Unconventional photon blockade via two-photon absorption

The unconventional photon blockade, which relies on the physical mechanism of quantum interference, is primarily investigated using a general master equation, where a weak nonlinearity must be presented in the system to achieve photon antibunching. In this study, we explore the unconventional photon blockade using an alternative master equation known as the two-photon absorption master equation, which is derived from the system and environment interaction via two-photon absorption. Specifically, we find that the unconventional photon blockade can be triggered in two-coupled cavities, where each cavity interacts with a two-photon absorption environment. Different from unconventional photon blockade via the general master equation, we show that the two-photon absorption acts as the weak nonlinearity, and this photon blockade corresponds to a large average photon number. To derive optimal conditions for achieving this blockade, we propose a non-Hermitian Hamiltonian method to describe the mode loss caused by the two-photon absorption. In addition, we highlight the distinctions between our proposal and other approaches for generating single-photon states based on two-photon absorption.