Fock-state stabilization and emission in superconducting circuits using   dc-biased Josephson junctions
  We present and analyze a reservoir-engineering approach to stabilizing Fock states in a superconducting microwave cavity which does not require any microwave-frequency control drives. Instead, our system makes use of a Josephson junction biased by a dc voltage which is coupled both to a principle storage cavity and a second auxiliary cavity. Our analysis shows that Fock states can be stabilized with an extremely high fidelity. We also show how the same system can be used to prepare on-demand propagating Fock states, again without the use of microwave pulses. 
J.-R. Souquet, A. A. Clerk
cond-mat.mes-hall quant-ph