Quantum Mode Mixing in the Teo Rotating Wormhole: From Casimir Emission to Superradiance

Rotating traversable wormholes allow the effects of frame-dragging and rotation to be
studied in the absence of event horizons. We develop a quantum field-theoretic treatment of massless scalar perturbations in the rotating Teo spacetime (an exact, stationary,
horizonless, traversable wormhole with two asymptotically flat regions). Using the
Bogoliubov transformation formalism, we construct “in” and “out” mode solutions in the
two asymptotic regions and compute the Bogoliubov coefficients (αωm,βωm) that quantify
mode mixing.
The effective radial potential induced by rotation and frame-dragging forms an
asymmetric scattering barrier. This asymmetry permits an exact analytic evaluation of
reflection and transmission amplitudes via the barrier penetration exponent, yielding
closed-form expressions for the Bogoliubov coefficients, mean particle number,
superradiant amplification, and the two-mode entanglement entropy Sωm as functions of
the rotation parameter a.
Because the spacetime is stationary, particle creation and amplification arise purely from
geometric asymmetry rather than explicit time-dependence. Co-rotating and
counter-rotating modes experience inequivalent scattering, rendering the process
intrinsically non-reciprocal. We thus identify a stationary geometric analog of the recently
proposed Asymmetric Dynamical Casimir Effect, in which rotation and frame-dragging
replace moving boundaries as the source of asymmetric mode mixing.
Our results unify classical superradiant scattering, quantum Bogoliubov amplification, and
asymmetric Casimir physics within a single horizonless geometry, demonstrating that
neither horizons nor time-dependent metrics are necessary for quantum particle creation
from the vacuum. The framework opens the door to future studies of higher-spin fields,
slowly varying rotation, and semiclassical backreaction effects.