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B. C. Sanctuary

Publications and source records attributed to B. C. Sanctuary.

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Disentanglement as particles separate

Disentanglement refers to decoherence that destroys the quantum interference terms between particles as they separate. This process reduces the pure isotropic entangled EPR state to a mixed anisotropic state. Averaging over the ensemble of states leads to correlations between separated particles that satisfies Bell's inequalities. Applying disentanglement to EPR pairs of photons shows that entanglement is characterized by various two-particle symmetry properties. These symmetry properties are destroyed by disentanglement but photon helicity is conserved. This is sufficient to account for the correlations needed to resolve the EPR paradox. Apart from a numerical factor, the functional form for the correlations due to entanglement and disentanglement is identical, thereby making it difficult to distinguish between the two in the current experiments.

quant-ph

The Statistical Interpretation of Entangled States

Entangled EPR spin pairs can be treated using the statistical ensemble interpretation of quantum mechanics. As such the singlet state results from an ensemble of spin pairs each with an arbitrary axis of quantization. This axis acts as a quantum mechanical hidden variable. If the spins lose coherence they disentangle into a mixed state. Whether or not the EPR spin pairs retain entanglement or disentangle, however, the statistical ensemble interpretation resolves the EPR paradox and gives a mechanism for quantum "teleportation" without the need for instantaneous action-at-a-distance.

quant-ph

Rationalization of EPR Coincidence Experiments

Coincidence experiments on EPR pairs show strong violations of Bell's Inequalities at certain filter settings which is widely believed to mean that local hidden variable models cannot explain these results. In this paper it is shown that the 'non-separable' singlet density matrix can be represented as a sum of separable density matrices which are products of individual non-hermitian spin operator states. This decomposition is consistent with the intuitive notion that after separation from the singlet the two physical systems should be described by a product state. In spite of the non-hermiticity, the values of the relevant spin observables are real. A new local hidden variable model inspired by this decomposition is discussed.

physics.gen-ph

Quantum correlations between separated particles

Long-range quantum correlations between particles are usually formulated by assuming the persistence of an entangled state after the particles have spearated. Here this approach is re-examined based upon studying the correlations present in a pair of EPR spins. Two types of correltions are identified. The first, due to the quantum interference terms is parity. This symmetry property characterizes entanglement. Second is correlation due to conservation of angular momentum. The two contributions are equal and have the same functional form. When entanglement is present, Bell's inequalities are violated but when parity is destroyed by disentanglement, Bell's inequalities are satisfied. It is shown tht some experiments which have hiterto been interpreted by entangled states can be better described by disentanglement. Implications for quantum non-locality are discussed.

quant-ph

Quantum "Teleportation" using local correlations

The phenomenon called quantum "teleportation" has been formulated assuming the presence of entangled states and is interpreted as a realization of quantum non-locality. In contrast, correlations from both entanglement and disentanglement upon particle spearation exists and both of these are built into the EPR pair as they move apart. Here it is shown that quantum "teleportaton" can be formulated and interpreted without invoking a non-local hypothesis of quantum mechanics, and is better descrited as "quantum state selection".

quant-ph

Correlations in Entangled States

Entangled EPR spin pairs can be treated using the statistical ensemble interpretation of quantum mechanics. As such the singlet state results from an ensemble of spin pairs each with its own specific axis of quantization. This axis acts like a quantum mechanical hidden variable. If the spins lose coherence they disentangle into a mixed state that contains classical correlations. In this paper an infinitesimal phase decoherence is introduced to the singlet state in order to reveal more clearly some of the correlations. It is shown that a singlet state has no classical correlations.

quant-ph

Structure of a spin 1/2

The non-hermitian states that lead to separation of the four Bell states are examined. In the absence of interactions, a new quantum state of spin magnitude 1/(root(2) is predicted. Properties of these states show that an isolated spin is a resonance state with zero net angular momentum, consistent with a point particle, and each resonance corresponds to a degenerate but well defined structure. By averaging and de-coherence these structures are shown to form ensembles which are consistent with the usual quantum description of a spin.

physics.gen-ph

Separation of Bell states

The four Bell states can be represented by separable coherent states which are products of individual non-hermitian spin operators. In the absence of interactions, the non-hermitian states are predicted to form a new quantum state of spin magnitude 1/sqrt(2) rather than 1/2. Properties of these states show that an isolated spin is a resonance state with zero net angular momentum, consistent with a point particle. In addition, the Bell states are shown to take on the identical mathematical form when the two spins are bound (local) or unbound (non-local). The bound Bell states are resonances between four states. When the separate, they do so from only one of its resonance states and their ensemble average defines the unbound Bell states. The bound and unbound Bell states have the same mathematical form due to the persistence of the rotationally invariance of sigma(1)dot sigma(2).

physics.gen-ph

The two dimensional spin and its resonance fringe

Violation of Bell's Inequalities gives experimental evidence for the existence of a spin 1/2 which has two simultaneous axes of spin quantization rather than one. These couple to form a resonance state, called the spin fringe, and this quantum effect is solely responsible for violation of Bell's Inequalities within this model. The Bell states can be represented by products of these spin states and leads to the intuitive concept that as entangled states decompose they form biparticles that are not entangled. In EPR coincidence experiments filter settings for both the Bell and CHSH forms of Bell's Inequalities are rationalized in terms of the correlation between biparticles.

physics.gen-ph

On the existence of Einstein-Podolsky-Rosen Channels

A physical theory without interpretation is mathematics. Since there are no paradoxes in science, only incorrect interpretations of phenomena or inadequate theories, it is necessary to use a consistent interpretation of quantum mechanics that makes physical sense and satisfies the experimental facts. Quantum "teleportation" provides such an example because the current treatments rely on unexplained connections between separated correlated particles. In this comment, a mechanism is suggested that avoids the instantaneous wave function collapse between non-interacting entangled particles at space like separations. This mechanism requires a statistical ensemble interpretation of the wave function.

quant-ph

Interpretation of "non-local" experiments using disentanglement

It is shown that a number of experiments designed to use entangled photon pairs in order to demonstrate the viability of quantum "teleportation" can, in fact, also be understood using disentanglement. Whether entangled or not, using an ensemble approach, the experiments can be explained without any non-local communication between Alice's photon and Bob's photon. Moreover, it is emphasized that entanglement maintains a symmetry property between the two photons that is absent in disentanglment, the symmetry being parity due to phase conerence.

quant-ph

Ground State Phase Diagram of S=1 XXZ Chains with Uniaxial Single-Ion-Type Anisotropy

One dimensional S=1 XXZ chains with uniaxial single-ion-type anisotropy are studied by numerical exact diagonalization of finite size systems. The numerical data are analyzed using conformal field theory, the level spectroscopy, phenomenological renormalization group and finite size scaling method. We thus present the first quantitatively reliable ground state phase diagram of this model. The ground states of this model contain the Haldane phase, large-D phase, Néel phase, two XY phases and the ferromagnetic phase. There are four different types of transitions between these phases: the Brezinskii-Kosterlitz-Thouless type transitions, the Gaussian type transitions, the Ising type transitions and the first order transitions. The location of these critical lines are accurately determined.

cond-mat.str-el

Magnetization plateaus and phase diagram in polymerized S=1/2 XXZ chains

The magnetization plateaus of $p$-merized $S=1/2$ XXZ chains are studied for general values of $p$. Two plateau-non-plateau critical lines and one plateau-plateau critical line are found for each value of $p$. The universality class of the plateau-non-plateau transition belongs to Brezinskii-Kosterlitz-Thouless (BKT) type and that of the plateau-plateau transition, to the Gaussian type. The critical points are determined by level spectroscopic analysis of the numerical diagonalization results for $4 \le p \le 8$. The multicritical points are calculated using the integral equations based on the Bethe ansatz solution of the XXZ model. The behavior of multicritical points are analyzed in detail for large $p$. It is found that the plateau region is enhanced with the increase of periodicity $p$ although the non-plateau region persists as far as $p$ is finite.

cond-mat.str-el

Magnetization plateaus in antiferromagnetic-(ferromagnetic)_{n} polymerized S=1/2 XXZ chains

The plateau-non-plateau transition in the antiferromagnetic-(ferromagnetic)$_{n}$ polymerized $S=1/2$ XXZ chains under the magnetic field is investigated. The universality class of this transition belongs to the Brezinskii-Kosterlitz-Thouless (BKT) type. The critical points are determined by level spectroscopy analysis of the numerical diagonalization data for $4 \leq p \leq 13$ where $p(\equiv n+1)$ is the size of a unit cell. It is found that the critical strength of ferromagnetic coupling decreases with $p$ for small $p$ but increases for larger enough $p$. It is also found that the plateau for large $p$ is wide enough for moderate values of exchange coupling so that it should be easily observed experimentally. This is in contrast to the plateaus for $p = 3$ chains which are narrow for a wide range of exchange coupling even away from the critical point.

cond-mat.stat-mech