  An optical resonator with intracavity Kerr nonlinearity can exhibit
dispersive bistability suitable for all-optical switching. With nanophotonic
elements it may be possible to achieve attojoule switching energies, which
would be very attractive for ultra-low power operation but potentially
problematic because of quantum fluctuation-induced spontaneous switching. In
this manuscript I derive a quantum-optical model of two Kerr-nonlinear ring
resonators connected in a coherent feedback loop, and show via numerical
simulation that a properly designed `controller' cavity can significantly
reduce the spontaneous switching rate of a bistable `plant' cavity in a
completely embedded and autonomous manner.
