Jorma Louko
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View article: Quenched entanglement harvesting
Quenched entanglement harvesting Open
Ultracold fermionic atoms in an optical lattice, with a sudden position-dependent change (a quench) in the effective dispersion relation, have been proposed by Rodríguez-Laguna as an analog spacetime test of the Unruh effect. We provide ne…
View article: Expansion-sensitive coupling of a local quantum system in de Sitter cosmology
Expansion-sensitive coupling of a local quantum system in de Sitter cosmology Open
When a local quantum system couples to a quantum field in a cosmological spacetime, the time dependence of the coupling strength is conventionally taken to reflect the design of the local quantum system but not to depend on the large-scale…
View article: Nondestructive optomechanical detection scheme for Bose-Einstein condensates
Nondestructive optomechanical detection scheme for Bose-Einstein condensates Open
We present a two-tone heterodyne optical readout scheme to extract unequal-time density correlations along an arbitrary stationary interaction path from a pancake-shaped Bose-Einstein condensate, using a modulated laser probe. Analysing th…
View article: Deep in the knotted black hole
Deep in the knotted black hole Open
We consider the transition rate of a freely falling Unruh-DeWitt detector, coupled linearly to a massless scalar quantum field prepared in the Hartle-Hawking-Israel state, as a probe of the interior of a black hole. Specifically, we consid…
View article: Probing hidden topology with quantum detectors
Probing hidden topology with quantum detectors Open
We consider the transition rate of a static Unruh-DeWitt detector in two (2+1)-dimensional black hole spacetimes that are isometric to the static Bañados-Teitelboim-Zanelli black hole outside the horizon but have no asymptotically locally …
View article: Connecting the circular and drifted Rindler Unruh effects
Connecting the circular and drifted Rindler Unruh effects Open
In Minkowski spacetime quantum field theory, each stationary motion is associated with an effective, energy-dependent notion of temperature, which generalizes the familiar Unruh temperature of uniform linear acceleration. Motivated by curr…
View article: Local quantum detection of the cosmological expansion: Unruh-DeWitt detectors in spatially compact Milne cosmology
Local quantum detection of the cosmological expansion: Unruh-DeWitt detectors in spatially compact Milne cosmology Open
We analyze the excitations and deexcitations of an inertial Unruh-DeWitt detector in the (1+1)-dimensional expanding Milne cosmology with compact spatial sections, coupled to a real massless scalar field with either untwisted or twisted bo…
View article: Deep in the knotted black hole
Deep in the knotted black hole Open
We consider the transition rate of a freely falling Unruh-DeWitt detector, coupled linearly to a massless scalar quantum field prepared in the Hartle-Hawking-Israel state, as a probe of the interior of a black hole. Specifically, we consid…
View article: Probing hidden topology with quantum detectors
Probing hidden topology with quantum detectors Open
We consider the transition rate of a static Unruh-DeWitt detector in two $(2+1)$-dimensional black hole spacetimes that are isometric to the static Bañados-Teitelboim-Zanelli black hole outside the horizon but have no asymptotically locall…
View article: Connecting the circular and drifted Rindler Unruh effects
Connecting the circular and drifted Rindler Unruh effects Open
In Minkowski spacetime quantum field theory, each stationary motion is associated with an effective, energy-dependent notion of temperature, which generalises the familiar Unruh temperature of uniform linear acceleration. Motivated by curr…
View article: Making two particle detectors in flat spacetime communicate quantumly
Making two particle detectors in flat spacetime communicate quantumly Open
A communication protocol with nonzero quantum capacity is found when the two communicating parts are particle detector models in (3+1)-dimensional spacetime. In particular, as detectors, we consider two harmonic oscillators interacting wit…
View article: Local quantum detection of cosmological expansion: Unruh-DeWitt in spatially compact Milne
Local quantum detection of cosmological expansion: Unruh-DeWitt in spatially compact Milne Open
We analyse the excitations and de-excitations of an inertial Unruh-DeWitt detector in the $(1+1)$-dimensional expanding Milne cosmology with compact spatial sections, coupled to a real massless scalar field with either untwisted or twisted…
View article: More excitement across the horizon
More excitement across the horizon Open
An Unruh-DeWitt detector falling radially into a four-dimensional Schwarzschild black hole, coupled linearly to a massless scalar field that has been prepared in the Hartle-Hawking or Unruh state, has recently been shown to exhibit a local…
View article: Circular motion in (anti-)de Sitter spacetime: thermality versus finite size
Circular motion in (anti-)de Sitter spacetime: thermality versus finite size Open
Anti-de Sitter spacetime and the static patch of de Sitter spacetime are arenas for investigating thermal and finite-size effects seen by an accelerated quantum observer. We consider an Unruh-DeWitt detector in uniform circular motion coup…
View article: Third sound detectors in accelerated motion
Third sound detectors in accelerated motion Open
An accelerated observer moving through empty space sees particles appearing and disappearing, while an observer with a constant velocity does not register any particles. This phenomenon, generally known as the Unruh effect, relies on an in…
View article: Ambient temperature versus ambient acceleration in the circular motion Unruh effect
Ambient temperature versus ambient acceleration in the circular motion Unruh effect Open
It is well known that the experience of a linearly accelerated observer with acceleration a, interacting with a massless scalar field in its vacuum state in 3+1 Minkowski spacetime, is identical to that of a static observer interacting wit…
View article: Vacua in locally de Sitter cosmologies, and how to distinguish them
Vacua in locally de Sitter cosmologies, and how to distinguish them Open
(1+1)-dimensional locally de Sitter–Friedmann-Robertson-Walker cosmologies with compact spatial sections allow cosh, sinh, and exponential evolution laws, each with a freely specifiable spatial circumference parameter, and the value of thi…
View article: Ambient temperature versus ambient acceleration in the circular motion Unruh effect
Ambient temperature versus ambient acceleration in the circular motion Unruh effect Open
It is well known that the experience of a linearly accelerated observer with acceleration $a$, interacting with a massless scalar field in its vacuum state in $3+1$ Minkowski spacetime, is identical to that of a static observer interacting…
View article: Circular motion analogue Unruh effect in a 2+1 thermal bath: robbing from the rich and giving to the poor
Circular motion analogue Unruh effect in a 2+1 thermal bath: robbing from the rich and giving to the poor Open
The Unruh effect states that a uniformly linearly accelerated observer with proper acceleration experiences the Minkowski vacuum as a thermal state at temperature . An observer in uniform circular motion experiences a simila…
View article: Vacua in locally de Sitter cosmologies, and how to distinguish them
Vacua in locally de Sitter cosmologies, and how to distinguish them Open
(1+1)-dimensional locally de Sitter Friedmann-Robertson-Walker cosmologies with compact spatial sections allow cosh, sinh and exponential evolution laws, each with a freely-specifiable spatial circumference parameter, and the value of this…
View article: Circular motion analogue Unruh effect in a $2+1$ thermal bath: Robbing from the rich and giving to the poor
Circular motion analogue Unruh effect in a $2+1$ thermal bath: Robbing from the rich and giving to the poor Open
The Unruh effect states that a uniformly linearly accelerated observer with proper acceleration $a$ experiences the Minkowski vacuum as a thermal state at temperature $T_U=a/(2π)$. An observer in uniform circular motion experiences a simil…
View article: Third sound detectors in accelerated motion
Third sound detectors in accelerated motion Open
An accelerated observer moving through empty space sees particles appearing and disappearing, while an observer with a constant velocity does not register any particles. This phenomenon, generally known as the Unruh effect, relies on an in…
View article: A little excitement across the horizon
A little excitement across the horizon Open
We analyse numerically the transitions in an Unruh-DeWitt detector, coupled linearly to a massless scalar field, in radial infall in (3 + 1)-dimensional Schwarzschild spacetime. In the Hartle–Hawking and Unruh states, the transition probab…
View article: Quantum kicks near a Cauchy horizon
Quantum kicks near a Cauchy horizon Open
We analyze a quantum observer who falls geodesically toward the Cauchy horizon of a (1 + 1)-dimensional eternal black hole spacetime with the global structure of the non-extremal Reissner–Nordström solution. The observer interacts with a m…
View article: A Little Excitement Across the Horizon
A Little Excitement Across the Horizon Open
We analyse numerically the transitions in an Unruh-DeWitt detector, coupled linearly to a massless scalar field, in radial infall in (3+1)-dimensional Schwarzschild spacetime. In the Hartle-Hawking and Unruh states, the transition probabil…
View article: Can a localised quantum system see soft photons?
Can a localised quantum system see soft photons? Open
We ask whether soft photons, defined by asymptotic charges, can have consequences for the outcome of localised quantum processes. We consider a spatially localised two-state system, at rest in flat spacetime, coupled to a $U(1)$ gauge inva…