A solid-state single-photon filter

TL;DR

This paper presents a highly efficient solid-state single-photon filter utilizing a quantum-dot cavity interface, achieving record nonlinearity at the single-photon level and effectively suppressing multi-photon components.

Contribution

The work introduces a novel solid-state single-photon filter with record nonlinearity threshold, improving photon filtering efficiency in quantum information applications.

Findings

Achieved a nonlinearity threshold of ~0.3 incident photons.

80% of reflected pulses are single-photon Fock states.

Strong suppression of two- and three-photon components.

Abstract

A strong limitation of linear optical quantum computing is the probabilistic operation of two-quantum bit gates based on the coalescence of indistinguishable photons. A route to deterministic operation is to exploit the single-photon nonlinearity of an atomic transition. Through engineering of the atom-photon interaction, phase shifters, photon filters and photon- photon gates have been demonstrated with natural atoms. Proofs of concept have been reported with semiconductor quantum dots, yet limited by inefficient atom-photon interfaces and dephasing. Here we report on a highly efficient single-photon filter based on a large optical non-linearity at the single photon level, in a near-optimal quantum-dot cavity interface. When probed with coherent light wavepackets, the device shows a record nonlinearity threshold around $0.3 \pm 0.1$ incident photons. We demonstrate that directly reflected pulses consist of 80% single-photon Fock state and that the two- and three-photon components are strongly suppressed compared to the single-photon one.