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Ambient temperature versus ambient acceleration in the circular motion Unruh effect (2024)
Journal Article
Bunney, C. R., Parry, L., Perche, T. R., & Louko, J. (2024). Ambient temperature versus ambient acceleration in the circular motion Unruh effect. Physical Review D, 109(6), Article 065001. https://doi.org/10.1103/physrevd.109.065001

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 with a massles... Read More about Ambient temperature versus ambient acceleration in the circular motion Unruh effect.

Vacua in locally de Sitter cosmologies, and how to distinguish them (2024)
Journal Article
Toussaint, V., & Louko, J. (2024). Vacua in locally de Sitter cosmologies, and how to distinguish them. Physical Review D, 109(2), Article 025007. https://doi.org/10.1103/physrevd.109.025007

(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 paramet... Read More about Vacua in locally de Sitter cosmologies, and how to distinguish them.

Circular motion analogue Unruh effect in a 2 + 1 thermal bath: robbing from the rich and giving to the poor (2023)
Journal Article
D Bunney, C. R., & Louko, J. (2023). Circular motion analogue Unruh effect in a 2 + 1 thermal bath: robbing from the rich and giving to the poor. Classical and Quantum Gravity, 40(15), Article 155001. https://doi.org/10.1088/1361-6382/acde3b

The Unruh effect states that a uniformly linearly accelerated observer with proper acceleration a experiences the Minkowski vacuum as a thermal state at temperature 𝘛ᵤ = 𝑎/(2π). An observer in uniform circular motion experiences a similar effective t... Read More about Circular motion analogue Unruh effect in a 2 + 1 thermal bath: robbing from the rich and giving to the poor.

A little excitement across the horizon (2022)
Journal Article
Ng, K. K., Zhang, C., Louko, J., & Mann, R. B. (2022). A little excitement across the horizon. New Journal of Physics, 24(10), Article 103018. https://doi.org/10.1088/1367-2630/ac9547

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 probability attai... Read More about A little excitement across the horizon.

The cost of building a wall for a fermion (2022)
Journal Article
Wan Mokhtar, W. M. H., & Louko, J. (2022). The cost of building a wall for a fermion. Journal of High Energy Physics, 2022(8), Article 69. https://doi.org/10.1007/JHEP08%282022%29069

We analyse the energy cost of building or demolishing a wall for a massless Dirac field in (1+1)-dimensional Minkowski spacetime and the response of an Unruh-DeWitt particle detector to the generated radiation. For any smoothly-evolving wall, both th... Read More about The cost of building a wall for a fermion.

Quantum kicks near a Cauchy horizon (2022)
Journal Article
Juárez-Aubry, B. A., & Louko, J. (2022). Quantum kicks near a Cauchy horizon. AVS Quantum Science, 4(1), Article 013201. https://doi.org/10.1116/5.0073373

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 massless sca... Read More about Quantum kicks near a Cauchy horizon.

Detecting the massive bosonic zero-mode in expanding cosmological spacetimes (2021)
Journal Article
Toussaint, V., & Louko, J. (2021). Detecting the massive bosonic zero-mode in expanding cosmological spacetimes. Physical Review D, 103(10), Article 105011. https://doi.org/10.1103/PhysRevD.103.105011

We examine a quantized 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... Read More about Detecting the massive bosonic zero-mode in expanding cosmological spacetimes.

Interferometric Unruh Detectors for Bose-Einstein Condensates (2020)
Journal Article
Gooding, C., Biermann, S., Erne, S., Louko, J., Unruh, W. G., Schmiedmayer, J., & Weinfurtner, S. (2020). Interferometric Unruh Detectors for Bose-Einstein Condensates. Physical Review Letters, 125(21), Article 213603. https://doi.org/10.1103/PhysRevLett.125.213603

The Unruh effect predicts a thermal response for an accelerated detector moving through the vacuum. Here we propose an interferometric scheme to observe an analogue of the circular Unruh effect using a localized laser coupled to a Bose-Einstein conde... Read More about Interferometric Unruh Detectors for Bose-Einstein Condensates.

Unruh and analogue Unruh temperatures for circular motion in 3+1 and 2+1 dimensions (2020)
Journal Article
Biermann, S., Erne, S., Gooding, C., Louko, J., Schmiedmayer, J., Unruh, W. G., & Weinfurtner, S. (2020). Unruh and analogue Unruh temperatures for circular motion in 3+1 and 2+1 dimensions. Physical Review D, 102(8), Article 085006. https://doi.org/10.1103/PhysRevD.102.085006

The Unruh effect states that a uniformly linearly accelerated observer with proper acceleration a experiences Minkowski vacuum as a thermal state in the temperature Tlin=a/(2?), operationally measurable via the detailed balance condition between exci... Read More about Unruh and analogue Unruh temperatures for circular motion in 3+1 and 2+1 dimensions.

Unruh effect and information flow (2020)
Journal Article
Sokolov, B., Louko, J., Maniscalco, S., & Vilja, I. (2020). Unruh effect and information flow. Physical Review D, 101(2), Article 024047. https://doi.org/10.1103/PhysRevD.101.024047

We study memory effects as information backflow for an accelerating two-level detector weakly interacting with a scalar field in the Minkowski vacuum. This is the framework of the well-known Unruh effect: the detector behaves as if it were in a therm... Read More about Unruh effect and information flow.

Inflation in loop quantum cosmology (2019)
Journal Article
Bhardwaj, A., Copeland, E. J., & Louko, J. (2019). Inflation in loop quantum cosmology. Physical Review D, 99(6), Article 063520. https://doi.org/10.1103/physrevd.99.063520

We develop a consistent analytic approach to determine the conditions under which slow-roll inflation can arise when the inflaton is the same scalar field that is responsible for the bounce in loop quantum cosmology (LQC). We find that the requiremen... Read More about Inflation in loop quantum cosmology.

P · Â vs x · Ê: Gauge invariance in quantum optics and quantum field theory (2019)
Journal Article
Funai, N., Louko, J., & Martin-Martinez, E. (2019). P · Â vs x · Ê: Gauge invariance in quantum optics and quantum field theory. Physical Review D, 99(6), Article 065014. https://doi.org/10.1103/physrevd.99.065014

We compare the predictions of the fundamentally motivated minimal coupling (^p⋅^A) and the ubiquitous dipole coupling (^x⋅^E) in the light-matter interaction. By studying the light-matter interaction for hydrogenlike atoms we find that the dipole app... Read More about P · Â vs x · Ê: Gauge invariance in quantum optics and quantum field theory.

Thermality from a Rindler quench (2018)
Journal Article
Louko, J. (2018). Thermality from a Rindler quench. Classical and Quantum Gravity, 35(20), 1-13. https://doi.org/10.1088/1361-6382/aadb34

© 2018 IOP Publishing Ltd. 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 et al as an analogue spacetime test of the Unr... Read More about Thermality from a Rindler quench.

Smooth and sharp creation of a spherical shell for a (3+1)-dimensional quantum field (2018)
Journal Article
Carrington, M. E., Kunstatter, G., Louko, J., & Zhou, L. J. (2018). Smooth and sharp creation of a spherical shell for a (3+1)-dimensional quantum field. Physical Review D, 98(2), https://doi.org/10.1103/PhysRevD.98.024035

We study the creation of a spherical, finite radius source for a quantized massless scalar field in 3 þ 1 dimensions. The goal is to model the breakdown of correlations that has been proposed to occur at the horizon of an evaporating black hole. We d... Read More about Smooth and sharp creation of a spherical shell for a (3+1)-dimensional quantum field.

Dynamical obstruction to perpetual motion from Lorentz-violating black holes (2018)
Journal Article
Benkel, R., Bhattacharyya, J., Louko, J., Mattingly, D., & Sotiriou, T. P. (2018). Dynamical obstruction to perpetual motion from Lorentz-violating black holes. Physical Review D, 98(2), Article 024034. https://doi.org/10.1103/PhysRevD.98.024034

Black holes in Lorentz-violating theories have been claimed to violate the second law of thermodynamics by perpetual motion energy extraction. We revisit this question for a Penrose splitting process in a spherically symmetric setting with two specie... Read More about Dynamical obstruction to perpetual motion from Lorentz-violating black holes.

Quantum fields during black hole formation: how good an approximation is the Unruh state? (2018)
Journal Article
Juárez-Aubry, B. A., & Louko, J. (in press). Quantum fields during black hole formation: how good an approximation is the Unruh state?. Journal of High Energy Physics, 2018(5), https://doi.org/10.1007/JHEP05%282018%29140

We study the quantum effects of a test Klein-Gordon field in a Vaidya space-time consisting of a collapsing null shell that forms a Schwazschild black hole, by explicitly obtaining, in a (1 + 1)-dimensional model, the Wightman function, the renormali... Read More about Quantum fields during black hole formation: how good an approximation is the Unruh state?.

Quantum memory for Rindler supertranslations (2018)
Journal Article
Kolekar, S., & Louko, J. (2018). Quantum memory for Rindler supertranslations. Physical Review D, 97(8), https://doi.org/10.1103/PhysRevD.97.085012

The Rindler horizon in Minkowski spacetime can be implanted with supertranslation hair by a matter shock wave without planar symmetry, and the hair is observable as a supertranslation memory on the Rindler family of uniformly linearly accelerated obs... Read More about Quantum memory for Rindler supertranslations.

Low-energy Lorentz violation from high-energy modified dispersion in inertial and circular motion (2018)
Journal Article
Louko, J., & Upton, S. D. (2018). Low-energy Lorentz violation from high-energy modified dispersion in inertial and circular motion. Physical Review D, 97(2), Article 025008. https://doi.org/10.1103/PhysRevD.97.025008

© 2018 American Physical Society. We consider an Unruh-DeWitt detector in inertial and circular motion in Minkowski spacetime of arbitrary dimension, coupled to a quantized scalar field with the Lorentz-violating dispersion relation ω=|k|f(|k|/M†), w... Read More about Low-energy Lorentz violation from high-energy modified dispersion in inertial and circular motion.

Unruh-DeWitt Fermion Detector on a (1+1)-Dimensional Cylindrical Spacetime: Arbitrary Worldlines and Inequivalent Spin Structures (2017)
Conference Proceeding
Louko, J., & Toussaint, V. (2017). Unruh-DeWitt Fermion Detector on a (1+1)-Dimensional Cylindrical Spacetime: Arbitrary Worldlines and Inequivalent Spin Structures. In Proceedings of the 14th Marcel Grossmann Meeting on General Relativity (2809-2815). https://doi.org/10.1142/9789813226609_0349

We examine an Unruh-DeWitt particle detector which couples linearly to the scalar density of a massless Dirac field on the static cylindrical quotient of the (1+1)-dimensional Minkowski spacetime, allowing the detector’s motion to remain arbitrary and... Read More about Unruh-DeWitt Fermion Detector on a (1+1)-Dimensional Cylindrical Spacetime: Arbitrary Worldlines and Inequivalent Spin Structures.

Gravitational memory for uniformly accelerated observers (2017)
Journal Article
Kolekar, S., & Louko, J. (2017). Gravitational memory for uniformly accelerated observers. Physical Review D, 96(2), Article 024054. https://doi.org/10.1103/PhysRevD.96.024054

Recently, Hawking, Perry and Strominger described a physical process that implants supertranslational hair on a Schwarzschild black hole by an infalling matter shock wave without spherical symmetry. Using the Bondi-Metzner-Sachs-type symmetries of th... Read More about Gravitational memory for uniformly accelerated observers.

Degenerate detectors are unable to harvest spacelike entanglement (2017)
Journal Article
Pozas-Kerstjens, A., Louko, J., & Martín-Martínez, E. (2017). Degenerate detectors are unable to harvest spacelike entanglement. Physical Review D, 95(10), https://doi.org/10.1103/PhysRevD.95.105009

We show, under a very general set of assumptions, that pairs of identical particle detectors in spacelike separation, such as atomic probes, can only harvest entanglement from the vacuum state of a quantum field when they have a nonzero energy gap. F... Read More about Degenerate detectors are unable to harvest spacelike entanglement.

Quantum communications and quantum metrology in the spacetime of a rotating planet (2017)
Journal Article
Kohlrus, J., Bruschi, D. E., Louko, J., & Fuentes, I. (2017). Quantum communications and quantum metrology in the spacetime of a rotating planet. EPJ Quantum Technology, 4, Article 7. https://doi.org/10.1140/epjqt/s40507-017-0061-0

We study how quantum systems that propagate in the spacetime of a rotating planet are affected by the curved background. Spacetime curvature affects wavepackets of photons propagating from Earth to a satellite, and the changes in the wavepacket encod... Read More about Quantum communications and quantum metrology in the spacetime of a rotating planet.

Smooth and sharp creation of a pointlike source for a (3+1)-dimensional quantum field (2017)
Journal Article
Zhou, L., Carrington, M. E., Kunstatter, G., & Louko, J. (2017). Smooth and sharp creation of a pointlike source for a (3+1)-dimensional quantum field. Physical Review D, 95(8), https://doi.org/10.1103/PhysRevD.95.085007

We analyze the smooth and sharp creation of a pointlike source for a quantized massless scalar field in (3+1)-dimensional Minkowski spacetime, as a model for the breakdown of correlations that has been proposed to occur at the horizon of an evaporati... Read More about Smooth and sharp creation of a pointlike source for a (3+1)-dimensional quantum field.

Unruh-DeWitt detector’s response to fermions in flat spacetimes (2016)
Journal Article
Louko, J., & Toussaint, V. (2016). Unruh-DeWitt detector’s response to fermions in flat spacetimes. Physical Review D, 94(6), Article 064027. https://doi.org/10.1103/PhysRevD.94.064027

We examine an Unruh-DeWitt particle detector that is coupled linearly to the scalar density of a massless Dirac field in Minkowski spacetimes of dimension d≥2 and on the static Minkowski cylinder in spacetime dimension two, allowing the detector’s mo... Read More about Unruh-DeWitt detector’s response to fermions in flat spacetimes.

Waiting for Unruh (2016)
Journal Article
Fewster, C. J., Juárez-Aubry, B. A., & Louko, J. (2016). Waiting for Unruh. Classical and Quantum Gravity, 33(16), Article 165003. https://doi.org/10.1088/0264-9381/33/16/165003

How long does a uniformly accelerated observer need to interact with a quantum field in order to record thermality in the Unruh temperature? We address this question for a pointlike Unruh–DeWitt detector, coupled linearly to a real Klein–Gordon field... Read More about Waiting for Unruh.

Smooth and sharp creation of a Dirichlet wall in 1+1 quantum field theory: how singular is the sharp creation limit? (2015)
Journal Article
Brown, E. G., & Louko, J. (2015). Smooth and sharp creation of a Dirichlet wall in 1+1 quantum field theory: how singular is the sharp creation limit?. Journal of High Energy Physics, 2015(8), https://doi.org/10.1007/jhep08%282015%29061

We present and utilize a simple formalism for the smooth creation of boundary conditions within relativistic quantum field theory. We consider a massless scalar field in (1 + 1)-dimensional flat spacetime and imagine smoothly transitioning from there... Read More about Smooth and sharp creation of a Dirichlet wall in 1+1 quantum field theory: how singular is the sharp creation limit?.

Ideal clocks - A convenient fiction (2015)
Journal Article
Lorek, K., Louko, J., & Dragan, A. (2015). Ideal clocks - A convenient fiction. Classical and Quantum Gravity, 32(17), Article 175003. https://doi.org/10.1088/0264-9381/32/17/175003

© 2015 IOP Publishing Ltd. We show that no device built according to the rules of quantum field theory can measure proper time along its path. Highly accelerated quantum clocks experience the Unruh effect, which inevitably influences their time rate.... Read More about Ideal clocks - A convenient fiction.

(1+1)D calculation provides evidence that quantum entanglement survives a firewall (2015)
Journal Article
Martín-Martínez, E., & Louko, J. (2015). (1+1)D calculation provides evidence that quantum entanglement survives a firewall. Physical Review Letters, 115(3), Article 031301. https://doi.org/10.1103/PhysRevLett.115.031301

We analyze how preexisting entanglement between two Unruh-DeWitt particle detectors evolves when one of the detectors falls through a Rindler firewall in (1+1)-dimensional Minkowski space. The firewall effect is minor and does not wash out the detect... Read More about (1+1)D calculation provides evidence that quantum entanglement survives a firewall.

Superconducting circuit boundary conditions beyond the dynamical Casimir effect (2015)
Journal Article
Doukas, J., & Louko, J. (2015). Superconducting circuit boundary conditions beyond the dynamical Casimir effect. Physical Review D - Particles, Fields, Gravitation and Cosmology, 91(4), Article 044010. https://doi.org/10.1103/PhysRevD.91.044010

© 2015 American Physical Society. We study analytically the time-dependent boundary conditions of superconducting microwave circuit experiments in the high plasma frequency limit, in which the conditions are Robin-type and relate the value of the fie... Read More about Superconducting circuit boundary conditions beyond the dynamical Casimir effect.

Renormalized vacuum polarization on rotating warped AdS3 black holes (2015)
Journal Article
Ferreira, H. R., & Louko, J. (2015). Renormalized vacuum polarization on rotating warped AdS3 black holes. Physical Review D, 91(2), Article 024038. https://doi.org/10.1103/PhysRevD.91.024038

We compute the renormalized vacuum polarization of a massive scalar field in the Hartle-Hawking state on (2+1)-dimensional rotating, spacelike stretched black hole solutions to topologically massive gravity, surrounded by a Dirichlet mirror that make... Read More about Renormalized vacuum polarization on rotating warped AdS3 black holes.

Onset and decay of the 1 + 1 Hawking–Unruh effect: what the derivative-coupling detector saw (2014)
Journal Article
Juárez-Aubry, B. A., & Louko, J. (2014). Onset and decay of the 1 + 1 Hawking–Unruh effect: what the derivative-coupling detector saw. Classical and Quantum Gravity, 31(24), Article 245007. https://doi.org/10.1088/0264-9381/31/24/245007

We study an Unruh–DeWitt particle detector that is coupled to the proper time derivative of a real scalar field in 1 + 1 spacetime dimensions. Working within first-order perturbation theory, we cast the transition probability into a regulator- free f... Read More about Onset and decay of the 1 + 1 Hawking–Unruh effect: what the derivative-coupling detector saw.

Unruh-DeWitt detector response across a Rindler firewall is finite (2014)
Journal Article
Louko, J. (2014). Unruh-DeWitt detector response across a Rindler firewall is finite. Journal of High Energy Physics, 2014(9), https://doi.org/10.1007/JHEP09%282014%29142

We investigate a two-level Unruh-DeWitt detector coupled to a massless scalar field or its proper time derivative in (1 + 1)-dimensional Minkowski spacetime, in a quantum state whose correlation structure across the Rindler horizon mimics the station... Read More about Unruh-DeWitt detector response across a Rindler firewall is finite.

Unruh-DeWitt detector response along static and circular-geodesic trajectories for Schwarzschild-anti-de Sitter black holes (2014)
Journal Article
Ng, K. K., Hodgkinson, L., Louko, J., Mann, R. B., & Martín-Martínez, E. (2014). Unruh-DeWitt detector response along static and circular-geodesic trajectories for Schwarzschild-anti-de Sitter black holes. Physical Review D - Particles, Fields, Gravitation and Cosmology, 90(6), Article 064003. https://doi.org/10.1103/PhysRevD.90.064003

© 2014 American Physical Society. We present novel methods to numerically address the problem of characterizing the response of particle detectors in curved spacetimes. These methods allow for the integration of the Wightman function, at least in pri... Read More about Unruh-DeWitt detector response along static and circular-geodesic trajectories for Schwarzschild-anti-de Sitter black holes.

Particle detectors and the zero mode of a quantum field (2014)
Journal Article
Martín-Martínez, E., & Louko, J. (2014). Particle detectors and the zero mode of a quantum field. Physical Review D - Particles, Fields, Gravitation and Cosmology, 90(2), Article 024015. https://doi.org/10.1103/PhysRevD.90.024015

We study the impact of the zero mode of a quantum field on the evolution of a particle detector. For a massless scalar field in a periodic cavity, we show that the impact of the zero mode on the Unruh-DeWitt detector and its derivative-coupling gener... Read More about Particle detectors and the zero mode of a quantum field.

Colliding branes and big crunches (2011)
Journal Article
Omotani, J., Saffin, P. M., & Louko, J. (2011). Colliding branes and big crunches. Physical Review D, 84(6), Article 063526. https://doi.org/10.1103/PhysRevD.84.063526

We examine the global structure of colliding domain walls in AdS spacetime and come to the conclusion that singularities forming from such collisions are of the big-crunch type rather than that of a black brane.