The Hybrid Topological Longitudinal Transmon Qubit

TL;DR

This paper proposes a hybrid qubit combining Majorana and transmon elements, enabling robust quantum operations and potential error correction by leveraging topological properties and charge interactions.

Contribution

It introduces a novel hybrid qubit design with topological quasiparticles, analyzing charge and phase interactions for improved quantum control and error correction capabilities.

Findings

Majorana self-charging can be eliminated by charge offset adjustment

Effective qubit-qubit interactions are derived analytically and numerically

Interactions depend on superconducting parity, aiding quasiparticle poisoning detection

Abstract

We introduce a new hybrid qubit consisting of a Majorana qubit interacting with a transmon longitudinally coupled to a resonator. To do so, we equip the longitudinal transmon qubit with topological quasiparticles, supported by an array of heterostructure nanowires, and derive charge- and phase-based interactions between the Majorana qubit and the resonator and transmon degrees of freedom. Inspecting the charge coupling, we demonstrate that the Majorana self-charging can be eliminated by a judicious choice of charge offset, thereby maintaining the Majorana degeneracy regardless of the quasiparticles spatial arrangement and parity configuration. We perform analytic and numerical calculations to derive the effective qubit-qubit interaction elements and discuss their potential utility for state readout and quantum error correction. Further, we find that select interactions depend strongly on the overall superconducting parity, which may provide a direct mechanism to characterize deleterious quasiparticle poisoning processes.