Quantum bath engineering of a high impedance microwave mode through quasiparticle tunneling.

In microwave quantum optics, dissipation usually corresponds to quantum jumps, where photons are lost one by one. Here we demonstrate a new approach to dissipation engineering. By coupling a high impedance microwave resonator to a tunnel junction, we use the photoassisted tunneling of quasiparticles as a tunable dissipative process.

Observation of the Unconventional Photon Blockade in the Microwave Domain.

We have observed the unconventional photon blockade effect for microwave photons using two coupled superconducting resonators. As opposed to the conventional blockade, only weakly nonlinear resonators are required. The blockade is revealed through measurements of the second order correlation function g^{(2)}(t) of the microwave field inside one of the two resonators.