The stabilization of O2p$minus; on $gamma;-Al2O3

Losee, D. Bruce

doi:10.1016/0021-9517(77)90066-5

Cited by 18 publications

(18 citation statements)

References 9 publications

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“…1) and differences (left cyan arrow) of the frequencies of the two individual nuclear spins. These two-spin frequencies are the same as the ones measured by 27 Al ENDOR and two-spin 1 H ELDOR-NMR. The three-spin spectra at the sum frequencies are shown in Fig.…”

Section: Correlating Multiple Nuclei To the Same R S Centersupporting

confidence: 78%

“…This suggested that the three different centers shared common electronic structural motifs. The B 0 dependence of ENDOR resonances (i.e., the 27 Al ENDOR-detected EPR spectra) of two aluminum atoms, designated Al 5 and Al 12 , was identical to the R s EPR spectrum (Fig. 4, B and C, and fig.…”

Section: The Structure Of R S and Its Localizationmentioning

confidence: 55%

“…After mapping the individual hyperfine interactions and identifying the 1 H and 27 Al nuclei associated with R s , we next turn to understanding whether the detected atoms belong to the same R s radical. Using ELDOR-NMR, we measured the spectra of three-spin transitions that involve the simultaneous flipping of the electron spin of the radical and two nuclear spins, typified by the cyan transitions in Fig.…”

Section: Correlating Multiple Nuclei To the Same R S Centermentioning

confidence: 99%

“…While the precise identity and the origin of these surface spins have so far remained elusive, various experiments ( 13 , 21 ), as well as density functional theory (DFT) calculations ( 13 , 14 ), have identified physisorbed molecular oxygen as one possible candidate for these noise centers. Less appreciated in this context is that many metal oxides forming in superconducting quantum devices are known to catalyze and stabilize products of one-electron reduction reactions of various molecules, such as superoxide (O2•−) ( 22 – 27 ). The densities of these surface sites range from 10 16 to 10 18 m −2 in the various polymorphs of Al 2 O 3 ( 26 , 28 ), comparable to the densities of paramagnetic centers associated with noise in quantum devices.…”

Section: Introductionmentioning

confidence: 99%

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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

Graaf

Bertet

et al. 2022

Sci. Adv.

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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.

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Section: Correlating Multiple Nuclei To the Same R S Centersupporting

confidence: 78%

Section: The Structure Of R S and Its Localizationmentioning

confidence: 55%

Section: Correlating Multiple Nuclei To the Same R S Centermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Graaf

Bertet

et al. 2022

Sci. Adv.

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“…[22] do suggest that neutral oxygen is involved, the signature of a triplet state would have been clearly detected in our measurements. Our observation of a doublet state instead suggests that if oxygen is present it would be in charged molecular form, O − 2 [29]. Indicatively, the observed concentration of free electron spins is very close to the density of Lewis base sites on Al 2 O 3 [19].…”

mentioning

confidence: 57%

Direct Identification of Dilute Surface Spins on Al2O3 : Origin of Flux Noise in Quantum Circuits

et al. 2017

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An on-chip electron spin resonance technique is applied to reveal the nature and origin of surface spins on Al_{2}O_{3}. We measure a spin density of 2.2×10^{17} spins/m^{2}, attributed to physisorbed atomic hydrogen and S=1/2 electron spin states on the surface. This is direct evidence for the nature of spins responsible for flux noise in quantum circuits, which has been an issue of interest for several decades. Our findings open up a new approach to the identification and controlled reduction of paramagnetic sources of noise and decoherence in superconducting quantum devices.

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Influence of O₂ on EPR spectra of SiO₂ surface defects

Tiller

Rudakoff

1979

Cryst Res and Technol

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The stabilization of O2p$minus; on $gamma;-Al2O3

Cited by 18 publications

References 9 publications

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

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

Direct Identification of Dilute Surface Spins on Al2O3 : Origin of Flux Noise in Quantum Circuits

Influence of O₂ on EPR spectra of SiO₂ surface defects

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The stabilization of O2p$minus; on $gamma;-Al2O3

Cited by 18 publications

References 9 publications

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

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

Direct Identification of Dilute Surface Spins on Al2O3 : Origin of Flux Noise in Quantum Circuits

Influence of O2 on EPR spectra of SiO2 surface defects

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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

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

Influence of O₂ on EPR spectra of SiO₂ surface defects