Decoherence due to nodal quasiparticles in d-wave qubits
Ya. V. Fominov + *, A. A. Golubov * 1), M. Yu. Kupriyanov
+L. D. Landau Institute for Theoretical Physics RAS, 117940 Moscow, Russia *Department of Applied Physics, University of Twente, 7500 AE Enschede, The Netherlands Nuclear Physics Institute, Moscow State University, 119992 Moscow, Russia
PACS: 73.23.-b, 74.50.+r, 85.25.-j
Abstract
We study the Josephson junction between two d-wave superconductors, which is discussed as an
implementation of a qubit. We propose an approach that allows to calculate the decoherence time due to an intrinsic
dissipative process: quantum tunneling between the two minima of the double-well potential excites nodal quasiparticles
which lead to incoherent damping of quantum oscillations. The decoherence is weakest in the mirror junction, where the
contribution of nodal quasiparticles corresponds to the superohmic dissipation and becomes small at small tunnel
splitting of the energy level in the double-well potential. For available experimental data, we estimate the quality
factor.
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