Strain designed Josephson $\pi$ junction qubits with topological insulators

TL;DR

This paper proposes a novel Josephson qubit design using strain-tuned topological insulators, enabling easy control and potential for quantum computing applications.

Contribution

It introduces a new method to create and control Josephson $\pi$ junction qubits through strain engineering on topological insulators.

Findings

Strain shifts the Dirac point without disrupting surface states.

Tunable strain can induce a $\pi$ junction in the device.

The paper derives conditions for qubit design and estimates operation time.

Abstract

A Josephson qubit is designed via the application of a tensile strain to a topological insulator surface sandwiched between two s-wave superconductors. The strain applied leads to a shift in the Dirac point without changing the pre-existing conducting states, on the surface of a topological insulator. Strain applied can be tuned to form a $\pi$ junction in such a structure. Combining two such junctions in a ring architecture leads to the ground state of the ring being in doubly degenerate state- the "0" and "1" states of a qubit. A qubit designed this way is quite easily controlled via the tunable strain applied. We report on the conditions necessary to design such a qubit. Finally the operating time of a single qubit phase gate is derived.