Temporal imaging for ultra-narrowband few-photon states of light

TL;DR

This paper demonstrates a high-resolution temporal imaging technique for ultra-narrowband single-photon states using a multimode gradient echo memory, enabling quantum information applications with unprecedented spectral precision.

Contribution

It introduces a novel far-field temporal imaging method with 20 kHz spectral resolution for narrow-band photons, surpassing previous limitations.

Findings

Achieved 20 kHz spectral resolution with MHz bandwidth.

Operated in the single-photon quantum regime with ultra-low noise.

Enabled manipulation of narrow-band photonic states for quantum information.

Abstract

Plenty of quantum information protocols are enabled by manipulation and detection of photonic spectro-temporal degrees of freedom via light-matter interfaces. While present implementations are well suited for high-bandwidth photon sources such as quantum dots, they lack the high resolution required for intrinsically narrow-band light-atom interactions. Here, we demonstrate far-field temporal imaging based on ac-Stark spatial spin-wave phase manipulation in a multimode gradient echo memory. We achieve spectral resolution of 20 kHz with MHz-level bandwidth and ultra-low noise equivalent to 0.023 photons, enabling operation in the single-quantum regime.