Complexity transitions of boson sampling in non-unitary dynamics
Ken Mochizuki
RIKEN

PT symmetry breaking, which is one of phenomena unique to open systems, has been observed in optical systems in both the classical regime with coherent light and the quantum regime with single photons. This means that the relation between PT symmetry breaking and quantum nature is vague so far. Meanwhile, quantum optical systems with many photons are related to quantum supremacy and computational complexity, since probability distributions of numerous photons can be hard to sample based on classical computers, which exhibits the intrinsic quantum nature. Extending single-photonic quantum systems into the many-photon regime, we found that PT symmetry breaking results in photon distributions easy to compute and leads to complexity transitions with no counterpart in closed systems.