Improvement in medium-long term frequency stability of integrating sphere cold atom clock

TL;DR

This paper reports improvements in the medium-long term frequency stability of an integrating sphere cold atom clock by addressing cavity heating and light power fluctuations, achieving a stability of 3.5E-15 at 20,000 seconds.

Contribution

The study introduces solutions to reduce cavity heating and power fluctuation effects, enhancing the clock's frequency stability over extended periods.

Findings

Achieved frequency stability of 3.5E-15 at 20,000 seconds.

Reduced cavity heating and light fluctuation effects.

Extended stable operation time of the cold atom clock.

Abstract

The medium-long term frequency stability of the integrating sphere cold atom clock was improved.During the clock operation, Rb atoms were cooled and manipulated using cooling light diffusely reflected by the inner surface of a microwave cavity in the clock. This light heated the cavity and caused a frequency drift from the resonant frequency of the cavity. Power fluctuations of the cooling light led to atomic density variations in the cavity's central area, which increased the clock frequency instability through a cavity pulling effect. We overcame these limitations with appropriate solutions. A frequency stability of 3.5E-15 was achieved when the integrating time ? increased to 2E4 s.