Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 26: Quantum Dynamics, Decoherence and Quantum Information (jointly with DY)
TT 26.5: Vortrag
Montag, 16. März 2015, 16:00–16:15, BH-N 334
Fully pulse-controlled gate operations on qubit chains with always on coupling — Holger Frydrych1, •Michael Marthaler2, and Gernot Alber1 — 1Institut für Angewandte Physik, Technische Universität Darmstadt, D-64289 Darmstadt — 2Institut für Theoretische Festkörperphysik , Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany
We investigate a linear chain of qubits with strong, always-on nearest-neighbour couplings. Always-on coupling is simple to realize, but it raises the question of how to decouple the qubits. One possibility would be strong detuning, but the energy splitting of many qubits can only be changed slowly or the energy is fixed by tuning to a symmetry point which reduces decoherence.We propose a selective dynamical decoupling scheme, which is capable of dynamically suppressing any coupling in the chain as needed, by applying certain sequences of local pulses to individual qubits. We demonstrate how this pulse control can be used to implement single-qubit rotations and an entangling two-qubit gate between any neighbouring qubits in the chain. We find that high fidelities can be achieved as long as the number of permanently coupled qubits is not too large. As a specific example we discuss the concrete parameters needed to implement our proposal with superconducting flux qubits.