Quantum-Circuit Black Hole Lasers

Abstract A black hole laser in analogues of gravity amplifies Hawking radiation, which is unlikely to be measured in real black holes, and makes it observable. There have been proposals to realize such black hole lasers. However, no progress has been made in electric circuits. Here we propose an optical analogue black hole laser in Josephson transmission lines incorporating metamaterial elements capable of producing Hawking-pair propagation modes and a Kerr nonlinearity due to the Josephson nonlinear inductance. A single dark soliton obeying the nonlinear Schrodinger equation produces a black hole-white hole horizon pair that acts as a laser cavity through a change in the refractive index due to the Kerr effect. We show that the resulting laser is a squeezed-state laser derived from Hawking radiation and then characterized by squeezing parameters related to Hawking temperatures depending on the soliton velocity. We also evaluate the degree of quantum correlation using entanglement entropy.