Electrical engineering

Physics

Relaxation oscillator

Sociology

Population

Mathematics

CMOS

Voltage-controlled oscillator

Phase noise

Time delay and integration

Optics

Statistics

Demography

Engineering

Frequency standard

Voltage

Atomic clock

Local oscillator

Clock rate

Standard deviation

Quantum mechanics

Optoelectronics

Allan variance

Applied Physics Letters

We report a high-performance pulsed coherent population trapping (CPT) Cs cell atomic clock using the implementation of a symmetric auto-balanced Ramsey (SABR) interrogation sequence. The latter method is found to reduce the light-power induced frequency shift by an order of magnitude compared to a previous experiment using a simple auto-balanced Ramsey interrogation. The contribution of this shift to the clock frequency stability is now rejected in the 10−16 range at 104 s averaging time. Additional tricks, including a compensation method to reduce the laser amplitude noise contribution and the generation of novel error signals for local oscillator frequency and phase correction, have been implemented using a FPGA-based digital electronics board in order to improve the clock short-term stability by a of factor 2. The Allan deviation of the SABR-CPT clock, extracted from a selected 3 × 104 s-long dataset, is 2 × 10−13 τ−1∕2 and averages down to the level of 2.5 × 10−15 at 104 s. These results are encouraging to stimulate the development of hot cell CPT-based clocks for industrial, scientific, and instrumentation applications.

Symmetric autobalanced Ramsey interrogation for high-performance coherent-population-trapping vapor-cell atomic clock