Candidate source of flux noise in SQUIDs: adsorbed oxygen molecules

Abstract

A major obstacle to using SQUIDs as qubits is flux noise. We propose that the heretofore mysterious spins producing flux noise could be $O_2$ molecules adsorbed on the surface. Using density functional theory calculations, we find that an $O_2$ molecule adsorbed on an α-alumina surface has a magnetic moment of ~1.8 μB. When the spin is oriented perpendicular to the axis of the O-O bond, the barrier to spin rotations is about 10 mK. Monte Carlo simulations of ferromagnetically coupled, anisotropic XY spins on a square lattice find 1/f magnetization noise, consistent with flux noise in Al SQUIDs.

22 pages include main text plus supplemental material

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Cited by in corpus (25)

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• Characterizing and optimizing qubit coherence based on SQUID geometry
• Suppression of 1/f noise in solid state quantum devices by surface spin desorption
• Direct identification of dilute surface spins on Al${}_2$O${}_3$: Origin of flux noise in quantum circuits
• Demonstration of a Parametrically-Activated Entangling Gate Protected from Flux Noise
• Superconducting granular aluminum resonators resilient to magnetic fields up to 1 Tesla
• AC flux sweet spots in parametrically-modulated superconducting qubits
• Possibility of Realizing Quantum Spin Hall Effect at Room Temperature in Stanene/Al2O3(0001)
• Identification of different types of high-frequency defects in superconducting qubits
• Effects of surface treatments on flux tunable transmon qubits
• Hydrogen as a Source of Flux Noise in SQUIDs
• Effect of strain and sulfur vacancies on the luminescence and valley polarization properties of CVD grown monolayer MoS${}_2$ films
• Decoherence induced by a sparse bath of two-level fluctuators: peculiar features of $1/f$ noise in high-quality qubits
• First-principles investigation of the effect of substitution and surface adsorption on magnetostrictive properties of Fe-Ga alloys
• Microscopic theory of supercurrent suppression by gate-controlled surface depairing
• Cosmological flux noise and measured noise power spectra in SQUIDs
• 1/f Flux Noise in low-T${}_c$ SQUIDs due to Superparamagnetic Phase Transitions in Defect Clusters
• Searching for Large-gap Quantum Spin Hall Insulators: Boron-Nitride/(Pb, Sn)/α-Al2O3 Sandwich Structures
• Kubo spins in nano-scale aluminum grains: A muon spin relaxation study
• Loss and decoherence in superconducting circuits on silicon: Insights from electron spin resonance
• Why Superconducting Ta Qubits Have Fewer Tunneling Two-Level Systems at the Air-Oxide Interface Than Nb Qubits
• Quantum theory of an atom in proximity to a superconductor