Macroscopic quantum tunneling and quasiparticle-tunneling blockade effect in s-wave/d-wave hybrid junctions

TL;DR

This paper theoretically studies macroscopic quantum tunneling in s-wave/d-wave hybrid Josephson junctions, revealing suppressed quasiparticle dissipation and potential for quantum information applications.

Contribution

It demonstrates that s-wave/d-wave junctions have weak inherent dissipation due to quasiparticle blockade, making MQT observable and promising for quantum devices.

Findings

Nodal quasiparticles and ZES cause suppressed dissipation in s-wave/d-wave junctions.

MQT is observable in realistic Nb/Au/YBCO junctions with existing technology.

S-wave/d-wave junctions are promising for quantum information applications.

Abstract

We have theoretically investigated macroscopic quantum tunneling (MQT) and the influence of nodal quasiparticles and zero energy bound states (ZES) on MQT in s-wave/ d-wave hybrid Josephson junctions. In contrast to d-wave/d-wave junctions, the low-energy quasiparticle dissipation resulting from nodal quasiparticles and ZES is suppressed due to a quasiparticle-tunneling blockade effect in an isotropic s-wave superconductor. Therefore, the inherent dissipation in these junctions is found to be very weak. We have also investigated MQT in a realistic s-wave/d-wave (Nb/Au/YBCO) junction in which Ohmic dissipation in a shunt resistance is stronger than the inherent dissipation and find that MQT is observable within the current experimental technology. This result suggests high potential of s-wave/d-wave hybrid junctions for applications in quantum information devices.