|
| related topics |
| {entanglement, phys, rev} |
| {state, states, entangled} |
| {equation, function, exp} |
| {bell, inequality, local} |
| {time, decoherence, evolution} |
| {information, entropy, channel} |
| {particle, mechanics, theory} |
| {cos, sin, state} |
| {field, particle, equation} |
| {states, state, optimal} |
|
Frontier between separability and quantum entanglement in a many spin
system
F. C. Alcaraz, C. Tsallis
abstract: We discuss the critical point $x_c$ separating the quantum entangled and
separable states in two series of N spins S in the simple mixed state
characterized by the matrix operator $\rho=x|\tilde{\phi}><\tilde{\phi}| +
\frac{1-x}{D^N} I_{D^N}$ where $x \in [0,1]$, $D =2S+1$, ${\bf I}_{D^N}$ is the
$D^N \times D^N$ unity matrix and $|\tilde {\phi}>$ is a special entangled
state. The cases x=0 and x=1 correspond respectively to fully random spins and
to a fully entangled state. In the first of these series we consider special
states $|\tilde{\phi}>$ invariant under charge conjugation, that generalizes
the N=2 spin S=1/2 Einstein-Podolsky-Rosen state, and in the second one we
consider generalizations of the Weber density matrices. The evaluation of the
critical point $x_c$ was done through bounds coming from the partial
transposition method of Peres and the conditional nonextensive entropy
criterion. Our results suggest the conjecture that whenever the bounds coming
from both methods coincide the result of $x_c$ is the exact one. The results we
present are relevant for the discussion of quantum computing, teleportation and
cryptography.
- oai_identifier:
- oai:arXiv.org:quant-ph/0110067
- categories:
- quant-ph cond-mat.stat-mech cs.CC
- comments:
- 4 pages in RevTeX format
- arxiv_id:
- quant-ph/0110067
- journal_ref:
- Phys. Lett. A {\bf 301}, 105 (2002).
- created:
- 2001-10-10
Full article ▸
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