A titanium-nitride near-infrared kinetic inductance photon-counting detector and its anomalous electrodynamics

TL;DR

This paper reports on the development of a titanium-nitride microwave kinetic inductance detector capable of single-photon counting at 1550 nm, with detailed analysis of its electrodynamics and anomalous behaviors.

Contribution

The study introduces a TiN-based near-infrared photon-counting detector and explores its unique electrodynamics deviating from standard theory, highlighting potential effects of quasiparticle traps.

Findings

Achieved 0.4 eV energy resolution and 1.2 microsecond timing resolution.

Resolved 0-, 1-, 2-photon events following Poisson statistics.

Observed anomalous electrodynamics possibly due to quasiparticle traps or subgap states.

Abstract

We demonstrate single-photon counting at 1550 nm with titanium-nitride (TiN) microwave kinetic inductance detectors. Energy resolution of 0.4 eV and arrival-time resolution of 1.2 microseconds are achieved. 0-, 1-, 2-photon events are resolved and shown to follow Poisson statistics. We find that the temperature-dependent frequency shift deviates from the Mattis-Bardeen theory, and the dissipation response shows a shorter decay time than the frequency response at low temperatures. We suggest that the observed anomalous electrodynamics may be related to quasiparticle traps or subgap states in the disordered TiN films. Finally, the electron density-of-states is derived from the pulse response.