Frequency-space few-photon diode effect

We study coherent few-photon transport in a dissipative nonlinear cavity coupled to a 1D waveguide, deriving analytical solutions that reveal how cavity dissipation regulates the few-photon diode effect. Key findings show that under Γ/�� = 1 (Γ:waveguide-cavity coupling, ��: dissipation) and ��1 = 0Γ:(1) For single photons, left incidence yields perfect transmission while right incidence causes complete dissipation absorption, forming an efficient single-photon diode;(2) For two photons under single-photon resonance, left incidence allows unimpeded transmission whereas right incidence results in near-total dissipation (> 99%)leaving only a faint bound state, maintaining strong diode characteristics despite minimal transmission. The condition Γ/�� = 1 optimizes directional suppression via cavity dissipation, providing a theoretical foundation for quantum diode devices in integrated quantum optics and information processing.