Observation of Lie algebraic invariants in Quantum Linear Optics

TL;DR

This paper experimentally demonstrates that Lie algebraic invariants underpin the dynamics of photonic quantum states in linear optical networks, providing a new method to verify Boson sampling experiments and ensure their correctness.

Contribution

It introduces the use of Lie algebraic invariants as a benchmark for verifying the correctness of linear optical quantum experiments, especially Boson sampling.

Findings

Sampling experiments satisfy Lie algebraic constraints

Lie invariants can verify the reliability of Boson Sampling

Provides a framework for algebraic verification in quantum optics

Abstract

Over the past few years, various methods have been developed to engineeer and to exploit the dynamics of photonic quantum states as they evolve through linear optical networks. Recent theoretical works have shown that the underlying Lie algebraic structure plays a crucial role in the description of linear optical Hamiltonians, as such formalism identifies intrinsic symmetries within photonic systems subject to linear optical dynamics. Here, we experimentally investigate the role of Lie algebra applied to the context of Boson sampling, a pivotal model to the current understanding of computational complexity regimes in photonic quantum information. Performing experiments of increasing complexity, realized within a fully-reconfigurable photonic circuit, we show that sampling experiments do indeed fulfill the constraints implied by a Lie algebraic structure. In addition, we provide a comprehensive picture about how the concept of Lie algebraic invariant can be interpreted from the point of view of n-th order correlation functions in quantum optics. Our work shows how Lie algebraic invariants can be used as a benchmark tool for the correctness of an underlying linear optical dynamics and to verify the reliability of Boson Sampling experiments. This opens new avenues for the use of algebraic-inspired methods as verification tools for photon-based quantum computing protocols.