A frequency shift compensation method for light shift and vapor-cell temperature shift in atomic clocks

TL;DR

This paper introduces a 'resonance-offset' locking method that effectively compensates for light shift and vapor-cell temperature shift in atomic clocks, enhancing their long-term stability.

Contribution

The paper presents a novel resonance-offset locking approach that simultaneously suppresses light and temperature-induced frequency shifts in atomic clocks.

Findings

Successfully demonstrated compensation on a 778 nm Rubidium two-photon standard.

Reduces net frequency impact from temperature and light shifts to nearly zero.

Applicable to compact vapor-cell microwave and optical atomic clocks.

Abstract

Light shift and vapor-cell temperature shift are the two most significant factors dominating the long-term instability of compact atomic clocks. Due to the different physical mechanisms, there is not yet a solution that can effectively suppress the frequency shifts induced by these two effects. Here, we propose a 'resonance-offset' locking approach that compensates for the two physical frequency shifts. In this approach, the additional offset locking shift can effectively counteract the atomic resonance shifts arising from changes in vapor-cell temperature and light power, reducing the net impact on the clock's frequency to nearly zero. We have demonstrated this strategy on the 778 nm Rubidium two-photon optical frequency standard, successfully compensating for light shift and cell-temperature shift, respectively. This general method is particularly appealing for compact vapor-cell microwave and optical atomic clocks designed for the excellent stability rather than accuracy.