Deterministic and highly indistinguishable single photons in the telecom C-band

TL;DR

This paper demonstrates a quantum dot single-photon source in the telecom C-band with unprecedented two-photon interference visibility, advancing quantum communication technologies.

Contribution

It reports the first quantum-dot emitter in the C-band achieving over 90% two-photon interference visibility, using optimized optical excitation schemes.

Findings

Achieved 91.7% two-photon interference visibility.

First demonstration of >90% indistinguishability in the C-band.

Enhanced quantum communication potential with solid-state sources.

Abstract

Quantum dots are promising candidates for deterministic single-photon sources, yet achieving high photon indistinguishability at telecom wavelengths remains a critical challenge. Here, we report a quantum dot-based single-photon source operating in the telecommunications C-band that achieves a raw two-photon interference visibility of up to (91.7+-0.2)%, thus setting a new benchmark for indistinguishability in this spectral range. The device consists of an indium arsenide (InAs) quantum dot embedded within indium aluminum gallium arsenide (InAlGaAs) and integrated into a circular Bragg grating resonator. We explore multiple optical excitation schemes to optimize coherence and source performance. To our knowledge, this is the first demonstration of two-photon interference visibility exceeding 90% from a quantum-dot emitter in the telecommunications C-band, advancing the viability of solid-state sources for quantum communication and photonic networks.