Observation of Asymmetric Sideband Generation in Strongly-driven Rydberg Atoms

TL;DR

This study investigates the asymmetric bandwidths of sidebands generated in strongly-driven Rydberg atoms, revealing that negative sidebands have higher bandwidths than positive ones, with potential for optimizing Rydberg atom-based receivers.

Contribution

The paper experimentally confirms the asymmetric bandwidths of sidebands in Rydberg atoms and explores how laser parameters influence these bandwidths, advancing understanding of Rydberg receiver limitations.

Findings

Negative sideband bandwidth ~11 MHz

Positive sideband bandwidth ~3.5 MHz

Bandwidth depends on laser Rabi frequency

Abstract

Improving the bandwidth of Rydberg atom-based receivers is an ongoing challenge owing to the long-lived Rydberg state lifetimes that limit the refresh rate of ground state atoms. In particular, the LO-based Rydberg mixer approach allows for bandwidths into the few-MHz range. Here, we use heterodyne detection of the Rydberg atom receiver probe laser to separate the negative and positive sidebands that originate from distinct six wave mixing processes, in order to investigate their individual bandwidths. We experimentally confirm the prediction that the negative sideband exhibits a higher bandwidth than the positive sideband. We further explore the effect of coupling and probe laser Rabi frequency on the bandwidth, which we find to be in good agreement with our model. We achieved a maximum experimental (and theoretical) bandwidth of about 11 (11) MHz and 3.5 (5) MHz for the negative and positive sidebands, respectively, from the -3dB roll-off point for optimized field parameters. This work provides insight into the bandwidth-limiting features of Rydberg atom receivers and points the way towards further optimization of their response.