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Seminar - Quantum State Routing and many-qubit Quantum State Transfer via a single channel


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).
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Seminar - Open quantum systems: life beyond the Markov approximation


on 20-07-2015

... Ines de Vega (LMU Munich)


Date & time: 20/07/2015 at 10:00.

Location: Room P3.10, Mathematics Building, Instituto Superior Técnico, Lisbon.


Abstract:
Open quantum systems (OQS) cannot always be described with the Markov approximation, which requires a large separation of system and environment time scales. In this talk I will give an overview of some recent advances to tackle the dynamics of an OQS beyond the Markov approximation, with special emphasis in hierarchy-based [1,2] and chain mapping-based [3] approaches. In the latter context, I will discuss the use of a thermofield transformation to describe thermal environments [4].

[1] Y. Tanimura. PRA, 41, 6676–6687 (1990).
[2] I. de Vega, J. Phys. A: Math. Theor. 48, 145202 (2015).
[3] A. W. Chin, J. Prior, S. F. Huelga, and M. B. Plenio, Phys. Rev. Lett. 107, 160601 (2011).
[4] I. de Vega and M.C. Banuls, arXiv:1504.07228.

Physics of Information Seminar
http://www.phys-info.org/physics-of-information-seminar.html

Supported with funding from FCT, FEDER and EU FP7, namely via projects PEst-OE/EEI/LA0008/2013, UID/EEA/50008/2013, IT/QuSim, CQVibes, Landauer (318287) and PAPETS (323901). More Information..