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Author |
Mayoral, C.; Recati, A.; Fabbri, A.; Parentani, R.; Balbinot, R.; Carusotto, I. |
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Title |
Acoustic white holes in flowing atomic Bose-Einstein condensates |
Type |
Journal Article |
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Year |
2011 |
Publication |
New Journal of Physics |
Abbreviated Journal |
New J. Phys. |
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Volume |
13 |
Issue  |
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Pages |
025007 - 29pp |
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Abstract |
We study acoustic white holes in a steadily flowing atomic Bose-Einstein condensate. A white hole configuration is obtained when the flow velocity goes from a super-sonic value in the upstream region to a sub-sonic one in the downstream region. The scattering of phonon wavepackets on a white hole horizon is numerically studied in terms of the Gross-Pitaevskii equation of mean-field theory: dynamical stability of the acoustic white hole is found, as well as a signature of a nonlinear back-action of the incident phonon wavepacket onto the horizon. The correlation pattern of density fluctuations is numerically studied by means of the truncated-Wigner method, which includes quantum fluctuations. Signatures of the white hole radiation of correlated phonon pairs by the horizon are characterized; analogies and differences with Hawking radiation from acoustic black holes are discussed. In particular, a short wavelength feature is identified in the density correlation function, whose amplitude steadily grows in time since the formation of the horizon. The numerical observations are quantitatively interpreted by means of an analytical Bogoliubov theory of quantum fluctuations for a white hole configuration within the step-like horizon approximation. |
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Address |
[Recati, Alessio; Carusotto, Iacopo] Univ Trent, INO CNR BEC Ctr, I-38123 Povo, Italy, Email: carusott@science.unitn.it |
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Iop Publishing Ltd |
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English |
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ISSN |
1367-2630 |
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Notes |
ISI:000287855400003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
556 |
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Author |
Balbinot, R.; Fabbri, A. |
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Title |
Amplifying the Hawking Signal in BECs |
Type |
Journal Article |
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Year |
2014 |
Publication |
Advances in High Energy Physics |
Abbreviated Journal |
Adv. High. Energy Phys. |
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Volume |
2014 |
Issue |
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Pages |
713574 - 8pp |
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Abstract |
We consider simple models of Bosep-Einstein condensates to study analog pairp-creation effects, namely, the Hawking effect from acoustic black holes and the dynamical Casimir effect in rapidly timep-dependent backgrounds. We also focus on a proposal by Cornell to amplify the Hawking signal in density-density correlators by reducing the atoms' interactions shortly before measurements are made. |
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Address |
[Balbinot, Roberto; Fabbri, Alessandro] Univ Bologna, Dipartimento Fis, I-40126 Bologna, Italy, Email: afabbri@ific.uv.es |
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Publisher |
Hindawi Publishing Corporation |
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English |
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ISSN |
1687-7357 |
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Notes |
WOS:000335740300001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1787 |
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Author |
Casals, M.; Fabbri, A.; Martinez, C.; Zanelli, J. |
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Title |
Quantum dress for a naked singularity |
Type |
Journal Article |
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Year |
2016 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
760 |
Issue |
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Pages |
244-248 |
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Keywords |
Semiclassical gravity; Quantum backreaction; Cosmic censorship; Black holes; Naked singularities; BTZ |
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Abstract |
We investigate semiclassical backreaction on a conical naked singularity space-time with a negative cosmological constant in (2 + 1)-dimensions. In particular, we calculate the renormalized quantum stress-energy tensor for a conformally coupled scalar field on such naked singularity space-time. We then obtain the backreacted metric via the semiclassical Einstein equations. We show that, in the regime where the semiclassical approximation can be trusted, backreaction dresses the naked singularity with an event horizon, thus enforcing (weak) cosmic censorship. |
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[Casals, Marc] Ctr Brasileiro Pesquisas Fis, BR-22290180 Rio De Janeiro, Brazil, Email: mcasals@cbpf.br; |
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Elsevier Science Bv |
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English |
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ISSN |
0370-2693 |
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Notes |
WOS:000382890500037 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2804 |
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Author |
Balbinot, R.; Fabbri, A. |
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Title |
Quantum energy momentum tensor and equal time correlations in a Reissner-Nordström black hole |
Type |
Journal Article |
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Year |
2023 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
108 |
Issue |
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Pages |
045004 - 9pp |
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Abstract |
We consider a Reissner-Nordström black hole formed by the collapse of a charged null shell. The renormalized expectation values of the energy-momentum tensor operator for a massless scalar field propagating in the two-dimensional section of this spacetime are given. We then analyze the across-the-horizon correlations of the related energy density operator for free-falling observers to reveal the correlations between the Hawking particles and their interior partners. |
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Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
6093 |
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Author |
Balbinot, R.; Fabbri, A. |
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Title |
The Unruh Vacuum and the “In-Vacuum” in Reissner-Nordström Spacetime |
Type |
Journal Article |
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Year |
2024 |
Publication |
Universe |
Abbreviated Journal |
Universe |
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Volume |
10 |
Issue |
1 |
Pages |
18 - 14pp |
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Keywords |
Hawking radiation; Unruh vacuum; Reissner-Nordstrom black holes |
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Abstract |
The Unruh vacuum is widely used as a quantum state to describe black hole evaporation since, near the horizon, it reproduces the physical state of a quantum field, the so-called “in-vacuum”, in the case where a black hole is formed by gravitational collapse. We examine the relation between these two quantum states in the background spacetime of a Reissner-Nordstrom black hole (both extremal and not), highlighting the similarities and striking differences. |
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Address |
[Balbinot, Roberto] Univ Bologna, Dipartimento Fis, Via Irnerio 46, I-40126 Bologna, Italy, Email: roberto.balbinot@unibo.it; |
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Mdpi |
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English |
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Notes |
WOS:001151025300001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5914 |
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