85 results on '"Benni Reznik"'
Search Results
2. Process tomography for systems in a thermal state
- Author
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Ran Ber, Shmuel Marcovitch, Oded Kenneth, and Benni Reznik
- Subjects
Science ,Physics ,QC1-999 - Abstract
We propose a new method for implementing process tomography which is based on the information extracted from temporal correlations between observables, rather than on state preparation and state tomography. As such, the approach is applicable to systems that are in mixed states, and in particular thermal states. We illustrate the method for an arbitrary evolution described by Kraus operators, as well as for simpler cases such as a general Gaussian channels, and qubit dynamics.
- Published
- 2013
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3. Continuous input nonlocal games.
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Netanel Aharon, Shai Machnes, Benni Reznik, Jonathan Silman, and Lev Vaidman
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- 2013
- Full Text
- View/download PDF
4. Simulating lattice gauge theories within quantum technologies
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Peter Zoller, Jacopo Catani, Matthew Wingate, Frank Verstraete, Benni Reznik, Maciej Lewenstein, Karel Van Acoleyen, Karl Jansen, Marcello Dalmonte, Mari Carmen Bañuls, Uwe-Jens Wiese, J. I. Cirac, Enrique Rico, Luca Tagliacozzo, Rainer Blatt, Alessio Celi, Christine A. Muschik, Leonardo Fallani, Simone Montangero, Jakub Zakrzewski, Bañuls, Mari Carmen [0000-0001-6419-6610], Catani, Jacopo [0000-0002-2951-7041], Celi, Alessio [0000-0003-4939-084X], Dalmonte, Marcello [0000-0001-5338-4181], Lewenstein, Maciej [0000-0002-0210-7800], Rico, Enrique [0000-0003-4414-6821], Zakrzewski, Jakub [0000-0003-0998-9460], Apollo - University of Cambridge Repository, and Wingate, Matthew [0000-0001-6568-988X]
- Subjects
High Energy Physics - Theory ,High Energy Physics::Lattice ,Quantum simulator ,edge states ,01 natural sciences ,fermi gas ,quant-ph ,quantum information ,Gauge theory ,massive schwinger model ,Quantum computer ,quantum technologies ,Physics ,Quantum Physics ,hep-th ,High Energy Physics - Lattice (hep-lat) ,Particle physics ,dynamics ,Atomic and Molecular Physics, and Optics ,yang-mills theory ,Mathematics and Statistics ,EDGE ,Colloquium ,Quantum simulation ,Condensed Matter - Quantum Gases ,cond-mat.quant-gas ,530 Physics ,FOS: Physical sciences ,hep-lat ,Yang–Mills theory ,field theories ,itinerant ferromagnetism ,Quantum simulation, quantum technologies ,Theoretical physics ,High Energy Physics - Lattice ,Lattice gauge theory ,anderson localization ,0103 physical sciences ,ddc:530 ,Quantum information ,010306 general physics ,Quantum information science ,010308 nuclear & particles physics ,matrix ,entangled pair states ,Quantum technology ,Cromodinàmica quàntica ,Physics and Astronomy ,STATES ,High Energy Physics - Theory (hep-th) ,Quantum Gases (cond-mat.quant-gas) ,Quantum Information ,Quantum Physics (quant-ph) ,Física de partícules ,Quantum chromodynamics - Abstract
The European physical journal / D 74(8), 165 (2020). doi:10.1140/epjd/e2020-100571-8, Lattice gauge theories, which originated from particle physics in the context of Quantum Chromodynamics (QCD), provide an important intellectual stimulus to further develop quantum information technologies. While one long-term goal is the reliable quantum simulation of currently intractable aspects of QCD itself, lattice gauge theories also play an important role in condensed matter physics and in quantum information science. In this way, lattice gauge theories provide both motivation and a framework for interdisciplinary research towards the development of special purpose digital and analog quantum simulators, and ultimately of scalable universal quantum computers. In this manuscript, recent results and new tools from a quantum science approach to study lattice gauge theories are reviewed. Two new complementary approaches are discussed: first, tensor network methods are presented - a classical simulation approach - applied to the study of lattice gauge theories together with some results on Abelian and non-Abelian lattice gauge theories. Then, recent proposals for the implementation of lattice gauge theory quantum simulators in different quantum hardware are reported, e.g., trapped ions, Rydberg atoms, and superconducting circuits. Finally, the first proof-of-principle trapped ions experimental quantum simulations of the Schwinger model are reviewed., Published by Springer, Heidelberg
- Published
- 2020
5. Entanglement on curved hypersurfaces: A field-discretizer approach
- Author
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Tal Schwartzman and Benni Reznik
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Physics ,High Energy Physics - Theory ,Quantum Physics ,Spacetime ,010308 nuclear & particles physics ,Mathematics::Complex Variables ,FOS: Physical sciences ,Quantum entanglement ,General Relativity and Quantum Cosmology (gr-qc) ,01 natural sciences ,General Relativity and Quantum Cosmology ,Hypersurface ,Mathematics::Algebraic Geometry ,High Energy Physics - Theory (hep-th) ,Lattice (order) ,0103 physical sciences ,Minkowski space ,Covariant transformation ,Mathematics::Differential Geometry ,Quantum field theory ,010306 general physics ,Quantum Physics (quant-ph) ,Mathematical physics - Abstract
We propose a covariant scheme for measuring entanglement on general hypersurfaces in relativistic quantum field theory. For that, we introduce an auxiliary relativistic field, ``the discretizer,'' that by locally interacting with the field along a hypersurface, fully swaps the field's and discretizer's states. It is shown, that the discretizer can be used to effectively cut off the field's infinities, in a covariant fashion, and without having to introduce a spatial lattice. This, in turn, provides us an efficient way to evaluate entanglement between arbitrary regions on any hypersurface. As examples, we study the entanglement between complementary and separated regions in $1+1$ dimensions, for flat hypersurfaces in Minkowski space, for curved hypersurfaces in Milne space, and for regions on hypersurfaces approaching null-surfaces. Our results show that the entanglement between regions on arbitrary hypersurfaces in $1+1$ dimensions depends only on the spacetime end points of the regions, and not on the shape of the interior. Our results corroborate and extend previous results for flat hypersurfaces.
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- 2020
6. Digital Quantum Simulation ofZ2Lattice Gauge Theories with Dynamical Fermionic Matter
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Erez Zohar, J. Ignacio Cirac, Alessandro Farace, and Benni Reznik
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Physics ,Optical lattice ,010308 nuclear & particles physics ,High Energy Physics::Lattice ,Lattice field theory ,General Physics and Astronomy ,Quantum simulator ,Lattice QCD ,01 natural sciences ,Hamiltonian lattice gauge theory ,Lattice gauge theory ,Quantum mechanics ,0103 physical sciences ,Gauge theory ,010306 general physics ,Lattice model (physics) - Abstract
We propose a scheme for digital quantum simulation of lattice gauge theories with dynamical fermions. Using a layered optical lattice with ancilla atoms that can move and interact with the other atoms (simulating the physical degrees of freedom), we obtain a stroboscopic dynamics which yields the four-body plaquette interactions, arising in models with (2+1) and higher dimensions, without the use of perturbation theory. As an example we show how to simulate a Z_{2} model in (2+1) dimensions.
- Published
- 2017
7. Digital lattice gauge theories
- Author
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J. Ignacio Cirac, Benni Reznik, Alessandro Farace, and Erez Zohar
- Subjects
High Energy Physics - Theory ,Physics ,Quantum Physics ,Introduction to gauge theory ,Quantum gauge theory ,010308 nuclear & particles physics ,High Energy Physics::Lattice ,Lattice field theory ,High Energy Physics - Lattice (hep-lat) ,FOS: Physical sciences ,01 natural sciences ,Theoretical physics ,High Energy Physics - Lattice ,Hamiltonian lattice gauge theory ,High Energy Physics - Theory (hep-th) ,Supersymmetric gauge theory ,Quantum Gases (cond-mat.quant-gas) ,Quantum mechanics ,Lattice gauge theory ,0103 physical sciences ,Condensed Matter - Quantum Gases ,010306 general physics ,Quantum Physics (quant-ph) ,Gauge anomaly ,Gauge fixing - Abstract
We propose a general scheme for a digital construction of lattice gauge theories with dynamical fermions. In this method, the four-body interactions arising in models with $2+1$ dimensions and higher, are obtained stroboscopically, through a sequence of two-body interactions with ancillary degrees of freedom. This yields stronger interactions than the ones obtained through pertubative methods, as typically done in previous proposals, and removes an important bottleneck in the road towards experimental realizations. The scheme applies to generic gauge theories with Lie or finite symmetry groups, both Abelian and non-Abelian. As a concrete example, we present the construction of a digital quantum simulator for a $\mathbb{Z}_{3}$ lattice gauge theory with dynamical fermionic matter in $2+1$ dimensions, using ultracold atoms in optical lattices, involving three atomic species, representing the matter, gauge and auxiliary degrees of freedom, that are separated in three different layers. By moving the ancilla atoms with a proper sequence of steps, we show how we can obtain the desired evolution in a clean, controlled way.
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- 2016
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8. Superoscillations underlying remote state preparation for relativistic fields
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Oded Kenneth, Ran Ber, and Benni Reznik
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High Energy Physics - Theory ,Physics ,Quantum Physics ,Vacuum state ,FOS: Physical sciences ,State (functional analysis) ,Atomic and Molecular Physics, and Optics ,Connection (mathematics) ,Classical mechanics ,High Energy Physics - Theory (hep-th) ,Light cone ,Relativistic aberration ,Field theory (psychology) ,Quantum field theory ,Quantum Physics (quant-ph) ,Quantum information science - Abstract
We present a physical (gedanken) implementation of a generalized remote state preparation of relativistic quantum field states for an arbitrary set of observers. The prepared states are created in regions that are outside the future light-cone of the generating region. The mechanism, which is based on utilizing the vacuum state of a relativistic quantum field as a resource, sheds light on the well known Reeh-Schlieder theorem, indicating its strong connection with the mathematical phenomenon of superoscillations., 9 pages, 5 figures
- Published
- 2015
9. Quantum Simulations of Lattice Gauge Theories using Ultracold Atoms in Optical Lattices
- Author
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Erez Zohar, J. Ignacio Cirac, and Benni Reznik
- Subjects
Quantum chromodynamics ,Quark ,Physics ,High Energy Physics - Theory ,Quantum Physics ,High Energy Physics::Lattice ,High Energy Physics - Lattice (hep-lat) ,General Physics and Astronomy ,Quantum simulator ,FOS: Physical sciences ,Lorentz covariance ,01 natural sciences ,010305 fluids & plasmas ,Theoretical physics ,High Energy Physics - Lattice ,High Energy Physics - Theory (hep-th) ,Ultracold atom ,Quantum Gases (cond-mat.quant-gas) ,0103 physical sciences ,Gauge theory ,Quantum field theory ,010306 general physics ,Condensed Matter - Quantum Gases ,Quantum Physics (quant-ph) ,Quantum - Abstract
Can high energy physics be simulated by low-energy, non-relativistic, many-body systems, such as ultracold atoms? Such ultracold atomic systems lack the type of symmetries and dynamical properties of high energy physics models: in particular, they manifest neither local gauge invariance nor Lorentz invariance, which are crucial properties of the quantum field theories which are the building blocks of the standard model of elementary particles. However, it turns out, surprisingly, that there are ways to configure atomic system to manifest both local gauge invariance and Lorentz invariance. In particular, local gauge invariance can arise either as an effective, low energy, symmetry, or as an "exact" symmetry, following from the conservation laws in atomic interactions. Hence, one could hope that such quantum simulators may lead to new type of (table-top) experiments, that shall be used to study various QCD phenomena, as the confinement of dynamical quarks, phase transitions, and other effects, which are inaccessible using the currently known computational methods. In this report, we review the Hamiltonian formulation of lattice gauge theories, and then describe our recent progress in constructing quantum simulation of Abelian and non-Abelian lattice gauge theories in 1+1 and 2+1 dimensions using ultracold atoms in optical lattices., Comment: A review; 55 pages, 14 figures
- Published
- 2015
- Full Text
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10. REMOTE GENERALIZED MEASUREMENTS USING PARTIALLY ENTANGLED STATES
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Benni Reznik
- Subjects
Physics ,POVM ,Physics and Astronomy (miscellaneous) ,Quantum mechanics ,TheoryofComputation_GENERAL ,Quantum entanglement ,Squashed entanglement - Abstract
We propose a method for implementing remotely a generalized measurement (POVM). We show that remote generalized measurements consume less entanglement compared with remote projective measurements, and can be optimally performed using non-maximally entangled states. We derive the entanglement cost of such measurements.
- Published
- 2006
11. A lower bound on ground state entanglement between two regions for a free field
- Author
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Alex Retzker, Benni Reznik, and Jonathan Silman
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Physics ,Classical mechanics ,Continuum (measurement) ,Quantum mechanics ,Bound state ,Quantum entanglement ,Quantum field theory ,Squashed entanglement ,Free field ,Ground state ,Upper and lower bounds ,Atomic and Molecular Physics, and Optics - Abstract
In discrete models, such as spin chains, the entanglement between a pair of particles in a chain has been shown to vanish beyond a certain separation. In the continuum, a quantum field ⊘(x) at a point represents a single degree of freedom, thus at a region of finite size there are infinite separate degrees of freedom. We show that as a consequence, in contrast to discrete models, the ground state of a free, quantized and relativistic field exhibits entanglement between any pair of arbitrarily separated finite regions. We also provide a lower bound on the decay rate of the entanglement as a function of the separation length between the regions and briefly discuss the physical reasons behind this different behaviour of discrete and continuous systems.
- Published
- 2004
12. Superluminal tunnelling times as weak values
- Author
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Yakir Aharonov, Noam Erez, and Benni Reznik
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Physics ,Superluminal motion ,Operator (physics) ,Dirac delta function ,Expectation value ,Atomic and Molecular Physics, and Optics ,Dwell time ,Superposition principle ,symbols.namesake ,Tunnel effect ,Classical mechanics ,Quantum mechanics ,symbols ,Quantum tunnelling - Abstract
We consider the tunnelling particle as a pre- and post-selected system and prove that the tunnelling time is the expectation value of the position of a ‘clock’ degree of freedom weakly coupled to it. Such a value, called a ‘weak value’, typically falls outside the eigenvalue spectrum of the operator. The appearance of unusual weak values has been associated with a unique interference structure called ‘superoscillations’ (band-limited functions which on a finite interval, approximate functions with spectra well outside their band). It is proposed that superoscillations play an important role in the interferences which give rise to superluminal effects. To demonstrate that, we consider a certain simple tunnelling barrier which allows a wave packet to travel in zero time and negligible distortion, a distance arbitrarily longer than the width of the wave packet. The peak is shown to result from a superoscillatory superposition at the tail. Similar reasoning applies to the dwell time. For this system,...
- Published
- 2003
13. Instantaneous measurements of nonlocal variables
- Author
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Benni Reznik, Berry Groisman, and Lev Vaidman
- Subjects
Physics ,Causality (physics) ,Multipartite ,Classical mechanics ,Quantum system ,Quantum Physics ,Quantum entanglement ,Hermitian matrix ,Atomic and Molecular Physics, and Optics - Abstract
Relativistic causality imposes rigid restrictions on nondemolition (repeatable) measurements of nonlocal variables. We show that there are no causal restrictions on demolition (nonrepeatable) measurements: all Hermitian operators of multipartite quantum system can be measured instantaneously, provided unlimited supply of entanglement resources.
- Published
- 2003
14. [Untitled]
- Author
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Benni Reznik
- Subjects
Physics ,Photon entanglement ,Quantum mechanics ,Quantum electrodynamics ,Vacuum state ,General Physics and Astronomy ,Quantum Physics ,Quantum entanglement ,W state ,Squashed entanglement ,Multipartite entanglement ,Entropy (arrow of time) ,Entanglement witness - Abstract
We explore the entanglement of the vacuum of a relativistic field by letting a pair of causally disconnected probes interact with the field. We find that, even when the probes are initially non-entangled, they can wind up to a final entangled state. This shows that entanglement persists between disconnected regions in the vacuum. However the probe entanglement, unlike correlations, vanishes once the regions become sufficiently separated. The relation between entropy, correlations and entanglement is discussed.
- Published
- 2003
15. Revisiting Hardy's paradox: counterfactual statements, real measurements, entanglement and weak values
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Sandu Popescu, Jeff Tollaksen, Benni Reznik, Yakir Aharonov, and Alonso Botero
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Physics ,Quantum Physics ,Hardy's paradox ,FOS: Physical sciences ,General Physics and Astronomy ,Quantum entanglement ,Electron ,Coincidence ,Theoretical physics ,Meaning (philosophy of language) ,Retrodiction ,Weak measurement ,Quantum Physics (quant-ph) ,Sign (mathematics) - Abstract
Classical-realistic analysis of entangled systems have lead to retrodiction paradoxes, which ordinarily have been dismissed on the grounds of counter-factuality. Instead, we claim that such paradoxes point to a deeper logical structure inherent to quantum mechanics, which is naturally described in the language of weak values, and which is accessible experimentally via weak measurements. Using as an illustration, a gedanken-experiment due to Hardy\cite{hardy}, we show that there is in fact an exact numerical coincidence between a) a pair of classically contradictory assertions about the locations of an electron and a positron, and b) the results of weak measurements of their location. The internal consistency of these results is due to the novel way by which quantum mechanics "resolves" the paradox: first, by allowing for two distinguishable manifestations of how the electron and positron can be at the same location: either as single particles or as a pair; and secondly, by allowing these properties to take either sign. In particular, we discuss the experimental meaning of a {\em negative} number of electron-positron pairs., Comment: 7 pages, 1 figure
- Published
- 2002
16. Complementarity between Local and Nonlocal Topological Effects
- Author
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Yakir Aharonov and Benni Reznik
- Subjects
Physics ,Computer Science::Computer Science and Game Theory ,Classical mechanics ,General Physics and Astronomy ,Observable ,Quantum Physics ,Topology ,Complementarity (physics) ,Quantum ,Physics::History of Physics - Abstract
In certain topological effects the accumulation of a quantum phase shift is accompanied by a local observable effect. We show that such effects manifest a complementarity between nonlocal and local attributes of the topology, which is reminiscent but different from the usual wave-particle complementarity. This complementarity is not a consequence of noncommutativity, rather it is due to the noncanonical nature of the observables. We suggest that a local/nonlocal complementarity is a general feature of topological effects that are "dual" to the Aharonov-Bohm effect.
- Published
- 2000
17. [Untitled]
- Author
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Jonathan Oppenheim, William G. Unruh, and Benni Reznik
- Subjects
Scheme (programming language) ,Physics ,Continuous measurement ,Event (relativity) ,Probability current ,General Physics and Astronomy ,Observable ,Measure (mathematics) ,Bohr model ,symbols.namesake ,symbols ,Calculus ,Set (psychology) ,computer ,computer.programming_language - Abstract
Within quantum mechanics, a complete set of commutting observables can be found which describe the attributes of a system at a given time. However, the correct way to describe attributes of a system in time is still an open question. We discuss the difficulties in extending the standard approach of quantum mechanics to describe attributes of a system in time. We find that measuring when an event occurred and measuring that it occurred, are complimentary in Bohr's sense. To exemplify the differences between measurements at a given time and in time, we will compare Rovelli's recent proposal (quant-ph/9802020), to determine “at what time does a measurement occurred” with another model of a continuous measurement in time. Rovelli's scheme answers the question “has the measurement already occurred at a certain time?”, but does not answer to the more difficult question: “when did the measurement occur?” We also discuss the use of the probability current to measure the time at which a particle arrives to a certain location.
- Published
- 2000
18. Unruh effect with back reaction—A first-quantized treatment
- Author
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Benni Reznik
- Subjects
Physics ,Nuclear and High Energy Physics ,Quantum field theory in curved spacetime ,Detector ,FOS: Physical sciences ,General Relativity and Quantum Cosmology (gr-qc) ,General Relativity and Quantum Cosmology ,Quantization (physics) ,Amplitude ,Unruh effect ,Quantum mechanics ,Physics::Accelerator Physics ,Quantum gravity ,Back-reaction ,Accelerated particle - Abstract
We present a first-quantized treatment of the back reaction on an accelerated particle detector. The accelerated detector is described as a first quantized, charged, pointlike particle in a constant field with internal energy levels. A quantum version of canonically conjugate future and past Rindler horizon operators is introduced to facilitate the calculation. The evaluated transition amplitude for detection agrees with previously obtained results., 17 pages, Revtex. Based on gr-qc/9511033
- Published
- 1998
19. Aharonov-Bohm type forces between magnetic fluxons
- Author
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Benni Reznik, Sandu Popescu, Shmuel Nussinov, and Yakir Aharonov
- Subjects
Physics ,Classical mechanics ,Quantum mechanics ,Mobile charge ,General Physics and Astronomy ,Type (model theory) ,Integer (computer science) - Abstract
Interactions related to A-B phases exist between fluxons with Φ = αΦ0, α ≠ integer when the fluxons are actually immersed in a region with non-vanishing mobile charge density. In particular, for the interesting case of α = 1 2 we find that this force is attractive. We briefly comment on the prospects of observing such forces.
- Published
- 1997
20. Quantum simulations of gauge theories with ultracold atoms: Local gauge invariance from angular-momentum conservation
- Author
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Erez Zohar, Benni Reznik, and J. Ignacio Cirac
- Subjects
High Energy Physics - Theory ,Physics ,Quantum Physics ,Gauge boson ,Introduction to gauge theory ,High Energy Physics::Lattice ,High Energy Physics - Lattice (hep-lat) ,Lattice field theory ,FOS: Physical sciences ,Atomic and Molecular Physics, and Optics ,Theoretical physics ,High Energy Physics - Lattice ,Classical mechanics ,Hamiltonian lattice gauge theory ,High Energy Physics - Theory (hep-th) ,Quantum Gases (cond-mat.quant-gas) ,Supersymmetric gauge theory ,Lattice gauge theory ,Condensed Matter - Quantum Gases ,Quantum Physics (quant-ph) ,Gauge anomaly ,Gauge fixing - Abstract
Quantum simulations of High Energy Physics, and especially of gauge theories, is an emerging and exciting direction in quantum simulations. However, simulations of such theories, compared to simulations of condensed matter physics, must satisfy extra restrictions, such as local gauge and Lorentz invariance. In this paper we discuss these special requirements, and present a new method for quantum simulation of lattice gauge theories using ultracold atoms. This method allows to include local gauge invariance as a fundamental symmetry of the atomic Hamiltonian, arising from natural atomic interactions and conservation laws (and not as a property of a low energy sector). This allows us to implement elementary gauge invariant interactions for three lattice gauge theories: compact QED (U(1)), SU(N) and Z_N, which can be used to build quantum simulators in 1+1 dimensions. We also present a new loop method, which uses the elementary interactions as building blocks in the effective construction of quantum simulations for d+1 dimensional lattice gauge theories (d>1), without having to use Gauss's law as a constraint, as in previous proposals. We discuss in detail the quantum simulation of 2+1 dimensional compact QED and provide a numerical proof of principle. The simplicity of the already gauge invariant elementary interactions of this model suggests it may be useful for future experimental realizations., 28 pages, 16 figures. Third version - references updated
- Published
- 2013
21. Cold-atom quantum simulator for SU(2) yang-mills lattice gauge theory
- Author
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Erez Zohar, Benni Reznik, and J. Ignacio Cirac
- Subjects
High Energy Physics - Theory ,High Energy Physics::Lattice ,Lattice field theory ,General Physics and Astronomy ,FOS: Physical sciences ,01 natural sciences ,High Energy Physics::Theory ,Hamiltonian lattice gauge theory ,High Energy Physics - Lattice ,Quantum mechanics ,Lattice gauge theory ,0103 physical sciences ,010306 general physics ,Gauge anomaly ,Physics ,Gauge boson ,Introduction to gauge theory ,Quantum Physics ,Quantum gauge theory ,010308 nuclear & particles physics ,High Energy Physics - Lattice (hep-lat) ,High Energy Physics - Theory (hep-th) ,Supersymmetric gauge theory ,Quantum Gases (cond-mat.quant-gas) ,Quantum Physics (quant-ph) ,Condensed Matter - Quantum Gases - Abstract
Non-abelian gauge theories play an important role in the standard model of particle physics, and unfold a partially unexplored world of exciting physical phenomena. In this letter, we suggest a realization of a non-abelian lattice gauge theory - SU(2) Yang-Mills in 1+1 dimensions, using ultracold atoms. Remarkably, and in contrast to previous proposals, in our model gauge invariance is a direct consequence of angular momentum conservation and thus is fundamental and robust. Our proposal may serve as well as a starting point for higher dimensional realizations., Including supplemental material. Second version: references added
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- 2013
- Full Text
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22. Entanglement Generation Using Discrete Solitons in Coulomb Crystals
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Alex Retzker, Benni Reznik, H. Landa, Tobias Schaetz, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University [Tel Aviv], Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), The Hebrew University of Jerusalem (HUJ), and University of Freiburg [Freiburg]
- Subjects
Physics ,Quantum Physics ,Condensed matter physics ,Sideband ,General Physics and Astronomy ,FOS: Physical sciences ,Quantum entanglement ,01 natural sciences ,010305 fluids & plasmas ,Ion ,Crystal ,Nonlinear system ,[PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph] ,0103 physical sciences ,Coulomb ,Soliton ,010306 general physics ,Quantum Physics (quant-ph) ,Doppler cooling - Abstract
Laser cooled and trapped ions can crystallize and feature discrete solitons, that are nonlinear, topologically-protected configurations of the Coulomb crystal. Such solitons, as their continuum counterparts, can move within the crystal, while their discreteness leads to the existence of a gap-separated, spatially-localized motional mode of oscillation above the spectrum. Suggesting that these unique properties of discrete solitons can be used for generating entanglement between different sites of the crystal, we study a detailed proposal in the context of state-of-the-art experimental techniques. We analyze the interaction of periodically-driven planar ion crystals with optical forces, revealing the effects of micromotion in radio-frequency traps inherent to such structures, as opposed to linear ion chains. The proposed method requires Doppler cooling of the crystal and sideband cooling of the soliton's localized modes alone. Since the gap separation of the latter is nearly independent of the crystal size, this approach could be particularly useful for producing entanglement and studying system-environment interactions in large, two- and possibly three-dimensional systems., Comment: 7 pages with appendix, 3 figures, v3 corresponds to the final published version
- Published
- 2013
- Full Text
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23. Trapping of Topological-Structural Defects in Coulomb Crystals
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S. Kahra, H. Landa, J. Brox, Benni Reznik, Tobias Schaetz, M Albert, Manuel Mielenz, and G Leschhorn
- Subjects
Physics ,Quantum Physics ,Condensed matter physics ,Atomic Physics (physics.atom-ph) ,Anharmonicity ,FOS: Physical sciences ,General Physics and Astronomy ,Trapping ,01 natural sciences ,Ion trapping ,010305 fluids & plasmas ,Topological defect ,Physics - Atomic Physics ,Vibration ,Crystal ,0103 physical sciences ,Coulomb ,Quantum Physics (quant-ph) ,010306 general physics ,Nonlinear Sciences::Pattern Formation and Solitons ,Excitation - Abstract
We study experimentally and theoretically structural defects which are formed during the transition from a laser cooled cloud to a Coulomb crystal, consisting of tens of ions in a linear radio frequency trap. We demonstrate the creation of predicted topological defects (`kinks') in purely two-dimensional crystals, and also find kinks which show novel dynamical features in a regime of parameters not considered before. The kinks are always observed at the centre of the trap, showing a large nonlinear localized excitation, and the probability of their occurrence surprisingly saturates at ~0.5. Simulations reveal a strong anharmonicity of the kink's internal mode of vibration, due to the kink's extension into three dimensions. As a consequence, the periodic Peierls-Nabarro potential experienced by a discrete kink becomes a globally confining potential, capable of trapping one cooled defect at the center of the crystal., 5 pages, 4 figures; some additional citations
- Published
- 2012
24. Interplay of Aharonov-Bohm and Berry Phases for a Quantum Cloud of Chargea
- Author
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Benni Reznik, Daniel Rohrlich, Yakir Aharonov, Alfred S. Goldhaber, Sandu Popescu, Shmuel Nussinov, Lev Vaidman, and Sidney Coleman
- Subjects
Physics ,History and Philosophy of Science ,business.industry ,General Neuroscience ,Quantum mechanics ,Cloud computing ,Berry ,business ,Quantum ,General Biochemistry, Genetics and Molecular Biology - Published
- 1995
25. Simulating Compact Quantum Electrodynamics with Ultracold Atoms: Probing Confinement and Nonperturbative Effects
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J. Ignacio Cirac, Benni Reznik, and Erez Zohar
- Subjects
High Energy Physics - Theory ,Physics ,Quantum Physics ,Optical lattice ,010308 nuclear & particles physics ,FOS: Physical sciences ,General Physics and Astronomy ,01 natural sciences ,symbols.namesake ,High Energy Physics - Theory (hep-th) ,Quantum Gases (cond-mat.quant-gas) ,Ultracold atom ,Lattice gauge theory ,Quantum mechanics ,Quantum electrodynamics ,Static Charges ,0103 physical sciences ,Atom ,Strong coupling ,symbols ,Quantum field theory ,Quantum Physics (quant-ph) ,Condensed Matter - Quantum Gases ,010306 general physics ,Hamiltonian (quantum mechanics) - Abstract
Recently, there has been much interest in simulating quantum field theory effects of matter and gauge fields. In a recent work [Phys. Rev. Lett. 107, 275301 (2011)] a method for simulating compact Quantum Electrodynamics (cQED) using Bose-Einstein condensates has been suggested. We suggest an alternative approach, which relies on single atoms in an optical lattice, carrying 2l+1 internal levels, which converges rapidly to cQED as l increases. That enables the simulation of cQED in 2+1 dimensions in both the weak and the strong coupling regimes, hence allowing to probe confinement as well as other nonperturbative effects of the theory. We provide an explicit construction for the case l=1 which is sufficient for simulating the effect of confinement between two external static charges., Supplementary material addeed
- Published
- 2012
26. Simulating (2+1)-dimensional lattice QED with dynamical matter using ultracold atoms
- Author
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Erez Zohar, J. Ignacio Cirac, and Benni Reznik
- Subjects
Condensed Matter::Quantum Gases ,Physics ,Wilson loop ,Flux tube ,High Energy Physics::Lattice ,General Physics and Astronomy ,01 natural sciences ,010305 fluids & plasmas ,symbols.namesake ,Hamiltonian lattice gauge theory ,Dirac fermion ,Ultracold atom ,Lattice (order) ,Quantum electrodynamics ,Quantum mechanics ,Lattice gauge theory ,0103 physical sciences ,symbols ,010306 general physics ,Hamiltonian (quantum mechanics) - Abstract
We suggest a method to simulate compact quantum electrodynamics using ultracold atoms in optical lattices, which includes dynamical Dirac fermions in 2+1 dimensions. This allows us to test the dynamical effects of confinement as well as the deformations and breaking of two-dimensional flux loops, and to observe the Wilson-loop area law.
- Published
- 2012
27. Modes of oscillation in radiofrequency Paul traps
- Author
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H. Landa, Michael Drewsen, Benni Reznik, and Alex Retzker
- Subjects
General Physics and Astronomy ,NONLINEAR RESONANCES ,FOS: Physical sciences ,Microclusters ,01 natural sciences ,010305 fluids & plasmas ,Ion ,Pseudopotential ,0103 physical sciences ,ddc:530 ,Physics::Atomic Physics ,010306 general physics ,Wave function ,Quantum ,Charged-Particle Optics ,Physics ,CHAOTIC MOTIONS ,Condensed Matter::Quantum Gases ,Quantum Physics ,2-ION CRYSTALS ,Oscillation ,DDC 530 / Physics ,LASER-COOLED IONS ,ION COULOMB CRYSTALS ,2 PARTICLES ,MOLECULAR-IONS ,Amplitude ,CHARGED-PARTICLES ,Cluster ,Quantum electrodynamics ,PHASE-TRANSITIONS ,Ion trap ,Multipole expansion ,Quantum Physics (quant-ph) - Abstract
We examine the time-dependent dynamics of ion crystals in radiofrequency traps. The problem of stable trapping of general three-dimensional crystals is considered and the validity of the pseudopotential approximation is discussed. We analytically derive the micromotion amplitude of the ions, rigorously proving well-known experimental observations. We use a recently proposed method to find the modes that diagonalize the linearized time-dependent dynamical problem. This allows one to obtain explicitly the (‘Floquet–Lyapunov’) transformation to coordinates of decoupled linear oscillators. We demonstrate the utility of the method by analyzing the modes of a small ‘peculiar’ crystal in a linear Paul trap. The calculations can be readily generalized to multispecies ion crystals in general multipole traps, and time-dependent quantum wavefunctions of ion oscillations in such traps can be obtained., publishedVersion
- Published
- 2012
28. Topological Wilson-loop area law manifested using a superposition of loops
- Author
-
Benni Reznik and Erez Zohar
- Subjects
Physics ,High Energy Physics - Theory ,Quantum Physics ,Wilson loop ,Meson ,High Energy Physics::Lattice ,General Physics and Astronomy ,Quantum simulator ,FOS: Physical sciences ,Topology ,Schrödinger equation ,Superposition principle ,symbols.namesake ,High Energy Physics - Theory (hep-th) ,symbols ,Gauge theory ,Color confinement ,Hamiltonian (quantum mechanics) ,Quantum Physics (quant-ph) - Abstract
We introduce a new topological effect involving interference of two meson loops, manifesting a path-independent topological area dependence. The effect also draws a connection between quark confinement, Wilson-loops and topological interference effects. Although this is only a gedanken experiment in the context of particle physics, such an experiment may be realized and used as a tool to test confinement effects and phase transitions in quantum simulation of dynamic gauge theories., Superceding arXiv:1206.2021v1 [quant-ph]
- Published
- 2012
29. Classical and quantum modes of coupled Mathieu equations
- Author
-
Michael Drewsen, Benni Reznik, Alex Retzker, and H. Landa
- Subjects
Statistics and Probability ,Physics ,Quantum Physics ,Linear system ,FOS: Physical sciences ,General Physics and Astronomy ,Motion (geometry) ,Statistical and Nonlinear Physics ,01 natural sciences ,010305 fluids & plasmas ,Nonlinear system ,Matrix (mathematics) ,Classical mechanics ,Transformation (function) ,Modeling and Simulation ,0103 physical sciences ,Quantum Physics (quant-ph) ,010306 general physics ,Wave function ,Quantum ,Mathematical Physics ,Parametric statistics - Abstract
We expand the solutions of linearly coupled Mathieu equations in terms of infinite-continued matrix inversions, and use it to find the modes which diagonalize the dynamical problem. This allows obtaining explicitly the ('Floquet-Lyapunov') transformation to coordinates in which the motion is that of decoupled linear oscillators. We use this transformation to solve the Heisenberg equations of the corresponding quantum-mechanical problem, and find the quantum wavefunctions for stable oscillations, expressed in configuration-space. The obtained transformation and quantum solutions can be applied to more general linear systems with periodic coefficients (coupled Hill equations, periodically driven parametric oscillators), and to nonlinear systems as a starting point for convenient perturbative treatment of the nonlinearity., 25 pages, v2 adds citations and small corrections
- Published
- 2012
- Full Text
- View/download PDF
30. Aharonov-Bohm and Berry Phases for a Quantum Cloud of Charge
- Author
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Yakir Aharonov, Benni Reznik, Lev Vaidman, Daniel Rohrlich, Sandu Popescu, Alfred S. Goldhaber, Sidney Coleman, and Shmuel Nussinov
- Subjects
Quantum phase transition ,Physics ,Condensed matter physics ,General Physics and Astronomy ,Charge (physics) ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Charged particle ,symbols.namesake ,Quantum state ,Phase (matter) ,Quantum mechanics ,symbols ,Berry connection and curvature ,Aharonov–Bohm effect ,Quantum - Abstract
We investigate the phase accumulated by a charged particle in an extended quantum state as it encircles one or more magnetic fluxons, each carrying half a flux unit. A simple, essentially topological analysis reveals an interplay between the Aharonov-Bohm phase and Berry's phase.
- Published
- 1994
31. Confinement and lattice quantum-electrodynamic electric flux tubes simulated with ultracold atoms
- Author
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Erez Zohar and Benni Reznik
- Subjects
Condensed Matter::Quantum Gases ,Physics ,Condensed matter physics ,010308 nuclear & particles physics ,High Energy Physics::Lattice ,Lattice field theory ,General Physics and Astronomy ,Electric flux ,01 natural sciences ,symbols.namesake ,Ultracold atom ,Quantum electrodynamics ,Electric field ,Lattice gauge theory ,0103 physical sciences ,symbols ,Quantum field theory ,010306 general physics ,Hamiltonian (quantum mechanics) ,Vector potential - Abstract
We propose a method for simulating $(2+1)\mathrm{D}$ compact lattice quantum-electrodynamics, using ultracold atoms in optical lattices. In our model local Bose-Einstein condensates' (BECs) phases correspond to the electromagnetic vector potential, and the local number operators represent the conjugate electric field. The well-known gauge-invariant Kogut-Susskind Hamiltonian is obtained as an effective low-energy theory. The field is then coupled to external static charges. We show that in the strong coupling limit this gives rise to ``electric flux tubes'' and to confinement. This can be observed by measuring the local density deviations of the BECs, and is expected to hold even, to some extent, outside the perturbative calculable regime.
- Published
- 2011
- Full Text
- View/download PDF
32. Interplay of Aharonov-Bohm and Berry phases
- Author
-
Yakir Aharonov and Benni Reznik
- Subjects
Physics ,Superconductivity ,Nuclear and High Energy Physics ,Fluxon ,Condensed matter physics ,Charge density ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Geometric phase ,Condensed Matter::Superconductivity ,Quantum mechanics ,Phase (matter) ,Higgs boson ,Nonlinear Sciences::Pattern Formation and Solitons ,Quantum ,Realization (systems) - Abstract
An interplay of the Aharonov-Bohm phase and the Berry phase appears as a fluxon circulates an extended (quantum) charge distribution. For a fluxon-charge system in a superconductor, we will show how the interplay of the phases leads to a net topological effect. The realization of the effect in the Higgs model is discussed.
- Published
- 1993
33. Hawking Radiation on an Ion Ring in the Quantum Regime
- Author
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Serena Fagnocchi, Ralf Schützhold, Birger Horstmann, J. Ignacio Cirac, and Benni Reznik
- Subjects
Physics ,High Energy Physics - Theory ,Quantum Physics ,Astrophysics::High Energy Astrophysical Phenomena ,General Physics and Astronomy ,FOS: Physical sciences ,General Relativity and Quantum Cosmology (gr-qc) ,Ring (chemistry) ,01 natural sciences ,General Relativity and Quantum Cosmology ,010305 fluids & plasmas ,Ion ,High Energy Physics - Theory (hep-th) ,Quantum mechanics ,0103 physical sciences ,010306 general physics ,Quantum Physics (quant-ph) ,Quantum ,Hawking radiation - Abstract
This paper discusses a recent proposal for the simulation of acoustic black holes with ions. The ions are rotating on a ring with an inhomogeneous, but stationary velocity profile. Phonons cannot leave a region, in which the ion velocity exceeds the group velocity of the phonons, as light cannot escape from a black hole. The system is described by a discrete field theory with a nonlinear dispersion relation. Hawking radiation is emitted by this acoustic black hole, generating entanglement between the inside and the outside of the black hole. We study schemes to detect the Hawking effect in this setup., 42 pages (one column), 17 figures, published revised version
- Published
- 2010
34. Superfast Laser Cooling
- Author
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Martin B. Plenio, Shai Machnes, Alex Retzker, Andrew M. Steane, and Benni Reznik
- Subjects
Condensed Matter::Quantum Gases ,Coupling ,Materials science ,Resolved sideband cooling ,General Physics and Astronomy ,01 natural sciences ,7. Clean energy ,Upper and lower bounds ,Ion ,010309 optics ,Raman cooling ,Laser cooling ,0103 physical sciences ,Physics::Atomic Physics ,Atomic physics ,010306 general physics ,Ground state ,Doppler cooling - Abstract
Currently, laser cooling schemes are fundamentally based on the weak coupling regime. This requirement sets the trap frequency as an upper bound to the cooling rate. In this work we present a numerical study that shows the feasibility of cooling in the strong-coupling regime which then allows cooling rates that are faster than the trap frequency with experimentally feasible parameters. The scheme presented here can be applied to trapped atoms or ions as well as to mechanical oscillators. It can also cool medium sized ion chains close to the ground state.
- Published
- 2010
35. Thermodynamics of event horizons in (2+1)-dimensional gravity
- Author
-
Benni Reznik
- Subjects
Physics ,Gravitation ,General Relativity and Quantum Cosmology ,Event horizon ,General relativity ,Horizon ,Einstein field equations ,Thermodynamics ,Black hole thermodynamics ,Entropy (arrow of time) ,Laws of thermodynamics ,Mathematical physics - Abstract
Although gravity in 2+1 dimensions is very different in nature from gravity in 3+1 dimensions, it is shown that the laws of thermodynamics for event horizons can be manifested also for (2+1)-dimensional gravity. The validity of the classical laws of horizon mechanics is verified in general and exemplified for the (2+1)-dimensional analogues of Reissner-Nordstroem and Schwarzschild--de Sitter spacetimes. We find that the entropy is given by 1/4{ital L}, where {ital L} is the length of the horizon. A consequence of having consistent thermodynamics is that the second law fixes the sign of Newton's constant to be positive.
- Published
- 1992
36. Quantum coherence of discrete kink solitons in ion traps
- Author
-
Benni Reznik, H. Landa, Martin B. Plenio, Alex Retzker, and Samuel Marcovitch
- Subjects
Physics ,Quantum Physics ,Time evolution ,General Physics and Astronomy ,FOS: Physical sciences ,01 natural sciences ,010305 fluids & plasmas ,Ion ,Zigzag ,0103 physical sciences ,Ion trap ,Physics::Atomic Physics ,Atomic physics ,Quantum information ,010306 general physics ,Quantum Physics (quant-ph) ,Quantum ,Trapped ion quantum computer ,Coherence (physics) - Abstract
We propose to realize quantized discrete kinks with cold trapped ions. We show that long-lived solitonlike configurations are manifested as deformations of the zigzag structure in the linear Paul trap, and are topologically protected in a circular trap with an odd number of ions. We study the quantum-mechanical time evolution of a high-frequency, gap separated internal mode of a static kink and find long coherence times when the system is cooled to the Doppler limit. The spectral properties of the internal modes make them ideally suited for manipulation using current technology. This suggests that ion traps can be used to test quantum-mechanical effects with solitons and explore ideas for the utilization of the solitonic internal-modes as carriers of quantum information., 5 pages, 4 figures ; minor corrections
- Published
- 2009
37. Critical and noncritical long-range entanglement in Klein-Gordon fields
- Author
-
Benni Reznik, Alex Retzker, Martin B. Plenio, and Samuel Marcovitch
- Subjects
Physics ,Quantum Physics ,010308 nuclear & particles physics ,Vacuum state ,FOS: Physical sciences ,Quantum entanglement ,Von Neumann entropy ,Scale invariance ,Squashed entanglement ,01 natural sciences ,Power law ,Atomic and Molecular Physics, and Optics ,Renormalization ,Quantum mechanics ,0103 physical sciences ,Quantum Physics (quant-ph) ,010306 general physics ,Entropy (arrow of time) - Abstract
We investigate the entanglement between two spatially separated intervals in the vacuum state of a free one-dimensional Klein-Gordon field by means of explicit computations in the continuum limit of the linear harmonic chain. We demonstrate that the entanglement, which we quantify by the logarithmic negativity, is finite with no further need for renormalization. We find that in the critical regime, the quantum correlations are scale invariant as they depend only on the ratio of distance to length. They decay much faster than the classical correlations as in the critical limit long-range entanglement decays exponentially for separations larger than the size of the blocks, while classical correlations follow a power-law decay. With decreasing distance of the blocks, the entanglement diverges as a power law in the distance. The noncritical regime manifests richer behavior, as the entanglement depends both on the size of the blocks and on their separation. In correspondence with the von Neumann entropy also long-range entanglement distinguishes critical from noncritical systems.
- Published
- 2009
38. Hawking radiation from an acoustic black hole on an ion ring
- Author
-
J. I. Cirac, Benni Reznik, Serena Fagnocchi, and Birger Horstmann
- Subjects
High Energy Physics - Theory ,Physics ,Quantum Physics ,Sonic black hole ,Quantum field theory in curved spacetime ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,General Physics and Astronomy ,General Relativity and Quantum Cosmology (gr-qc) ,Electromagnetic radiation ,General Relativity and Quantum Cosmology ,Black hole ,Micro black hole ,High Energy Physics - Theory (hep-th) ,Quantum electrodynamics ,Quantum mechanics ,Extremal black hole ,Group velocity ,Quantum Physics (quant-ph) ,Hawking radiation - Abstract
In this article we propose to simulate acoustic black holes with ions in rings. If the ions are rotating with a stationary and inhomogeneous velocity profile, regions can appear where the ion velocity exceeds the group velocity of the phonons. In these regions phonons are trapped like light in black holes, even though we have a discrete field theory and a nonlinear dispersion relation. We study the appearance of Hawking radiation in this setup and propose a scheme to detect it., 4 pages, 3 figures, minor revisions, published version
- Published
- 2009
39. Entanglement of solitons in the Frenkel-Kontorova model
- Author
-
Benni Reznik and Samuel Marcovitch
- Subjects
Physics ,Quantum Physics ,Frenkel–Kontorova model ,Condensed matter physics ,Logarithmic growth ,FOS: Physical sciences ,Quantum entanglement ,Atomic and Molecular Physics, and Optics ,Nonlinear system ,Nonlinear Sciences::Exactly Solvable and Integrable Systems ,Quantum mechanics ,Soliton ,Quantum information ,Quantum Physics (quant-ph) ,Nonlinear Sciences::Pattern Formation and Solitons ,Critical field - Abstract
We investigate entanglement of solitons in the continuum-limit of the nonlinear Frenkel-Kontorova chain. We find that the entanglement of solitons manifests particle-like behavior as they are characterized by localization of entanglement. The von-Neumann entropy of solitons mixes critical with noncritical behaviors. Inside the core of the soliton the logarithmic increase of the entropy is faster than the universal increase of a critical field, whereas outside the core the entropy decreases and saturates the constant value of the corresponding massive noncritical field. In addition, two solitons manifest long-range entanglement that decreases with the separation of the solitons more slowly than the universal decrease of the critical field. Interestingly, in the noncritical regime of the Frenkel-Kontorova model, entanglement can even increase with the separation of the solitons. We show that most of the entanglement of the so-called internal modes of the solitons is saturated by local degrees of freedom inside the core, and therefore we suggest using the internal modes as carriers of quantum information., 16 pages, 22 figures
- Published
- 2008
40. Methods for Detecting Acceleration Radiation in a Bose-Einstein Condensate
- Author
-
J. I. Cirac, Benni Reznik, Martin B. Plenio, and Alex Retzker
- Subjects
Condensed Matter::Quantum Gases ,Physics ,Scalar field theory ,Condensed Matter::Other ,Phonon ,General Physics and Astronomy ,Radiation ,law.invention ,General Relativity and Quantum Cosmology ,Acceleration ,Thermalisation ,law ,Quantum electrodynamics ,Atom ,Physics::Accelerator Physics ,Quantum information ,Bose–Einstein condensate - Abstract
We propose and study methods for detecting Unruh-like acceleration radiation effects in a Bose-Einstein condensate in a (1+1)-dimensional setup. The Bogoliubov vacuum of a Bose-Einstein condensate is used to simulate a scalar field theory, and accelerated atom dots or optical lattices serve as detectors of phonon radiation due to acceleration effects. In particular, we study the dispersive effects of the Bogoliubov spectrum on the ideal case of exact thermalization. Our results suggest that acceleration radiation effects can be observed using currently accessible experimental methods.
- Published
- 2008
41. Time as an observable
- Author
-
Benni Reznik, William G. Unruh, and Jonathan Oppenheim
- Subjects
Computer Science::Performance ,Physics ,Current (mathematics) ,media_common.quotation_subject ,Particle ,Observable ,Statistical physics ,Ambiguity ,Kinetic energy ,Quantum ,Event (particle physics) ,Measure (mathematics) ,media_common - Abstract
The role of time in quantum mechanics is discussed. The differences between ordinary observables and an observable which corresponds to the time of an event is examined. In particular, the time-of-arrival of a particle to a fixed location is not an ordinary quantum mechanical observable. While we can measure if the particle arrives, we argue that the time at which it arrives always has an inherent ambiguity. The minimum inaccuracy of time-of-arrival measurements is given by dt>1/E where E is the kinetic energy of the particle. The use of time-of-arrival operators, as well as current operators, is examined critically.
- Published
- 2008
42. Implications of communication complexity in multipartite systems
- Author
-
Samuel Marcovitch and Benni Reznik
- Subjects
Discrete mathematics ,Physics ,Class (set theory) ,Multipartite ,Conjecture ,Quantum mechanics ,Quantum Physics ,Quantum information science ,Communication complexity ,Constant (mathematics) ,Triviality ,Atomic and Molecular Physics, and Optics ,Quantum complexity theory - Abstract
We present a class of noisy $N$-partite nonlocal boxes which reduces all communication complexity problems of $N$ parties to triviality. The noise level is constant for any number of parties and gives a probability of simulating the nonlocal box only slightly higher than that of quantum mechanics. Intriguingly, this class of multipartite nonlocal boxes corresponds to the Bell-Svetlichny inequality, which manifests genuine multipartite nonseparability. These results provide further support for the recent conjecture by Brassard et al., [Phys. Rev. Lett. 96, 250401 (2006)] that had nature been more nonlocal than quantum mechanics allows, communication complexity would have been trivial.
- Published
- 2008
43. Entanglement and the Speed of Evolution in Mixed States
- Author
-
Benni Reznik and Judy Kupferman
- Subjects
Physics ,Quantum Physics ,Spin states ,Mixed states ,FOS: Physical sciences ,Quantum entanglement ,Squashed entanglement ,Multipartite entanglement ,Atomic and Molecular Physics, and Optics ,Quantum mechanics ,Bipartite graph ,Quantum Physics (quant-ph) ,Entropy (arrow of time) ,Counterexample - Abstract
Entanglement speeds up evolution of a pure bipartite spin state, in line with the time-energy uncertainty. However, if the state is mixed this is not necessarily the case. We provide a counterexample and point to other factors affecting evolution in mixed states, including classical correlations and entropy.
- Published
- 2008
- Full Text
- View/download PDF
44. Combined Electric and Magnetic Aharonov-Bohm Effects
- Author
-
Samuel Marcovitch, Yakir Aharonov, Benni Reznik, and Tirza Kaufferr
- Subjects
Physics ,Quantum Physics ,Quantum electrodynamics ,Path (graph theory) ,General Physics and Astronomy ,FOS: Physical sciences ,Quantum Physics (quant-ph) ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Charged particle ,Gauge fixing - Abstract
It is well-known that the electric and magnetic Aharonov-Bohm effects may be formally described on equal footing using the four-vector potential in a relativistic framework. We propose an illustrative manifestation of both effects in a single configuration, in which the specific path of the charged particle determines the weight of the electric and magnetic acquired relative phases. The phases can be distinctively obtained in the Coulomb gauge. The scheme manifests the pedagogical lesson that though each of the relative phases is gauge-dependent their sum is gauge-invariant., 6 figures
- Published
- 2007
45. Continuous input nonlocal games
- Author
-
Benni Reznik, Shai Machnes, Jonathan Silman, N. Aharon, and Lev Vaidman
- Subjects
Theoretical physics ,Quantum Physics ,Conjecture ,FOS: Physical sciences ,Quantum entanglement ,Quantum Physics (quant-ph) ,Quantum ,Computer Science Applications ,Mathematics - Abstract
We present a family of nonlocal games in which the inputs the players receive are continuous. We study three representative members of the family. For the first two a team sharing quantum correlations (entanglement) has an advantage over any team restricted to classical correlations. We conjecture that this is true for the third member of the family as well., Journal version, slight modifications
- Published
- 2007
46. Tavis-Cummings model and collective multi-qubit entanglement in trapped ions
- Author
-
Alex Retzker, Benni Reznik, and Enrique Solano
- Subjects
Quantum optics ,Physics ,Quantum Physics ,Postselection ,Quantum mechanics ,Qubit ,FOS: Physical sciences ,Quantum entanglement ,Quantum Physics (quant-ph) ,Atomic and Molecular Physics, and Optics ,Ion ,Quantum computer - Abstract
We present a method of generating collective multi-qubit entanglement via global addressing of an ion chain following the guidelines of the Tavis-Cummings model, where several qubits are coupled to a collective motional mode. We show that a wide family of Dicke states and irradiant states can be generated by single global laser pulses, unitarily or helped with suitable postselection techniques., 6 pages, 3 figures. Accepted for publication in Physical Review A
- Published
- 2006
47. Aharonov-Bohm effect without closing a loop
- Author
-
Shmuel Nussinov, Alonso Botero, Yakir Aharonov, Benni Reznik, and Alex Retzker
- Subjects
Physics ,Annihilation ,Photon ,Phase (waves) ,Atomic and Molecular Physics, and Optics ,Magnetic flux ,Charged particle ,Loop (topology) ,Multipartite ,symbols.namesake ,Quantum electrodynamics ,Quantum mechanics ,symbols ,Aharonov–Bohm effect - Abstract
We discuss the consequences of the Aharonov-Bohm (AB) effect in setups involving several charged particles, wherein none of the charged particles encloses a closed loop around the magnetic flux. We show that in such setups, the AB phase is encoded either in the relative phase of a bipartite or multipartite entangled photons states, or alternatively, gives rise to an overall AB phase that can be measured relative to another reference system. These setups involve processes of annihilation or creation of electron-hole pairs. We discuss the relevance of such effects in ``vacuum birefringence" in QED, and comment on their connection to other known effects.
- Published
- 2006
48. Quantum Mechanical Realization of a Popescu-Rohrlich Box
- Author
-
Samuel Marcovitch, Benni Reznik, and Lev Vaidman
- Subjects
Combinatorics ,Causality (physics) ,Physics ,Quantum Physics ,Quantum mechanics ,Bipartite graph ,FOS: Physical sciences ,CHSH inequality ,Quantum Physics (quant-ph) ,Realization (systems) ,Quantum ,Atomic and Molecular Physics, and Optics - Abstract
We consider quantum ensembles which are determined by pre- and post-selection. Unlike the case of only pre-selected ensembles, we show that in this case the probabilities for measurement outcomes at intermediate times satisfy causality only rarely; such ensembles can in general be used to signal between causally disconnected regions. We show that under restrictive conditions, there are certain non-trivial bi-partite ensembles which do satisfy causality. These ensembles give rise to a violation of the CHSH inequality, which exceeds the maximal quantum violation given by Tsirelson's bound, $B_{\rm CHSH}\le 2\sqrt2$, and obtains the Popescu-Rohrlich bound for the maximal violation, $B_{\rm CHSH}\le 4$. This may be regarded as an a posteriori realization of super-correlations, which have recently been termed Popescu-Rohrlich boxes., 5 pages
- Published
- 2006
49. Long-range entanglement in the Dirac vacuum
- Author
-
Jonathan Silman and Benni Reznik
- Subjects
Physics ,Quantum Physics ,Dirac (software) ,FOS: Physical sciences ,Quantum entanglement ,Fermion ,Function (mathematics) ,Approx ,Atomic and Molecular Physics, and Optics ,Massless particle ,symbols.namesake ,Quantum mechanics ,Excited state ,symbols ,Quantum Physics (quant-ph) ,Klein–Gordon equation - Abstract
Recently, there have been a number of works investigating the entanglement properties of distinct noncomplementary parts of discrete and continuous Bosonic systems in ground and thermal states. The Fermionic case, however, has yet to be expressly addressed. In this paper we investigate the entanglement between a pair of far-apart regions of the 3+1 dimensional massless Dirac vacuum via a previously introduced distillation protocol [B. Reznik et al., Phys. Rev. A 71, 042104 (2005)]. We show that entanglement persists over arbitrary distances, and that as a function of L/R, where L is the distance between the regions and R is their typical scale, it decays no faster than exp(-(L/R)^2). We discuss the similarities and differences with analogous results obtained for the massless Klein-Gordon vacuum., Comment: 11 pages, 1 figure
- Published
- 2006
- Full Text
- View/download PDF
50. Many-region vacuum entanglement: Distilling aWstate
- Author
-
Jonathan Silman and Benni Reznik
- Subjects
Physics ,Quantum Physics ,Field (physics) ,FOS: Physical sciences ,Quantum entanglement ,State (functional analysis) ,Squashed entanglement ,Coupling (probability) ,Atomic and Molecular Physics, and Optics ,symbols.namesake ,Hidden variable theory ,Quantum mechanics ,symbols ,W state ,Quantum Physics (quant-ph) ,Klein–Gordon equation - Abstract
We investigate the correlations between any number of arbitrarily far-apart regions of the vacuum of the free Klein-Gordon field by means of its finite duration coupling to an equal number of localized detectors. We show that the correlations between any N such regions enable us to distill an N-partite W state, and therefore exhibit true $N$-fold entanglement. Furthermore, we show that for N=3, the correlations cannot be reproduced by a hybrid local-nonlocal hidden-variable model. For N >= 4 the issue remains open., Supersedes quant-ph/0501028
- Published
- 2005
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