Detecting the massive bosonic zero-mode in expanding cosmological spacetimes

Abstract

We examine a quantised massive scalar field in $(1+1)$-dimensional spatially compact cosmological spacetimes in which the early time and late time expansion laws provide distinguished definitions of Fock "in" and "out" vacua, with the possible exception of the spatially constant sector, which may become effectively massless at early or late times. We show, generalising the work of Ford and Pathinayake, that when such a massive zero mode occurs, the freedom in the respective "in" and "out" states is a family with two real parameters. As an application, we consider massive untwisted and twisted scalar fields in the $(1+1)$-dimensional spatially compact Milne spacetime, where the untwisted field has a massive "in" zero mode. We demonstrate, by a combination of analytic and numerical methods, that the choice of the massive "in" zero mode state has a significant effect on the response of an inertial Unruh-DeWitt detector, especially in the excitation part of the spectrum. The detector's peculiar velocity with respect to comoving cosmological observers has the strongest effect in the "in" vacuum of the untwisted field, where it shifts the excitation and de-excitation resonances towards higher values of the detector's energy gap.

arXiv comment37 pages, 13 figures

References in corpus (21)

• Entangling Power of an Expanding Universe
• Wavepacket detection with the Unruh-DeWitt model
• Hadamard renormalization of the stress-energy tensor for a quantized scalar field in a general spacetime of arbitrary dimension
• Infrared Sensitivity of Unstable Vacua
• A general worldline quantum inequality
• Massless Minimally Coupled Fields in De Sitter Space: O(4)-Symmetric States Versus De Sitter Invariant Vacuum
• Response of finite-time particle detectors in non-inertial frames and curved spacetime
• Casimir forces on atoms in optical cavities
• General Relativistic Quantum Optics: Finite-size particle detector models in curved spacetimes
• Waiting for Unruh
• Harvesting correlations from thermal and squeezed coherent states
• Unruh-DeWitt detectors and entanglement: the anti-de Sitter space
• Entanglement harvesting and divergences in quadratic Unruh-DeWitt detectors pairs
• Unruh-DeWitt detector's response to fermions in flat spacetimes
• Particle detectors and the zero mode of a quantum field
• Secularly growing loop corrections in strong electric fields
• New techniques for entanglement harvesting in flat and curved spacetimes
• Echo of the Quantum Bounce
• Vacuum entanglement harvesting with a zero mode
• On quantization in background scalar fields
• A few more comments on secularly growing loop corrections in strong electric fields

Cited by in corpus (6)

• The time traveler's guide to the quantization of zero modes
• Unruh-Fulling effect in nonlocal field theory: The role of Unruh decomposition
• Vacua in locally de Sitter cosmologies, and how to distinguish them
• Back-action from inertial and non-inertial Unruh-DeWitt detectors revisited in covariant perturbation theory
• Unruh-DeWitt detector's response to a non-relativistic particle
• Expansion-sensitive coupling of a local quantum system in de Sitter cosmology