Spectrum-to-position mapping via programmable spatial dispersion implemented in an optical quantum memory

TL;DR

This paper introduces a novel spectrum-to-position conversion protocol using spatial spin wave modulation in quantum memory, enabling complex spectro-temporal processing in the spatial domain for quantum and classical applications.

Contribution

It presents a new method for spectrum-to-position mapping in quantum memory, linking spectro-temporal and spatial modes for enhanced processing capabilities.

Findings

Successful implementation at single-photon level

Low added noise demonstrated

Comparable to Cramér-Rao bound in frequency estimation

Abstract

Spectro-temporal processing is essential in reaching ultimate per-photon information capacity in optical communication and metrology. In contrast to the spatial domain, complex multimode processing in the time-frequency domain is however challenging. Here we propose a protocol for spectrum-to-position conversion using spatial spin wave modulation technique in gradient echo quantum memory. This way we link the two domains and allow the processing to be performed purely on the spatial modes using conventional optics. We present the characterization of our interface as well as the frequency estimation uncertainty discussion including the comparison with Cram\'er-Rao bound. The experimental results are backed up by numerical numerical simulations. The measurements were performed on a single-photon level demonstrating low added noise and proving applicability in a photon-starved regime. Our results hold prospects for ultra-precise spectroscopy and present an opportunity to enhance many protocols in quantum and classical communication, sensing, and computing.