On the nature of decoherence in quantum circuits: Revealing the structural motif of the surface radicals in α-Al2O3
Journal article, 2022

Quantum information technology puts stringent demands on the quality of materials and interfaces in the pursuit of increased device coherence. Yet, little is known about the chemical structure and origins of paramagnetic impurities that produce flux/charge noise that causes decoherence of fragile quantum states and impedes the progress toward large-scale quantum computing. Here, we perform high magnetic field electron paramagnetic resonance (HFEPR) and hyperfine multispin spectroscopy on α-Al2O3, a common substrate for quantum devices. In its amorphous form, α-Al2O3 is also unavoidably present in aluminum-based superconducting circuits and qubits. The detected paramagnetic centers are immanent to the surface and have a well-defined but highly complex structure that extends over multiple hydrogen, aluminum, and oxygen atoms. Modeling reveals that the radicals likely originate from well-known reactive oxygen chemistry common to many metal oxides. We discuss how EPR spectroscopy might benefit the search for surface passivation and decoherence mitigation strategies.


Sun Un

University Paris-Saclay

Sebastian Erik de Graaf

National Physical Laboratory (NPL)

Patrice Bertet

Service de Physique de l'Etat Condensé

Sergey Kubatkin

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Andrey Danilov

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Science advances

2375-2548 (eISSN)

Vol. 8 14 eabm6169-

Subject Categories

Inorganic Chemistry

Other Physics Topics

Condensed Matter Physics





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