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On the nature of decoherence in quantum circuits: Revealing the structural motif of the surface radicals in α-Al(2)O(3)

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 qu...

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Detalles Bibliográficos
Autores principales: Un, Sun, de Graaf, Sebastian, Bertet, Patrice, Kubatkin, Sergey, Danilov, Andrey
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Association for the Advancement of Science 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8985919/
https://www.ncbi.nlm.nih.gov/pubmed/35385297
http://dx.doi.org/10.1126/sciadv.abm6169
Descripción
Sumario: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-Al(2)O(3), a common substrate for quantum devices. In its amorphous form, α-Al(2)O(3) 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.