Characterizing entanglement in qubits created with spatially correlated twin photons
- Clarendon Laboratory, Oxford University, Parks Road, Oxford, OX1 3PU (United Kingdom)
- Departamento de Fisica, Universidade Federal de Minas Gerais, Caixa Postal 702, Belo Horizonte, MG 30123-970 (Brazil)
- Instituto de Fisica, Universidade Federal de Alagoas, Cidade Universiaria, Maceio, AL 57072-970 (Brazil)
- Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972, Rio de Janeiro, RJ (Brazil)
We characterize entanglement in two-qubit pure states encoded in transverse momenta of twin photons obtained from spontaneous parametric down-conversion. Two alternate methods are employed: (i) measurement of conditional interference patterns and (ii) measurement of the marginal probability that yields the single-photon interference pattern. Both methods are local with classical communication and rely on Schmidt decomposition of the quantum state, which is generated by letting the photons propagate through an appropriate lens system. In both cases we can obtain the concurrence either through the Schmidt coefficients in the first method or directly relating the concurrence to the visibility of the interference pattern in the second one.
- OSTI ID:
- 21015945
- Journal Information:
- Physical Review. A, Vol. 76, Issue 3; Other Information: DOI: 10.1103/PhysRevA.76.032314; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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