Abstract
It is usually argued that the presence of gapless quasiparticle excitations at the nodes of the -wave superconducting gap should strongly decohere the quantum states of a -wave qubit, making quantum effects practically unobservable. Using a self-consistent linear response nonequilibrium quasiclassical formalism, we show that this is not necessarily true. We find quasiparticle conductance of a -wave grain boundary junction to be strongly phase dependent. Midgap states as well as nodal quasiparticles contribute to the conductance and therefore decoherence. Quantum behavior is estimated to be detectable in a qubit containing a -wave junction with appropriate parameters.
- Received 29 May 2003
DOI:https://doi.org/10.1103/PhysRevLett.92.017001
©2004 American Physical Society