A reference time generator including a first clock source including a reference synthesizer and cesium atomic clock configured to produce a cesium reference signal and a cesium QOT metric, a second clock source including a reference synthesizer and rubidium atomic clock configured to produce a rubidium reference signal and a rubidium QOT metric, and a circuit for selecting from the clock sources one reference signal based on the best QOT metric.

The invention discloses a physical system of strontium optical clock applied for space station, relating to the field of optical atomic clocks, comprising a special-shaped cavity and a MOT cavity. A Zeeman slower is arranged between the special-shaped cavity and the MOT cavity, and the special-shaped cavity and the MOT cavity are provided with a plurality of interfaces that communicate with their interiors; an internal heating atomic oven is arranged in the special-shaped cavity, and an anti-Helmholtz coil and a remanence compensation coil are arranged on the outer wall of the MOT cavity; the two cavities are both connected with a vacuum device for forming a vacuum, and both the special-shaped cavity and the MOT cavity are provided with optomechanical components. The system integrates the internal heating atomic oven in the special-shaped cavity to reduce the space occupied by the heating atomic oven.

A modular programmable software defined atomic clock system includes an oscillator configured to output a periodic, oscillating electrical signal, an atomic clock physics package system, and a programmable logic controller. The atomic clock physics package system is configured to generate a reference signal based on detected electron spin transitions between two hyperfine energy levels in atoms stored in the atomic clock physics package system. The programmable logic controller is coupled to the oscillator and the atomic clock physics package system. The programmable logic controller is configured to: detect an error signal based on the generated reference signal and the periodic, oscillating electrical signal; adjust the periodic, oscillating electrical signal based on the detected error signal; and generate and output one or more output signals in one or more frequencies from the adjusted periodic, oscillating electrical signal.

A millimeter wave apparatus, with a substrate, a transceiver in a first fixed position relative to the substrate, and a gas cell in a second fixed position relative to the substrate. The clock apparatus also comprises at least four waveguides.

A millimeter wave apparatus, with a substrate, a transceiver in a first fixed position relative to the substrate, and a gas cell in a second fixed position relative to the substrate. The clock apparatus also comprises at least four waveguides.

A miniature atomic clock with pulse mode operation. The clock includes: a local oscillator; a dual-frequency laser source; a pulsing element to pulse the output signal from the source according to a Ramsey-type interrogation sequence having pulses with duration T1 separated by intervals with duration T2; an alkaline vapour microcell; a photodiode; a feedback control loop for controlling the microwave frequency of the local oscillator; and a feedback control loop for controlling the optical frequency of the source by using a pulse control block receiving the output signal from the photodiode and the interrogation sequence, and providing a correction signal to the source. During the period T1, the block extracts an error signal from the output signal received from the photodiode and generates the correction signal from the error signal. During the period T2, the block resets the error signal to zero and generates the correction signal by extrapolation.

In a described example, an apparatus includes a package substrate having a device side surface and a board side surface opposite the device side surface, a physics cell mounted on the device side surface having a first end and a second end, a first opening extending through the package substrate and lined with a conductor, aligned with the first end, a second opening extending through the package substrate and lined with the conductor, aligned with the second end, a millimeter wave transmitter module on the board side, having a millimeter wave transfer structure including a transmission line coupled to an antenna aligned with the first opening, and a millimeter wave receiver module mounted on the board side surface of the package substrate and having a millimeter wave transfer structure including a transmission line coupled to an antenna for receiving millimeter wave signals, aligned with the second opening.

The invention relates to a differential detection of double-modulation (DM) CPT method and a system for implementing the method of this invention. The method comprises the following steps: Generating a coherent bichromatic light, in which the polarization and the relative phase are synchronously modulated. The DM light interacts with a quantum resonance system and prepares it into a CPT state. Then the polarization of coherent bichromatic light is switched from circular polarization to linear polarization. After interacting with the CPT state prepared in the previous stage, the constructive and destructive quantum interference occur simultaneously. The polarization of the transmitted light from the quantum resonance system is converted and spatially separated. Then two CPT signals, detected by balanced photodetectors, are observed with constructive and destructive interference respectively. Finally, a differential CPT signal with high signal-to-noise ratio is obtained by subtracting the above-mentioned two CPT signals.

In the present invention an alkali vapor cell is proposed comprising a sealed chamber enclosing an alkali atomic gas therein and having at least one optically transparent window. The chamber and the transparent window define an optical beam path through which a light beam can pass and which interacts with the alkali atomic gas in the chamber. The alkali vapor cell comprises at least one localized condensation area of alkali atoms at a predetermined location in the sealed chamber and the predetermined location is located inside or outside the optical beam path. The localized condensation area has higher alkali metal wettability than any other surface portion of the alkali vapor cell outside said localized condensation area.

In the present invention an alkali vapor cell is proposed comprising a sealed chamber enclosing an alkali atomic gas therein and having at least one optically transparent window. The chamber and the transparent window define an optical beam path through which a light beam can pass and which interacts with the alkali atomic gas in the chamber. The alkali vapor cell comprises at least one localized condensation area of alkali atoms at a predetermined location in the sealed chamber and the predetermined location is located inside or outside the optical beam path. The localized condensation area has higher alkali metal wettability than any other surface portion of the alkali vapor cell outside said localized condensation area.