Simulating boson sampling in lossy architectures

TL;DR

This paper demonstrates that photon loss in boson sampling architectures enables classical simulation, challenging the feasibility of quantum advantage in such lossy systems and indicating the need for new experimental platforms.

Contribution

It provides a theoretical framework showing classical simulability of lossy boson sampling architectures based on circuit depth and transmission decay.

Findings

Classical algorithms can efficiently simulate deep lossy boson sampling circuits.

Thermal noise simulation is effective for large-depth circuits.

Tensor network methods are suitable for shallow circuits.

Abstract

Photon losses are among the strongest imperfections affecting multi-photon interference. Despite their importance, little is known about their effect on boson sampling experiments. In this work we show that using classical computers, one can efficiently simulate multi-photon interference in all architectures that suffer from an exponential decay of the transmission with the depth of the circuit, such as integrated photonic circuits or optical fibers. We prove that either the depth of the circuit is large enough that it can be simulated by thermal noise with an algorithm running in polynomial time, or it is shallow enough that a tensor network simulation runs in quasi-polynomial time. This result suggests that in order to implement a quantum advantage experiment with single-photons and linear optics new experimental platforms may be needed.