Fast and Continuous Detection of Single Microwave Photons via Photo-assisted Quasiparticle Tunneling to a Superconducting Island

TL;DR

This paper introduces a microwave single-photon detector using photo-assisted quasiparticle tunneling on a superconducting island, achieving fast, efficient, and continuous detection suitable for quantum applications.

Contribution

The work presents a novel microwave photon detector with high temporal resolution and efficiency, utilizing a superconducting island and granular aluminum resonator for enhanced light-matter interaction.

Findings

10% detection efficiency at 10 GHz

Sub 50 ns time resolution

1 microsecond dead time

Abstract

We demonstrate a single-photon detector operating in the microwave domain, based on photo-assisted quasiparticle tunneling events that poison a superconducting island. The detection relies on continuously monitoring the island's charge parity using microwave reflectometry. This scheme achieves 10% detection efficiency with sub 50 ns time resolution and short dead time 1 microsecond, for microwave photons at 10 GHz. The detector features three junctions connected to a superconducting island, which together carry out photoelectric conversion and charge readout. The enhanced light-matter coupling, crucial to photon to quasiparticle conversion, is provided by a granular aluminum-based high-impedance microwave resonator. The time resolved detection of itinerant microwave photon opens up new perspectives in quantum sensing, microwave quantum optics, readout of superconducting qubits and mesoscopic physics.