Spin-blockade qubit in a superconducting junction

TL;DR

This paper introduces a new superconducting qubit design based on spin blockade in a break junction, enabling coherent control of quasiparticle spin states and proposing a read-out method leveraging spin blockade effects.

Contribution

It presents a novel qubit architecture exploiting quasiparticle spin states and details methods for coherent control and read-out based on spin blockade phenomena.

Findings

Coherent control of four spin states via resonant manipulation

Estimation of Rabi frequencies for quasiparticle spin transitions

Proposed read-out technique based on spin blockade inhibiting recombination

Abstract

We interpret a recent pioneering experiment [Zgirski M. et al., Phys. Rev. Lett., 106 (2011) 257003] on quasiparticle manipulation in a superconducting break junction in terms of spin blockade drawing analogy with spin qubits. We propose a novel qubit design that exploits the spin state of two trapped quasiparticles. We detail the coherent control of all four spin states by resonant quantum manipulation and compute the corresponding Rabi frequencies. The read-out technique is based on the spin-blockade that inhibits quasiparticle recombination in triplet states. We provide extensive microscopic estimations of the parameters of our model.