Apr 24 – 30, 2022
Ettore Majorana Foundation and Centre for Scientific Culture
Europe/Rome timezone

Session

A. Ustinov

Apr 28, 2022, 8:30 AM
Ettore Majorana Foundation and Centre for Scientific Culture

Ettore Majorana Foundation and Centre for Scientific Culture

Via Gian Filippo Guarnotti, 26, 91016 Erice TP (Italy)

Description

Abstract:
Material defects are currently recognized to be the main source of decoherence in superconducting
circuits employed for modern quantum computers. In structurally disordered solids, atoms or groups of
atoms are able to quantum mechanically tunnel between two nearly equivalent sites. These atomic
tunnelling systems have been previously identified as the cause of various low-temperature anomalies of
bulk glasses and as a source of decoherence of quantum circuits where they are sparsely present in the
disordered oxide barriers and on the surfaces of superconducting thin films. A tiny mechanical
deformation of the oxide barrier changes the energies of the atomic tunnelling systems. These changes
can be extracted from the microwave spectra of superconducting qubits and resonators. Tuning the
properties of individual defects by applying mechanical strain and/or external electrical fields allow to
study spectral properties, intrinsic relaxation and dephasing times, and detect mutual interactions between
defects. Progress towards reliable large-scale quantum processors requires prevention of defects by
improvements in device fabrication. On the other hand, quantum circuits also provide a novel and
effective method for studying the physics of defects and origins of noise which limit their operation.

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