On-chip quantum filter with a Bragg-grating emitter chain
Phys. Rev. A 114, 033703 – Published 3 September, 2026
DOI: https://doi.org/10.1103/crkn-yfkr
Abstract
Integrated single-photon filters capable of spectral purification and mode selection are essential components for scalable quantum photonics. However, achieving on-chip filters with sharp roll-offs and high reconfigurablity remains challenging in quantum photonics, due to the requirement of a large number of accurately coupled high-Q stages. We propose a Bragg grating chain of quantum emitters as an on-chip spectral filter with a near-rectangular response, enabling efficient suppression of sideband emission from solid-state single-photon sources without loss of brightness. The proposed architecture allows continuous tuning of both the central frequency and bandwidth. Crucially, spectral filtering of a weak coherent-state pulse by the atomic chain significantly reduces the two-photon component, demonstrating strong nonlinearity at the single-photon level. This nonlinear filter offers a promising route to simultaneously enhance the indistinguishability and purity of quantum resources.
