Quantum Computation and Information Seminar

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

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 $n\gt 1$ 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 $n\gt 1$ 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

1. 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).
2. 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).
3. 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).

Supported by: Phys-Info (IT), SQIG (IT), CeFEMA and CAMGSD, with funding from FCT, FEDER and EU FP7, specifically through the Doctoral Programme in the Physics and Mathematics of Information (DP-PMI), FCT strategic projects PEst-OE/EEI/LA0008/2013 and UID/EEA/50008/2013, IT project QuSim, project CRUP-CPU CQVibes, the FP7 Coordination Action QUTE-EUROPE (600788), and the FP7 projects Landauer (GA 318287) and PAPETS (323901).