Scalar and fermionic Unruh Otto engines

Abstract

We investigate the behaviour of quantum heat engines, in which a qubit is put through the quantum equivalent of the Otto cycle and the heat reservoirs are due to the Unruh effect. The qubit is described by an Unruh-DeWitt detector model coupled quadratically to a scalar field and alternately to a fermion field. In the cycle, the qubit undergoes two stages of differing constant acceleration corresponding to thermal contact with a hot and cold reservoir. Explicit conditions are derived on the accelerations required for this cycle to have positive work output. By analytically calculating the detector response functions, we show that the dimensionality of the quadratic and fermionic coupling constants introduces qualitatively different behaviour of the work output from this cycle as compared to the case in which the qubit linearly couples to a scalar field.

Unruh quantum Otto heat engine with level degeneracy

“…where J(x, y) = (y/2) 2 e −|x|y 16 sin 2 (y/2) is the Lerch-Hurwitz function. This result agrees with (C.16) of [31], but differs from [30] for a factor 1/2, which is just a simple omission and does not affect the qualitative features of δp H . There is also an extra −1/8 in [30], which was introduced to resolve τ H → 0 case.…”

“…where the interaction time 2τ H = 2 artanh(v)/α H , (3.5) so that the two-level system undergoes the acceleration α H from speed v to −v. The method to calculate δp H (t) is discussed in the appendixes of [30,31]. Here we only present the basic steps and results.…”

“…Moreover, Arias et al derived the conditions to have both a thermodynamic and a kinematic cycle, which define a range of allowed accelerations for the Unruh engine. This model was extended to quadratically coupled scalar and fermionic fields in [31].…”

Unruh detectors and quantum chaos in JT gravity

“…See [78] for a comprehensive study of different Unruh-DeWitt detector types and their effects and [79,80] for recent studies. The normal ordering defined by (ψψ) =ψψ− ψ ψ CFT is required in order to sensibly define this detector coupling.…”

Accelerated paths and Unruh effect. Part I. Scalars and fermions in Anti De Sitter spacetime

“…Following Sewell's result [57], Takagi [58] has shown this kind of behaviour for a free field and Ooguri [56] concluded the arguments for the interacting theory. In the case of Dirac fields in Minkowski spacetime, Louko and Toussaint [59] proved that uniformly accelerated detectors detect Bose-Einstein distributions in any dimension D. Based on the Unruh effect observed by accelerated detectors, several construction of quantum heat engine [60,61] have been proposed for flat space.…”