Tomographic Signatures of Interacting Majorana and Andreev States in Superconductor-Semiconductor Transmon Qubits

TL;DR

This paper explores how tomographic reconstruction of charge distributions in superconductor-semiconductor Josephson junctions can identify complex many-body states, including topological and interacting Andreev states, and analyze their entanglement properties.

Contribution

It introduces a method to distinguish topological and interacting states via charge distribution signatures and applies information theory metrics to classify junction excitations.

Findings

Distinct charge distribution signatures for different states

Access to entanglement metrics between superconductor and microscopic degrees

Potential to identify topological states in superconducting qubits

Abstract

Semiconductor-based Josephson junctions embedded within a Cooper-pair-box can host complex many-body states, such as interacting Andreev states and potentially other quasi-particles of topological origin. Here, we study the insights that could be revealed from a tomographic reconstruction of the Cooper-pair charge distribution of the junction prepared in its ground state. We posit that interacting and topological states can be identified from distinct signatures within the probability distribution of the charge states. Furthermore, the comprehensive dataset provides direct access to information theory metrics elucidating the entanglement between the charge sector of the superconductor and the microscopic degrees of freedom in the junction. We demonstrate how these metrics serve to further classify differences between the types of excitations in the junction.