By properly driving a qubit-resonator system in the strong dispersive regime, we implement an "impedance-matched" Λ 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 Λ 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.
@article{arxiv.1501.03881,
title = {Theory of microwave single-photon detection using an impedance-matched $\Lambda$ system},
author = {Kazuki Koshino and Kunihiro Inomata and Zhirong Lin and Yasunobu Nakamura and Tsuyoshi Yamamoto},
journal= {arXiv preprint arXiv:1501.03881},
year = {2015}
}