|
| related topics |
| {state, states, entangled} |
| {key, protocol, security} |
| {states, state, optimal} |
| {alice, bob, state} |
| {operator, operators, space} |
| {bell, inequality, local} |
| {measurement, state, measurements} |
| {cos, sin, state} |
| {let, theorem, proof} |
| {photon, photons, single} |
| {state, phys, rev} |
|
Detecting two-party quantum correlations in quantum key distribution
protocols
Marcos Curty, Otfried Gühne, Maciej Lewenstein, Norbert Lütkenhaus
abstract: A necessary precondition for secure quantum key distribution (QKD) is that
sender and receiver can prove the presence of entanglement in a quantum state
that is effectively distributed between them. In order to deliver this
entanglement proof one can use the class of entanglement witness (EW) operators
that can be constructed from the available measurements results. This class of
EWs can be used to provide a necessary and sufficient condition for the
existence of quantum correlations even when a quantum state cannot be
completely reconstructed. The set of optimal EWs for two well-known
entanglement based (EB) schemes, the 6-state and the 4-state EB protocols, has
been obtained recently [M. Curty et al., Phys. Rev. Lett. 92, 217903 (2004)].
Here we complete these results, now showing specifically the analysis for the
case of prepare&measure (P&M) schemes. For this, we investigate the signal
states and detection methods of the 4-state and the 2-state P&M schemes. For
each of these protocols we obtain a reduced set of EWs. More importantly, each
set of EWs can be used to derive a necessary and sufficient condition to prove
that quantum correlations are present in these protocols.
- oai_identifier:
- oai:arXiv.org:quant-ph/0409047
- categories:
- quant-ph
- comments:
- 13 pages, 1 figure
- doi:
- 10.1103/PhysRevA.71.022306
- arxiv_id:
- quant-ph/0409047
- journal_ref:
- Phys. Rev. A 71, 022306 (2005)
- created:
- 2004-09-08
Full article ▸
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