  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. We support these theoretical predictions with
numerical simulations for realistic sample parameters, specify general
conditions under which time-reversal is broken, and discuss the application to
chiral Fock state transfer, an on-chip circulator, and tunable band structure
for the Kagome lattice.
