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  • Letter
  • Open Access

Interference of colliding Fock states and vacuum-generated photon pairs at time interfaces

Nikita Nefedkin1,*, Emanuele Galiffi1,†,‡, and Andrea Alù1,2,§

  • *Contact author: nnefedkin@gc.cuny.edu
  • †Contact author: egaliffi@gc.cuny.edu
  • ‡Present address: Chandra Department of Electrical and Computer Engineering, University of Texas at Austin, Austin, Texas 78712, USA.
  • §Contact author: aalu@gc.cuny.edu
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Phys. Rev. Research 8, L012068 – Published 23 March, 2026

DOI: https://doi.org/10.1103/z61w-gdvl

Abstract

We investigate the scattering of counterpropagating photon Fock states at a time interface, induced by an abrupt variation of the dielectric permittivity of the host material. We unveil the role of vacuum-generated photons in determining the final photon number distribution and coherence properties. Such vacuum-generated photons interfere with the photons in the initial Fock states, producing distinctive interference patterns, which can be broadly controlled, together with the temperature of the final photon gas, by the time-interface parameters and the number of photons in the initial states.

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Phys. Rev. Research 8, L012068– Published 23 March, 2026
  • Received 2 April 2025
  • Accepted 11 February 2026
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