Quasiparticle poisoning rate in a superconducting transmon qubit involving Majorana zero modes

TL;DR

This paper investigates quasiparticle poisoning in a superconducting transmon qubit with Majorana zero modes, revealing how Majorana coupling affects parity and proposing design strategies to suppress poisoning.

Contribution

It provides a theoretical analysis of quasiparticle poisoning mechanisms in Majorana-involving transmon qubits and suggests ways to mitigate poisoning through qubit parameter optimization.

Findings

Majorana coupling causes parity mixing and 4π Josephson effect.

Derived an expression for parity switching rate dependent on qubit parameters.

Reducing E_J/E_C ratio significantly suppresses quasiparticle poisoning.

Abstract

Majorana zero modes have been attracting considerable attention because of their prospective applications in fault-tolerant topological quantum computing. In recent years, some schemes have been proposed to detect and manipulate Majorana zero modes using superconducting qubits. However, manipulating and reading the Majorana zero modes must be kept in the time window of quasiparticle poisoning. In this work, we study the problem of quasiparticle poisoning in a split transmon qubit containing hybrid Josephson junctions involving Majorana zero modes. We show that Majorana coupling will cause parity mixing and 4{\pi} Josephson effect. In addition, we obtained the expression of qubit parameter-dependent parity switching rate and demonstrated that quasiparticle poisoning can be greatly suppressed by reducing E_J/E_C via qubit design.