Atomic oscillator and frequency signal generation system

1. An atomic oscillator comprising:

a light source;

an atom cell containing a gaseous alkali metal atom, and a nitrogen- and argon-containing buffer gas, and through which light from the light source passes;

a photodetector that detects light having passed through the atom cell; and

a container containing only a mixed gas containing nitrogen and argon, and housing the atom cell,

wherein

15.0≤x≤40.0, and

0.132 x+ 51.8≤ y≤ 0.132 x+ 86.9,

where x is the fraction (%) of a partial pressure of the argon in the buffer gas with respect to a total pressure of the buffer gas, and

y is the fraction (%) of a partial pressure of the argon in the mixed gas with respect to a total pressure of the mixed gas.

2. The atomic oscillator according to claim 1 , wherein 0.132x+67.6≤y≤0.132x+71.1.

3. The atomic oscillator according to claim 1 , wherein 25.0≤x≤37.0.

4. The atomic oscillator according to claim 1 , wherein:

the container has a first surface, a second surface, a third surface, a fourth surface, a fifth surface, and a sixth surface;

the first surface has a first through hole; and

at least one of the second surface, the third surface, the fourth surface, the fifth surface, and the sixth surface has a second through hole.

5. The atomic oscillator according to claim 4 , wherein the second through hole is positioned on the opposite side of a first imaginary plane from the first through hole, the first imaginary plane being a plane that passes through a center of the container, and is parallel to the first surface.

6. The atomic oscillator according to claim 1 , wherein the second through hole is positioned on the opposite side of a second imaginary plane from the first through hole, the second imaginary plane being a plane that passes through the center of the container, and is perpendicular to the first surface.

7. The atomic oscillator according to claim 6 , wherein the third surface joins the first surface, and the third surface has the second through hole.

8. The atomic oscillator according to claim 5 , wherein the first through hole is a hole for supplying the mixed gas, and the light source and the atom cell are disposed on the same side of the first imaginary plane as the first through hole.

9. A frequency signal generation system comprising an atomic oscillator,

wherein the atomic oscillator includes:

a light source;

an atom cell containing a gaseous alkali metal atom, and a nitrogen- and argon-containing buffer gas, and through which light from the light source passes;

a photodetector that detects light having passed through the atom cell; and

a container containing only a mixed gas containing nitrogen and argon, and housing the atom cell,

wherein

15.0≤x≤40.0, and

0.132 x+ 51.8≤ y≤ 0.132 x+ 86.9,

where x is the fraction (%) of a partial pressure of the argon in the buffer gas with respect to a total pressure of the buffer gas, and

y is the fraction (%) of a partial pressure of the argon in the mixed gas with respect to a total pressure of the mixed gas.