Perfect state transfers based on selective quantum interferences within a complex spin network

GONZALO A. ÁLVAREZ; MOR MISHKOVSKY; ERNESTO P. DANIELI; PATRICA R. LEVSTEIN; HORACIO M. PASTAWSKI; LUCIO FRYDMAN

PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS

AMER PHYSICAL SOC

Lugar: New York; Año: 2010 vol. 81 p. 60302 - 60302

1050-2947

We present a method that implements directional, perfect state transfers within a branched spin network by exploiting quantum interferences in the time domain. This method provides a tool for isolating subsystems from a large and complex one. Directionality is achieved by interrupting the spin-spin coupled evolution with periods of free Zeeman evolutions, whose timing is tuned to be commensurate with the relative phases accrued by specific spin pairs. This leads to a resonant transfer between the chosen qubits and to a detuning of all remaining pathways in the network, using only global manipulations. Since the transfer is perfect when the selected pathway is mediated by two or three spins, distant state transfers over complex networks can be achieved by successive recouplings among specific pairs or triads of spins. These effects are illustrated with a quantum simulator involving 13C NMR on leucine?s backbone; a six-spin network.