Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 39: Transport: Quantum Coherence and Quantum Information Systems - Theory II
TT 39.2: Vortrag
Dienstag, 1. April 2014, 11:00–11:15, BEY 81
Measurement and dephasing of a flux qubit due to heat currents — •Samuele Spilla1,2,3, Fabian Hassler2,4, and Janine Splettstoesser1,2 — 1Institut für Theorie der Statistischen Physik, RWTH Aachen University, D-52056 Aachen, Germany — 2JARA-Fundamentals of Future Information Technology — 3Dipartimento di Fisica e Chimica, Università di Palermo, I-90123 Palermo, Italy — 4Institute for Quantum Information, RWTH Aachen University, D-52056 Aachen, Germany
The existence of a phase-dependent thermal current through a temperature-biased Josephson junction has been recently demonstrated experimentally. It is this phase-dependence of the thermal current, which makes it interesting to study its sensitivity and impact on the states of superconducting circuits for quantum computing, e.g., superconducting qubits. I will present an analysis of the thermal current through a superconducting persistent current qubit, made of a superconducting loop interrupted by three Josephson junctions, which is subject to a temperature gradient. It can be shown that the thermal current induced by the temperature gradient depends significantly on the state of the qubit. I will furthermore investigate the impact of the heat current on the coherence properties of the qubit state. We find that even small temperature gradients can lead to dephasing times of the order of microseconds for the Delft-qubit design.