Theory of microwave single-photon detection using an impedance-matched $\Lambda$ system

TL;DR

This paper proposes a microwave photon detector based on an impedance-matched $bbi$ system that deterministically detects single photons with high efficiency, quick reset, and without precise pulse shaping.

Contribution

It introduces a theoretical framework for a microwave single-photon detector using an impedance-matched $bbi$ system in the dressed states, achieving near-unity efficiency.

Findings

High detection efficiency close to unity.

Fast reset capability with microwave pulses.

No need for precise input pulse shaping.

Abstract

By properly driving a qubit-resonator system in the strong dispersive regime, we implement an "impedance-matched" $\Lambda$ system in the dressed states, where a resonant single photon deterministically induces a Raman transition and excites the qubit. Combining this effect and a fast dispersive readout of the qubit, we realize a detector of itinerant microwave photons. We theoretically analyze the single-photon response of the $\Lambda$ system and evaluate its performance as a detector. We achieve a high detection efficiency close to unity without relying on precise temporal control of the input pulse shape and under a conservative estimate of the system parameters. The detector can also be reset quickly by applying microwave pulses, which allows a short dead time and a high repetition rate.