Time-resolved boson sampling with photons of different colors

TL;DR

This paper demonstrates a time-resolved boson sampling experiment using photons of different colors from atomic ensembles, showing potential for quantum supremacy with distinguishable photons.

Contribution

It introduces a time-resolved boson sampling method with non-overlapping photons, expanding the feasibility of quantum experiments with distinguishable photons.

Findings

Average fidelity of 0.936 measured across configurations

Nonclassical multiphoton correlation landscapes observed

Symmetries in landscapes reflect optical network symmetries

Abstract

Interference of multiple photons via a linear-optical network has profound applications for quantum foundation, quantum metrology and quantum computation. Particularly, a boson sampling experiment with a moderate number of photons becomes intractable even for the most powerful classical computers, and will lead to "quantum supremacy". Scaling up from small-scale experiments requires highly indistinguishable single photons, which may be prohibited for many physical systems. Here we experimentally demonstrate a time-resolved version of boson sampling by using photons not overlapping in their frequency spectra from three atomic-ensemble quantum memories. Time-resolved measurement enables us to observe nonclassical multiphoton correlation landscapes. An average fidelity over several interferometer configurations is measured to be 0.936(13), which is mainly limited by high-order events. Symmetries in the landscapes are identified to reflect symmetries of the optical network. Our work thus provides a route towards quantum supremacy with distinguishable photons.