Quantum Phase Dynamics in High-Tc Josephson Junctions

Conference poster, 2008

We study quantum phase fluctuations in planar junctions between high-Tc superconductors for a range of relative orientations of the a-b crystal axes. Specifically, attention is directed towards the fermionic subspace of low energy Andreev bound states (MGS). This subspace, being responsible for most of the Josephson current, strongly couples to the phase degree of freedom. At the same time, low frequency phase fluctuations introduce intrinsic dynamics in this subspace. For a given quasiclassical trajectory there may exist two bound state levels. Change in the occupations of these levels due to the phase fluctuations would lead to a strong dynamical modulation of the Josephson current. In this article it is found that transitions between pairs of MGS induced by the phase fluctuations are forbidden due to specific symmetry properties of the MGS, and the macroscopic quantum Hamiltonian remains essentially adiabatic within the assumption of a specular interface.