A quantum optical shutter

Abstract

A time-dependent dielectric cmedium is used to model a time-varying beam-splitter inside a cavity. The time-varying boundary conditions smoothly evolve from a highly transmitting to a highly reflecting beam-splitter. These approximately correspond to a transformation from a single cavity to a pair of cavities. Quantum field-theoretic calculations show that such a smooth change yields non-singular evolution of the field. However, it predicts a production of photons up to frequencies comparable to the rate of change of the transition. We find that a time-varying beam-splitter operating at optical frequencies would produce an observable number of photons.

QED effects in a cavity with a time-dependent thin semiconductor slab excited by laser pulses

“…The 'dynamical interferometers' with timedependent reflection and transmission coefficients or spacetime field modulation were studied in [24,25]). The generation of photons by time-varying beam-splitters was discussed in [26,27].…”

“…Here we consider the problem of photon generation from vacuum (or initial thermal state) in the selected mode of electromagnetic field inside a closed high-Q cavity due to periodical variations of the conductivity of a thin semiconductor layer deposited on the plane surface of a cavity wall. Quantum effects caused by the time dependence of properties of thin slabs were studied by several authors [27][28][29][30][31]. However, only very simple models of the media were considered in those papers: lossless homogeneous dielectrics with time-dependent permeability [27,31], ideal dielectrics or ideal conductors suddenly removed from the cavity [28,29] or infinitely thin conducting slabs modelled by δ-potentials with time-dependent strength [30] (this model of 'plasma sheet' was introduced in [16]).…”

“…Quantum effects caused by the time dependence of properties of thin slabs were studied by several authors [27][28][29][30][31]. However, only very simple models of the media were considered in those papers: lossless homogeneous dielectrics with time-dependent permeability [27,31], ideal dielectrics or ideal conductors suddenly removed from the cavity [28,29] or infinitely thin conducting slabs modelled by δ-potentials with time-dependent strength [30] (this model of 'plasma sheet' was introduced in [16]).…”