Time-reversal symmetry breaking in circuit-QED based photon lattices

Understand

Breaking time-reversal symmetry is a prerequisite for accessing certain interesting many-body states such as fractional quantum Hall states.

• For polaritons, charge neutrality prevents magnetic fields from providing a direct symmetry breaking mechanism and similar to the situation in ultracold atomic gases, an effective magnetic field has to be synthesized.
• We show that in the circuit QED architecture, this can be achieved by inserting simple superconducting circuits into the resonator junctions.
• In the presence of such coupling elements, constant parallel magnetic and electric fields suffice to break time-reversal symmetry.