Simulation of boson sampling with optical feedback

TL;DR

This paper introduces a theoretical model for boson sampling with optical feedback, demonstrating how feedback induces a stationary state and proposing new computational methods for analyzing output distributions.

Contribution

It presents a novel theoretical framework for boson sampling with optical feedback, including new methods for computing output distributions and defining a harder computational problem.

Findings

System evolves to a unique stationary state with feedback

New methods for output distribution computation

Stationary Distribution Boson Sampling is computationally harder

Abstract

This work presents a theoretical model of boson sampling with optical feedback, in which a subset of the interferometer's output modes is looped back into the input modes. If the bosons are injected periodically into the input modes of the interferometer and optical feedback lines' length match the period of injection, it allows for interference between bosons injected at the consequent time iterations. We propose several methods methods for computing the output photon distributions in both output spacial and temporal modes, including not only standard spatiotemporal mode-unfolding technique, but also the Kraus-operator formalism, and a correlation-tensor-based approach. The two latter approaches help us to reveal that for random interferometers this system evolves to a unique stationary state over time. Because of the existence of the stationary state, we introduce new computational problem \textit{Stationary Distribution Boson Sampling} which appears to be harder than conventional boson sampling problem and contains it as a special case when there are no optical feedback lines.