Resolving photon numbers using a superconducting tapered nanowire detector

TL;DR

This paper presents a superconducting nanowire detector capable of resolving up to five photons at telecommunication wavelengths with high timing precision, low dark counts, and practical integration for quantum photonics.

Contribution

It introduces a novel superconducting nanowire detector with an impedance-matching taper that achieves high photon-number resolution and excellent timing performance at 1550 nm.

Findings

Resolved up to five photons simultaneously

Achieved 16.1 ps timing jitter

Demonstrated low dark count rate (<2 cps)

Abstract

Time- and number-resolved photon detection is crucial for photonic quantum information processing. Existing photon-number-resolving (PNR) detectors usually have limited timing and dark-count performance or require complex fabrication and operation. Here we demonstrate a PNR detector at telecommunication wavelengths based on a single superconducting nanowire with an integrated impedance-matching taper. The prototyping device was able to resolve up to five absorbed photons and had 16.1 ps timing jitter, <2 c.p.s. device dark count rate, $\sim$86 ns reset time, and 5.6% system detection efficiency (without cavity) at 1550 nm. Its exceptional distinction between single- and two-photon responses is ideal for coincidence counting and allowed us to directly observe bunching of photon pairs from a single output port of a Hong-Ou-Mandel interferometer. This detector architecture may provide a practical solution to applications that require high timing resolution and few-photon discrimination.