Abstract:
We study the detailed balance temperatures recorded along all classes of stationary, uniformly accelerated worldlines in four-dimensional Minkowski spacetime, namely
along (i) linear uniform acceleration, (ii) cusped, (iii) circular, (iv) catenary, and (v) helix
worldlines, among which the Unruh temperature is the particular case for linear uniform
acceleration. As a measuring device, we employ an Unruh-DeWitt detector, modeled as a
qubit that interacts for a long time with a massless Klein-Gordon field in the vacuum state.
The temperatures in each case (i) - (v) are functions of up to three invariant quantities:
curvature or proper acceleration, κ, torsion, b, and hypertorsion, ν, and except for the case
(i), they depend on the transition frequency difference of the detector, ω. We investigate
numerically the behavior of the frequency-dependent temperatures for different values of
κ, b, and ν along the stationary worldlines (ii) - (v) and evaluate analytically the regimes
where the temperatures recorded along the different worldlines coincide with each other in
terms of relevant asymptotic limits for κ, b, or ν, and discuss their physical meaning. We
demonstrate that the temperatures in cases (ii) - (v) dip under the Unruh temperature at
low frequencies and go above the Unruh temperature for large |ω|. It is our hope that this
study will be relevant to the design of experiments seeking to verify the Unruh effect or
generalizations thereof.