Coherent All-Optical Radio Frequency Phase Sensing Using Multiphoton Dressing and Interference

TL;DR

This paper demonstrates an all-optical scheme for radio frequency phase sensing using multiphoton dressing and interference in atomic systems, offering a potentially simpler and more transparent alternative to heterodyne methods.

Contribution

The authors experimentally realize a five-level closed-loop atomic system for RF phase detection, overcoming limitations of traditional heterodyne techniques.

Findings

Coherence time of the loop is on the order of milliseconds.

In-phase and quadrature signals can be extracted from RF signals.

The scheme provides a new method for RF phase sensing without external heterodyning.

Abstract

Multi-photon dressing and interference in atomic systems is a key to several cutting edge technologies like Rydberg atom radio frequency sensors, clocks and magnetometers because it enables the engineering of atomic properties. Rydberg atom sensors are attracting significant interest because they can be used for applications where it is difficult or impossible to use conventional antennas, opening a number of new opportunities in fields like communications, test and measurement and radar. To date, radio frequency field amplitude detection is well-established in Rydberg electrometry. Phase detection, which is crucial for encoding radio frequency signals, typically requires an external heterodyning field or an atomic closed-loop interferometer. The heterodyne method compromises the intrinsic transparency of the sensor to the radio frequency wave and its inherently broad carrier bandwidth, in addition to increasing its complexity by introducing a local oscillator. In prior theoretical work, aimed at overcoming the disadvantages of the heterodyne method, we theoretically investigated the possibility of using the oscillatory dynamics of an all-optical five-level closed loop to sense the phase and amplitude of the target radio frequency fields. In this work, we experimentally demonstrate the scheme. We determine the coherence time of the loop to be on the order of ms and show that in-phase and quadrature signals can be extracted from a radio frequency signal.