Reconfigurable resonant photon blockade via photon-pair exchange

Abstract

Photon blockade in weakly nonlinear resonators is often limited by a trade-off among antibunching, resonant excitation, and tunability. We consider a driven two-mode bosonic system coupled by photon-pair exchange. The exchange interaction vanishes in the one-photon manifold but couples the target and auxiliary two-photon states. Destructive interference can therefore suppress the leading target two-photon amplitude without detuning the target mode. In the weak-drive limit, we derive the required drive-amplitude ratio and relative phase, together with the leading correction due to an auxiliary-mode Kerr shift. Steady-state master-equation calculations confirm the analytical condition and quantify the effects of finite drive, loss asymmetry, pair mismatch, residual nonlinearities, single-photon hopping, dephasing, phase fluctuations, and thermal occupation. Under the stated matched linewidth, coherent-drive, and nonlinear-resource convention, the resonant pair-exchange scheme yields a target single-photon population approximately 9.5 times that of an optimized canonical Kerr-UPB benchmark at ga(2)(0)⩽10−2. A normalized post-fabrication recovery test further shows that external-drive recalibration restores the interference minimum across the sampled uncertainty window. These results support photon-pair exchange as a controllable route to continuous-wave resonant antibunched emission.