Optically-Sampled Superconducting-Nanostrip Photon-Number Resolving Detector for Non-Classical Quantum State Generation

TL;DR

This paper introduces an optical sampling technique using a dual-output Mach Zehnder modulator and ultra-short laser pulses to enable real-time photon number resolution with superconducting nanostrip detectors, advancing practical quantum state generation.

Contribution

It presents a novel optical sampling method that enhances the photon number resolving capability of SNSPDs, enabling practical applications in quantum optics.

Findings

Achieved 1.9 ps temporal resolution for photon detection.

Enabled real-time photon number resolution with superconducting nanostrips.

Produced and enhanced non-classical quantum states using the new method.

Abstract

Photon number-resolving detectors (PNRDs) are the ultimate optical sensors. Superconducting-nanostrip photon detectors (SNSPDs), traditionally known as ON-OFF detectors, have recently been found to have photon number resolving capability without multiplexing. This discovery positions them to become true PNRDs. However, their practical use is limited by the need to precisely detect tiny signal differences with low signal-to-noise ratios within sub-nanosecond time frames. We overcome this challenge using optical sampling with a dual-output Mach Zehnder modulator (DO-MZM) and ultra-short pulsed laser. By adjusting the DO-MZM's bias voltage to nearly balance the outputs, this method enables sensitive detection of picosecond-order signal differences, achieving a temporal resolution of 1.9 ps and facilitating real-time photon number resolution. We applied this method to produce various non-classical quantum states, enhancing their non-classicality through photon number resolution. This advancement marks a significant shift from principle verification to practical application for SNSPD-type PNRDs in diverse quantum optics fields.