Researchers Extend Qubit Coherence Using Inductive Protection

Adding a linear inductor to an Andreev spin qubit enhances its relaxation time by creating separate potential wells for each spin state, nearly eliminating wavefunction overlap. J. L. del Olmo N. and colleagues Wales, Canberra, have shown that this design, termed the inductively protected Andreev (IPA) qubit, achieves a phase separation up to φIPA ≲2π, combining long coherence with the benefits of a spin degree of freedom. The IPA spin qubit improves upon existing designs by increasing the time quantum information can be stored.

This advancement involves adding an inductor to the qubit’s circuit, creating separate energy levels for each spin state and reducing errors caused by unwanted interactions. This qubit builds upon the Andreev spin qubit, which functions like a tiny switch created from semiconductor and superconducting materials, storing information in the spin of an electron.

A key limitation of current designs is wavefunction overlap; if these states overlap, the qubit becomes uncertain, leading to errors. This new design promises to combine the benefits of long coherence with the advantages of using an electron’s spin, but detailed analysis of its properties is required to fully understand its potential.