Ultrafast single-photon detection using nanophotonic parametric amplifiers

TL;DR

This paper introduces a room-temperature, ultrafast single-photon detector based on nanophotonic lithium niobate, achieving high efficiency and low dark counts, advancing scalable quantum photonic information processing.

Contribution

The work demonstrates a novel single-photon detection scheme using nanophotonic parametric amplification in lithium niobate, with significant improvements in efficiency and operational speed at room temperature.

Findings

Achieved 26.5% efficiency with 2.2% dark count rate experimentally.

Projected 69% efficiency with 0.9% dark count rate using improved nonlinearity-to-loss ratio.

Operates at room temperature with no intrinsic dead time, suitable for integrated quantum photonics.

Abstract

Integrated photonic quantum information processing (QIP) has advanced rapidly due to progress in various nanophotonic platforms. Single photon detectors have been the subject of intense study due to their ubiquity in QIP systems, yet many state-of-the art detectors operate at cryogenic temperatures under vacuum and suffer from long dead times. We propose and demonstrate a single photon detection scheme based on optical parametric amplification in nanophotonic lithium niobate (LN) combined with a classical photodetector. We use quantum detector tomography and experimentally demonstrate an efficiency of 26.5% with a 2.2% dark count rate. We show that by improving the nonlinearity-to-loss ratio in nanophotonics and using homodyne detection on a squeezed pump, the detector can achieve 69% efficiency with 0.9% dark count rate. The detector operates at room temperature, has no intrinsic dead time, and is readily integrated in LN nanophotonics, in which many other components of photonic QIP are available. Our results represent a step towards all-optical ultrafast photon detection for scalable nanophotonic QIP.