Nonreciprocal unconventional photon blockade with spinning two-mode cavity coupled via χ(2) nonlinearities

In this paper, we propose how to achieve nonreciprocal unconventional photon blockade (NUPB) in a spinning system consisting of two single-mode cavities with [Formula: see text] nonlinearity through the Fizeau drag when the two cavities are driven simultaneously. Under the weak driving condition, we discuss the physical origins of nonreciprocal unconventional photon blockade, which originates from the destructive interference between different paths from the ground state to the two-photon state by driving the device from the left side. While the quantum interference paths are broken when the device is driven from the right side, resulting in photon bunching. The optimal condition for the nonreciprocal unconventional photon blockade is analytically derived. We also calculate the analytical expression of the delayed-time second-order correction function and compare it with the numerical simulation. Finally, we show that nonreciprocal unconventional photon blockade never occurs with a single driving since two closed quantum pathways cannot be formed.