On Chip Quantum States Generation by Incoherent Light

TL;DR

This paper demonstrates that incoherent light can be effectively used in on-chip quantum photon sources, improving efficiency and enabling high-purity, entangled photon states, challenging the traditional emphasis on pump coherence.

Contribution

The work reveals the constructive role of temporal incoherence in quantum photon sources and provides experimental evidence for high-brightness, high-purity, and entangled photon generation using incoherent light.

Findings

Incoherent light improves pumping efficiency and source brightness.

Spectral uncorrelation of incoherent light leads to high-purity photon states.

Successful generation of polarization-entangled photons with high fidelity.

Abstract

On-chip quantum sources based on nonlinear processes are pivotal components in integrated photonics, driving significant advancements in quantum information technologies over recent decades. Usually, the pump coherence has been considered to be crucial for ensuring the quality of generated states, therefore incoherent light is rarely used in quantum information processing. In this work, we explore and reveal the constructive influence of pumped temporal incoherence on the quantum properties of photon sources. Taking silicon waveguides as nonlinear media, we theoretically show that temporal incoherence of light can improve pumping utilization efficiency, resulting in higher source brightness in a spontaneous four-wave mixing process, and the spectrally uncorrelated nature of incoherent light is transferred to the generated photon source, allowing high-purity state preparation. Experimentally, we obtain a higher photon pair generation rate and the lower heralded second-order autocorrelation with an Amplified Spontaneous Emission source. Additionally, we successfully generate a polarization-entangled state with Bell inequality violation of S = 2.64 and a fidelity of 95.7%. Our study reveals the mechanism behind incoherently pumped quantum states and presents a method for generating photon sources using an easily accessible incoherent light.