on 29-07-2015
Niaz Ali Khan, University of Porto
29/07/2015, 12:00. * * * Please note exceptional time. * * *
Room P3.10, Pavilhão de Matemática, IST
We investigate the properties of entanglement between two modes of a free Dirac and Scaler Field as seen by two relatively accelerated parties. A uniformly accelerated observer is unable to access information about the whole of spacetime, therefore there is a loss of information and a corresponding degradation of entanglement. The entanglement degradation in the limit of infinite acceleration for the Dirac field asymptotically reaches a non-vanishing minimum value. While for the case of bososnic field, a bipartite system becomes fully seperable in the limit of infinite acceleration. This means that the state always remains entangled to a degree for fermionic field and can be used in quantum information tasks, such as teleportation, between parties in relative uniform acceleration. We also investigate the effect of relativity on a tripartite maximally entangled GHZ state
Quantum Computation and Information Seminar
Support: Phys-Info (IT), SQIG (IT), CFIF and CAMGSD, with support from FCT, FEDER and EU FP7, namely via projects PEst-OE/EEI/LA0008/2013, Landauer (GA 318287) and PAPETS (323901).
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on 23-07-2015
Tony Apollaro, NEST - CNR & Università degli Studi di Palermo
23/07/2015, 10:00
Room P3.10, Pavilhão de Matemática, IST
The transfer of an unknown quantum state (QST) from a sender to a receiver is one of the main requirements to perform quantum information processing tasks. In this respect, QST of a single qubit by means of spin chains has been widely discussed, and many protocols aiming at performing this task have been proposed (for a review see Refs. [1] and references therein).
In this talk quantum state routing (QSR) and the transfer of the quantum state of n>1 qubits (n-QST) by means of spin-1/2 chains is addressed. In the case of QSR, the aim is to design a transfer scheme such that the sender is in condition to choose one receiver of the QST out of several spins. The transfer of a quantum state of n>1 quits consists in achieving a high-fidelity transfer of the quantum state of many qubits via the use of a spin chain [2]. For the 2-QST, an analytical expression of the average fidelity as a function of the allowed excitations transfer amplitude are derived and, hence, theoretical investigations on the search and optimisation of other QST protocols may be triggered [3].
References
S. Bose, Quantum communication through spin chain dynamics: an introductory overview, Contemp. Phys. 48, 13 (2007); T.J.G. Apollaro, S. Lorenzo, F. Plastina, Transport of quantum correlations across a spin chain, Int. J. Mod. Phys. B 27, 1345035 (2013).
S. Paganelli, S. Lorenzo, T. J. G. Apollaro, F. Plastina, and G.L. Giorgi, Routing quantum information in spin chains, Phys. Rev. A 87, 062309 (2013).
T. J. G. Apollaro, S. Lorenzo, A. Sindona, S. Paganelli, G. L. Giorgi, and F. Plastina, Many-qubit quantum state transfer via spin chains, Phys. Rev. A 91, 042321 (2015).
Quantum Computation and Information Seminar
http://math.ist.utl.pt/seminars/qci/?action=next
Support: Phys-Info (IT), SQIG (IT), CFIF and CAMGSD, with support from FCT, FEDER and EU FP7, namely via projects PEst-OE/EEI/LA0008/2013, Landauer (GA 318287) and PAPETS (323901).
More Information..