Deterministic Photon Sorting in Waveguide QED Systems

TL;DR

This paper demonstrates a highly efficient method for sorting quantum light into different modes using a pair of emitters in a waveguide, enabling advanced quantum information processing with near-perfect fidelity.

Contribution

It introduces a novel scheme utilizing two-level emitters in waveguide QED to achieve deterministic photon sorting with extremely high fidelity, including a detailed theoretical framework and analysis.

Findings

Achieves photon sorting fidelity > 0.9997

Reveals self-time reversal in two-photon scattering

Enables construction of high-fidelity quantum logic gates

Abstract

Sorting quantum fields into different modes according to their Fock-space quantum numbers is a highly desirable quantum operation. In this Letter, we show that a pair of two-level emitters, chirally coupled to a waveguide, may scatter single- and two-photon components of an input pulse into orthogonal temporal modes with a fidelity $\gtrsim 0.9997$. We develop a general theory to characterize and optimize this process and observe an interesting dynamics in the two-photon scattering regime: while the first emitter gives rise to a complex multimode field, the second emitter recombines the field amplitudes and the net two-photon scattering induces a self-time reversal of the pulse mode. The presented scheme can be employed to construct logic elements for propagating photons, such as a deterministic nonlinear-sign gate with a fidelity $\gtrsim 0.9995$