On-chip quantum information processing with distinguishable photons

TL;DR

This paper demonstrates that high temporal resolution detection can compensate for spectral distinguishability in integrated photonic quantum sources, enabling scalable quantum interference and information processing with multiple detuned photons.

Contribution

It experimentally shows that increasing timing resolution enhances interference visibility and improves quantum operation fidelity despite photon detuning in integrated sources.

Findings

20% increase in interference visibility with 20ps timing resolution

Time-resolved detection improves entangling operation fidelity

Mitigates complexity reduction in boson sampling with detuned photons

Abstract

Multi-photon interference is at the heart of photonic quantum technologies. Arrays of integrated cavities can support bright sources of single-photons with high purity and small footprint, but the inevitable spectral distinguishability between photons generated from non-identical cavities is an obstacle to scaling. In principle, this problem can be alleviated by measuring photons with high timing resolution, which erases spectral information through the time-energy uncertainty relation. Here, we experimentally demonstrate that detection can be implemented with a temporal resolution sufficient to interfere photons detuned on the scales necessary for cavity-based integrated photon sources. By increasing the effective timing resolution of the system from 200ps to 20ps, we observe a 20% increase in the visibility of quantum interference between independent photons from integrated micro-ring resonator sources that are detuned by 6.8GHz. We go on to show how time-resolved detection of non-ideal photons can be used to improve the fidelity of an entangling operation and to mitigate the reduction of computational complexity in boson sampling experiments. These results pave the way for photonic quantum information processing with many photon sources without the need for active alignment.