Ionizing radiation may hinder popular qubit technology

Superconducting circuits are the qubits of choice for Google, IBM, and multiple other companies and institutions developing quantum computers. The qubits in the latest devices can sustain their delicate quantum states for more than 100 µs at a time; that longevity enables advances such as modeling chemical reactions. But extending qubit coherence times by orders of magnitude may prove challenging. Antti Vepsäläinen and William Oliver from MIT and colleagues have now investigated one potential threat: environmental radiation from sources such as cosmic rays, which is suspected to trigger decoherence by breaking some of the superconducting material’s Cooper pairs of electrons.