Geometric Ramsey Interferometry with a Tripod Scheme

TL;DR

This paper introduces a geometric Ramsey interferometry method using a tripod scheme in ultracold atoms, which eliminates temporal interaction dependence and enhances robustness for quantum measurements.

Contribution

It demonstrates a novel geometric approach to Ramsey interferometry with a tripod scheme, avoiding time-dependent interactions and enabling multi-port operations.

Findings

Interferometric phase arises from a geometric scalar term in dark states.

The method operates without temporal electromagnetic pulses during free evolution.

The approach offers increased robustness and potential for complex quantum interferometers.

Abstract

Ramsey interferometry is a key technique for precision spectroscopy and to probe the coherence of quantum systems. Typically, an interferometer is constructed using two quantum states and involves a time-dependent interaction with two short resonant electromagnetic pulses. Here, we explore a different type of Ramsey interferometer where we perform quantum state manipulations by geometrical means, eliminating the temporal dependence of the interaction. We use a resonant tripod scheme in ultracold strontium atoms where the interferometric operation is restricted to a two-dimensional dark-state subspace in the dressed-state picture. The observed interferometric phase accumulation is due to an effective geometric scalar term in the dark-state subspace, which remarkably does not vanish during the free evolution time when the light-matter interaction is turned off. This study opens the door for more robust interferometers operating on multiple input-output ports.