Abstract
We study novel contributions to the partition function of the Maxwell system defined on a small compact manifold with nontrivial mappings . These contributions cannot be described in terms of conventional physical propagating photons with two transverse polarizations and instead emerge as a result of tunneling transitions between topologically different but physically identical vacuum winding states. We argue that if the same system is considered in the background of a small external time-dependent electromagnetic field, then real physical photons will be emitted from the vacuum, similar to the dynamical Casimir effect where photons are radiated from the vacuum due to time-dependent boundary conditions. The fundamental technical difficulty for such an analysis is that the radiation of physical photons on mass shell is inherently a real-time Minkowskian phenomenon while the vacuum fluctuations interpolating between topological sectors rest upon a Euclidean instanton formulation. We overcome this obstacle by introducing auxiliary topological fields, which allows for a simple analytical continuation between Minkowski and Euclidean descriptions, and develop a quantum mechanical technique to compute these effects. We also propose an experimental realization of such small effects using a microwave cavity with appropriate boundary conditions. Finally, we comment on the possible cosmological implications of this effect.
- Received 20 May 2016
DOI:https://doi.org/10.1103/PhysRevD.95.065018
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