| | 1 | Author
| Yakir Aharonova, Alonso Boterob, Marian Scullya | Requires cookie* | | | Title
| Locality or Non-Locality in Quantum Mechanics: Hidden Variables without "Spooky Action-at-a-Distance"  | | | | Abstract
| The folklore notion o f the "Non-Locality o f Quantum Mechanics" is examined from the point of view o f hidden-variables theories according to Belinfante's classification in his Survey o f Hidden Variables Theories. It is here shown that in the case o f EPR, there exist hidden variables theories that successfully reproduce quantum-mechanical predictions, but which are explicitly local. Since such theories do not fall into Belinfante's classification, we propose an expanded classification which includes similar theories, which we term as theories o f the "third" kind. Causal implications of such theories are explored. -Pacs: 03.65.Bz | | | |
Reference
| Z. Naturforsch. 56a, 5—1235 (2001); received February 16 2001 | | | |
Published
| 2001 | | | |
Keywords
| Non-Locality, Hidden Variables, EPR | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_A/56/ZNA-2001-56a-0005.pdf | | | | Identifier
| ZNA-2001-56a-0005 | | | | Volume
| 56 | |
| 2 | Author
| Yakir Aharonova, Berthold-Georg Englertc | Requires cookie* | | | Title
| The Mean King's Problem: Spin | | | | Abstract
| We show how one can ascertain the values o f four mutually complementary observables o f a spin-1 degree o f freedom. -Pacs: 03.65.Bz | | | |
Reference
| Z. Naturforsch. 56a, 16—19 (2001); received January 12 2001 | | | |
Published
| 2001 | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_A/56/ZNA-2001-56a-0016.pdf | | | | Identifier
| ZNA-2001-56a-0016 | | | | Volume
| 56 | |
| 4 | Author
| DimitrisG. Angelakis, Almut Beigea, PeterL. Knight, WilliamJ. Munrob, Ben Tregenna | Requires cookie* | | | Title
| Verifying Atom Entanglement Schemes by Testing Bell's Inequality | | | | Abstract
| Recent experiments to test B ell's inequality using entangled photons and ions aimed at tests of basic quantum mechanical principles. Interesting results have been obtained and many loopholes could be closed. In this paper we want to point out that tests of Bell's inequality also play an important role in verifying atom entanglement schemes. We describe as an example a scheme to prepare arbitrary entangled states o f N two-level atoms using a leaky optical cavity and a scheme to entangle atoms inside a photonic crystal. During the state preparation no photons are emitted, and observing a violation o f B ell's inequality is the only way to test whether a scheme works with a high precision or not. | | | |
Reference
| Z. Naturforsch. 56a, 27 (2001); received February 16 2001 | | | |
Published
| 2001 | | | |
Keywords
| Present address: Hewlett-Packard Laboratories, Filton Road, Stoke Gifford, Bristol BS34 8QZ, UK Key words: Bell Inequality Tests, Atom Entanglement Schemes, Quantum Computing, Manipulation o f Decoherence-free States | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_A/56/ZNA-2001-56a-0027.pdf | | | | Identifier
| ZNA-2001-56a-0027 | | | | Volume
| 56 | |
| 9 | Author
| DanielM. Greenberger | Requires cookie* | | | Title
| The Inconsistency of the Usual Galilean Transformation in Quantum Mechanics and How To Fix It | | | | Abstract
| It is shown that the generally accepted statement that one cannot superpose states of different mass in non-relativistic quantum mechanics is inconsistent. It is pointed out that the extra phase induced in a moving system, which was previously thought to be unphysical, is merely the non-relativistic residue of the "twin-paradox" effect. In general, there are phase effects due to proper time differences between moving frames that do not vanish non-relativistically. There are also effects due to the equivalence of mass and energy in this limit. The remedy is to include both proper time and rest energy non-relativis-tically. This means generalizing the meaning of proper time beyond its classical meaning, and introduc ing the mass as its conjugate momentum. The result is an uncertainty principle between proper time and mass that is very general, and an integral role for both concepts as operators in non-relativistic physics. | | | |
Reference
| Z. Naturforsch. 56a, 67—75 (2001); received February 8 2001 | | | |
Published
| 2001 | | | |
Keywords
| Galilean Transformation, Symmetry, Superselection Rules, Proper Time, Mass | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_A/56/ZNA-2001-56a-0067.pdf | | | | Identifier
| ZNA-2001-56a-0067 | | | | Volume
| 56 | |
| 10 | Author
| Rudolf Haag | Requires cookie* | | | Title
| Quantum Physics and Reality | | | | Abstract
| Apparent paradoxes in Quantum Physics demand a sharp distinction between a "real part of the world" and the realm of possibilities. In the former we may distinguish individual elements (coarse events) relating to space-time, with causal connections between them respecting the relativistic locality principle. The latter, quantitatively described by probability assignments conditioned on existing facts and depending on the definition of equivalence classes of situations, cannot be subdivided in space-time categories. There are global correlations (Pauli principle...). The cut between the realms of facts and possibilities implies an evolutionary picture of the "real world" in which the (generalized) arrow of time assumes basic significance. Some deficiencies of existing theory are pointed out. | | | |
Reference
| Z. Naturforsch. 56a, 76—82 (2001); received January 12 2001 | | | |
Published
| 2001 | | | |
Keywords
| Quantum Philosophy, Entanglement, Irreversibility | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_A/56/ZNA-2001-56a-0076.pdf | | | | Identifier
| ZNA-2001-56a-0076 | | | | Volume
| 56 | |
| 12 | Author
| B. Kraus, W. Dür, G. Vidal, J. I. Cirac, M. Lewensteina, N. Lindenb, S. Popescuc, H. H. | Requires cookie* | | | Title
| Entanglement Capability of Two-qubit Operations | | | | Abstract
| We study the optimal way of creating bi-partite entanglement using a general two-qubit in teraction. On the one hand, we analyze the entanglement capability of an arbitrary non-local Hamiltonian acting on two qubits. We explicitly calculate the state which maximizes the entangle ment produced per time step 81 during the non-local evolution. On the other hand, we determine the maximal amount of entanglement which can be produced by an arbitrary two-qubit gate. We also give the separable state which leads to the output state containing this amount of entanglement. Furthermore, we consider the situation where auxiliary systems are present. Finally, we determine the non-unitary processes which are able to create entanglement from an initially separable state of two systems. | | | |
Reference
| Z. Naturforsch. 56a, 91—99 (2001); received February 6 2001 | | | |
Published
| 2001 | | | |
Keywords
| Entanglement, Quantum Information, Quantum Gates | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_A/56/ZNA-2001-56a-0091.pdf | | | | Identifier
| ZNA-2001-56a-0091 | | | | Volume
| 56 | |
| 13 | Author
| L. Vaidman | Requires cookie* | | | Title
| The Paradoxes of the Interaction-free Measurements | | | | Abstract
| Interaction-free measurements introduced by Elitzur and Vaidman [Found. Phys. 23,987 (1993)] allow finding infinitely fragile objects without destroying them. Paradoxical features of these and related measurements are discussed. The resolution of the paradoxes in the framework of the Many-Worlds Interpretation is proposed. | | | |
Reference
| Z. Naturforsch. 56a, 100—107 (2001); received January 12 2001 | | | |
Published
| 2001 | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_A/56/ZNA-2001-56a-0100.pdf | | | | Identifier
| ZNA-2001-56a-0100 | | | | Volume
| 56 | |
| 17 | Author
| E. Delre, B. Crosignani3, R.Di Porto3 | Requires cookie* | | | Title
| Bell States, Bell Operators, and Total Teleportation | | | | Abstract
| We identify the operators and the corresponding physical quantities whose measurement allows in principle to obtain total teleportation o f the unknown spin state of a single electron. We introduce an analogous scheme for a single photon and discuss its experimental implementation. | | | |
Reference
| Z. Naturforsch. 56a, 128—132 (2001); received February 3 2001 | | | |
Published
| 2001 | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_A/56/ZNA-2001-56a-0128.pdf | | | | Identifier
| ZNA-2001-56a-0128 | | | | Volume
| 56 | |
| 18 | Author
| P. D. Drumm, S. Chaturvedi, K. Dechoum, J. Com | Requires cookie* | | | Title
| Quantum Criticality | | | | Abstract
| We investigate the theory of quantum fluctuations in non-equilibrium systems having large crit ical fluctuations. This allows us to treat the limits imposed by nonlinearities to quantum squeezing and noise reduction, and also to envisage future tests o f quantum theory in regions of macroscopic quantum fluctuations. A long-term objective of this research is to identify suitable physical sys tems in which macroscopic 'Schrödinger cat'-like behaviour may be observed. We investigate two systems in particular o f much current experimental interest, namely the degenerate parametric oscillator near threshold, and the evaporatively cooled (BEC). We compare the results obtained in the positive-P representation, as a fully quantum mechanical calculation, with the truncated Wigner phase space equation, also known as semi-classical theory. We show when these results agree and differ in calculations taken beyond the linearized approximation. In the region where the largest quantum fluctuations and Schrödinger cat-like behaviour might be expected, we find that the quantum predictions correspond very closely to the semi-classical theory. Nature abhors observing a Schrödinger cat. -Pacs: 03.65.Bz | | | |
Reference
| Z. Naturforsch. 56a, 133—139 (2001); received January 12 2001 | | | |
Published
| 2001 | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_A/56/ZNA-2001-56a-0133.pdf | | | | Identifier
| ZNA-2001-56a-0133 | | | | Volume
| 56 | |
|
