Professor JORMA LOUKO's Outputs (41)

Probing hidden topology with quantum detectors (2025)
Journal Article
Bhattacharya, D., Louko, J., & Mann, R. B. (2025). Probing hidden topology with quantum detectors. Physical Review D, 111(4), Article 045005. https://doi.org/10.1103/physrevd.111.045005

We consider the transition rate of a static Unruh-DeWitt detector in two ()-dimensional black hole spacetimes that are isometric to the static Bañados-Teitelboim-Zanelli black hole outside the horizon but have no asymptotically locally anti–de Sitter... Read More about Probing hidden topology with quantum detectors.

Connecting the circular and drifted Rindler Unruh effects (2025)
Journal Article
Parry, L. J., & Louko, J. (2025). Connecting the circular and drifted Rindler Unruh effects. Physical Review D, 111(2), Article 025012. https://doi.org/10.1103/physrevd.111.025012

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 current experim... Read More about Connecting the circular and drifted Rindler Unruh effects.

Local quantum detection of the cosmological expansion: Unruh-DeWitt detectors in spatially compact Milne cosmology (2025)
Journal Article
Wilkinson, A. S., & Louko, J. (2025). Local quantum detection of the cosmological expansion: Unruh-DeWitt detectors in spatially compact Milne cosmology. Physical Review D, 111(2), Article 025008. https://doi.org/10.1103/physrevd.111.025008

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 boundary cond... Read More about Local quantum detection of the cosmological expansion: Unruh-DeWitt detectors in spatially compact Milne cosmology.

Making two particle detectors in flat spacetime communicate quantumly (2024)
Journal Article
Lapponi, A., Louko, J., & Mancini, S. (2024). Making two particle detectors in flat spacetime communicate quantumly. Physical Review D, 110(2), Article 025018. https://doi.org/10.1103/physrevd.110.025018

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 with a scalar... Read More about Making two particle detectors in flat spacetime communicate quantumly.

More excitement across the horizon (2024)
Journal Article
Preciado-Rivas, M. R., Naeem, M., Mann, R. B., & Louko, J. (2024). More excitement across the horizon. Physical Review D, 110(2), Article 025002. https://doi.org/10.1103/physrevd.110.025002

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 extremum i... Read More about More excitement across the horizon.

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/(2π), 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.