IRIS Università degli Studi di Bolognahttps://cris.unibo.itIl sistema di repository digitale IRIS acquisisce, archivia, indicizza, conserva e rende accessibili prodotti digitali della ricerca.Sat, 19 Jun 2021 09:21:24 GMT2021-06-19T09:21:24Z10261Numerical observation of Hawking radiation from acoustic black holes in atomic BECs.http://hdl.handle.net/11585/67547.1Titolo: Numerical observation of Hawking radiation from acoustic black holes in atomic BECs.
Abstract: We report numerical evidence of Hawking emission of Bogoliubov phonons from a sonic horizon in a flowing one-dimensional atomic Bose-Einstein condensate. The presence of Hawking radiation is revealed from peculiar long-range patterns in the density-density correlation function of the gas. Quantitative agreement between our fully microscopic calculations and the prediction of analog models is obtained in the hydrodynamic limit. New features are predicted and the robustness of the Hawking signal against a finite temperature discussed.
Tue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/11585/67547.12008-01-01T00:00:00ZGray body factor and infrared divergences in BEC acoustic black holeshttp://hdl.handle.net/11585/388899Titolo: Gray body factor and infrared divergences in BEC acoustic black holes
Abstract: It is shown that the gray-body factor for a one-dimensional Bose-Einstein condensate (BEC) acoustic black hole with one horizon does not vanish in the low-frequency ($\omega\to 0$) limit. This implies that the analog Hawking radiation is dominated by the emission of an infinite number ($\frac{1}{\omega}$) of soft phonons in contrast with the case of a Schwarzschild black hole where the gray-body factor vanishes as $\omega\to 0$ and the spectrum is not dominated by low-energy particles. The infrared behaviors of certain correlation functions are also discussed.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/11585/3888992014-01-01T00:00:00ZHawking effect in BEC's acoustic white holeshttp://hdl.handle.net/11585/266294Titolo: Hawking effect in BEC's acoustic white holes
Abstract: Bogoliubov pseudoparticle creation in a BEC undergoing a WH-like flow is investigated analytically in the case of a one-dimensional geometry with stepwise homogeneous regions. Comparison of the results with those corresponding to a BH flow is performed. The implications for the analogous gravitational problem is discussed.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/11585/2662942013-01-01T00:00:00ZAmplifying the Hawking signal in BECshttp://hdl.handle.net/11585/388905.1Titolo: Amplifying the Hawking signal in BECs
Abstract: It is shown that the gray-body factor for a one-dimensional Bose-Einstein condensate (BEC) acoustic black hole with one horizon does not vanish in the low-frequency ($\omega\to 0$) limit. This implies that the analog Hawking radiation is dominated by the emission of an infinite number ($\frac{1}{\omega}$) of soft phonons in contrast with the case of a Schwarzschild black hole where the gray-body factor vanishes as $\omega\to 0$ and the spectrum is not dominated by low-energy particles. The infrared behaviors of certain correlation functions are also discussed
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/11585/388905.12014-01-01T00:00:00ZUnderstanding Hawking Radiation from Simple Models of Atomic Bose-Einstein Condensateshttp://hdl.handle.net/11585/266297Titolo: Understanding Hawking Radiation from Simple Models of Atomic Bose-Einstein Condensates
Abstract: This chapter is an introduction to the Bogoliubov theory of dilute Bose condensates as applied to the study of the spontaneous emission of phonons in a stationary condensate flowing at supersonic speeds. This emission process is a condensed-matter analog of Hawking radiation from astrophysical black holes but is derived here from a microscopic quantum theory of the condensate without any use of the analogy with gravitational systems. To facilitate physical understanding of the basic concepts, a simple one-dimensional geometry with a stepwise homogenous flow is considered which allows for a fully analytical treatment.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/11585/2662972013-01-01T00:00:00ZThe depletion in Bose Einstein condensates using Quantum Field Theory in curved spacehttp://hdl.handle.net/11585/52954Titolo: The depletion in Bose Einstein condensates using Quantum Field Theory in curved space
Abstract: Using methods developed in Quantum Field Theory in curved space we can estimate the effects of the inhomogeneities and of a non vanishing velocity on the depletion of a Bose Einstein condensate within the hydrodynamical approximation.
Mon, 01 Jan 2007 00:00:00 GMThttp://hdl.handle.net/11585/529542007-01-01T00:00:00ZNon-local density correlations as signal of Hawking radiation in BEC acoustic black holes.http://hdl.handle.net/11585/67554Titolo: Non-local density correlations as signal of Hawking radiation in BEC acoustic black holes.
Abstract: We have used the analogy between gravitational systems and nonhomogeneous fluid flows to calculate the density-density correlation function of an atomic Bose-Einstein condensate in the presence of an acoustic black hole. The emission of correlated pairs of phonons by Hawking-like process results into a peculiar long-range density correlation. Quantitative estimations of the effect are provided for realistic experimental configurations.
Tue, 01 Jan 2008 00:00:00 GMThttp://hdl.handle.net/11585/675542008-01-01T00:00:00ZNumerical analysis of backreaction in acoustic black holes.http://hdl.handle.net/11585/35553Titolo: Numerical analysis of backreaction in acoustic black holes.
Abstract: Using methods of Quantum Field Theory in curved spacetime, the first order in hbar quantum corrections to the motion of a fluid in an acoustic black hole configuration are numerically computed. These corrections arise from the non linear backreaction of the emitted phonons. Time dependent (isolated system) and equilibrium configurations (hole in a sonic cavity) are both analyzed.
Sun, 01 Jan 2006 00:00:00 GMThttp://hdl.handle.net/11585/355532006-01-01T00:00:00ZQUANTUM EFFECTS IN ACOUSTIC BLACK HOLES: THE BACKREACTION.http://hdl.handle.net/11585/12461Titolo: QUANTUM EFFECTS IN ACOUSTIC BLACK HOLES: THE BACKREACTION.
Abstract: We investigate the backreaction equations for an acoustic black hole formed in a Laval nozzle under the assumption that the motion of the fluid is one-dimensional. The solution in the near-horizon region shows that as phonons are (thermally) radiated the sonic horizon shrinks and the temperature decreases. This contrasts with the behaviour of Schwarzschild black holes, and is similar to what happens in the evaporation of (near-extremal) Reissner-Nordstrom black holes (i.e. infinite evaporation time). Finally, by appropriate boundary conditions the solution is extended in both the asymptotic regions of the nozzle.
Sat, 01 Jan 2005 00:00:00 GMThttp://hdl.handle.net/11585/124612005-01-01T00:00:00ZBACKREACTION IN ACOUSTIC BLACK HOLES.http://hdl.handle.net/11585/12491Titolo: BACKREACTION IN ACOUSTIC BLACK HOLES.
Abstract: The backreaction equations for the linearized quantum fluctuations in an acoustic black hole are given. The solution near the horizon, obtained within a dimensional reduction, indicates that acoustic black holes, unlike Schwarzschild ones, get cooler as they radiate phonons. They show remarkable analogies with near-extremal Reissner-Nordstrom black holes.
Thu, 01 Jan 2004 00:00:00 GMThttp://hdl.handle.net/11585/124912004-01-01T00:00:00Z