Irreversible photon transfer in an ensemble of Lambda-type atoms and a photon diode

We show that a pair of quantized modes interacting with a spectrally broadened ensemble of Lambda-type atoms is analogous to an ensemble of two-level systems coupled to a bosonic reservoir. This enables an irreversible photon transfer between photon modes. The reservoir can be engineered which allows the observation of effects such as the Zeno and anti-Zeno effect, the destructive interference of decay channels, and the decay in a squeezed vacuum. We also consider a photon diode, i.e., a device which directs a single photon from any one of two input ports to a common output port.