Spontaneous photon production in time-dependent epsilon-near-zero materials

Angus Prain, Stefano Vezzoli, Niclas Westerberg, Thomas Roger, Daniele Franco Angelo Faccio

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27 Citations (Scopus)
54 Downloads (Pure)


Quantum field theory predicts that a spatially homogeneous but temporally varying medium will excite photon pairs out of the vacuum state. However, this important theoretical prediction lacks experimental verification due to the difficulty in attaining the required non-adiabatic and large
amplitude changes in the medium. Recent work has shown that in epsilon-near-zero (ENZ) materials it is possible to optically induce changes of the refractive index of the order of unity, in femtosecond timescales. By studying the quantum eld theory of a spatially homogeneous, time-varying ENZ medium, we theoretically predict photon pair production that is up to several orders of magnitude larger than in non-ENZ time-varying materials. We also nd that whilst in standard materials the emission spectrum depends on the time scale of the perturbation, in ENZ materials the emission is always peaked at the ENZ wavelength. These studies pave the way to technologically feasible
observation of photon pair emission from a time-varying background with implications for quantum field theories beyond condensed matter systems and with potential applications as a new source of entangled light.
Original languageEnglish
Article number133904
JournalPhysical Review Letters
Issue number13
Publication statusPublished - 29 Mar 2017


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