497 research outputs found
Probing the spacetime structure of vacuum entanglement
No full textWe introduce a framework for probing the spacetime structure of vacuum entanglement that exhibits infinite range correlations between the future and the past, as well as spatially separated regions. Our results are non-perturbative and analytical
Quantum state reduction via gravity, and possible tests using Bose-Einstein Condensates
No full textIt has been proposed that because of a fundamental conflict between basic principles of quantum mechanics and general relativity, a superposition between stationary quantum states that differ in mass distribution would reduce spontaneously to one or the other in a timescale inversely proportional to the gravitational self-energy of this mass-distribution difference. Here, we present arguments in favour of this proposal and suggest a possible test using Bose-Einstein condensates
Testing small scale gravitational wave detectors with dynamical mass distributions
No full textThe recent discovery of gravitational waves by the LIGO-Virgo collaboration created renewed interest in the investigation of alternative gravitational wave detector designs, such as small scale resonant detectors. In this article, it is shown how proposed small scale detectors can be tested by generating dynamical gravitational fields with appropriate distributions of moving masses. A series of interesting experiments will be possible with this setup. In particular, small scale detectors can be tested very early in the development phase and tests can be used to progress quickly in their development. This could contribute to the emerging field of gravitational wave astronomy
Active interferometry with gaussian channels
No full textWe consider an interferometer that contains active elements, such as a parametric amplifier, with general two-mode Gaussian unitary channels rather than the usually considered phase-shift channel. We concentrate on a scheme based on the recently proposed pumped-up SU(1,1) active interferometer where all input particles participate in the parameter estimation, and from which a conventional SU(1,1) interferometer is a limiting case. Using the covariance matrix formalism, we derive the quantum Fisher information of this active interferometer with a general two-mode Gaussian unitary channel, as well as the sensitivity for a number-sum measurement scheme, finding simple expressions for the latter. As an example application, we apply our results to Bose-Einstein condensates (BECs), and in particular a BEC gravitational-wave detector based on resonance, finding that the sensitivity of the detector can be improved by several orders of magnitude with this new interferometry scheme
On relativistic particle creation in Bose-Einstein condensates
No full textWe show that particle creation of Bogoliubov modes in a Bose-Einstein
condensate due to the accelerated motion of the trap is a genuinely
relativistic effect. To this end we show that Bogoliubov modes can be
described by a time rescaling of the Minkowski metric. A consequence of
this is that Rindler transformations are perceived by the phonons as
generalised Rindler transformations where the speed of light is replaced
by the speed of sound, enhancing particle creation at small velocities.
Since the non-relativistic limit of a Rindler transformation is just a
Galilean transformation entailing no length contraction or time
dilation, we show that the effect vanishes in the non-relativistic
limit
Redistribution of particle and antiparticle entanglement in noninertial frames
No full textWe analyze the entanglement tradeoff between particle and antiparticle modes of a Dirac field from the perspective of inertial and uniformly accelerated observers. Our results show that a redistribution of entanglement between particle and antiparticle modes plays a key role in the survival of femionic field entanglement in the infinite-acceleration limit. © 2011 American Physical Society.. I.F. was supported by EPSRC [CAF Grant No. EP/G00496X/2]. E.M.-M. was supported by a CSIC JAE-PREDOC2007 grant, the Spanish MICINN Project FIS2008-05705/FIS, and the QUITEMAD consortium.Peer Reviewe
Observer-dependent entanglement
No full textUnderstanding the observer-dependent nature of quantum entanglement has been a central question in relativistic quantum information. In this paper, we will review key results on relativistic entanglement in flat and curved spacetime and discuss recent work which shows that motion and gravity have observable effects on entanglement between localized systems.</p
Correlation loss and multipartite entanglement across a black hole horizon
No full textWe investigate the Hawking effect on entangled fields. By considering a scalar field which is in a two-mode squeezed state from the point of view of freely falling (Kruskal) observers crossing the horizon of a Schwarzschild black hole, we study the degradation of quantum and classical correlations in the state from the perspective of Schwarzschild observers confined outside the horizon. Due to monogamy constraints on the entanglement distribution, we show that the lost bipartite entanglement is recovered as multipartite entanglement among modes inside and outside the horizon. In the limit of a small-mass black hole, no bipartite entanglement is detected outside the horizon, while the genuine multipartite entanglement interlinking the inner and outer regions grows infinitely.</p
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