  Superradiance, the enhanced collective emission of light from a coherent
ensemble of quantum systems, has been typically studied in atomic ensembles. In
this work we study the enhanced emission of energy from coherent ensembles of
harmonic oscillators. We show that it should be possible to observe harmonic
oscillator superradiance in a variety of physical platforms such as waveguide
arrays in integrated photonics and resonator arrays in circuit QED. We find
general conditions specifying when emission is superradiant and subradiant and
find that superradiant, subradiant and dark states take the form of multimode
squeezed coherent states and highly entangled multimode Fock states. The
intensity, two-mode correlations and fraction of quanta trapped in the system
after decay are calculated for a range of initial states including multimode
Fock, squeezed, coherent and thermal states. In order to explore these effects,
the Law and Eberly protocol [C. K. Law and J. H. Eberly, Phys. Rev. Lett. 76,
1055 (1996)] is generalized to prepare highly entangled multimode Fock states
in circuit QED.

Quantum Physics