Quantum Zeno effect in the Cooper-pair transport through a double-island Josephson system
A. Shnirman+, Y. Makhlin+,*
+Institut für Theoretische Festkörperphysik, Universität Karlsruhe, D-76128 Karlsruhe, Germany
*L.D. Landau Institute for Theoretical Physics RAS, 117940 Moscow, Russia
PACS: 73.23.Hk, 74.50.+r, 85.25.Cp
Abstract
Motivated by recent experiments, we analyze transport of Cooper
pairs through a double-island Josephson qubit. At low bias in a
certain range of gate voltages coherent superpositions of charge
states play a crucial role. Analysis of the evolution of the
density matrix allows us to cover a wide range of parameters,
incl. situations with degenerate levels, when dissipation strongly
affects the coherent eigenstates. At high noise levels the
so-called Zeno effect can be observed, which slows down the
transport. Our analysis explains certain features of the I-V
curves, in particular the visibility and shape of resonant peaks
and lines.