a set temperature for the light source, as will be described later. The light source temperature regulator is configured, for example, by a resistance heater, but may be configured by any device that has a heating or heating / cooling function and is capable of regulating the temperature of the VCSEL.

[0018] The magnetic field application device 2 generates a magnetic field M parallel or anti-parallel to the irradiated light at a predetermined position inside the gas cell 3. The magnetic field application device 2 is, for example, a coil arranged to cover the gas cell 3, and by adjusting the direction and magnitude of the current applied to the coil, the direction and strength of the static magnetic field applied to the predetermined position inside the gas cell 3 can be controlled.

[0019] Alkali metal atoms are sealed in the gas cell 3. The alkali metal atoms sealed in the gas cell 3 may be, for example, cesium atoms, rubidium atoms, sodium atoms, or potassium atoms. The material constituting the container of the gas cell 3 is preferably a transparent material such as glass that has a high transmittance for the irradiated light generated from the light generating unit 1. In addition to the alkali metal atoms, the gas cell 3 may also be sealed with a buffer gas that does not contribute to absorbing the irradiated light, in order to reduce the effect of collisions between the container wall and the gaseous alkali metal atoms.

[0020] The gas cell 3 is also equipped with a gas cell temperature regulator (temperature regulator) that regulates its own temperature. The gas cell temperature regulator regulates the temperature of the gas cell 3 to a set temperature in response to a control command specifying a set temperature for the gas cell from the temperature control unit 52, as will be described later. The gas cell temperature regulator is installed so as not to obstruct the optical path of the irradiated light, and is composed of, for example, a resistance heater. However, the temperature regulator may be composed of any device as long as it has a heating or heating / cooling function and is capable of regulating the temperature of the gas cell 3.

[0021] The light detection unit 4 has a device for detecting transmitted light, which is light that has passed through the gas cell 3. The light detection unit 4 is realized, for example, by using a photodiode, but can also be realized by a photodetector, which is a light detection means. Information about the light detected by the light detection unit 4 is converted into an electric signal or the like and input to the control unit 5.

[0022] The frequency control unit 51 included in the control device 5 determines the resonant frequency from the amount of transmitted light input from the light detection unit 4 as described above during initialization, such as when starting up the atomic oscillator, and controls the oscillation frequency of the oscillation device 6 based on the determined resonant frequency. Specifically, the frequency control unit 51 sweeps the difference frequency of the irradiated light and determines the resonant frequency from the transmitted light spectrum. Once the resonant frequency is determined, the frequency control unit 51 adjusts the control voltage of the oscillation device 6 so that the error signal of the transmitted light spectrum detected by lock-in detection is at a predetermined signal level. Here, the oscillation device 6 is composed of a VCXO (voltage-controlled crystal oscillator) that oscillates at approximately 10 MHz. It generates an oscillation signal in response to the control voltage output from the frequency control unit 51 and applies it, and outputs it as the oscillation frequency, which is the external output of the atomic oscillator. As a result, the oscillation frequency is stabilized at 10 MHz unless the resonant frequency changes. The difference frequency of the irradiated light is generated by converting the VCXO oscillation signal into a signal of several GHz using a multiplier, and is input to the light generation unit 1.

[0023] The temperature control unit 52 (temperature adjustment unit) included in the control device 5 has a function of issuing control commands specifying set temperatures to the temperature adjustment device provided on the VCSEL of the light generating unit 1 and the temperature adjustment device provided on the gas cell 3, thereby adjusting the temperatures of the VCSEL and the gas cell 3. At this time, when performing a process of determining control target values ​​for the temperatures of the VCSEL and the gas cell 3 during initialization processing, as described below, the temperature control unit 52 controls the adjustment of the temperatures of the VCSEL and the gas cell 3 by specifying multiple set temperatures within a predetermined range. Furthermore, during operation after the resonance frequency is determined by initialization processing, the temperature control unit 52 controls the adjustment of the temperatures of the VCSEL and the gas cell 3 using the set temperatures set by the initialization processing as control target values, as described below.

[0024] Here, the frequency control unit 51 further has a temperature setting function (temperature setting unit) that sets a light source set temperature, which is a control target value for the temperature of the VCSEL, which is the light source provided in the light generating unit 1, and a gas cell set temperature, which is a control target value for the temperature of the gas cell 3, during the initialization process described above. The temperature setting function of the frequency control unit 51 stores relationship data, such as a graph showing the relationship between the temperature of the VCSEL and the resonant frequency, and a graph showing the relationship between the temperature of the gas cell and the resonant frequency, as shown in FIG. 3, and sets each set temperature using such relationship data. FIG. 3 (3-1) shows the characteristics of the resonant frequency fluctuation with respect to the temperature fluctuation of the VCSEL, and the example of FIG. 3 (3-2) shows the characteristics of the resonant frequency fluctuation with respect to the temperature fluctuation of the gas cell 3. Note that the relationship data shown in FIG. 3 is an example, and the characteristics of the resonant frequency fluctuation with respect to the temperature fluctuation of the VCSEL or the gas cell 3 may be any characteristics and are not necessarily limited to data in a graph format. The temperature setting function of the frequency control unit 51 will be described in detail below.

[0025] The temperature setting function of the frequency control unit 51 first sets a plurality of combinations of the VCSEL temperature and the gas cell 3 temperature within a predetermined temperature range. For example, as shown in the table of FIG. 4, VCSEL ” and the temperature of gas cell 3 “T GC " combination (T VCSEL " [1], T GC [1]),(T VCSEL " [2], T GC [2]),···,(T VCSEL " [N V ],T GC [N G ]) are set. The temperature setting function controls the temperature control unit 52 so that the VCSEL and gas cell 3 are set to the temperature of each combination, and acquires the resonance signal at the temperature of each combination of the VCSEL and gas cell 3 to obtain the resonance frequency "f0" and the zero point slope "slope". As an example, as shown in the table of FIG. 4, VCSEL " [1], T GCFor the temperature (temperature [1]), the resonance frequency "f0[1,1]" and zero-point slope "slope[1,1]" are obtained, and for other temperature combinations, the resonance frequency "f0" and zero-point slope "slope" are also obtained. As shown in Figure 2 (2-2), the zero-point slope is a value that represents the amount of change in the error signal of the spectrum of the transmitted light when the difference frequency of the irradiated light matches the transition frequency between specific quantum states. In other words, the zero-point slope is a value that represents the amount of change, or gradient, of the error signal at the resonance frequency, and the steeper the gradient, the larger the absolute value. The steeper the gradient of the zero-point slope, the better the detection sensitivity of resonance frequency fluctuations.

[0026] Next, the temperature setting function checks the characteristics of the amount of change in the resonant frequency when the temperatures of the VCSEL and gas cell fluctuate for each of the above combinations. Specifically, the temperature setting function uses the above-mentioned relationship data as shown in Figure 3 to calculate the amount of change in the resonant frequency with respect to the temperature fluctuation of the VCSEL at the temperature of the combination, expressed as "df0 / dT VCSEL " and the amount of change in the resonant frequency with respect to the change in the temperature of the gas cell 3 at the temperature of the combination, "df0 / dT GC At this time, the temperature setting function checks whether the change in the resonant frequency is positive or negative.

number

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[0027] As an example, if the temperature of the combination (T VCSEL " [n],T GC3, the amount of change in the resonant frequency with respect to the temperature change of the VCSEL and the amount of change in the resonant frequency with respect to the temperature change of the gas cell 3, which are the values ​​respectively shown in the above formulas 1 and 2, are examined. It is found that the amount of change in the resonant frequency with respect to the temperature change of the VCSEL has a "negative" sign as indicated by the arrow, and the amount of change in the resonant frequency with respect to the temperature change of the gas cell 3 has a "positive" sign as indicated by the arrow.

[0028] The temperature setting function stores, in association with each temperature combination set as described above, the resonance frequency "f0" and zero-point slope "slope" obtained for each temperature combination, and the amount of change in resonance frequency in response to temperature fluctuations of the VCSEL and gas cell 3 investigated for each temperature combination.

[0029] Next, the temperature setting function extracts, as candidate temperatures, temperature combinations that satisfy the set conditions based on the stored amount of change in resonance frequency with respect to temperature change of the VCSEL and the gas cell 3, from among the temperature combinations set as shown in Fig. 4. Specifically, the temperature setting function extracts, as candidate temperatures, temperature combinations in which the amount of change in resonance frequency with respect to temperature change of the VCSEL and the amount of change in resonance frequency with respect to temperature change of the gas cell 3 have opposite signs. For example, the temperature combination (T VCSEL [n],T GC In the case of [n]), the amount of change in the resonant frequency with respect to the temperature change of the VCSEL and the gas cell 3 is "negative" and "positive", respectively, so such a temperature combination is extracted as a candidate temperature. VCSEL [i1],T GC [j1]),(T VCSEL [i2],T GC Multiple temperature combinations can be extracted, such as [j2]),...

[0030] Then, the temperature setting function determines one combination of temperatures from the extracted candidate temperatures as the control target value. At this time, the temperature setting function determines the candidate temperature at which the absolute value of the associated and stored zero-point slope "slope[i,j]" is maximum as the control target value (T VCSEL " [i],T GC [j]) is determined as the set temperature.

[0031] Here, the combination of set temperatures, which are control target values ​​determined as described above, can be said to be set temperatures that are set to reduce the amount of fluctuation in the resonant frequency when the temperatures of the VCSEL and the gas cell 3 fluctuate. This will be explained below.

[0032] First, the ambient temperature "T env When the temperature "T" of the VCSEL and the gas cell 3 of the light generating unit 1 mounted on the atomic oscillator fluctuates, VCSEL ", "T GC Then, the resonance frequency "f0" also fluctuates due to the characteristics of the resonance frequency with respect to the temperature of the VCSEL and gas cell 3 of the light generating unit 1 as shown in FIG. 3. At this time, the environmental temperature "T env The change in the resonance frequency "f0" with respect to the change in "df0 / dT env ” are the respective temperatures of the VCSEL and the gas cell 3, “T VCSEL ", "T GC " can be expressed as in the following formula 3. i " is a control parameter.

number

[0033] Here, in order to achieve frequency stability of the atomic oscillator, the environmental temperature "T env The change in the resonance frequency "f0" with respect to the change in "df0 / dT env It is desirable to make "dT" smaller, for example, closer to 0.VCSEL / dT env " and "dT GC / dT env " is difficult to approach 0, so "df0 / dT VCSEL " and "df0 / dT GC " will be combined to realize equation 4.

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[0034] In order to realize the above formula (4), the amount of change in the resonant frequency of the VCSEL with respect to the temperature change, "df0 / dT VCSEL ” and the amount of change in the resonant frequency with respect to the temperature change of the gas cell 3, “df0 / dT GC Therefore, the amount of change in the resonant frequency of the VCSEL, "df0 / dT VCSEL ” and the fluctuation of the resonant frequency of gas cell 3 “df0 / dT GC " and " can have opposite signs. This allows an increase in the amount of fluctuation in one resonance frequency to be reduced by the amount of fluctuation in the other resonance frequency. For example, when the ambient temperature (temperature outside the housing) of the atomic oscillator changes suddenly, it is thought that a temporary deviation in the temperature control of the gas cell and VCSEL housed in the same housing will often occur at the same time. In this case, even if an increase in the amount of fluctuation in one resonance frequency occurs, if it can be reduced at the same time by the amount of fluctuation in the other resonance frequency, the sum of these (Equation 4) can be kept close to 0, even if a sudden change in the ambient temperature occurs.

[0035] [Operation] Next, the operation of the above-mentioned atomic oscillator will be described. When the atomic oscillator is started up and initialization is performed, the control device 5 performs processing to set a set temperature, which is a target value for temperature control, using the temperature setting function.

[0036] Specifically, the temperature setting function first sets a plurality of combinations of the VCSEL temperature and the gas cell 3 temperature within a predetermined temperature range (step S1 in FIG. 5). For example, as shown in the table in FIG. 4, the VCSEL temperature "TVCSEL ” and the temperature of gas cell 3 “T GC " combination (T VCSEL [1],T GC [1]),(T VCSEL [2],T GC [2]),···,(T VCSEL [N V ],T GC [N G Then, the temperature setting function controls the temperature control unit 52 so that the VCSEL and the gas cell 3 reach the temperature of each combination, and acquires the CPT resonance signal at the temperature of each combination of the VCSEL and the gas cell 3 (step S2 in FIG. 5).

[0037] Next, the temperature setting function obtains the resonance frequency "f0" and the zero-point slope "slope" from the CPT resonance signal obtained at each temperature combination (step S2 in FIG. 5). The temperature setting function also checks the amount of change in the resonance frequency when the temperatures of the VCSEL and the gas cell fluctuate at each temperature combination. Specifically, the temperature setting function uses the above-mentioned relationship data as shown in FIG. 3 to calculate the amount of change in the resonance frequency with respect to the temperature fluctuation of the VCSEL at the temperature combination, "df0 / dT VCSEL " and the amount of change in the resonant frequency with respect to the change in the temperature of the gas cell 3 at the temperature of the combination, "df0 / dT GC (Step S3 in FIG. 5). At this time, the temperature setting function particularly checks whether the change in the resonant frequency is positive or negative.

[0038] The temperature setting function extracts, as candidate temperatures, temperature combinations that satisfy the set conditions based on the stored amount of change in resonance frequency with respect to temperature change of the VCSEL and the gas cell 3, from among the temperature combinations set as shown in Fig. 4. In particular, the temperature setting function extracts, as candidate temperatures, temperature combinations in which the amount of change in resonance frequency with respect to temperature change of the VCSEL and the amount of change in resonance frequency with respect to temperature change of the gas cell 3 have opposite signs (step S4 in Fig. 5). For example, the temperature combination (T VCSEL [n],TGC In [n]), the amount of change in the resonant frequency with respect to temperature fluctuations of the VCSEL and the gas cell 3 is "negative" and "positive," respectively, so this temperature combination is extracted as a candidate temperature. It can be said that such a temperature combination is a set temperature that is set so that the amount of change in the resonant frequency when the temperatures of both the VCSEL and the gas cell 3 fluctuate is smaller than the amount of change in the resonant frequency when the temperature of either the VCSEL or the gas cell 3 fluctuates. In other words, by setting the VCSEL and the gas cell to such a set temperature, the increase in the amount of change in the resonant frequency due to temperature fluctuations of one can be reduced by the amount of change in the resonant frequency due to temperature fluctuations of the other.

[0039] Next, the temperature setting function determines one combination of temperatures from the extracted candidate temperatures as the control target value. At this time, the temperature setting function determines the candidate temperature at which the absolute value of the associated and stored zero-point slope "slope[i,j]" is maximized as the control target value (T VCSEL [i],T GC [j]) is determined as the set temperature (step S5 in FIG. 5).

[0040] Then, the temperature control unit 52 of the control device 5 controls the temperatures of the VCSEL and the gas cell 3 using the set temperature determined as described above as a control target value (step S6 in FIG. 5). As a result, even if the temperatures of the VCSEL and the gas cell 3 subsequently fluctuate due to a change in the external environmental temperature, the amount of fluctuation in the resonant frequency can be kept small, thereby improving frequency stability.

[0041] The process of determining the target temperature control values ​​for the VCSEL and the gas cell 3 described above is not limited to being performed during the initialization process, but may be performed at any timing, such as at regular time intervals.

[0042] <Embodiment 2> Next, a second embodiment of the present invention will be described with reference to Figure 6. Note that the drawings can relate to any of the embodiments.

[0043] As shown in FIG. 6, the atomic oscillator 100 in this embodiment includes: a gas cell 101 in which alkali metal atoms are sealed; a light generating unit 102 that irradiates the gas cell with irradiation light having at least two different frequency components; a light detection unit 103 that detects transmitted light that has passed through the gas cell; a control unit 104 that determines a resonance frequency based on the detected amount of transmitted light and controls the oscillation frequency of an oscillation signal that is output to the outside based on the determined resonance frequency; a temperature adjusting unit 105 that adjusts the temperatures of the gas cell and the light generating unit; Equipped with. Then, based on the relationship between the temperature and the resonant frequency in the gas cell and the light generating unit, the temperature adjustment unit 105 adjusts the temperature of the gas cell and the temperature of the light generating unit to the set temperature of the gas cell and the set temperature of the light generating unit, respectively, which are set so as to reduce the amount of fluctuation in the resonant frequency when the temperatures of the gas cell and the light generating unit fluctuate.

[0044] In the atomic oscillator 100 of this embodiment, by adjusting the temperatures of the gas cell 101 and the light generating unit 102 to the above-mentioned set temperatures, even if temperature fluctuations occur in the gas cell 101 and the light generating unit 102 due to the external environmental temperature or the like, the amount of fluctuation in the resonant frequency due to such temperature fluctuations is reduced, thereby improving frequency stability.

[0045] Although the present disclosure has been described above with reference to the above-described embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration of the present disclosure within the scope of the present disclosure.

[0046] <Additional Notes> A part or all of the above-described embodiments can be described as follows: The following provides an overview of the configurations of the atomic oscillator and control method according to the present disclosure. However, the present invention is not limited to the following configurations.

[0047] (Appendix 1) a gas cell in which alkali metal atoms are sealed; a light generating unit that irradiates the gas cell with irradiation light having at least two different frequency components; a light detection unit that detects transmitted light that has passed through the gas cell; a control unit that determines a resonance frequency based on the detected amount of transmitted light and controls an oscillation frequency of an oscillation signal that is output based on the determined resonance frequency; a temperature adjusting unit that adjusts the temperatures of the gas cell and the light generating unit; Equipped with the temperature adjusting unit adjusts the temperature of the gas cell and the temperature of the light generating unit to set temperatures of the gas cell and the light generating unit, respectively, based on the relationship between the temperature and the resonance frequency in the gas cell and the light generating unit, such that a fluctuation amount of the resonance frequency when both the temperatures of the gas cell and the light generating unit fluctuate is smaller than a fluctuation amount of the resonance frequency when either the temperature of the gas cell or the light generating unit fluctuates. Atomic oscillator. (Appendix 2) 2. The atomic oscillator according to claim 1, the temperature adjusting unit adjusts the temperature of the gas cell and the temperature of the light generating unit to set temperatures of the gas cell and the light generating unit, respectively, that are set so as to reduce a fluctuation amount of the resonant frequency when the temperature of the gas cell fluctuates by a fluctuation amount of the resonant frequency when the temperature of the light generating unit fluctuates, based on the relationship. Atomic oscillator. (Appendix 3) 2. The atomic oscillator according to claim 1, the temperature adjusting unit adjusts the temperature of the gas cell and the temperature of the light generating unit to set temperatures of the gas cell and the light generating unit, respectively, that are set based on the relationship so that the amount of change in the resonant frequency due to the change in the temperature of the gas cell and the amount of change in the resonant frequency due to the change in the temperature of the light generating unit have mutually opposite signs. Atomic oscillator. (Appendix 4) 2. The atomic oscillator according to claim 1, the control unit sets a plurality of combinations of the temperature of the gas cell and the temperature of the light generating unit, and determines a resonant frequency for each of the plurality of combinations; further, the control unit is configured to extract, from the plurality of combinations based on the relationship, a combination in which a change in the resonant frequency due to a change in the temperature of the gas cell and a change in the resonant frequency due to a change in the temperature of the light generating unit have opposite signs; and to set the set temperature of the gas cell and the set temperature of the light generating unit based on the extracted combination; the temperature adjusting unit adjusts the temperature of the gas cell and the temperature of the light generating unit to the set temperatures of the gas cell and the light generating unit, respectively; Atomic oscillator. (Appendix 5) 5. The atomic oscillator according to claim 4, the temperature setting unit determines a resonance frequency for each of the plurality of combinations, and acquires a zero-point slope that represents a change in an error signal of the spectrum of the transmitted light when the difference frequency of the irradiated light matches a transition frequency between specific quantum states, and sets a set temperature of the gas cell and a set temperature of the light generating unit based on the extracted combination and the zero-point slope. Atomic oscillator. (Appendix 6) 6. The atomic oscillator according to claim 5, the temperature setting unit sets the combination having the largest absolute value of the zero point slope from among the extracted combinations as the set temperature of the gas cell and the set temperature of the light generating unit. Atomic oscillator. (Appendix 7) a gas cell in which alkali metal atoms are sealed; a light generating unit that irradiates the gas cell with irradiation light having at least two different frequency components; a light detection unit that detects transmitted light that has passed through the gas cell; A control method for an atomic oscillator comprising: determining a resonance frequency based on the detected amount of transmitted light; based on the relationship between the temperature and the resonant frequency in each of the gas cell and the light generating unit, the temperature of the gas cell and the temperature of the light generating unit are controlled to be adjusted to the set temperature of the gas cell and the set temperature of the light generating unit, which are set so that the amount of change in the resonant frequency when both the temperatures of the gas cell and the light generating unit change is smaller than the amount of change in the resonant frequency when either the temperature of the gas cell or the temperature of the light generating unit changes; Control method. (Appendix 8) 8. The control method of claim 7, further comprising: a plurality of combinations of the temperature of the gas cell and the temperature of the light generating unit are set, and a resonant frequency is determined for each of the plurality of combinations; further, based on the relationship, a combination is extracted from the plurality of combinations in which the amount of change in the resonant frequency due to a change in the temperature of the gas cell and the amount of change in the resonant frequency due to a change in the temperature of the light generating unit have opposite signs; and a set temperature of the gas cell and a set temperature of the light generating unit are set based on the extracted combination; adjusting the temperature of the gas cell and the temperature of the light generating unit to the set temperatures of the gas cell and the light generating unit, respectively; Control method. [Explanation of symbols]

[0048] 1 Light generating unit 2 Magnetic field application device 3 Gas Cell 4. Light detection unit 5. Control device 51 Frequency control section 52 Temperature control unit 6. Oscillator 100 Atomic Oscillator 101 Gas Cell 102 Light generating unit 103 Light detection unit 104 Control Unit 105 Temperature adjustment section

Claims

1. a gas cell in which alkali metal atoms are sealed; a light generating unit that irradiates the gas cell with irradiation light having at least two different frequency components; a light detection unit that detects transmitted light that has passed through the gas cell; a control unit that determines a resonance frequency based on the detected amount of transmitted light and controls an oscillation frequency of an oscillation signal that is output to the outside based on the determined resonance frequency; a temperature adjusting unit that adjusts the temperatures of the gas cell and the light generating unit; Equipped with the temperature adjusting unit adjusts the temperature of the gas cell and the temperature of the light generating unit to set temperatures of the gas cell and the light generating unit, respectively, based on the relationship between the temperature and the resonance frequency in the gas cell and the light generating unit, such that a fluctuation amount of the resonance frequency when both the temperatures of the gas cell and the light generating unit fluctuate is smaller than a fluctuation amount of the resonance frequency when either the temperature of the gas cell or the light generating unit fluctuates. Atomic oscillator.

2. 2. The atomic oscillator according to claim 1, the temperature adjusting unit adjusts the temperature of the gas cell and the temperature of the light generating unit to set temperatures of the gas cell and the light generating unit, respectively, that are set so as to reduce a fluctuation amount of the resonant frequency when the temperature of the gas cell fluctuates by a fluctuation amount of the resonant frequency when the temperature of the light generating unit fluctuates, based on the relationship. Atomic oscillator.

3. 2. The atomic oscillator according to claim 1, the temperature adjusting unit adjusts the temperature of the gas cell and the temperature of the light generating unit to set temperatures of the gas cell and the light generating unit, respectively, that are set based on the relationship so that the amount of change in the resonant frequency due to the change in the temperature of the gas cell and the amount of change in the resonant frequency due to the change in the temperature of the light generating unit have mutually opposite signs. Atomic oscillator.

4. 2. The atomic oscillator according to claim 1, the control unit sets a plurality of combinations of the temperature of the gas cell and the temperature of the light generating unit, and determines a resonant frequency for each of the plurality of combinations; further, the control unit is configured to extract, from the plurality of combinations based on the relationship, a combination in which a change in the resonant frequency due to a change in the temperature of the gas cell and a change in the resonant frequency due to a change in the temperature of the light generating unit have opposite signs; and to set the set temperature of the gas cell and the set temperature of the light generating unit based on the extracted combination; the temperature adjusting unit adjusts the temperature of the gas cell and the temperature of the light generating unit to the set temperatures of the gas cell and the light generating unit, respectively; Atomic oscillator.

5. 5. The atomic oscillator according to claim 4, the temperature setting unit determines a resonance frequency for each of the plurality of combinations, and acquires a zero-point slope that represents a change in an error signal of the spectrum of the transmitted light when the difference frequency of the irradiated light matches a transition frequency between specific quantum states, and sets a set temperature of the gas cell and a set temperature of the light generating unit based on the extracted combination and the zero-point slope. Atomic oscillator.

6. 6. The atomic oscillator according to claim 5, the temperature setting unit sets the combination having the largest absolute value of the zero point slope from among the extracted combinations as the set temperature of the gas cell and the set temperature of the light generating unit. Atomic oscillator.

7. a gas cell in which alkali metal atoms are sealed; a light generating unit that irradiates the gas cell with irradiation light having at least two different frequency components; a light detection unit that detects transmitted light that has passed through the gas cell; A control method for an atomic oscillator comprising: determining a resonance frequency based on the detected amount of transmitted light; based on the relationship between the temperature and the resonant frequency in each of the gas cell and the light generating unit, the temperature of the gas cell and the temperature of the light generating unit are controlled to be adjusted to the set temperature of the gas cell and the set temperature of the light generating unit, which are set so that the amount of change in the resonant frequency when both the temperatures of the gas cell and the light generating unit change is smaller than the amount of change in the resonant frequency when either the temperature of the gas cell or the temperature of the light generating unit changes; Control method.

8. 8. The control method according to claim 7, a plurality of combinations of the temperature of the gas cell and the temperature of the light generating unit are set, and a resonant frequency is determined for each of the plurality of combinations; further, based on the relationship, a combination is extracted from the plurality of combinations in which the amount of change in the resonant frequency due to a change in the temperature of the gas cell and the amount of change in the resonant frequency due to a change in the temperature of the light generating unit have opposite signs; and a set temperature of the gas cell and a set temperature of the light generating unit are set based on the extracted combination; adjusting the temperature of the gas cell and the temperature of the light generating unit to the set temperatures of the gas cell and the light generating unit, respectively; Control method.

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