Evidence for temperature-dependent spin diffusion as a mechanism of intrinsic flux noise in SQUIDs

Lanting, T.; Amin, M. H. S.; Berkley, A. J.; Rich, Chris; Chen, S.-F.; LaForest, S.; Sousa, Rogério de

doi:10.1103/physrevb.89.014503

Cited by 27 publications

(36 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Recent theory and experiment 25 provided evidence that low temperature/low frequency SQUID flux noise can be explained by a spin diffusion model, with spin diffusion constant measured to be of the order of 10 µm 2 /s.…”

Section: -24mentioning

confidence: 99%

“…31 More recently, extensive numerical studies 25,32 showed that these calculations greatly underestimated the value of the flux produced by spins located at the wire surfaces, because they did not take account of the singular nature of the spin's dipole field. Indeed, analytic expressions for the flux noise power that take into account the spin's singular behaviour are still absent from the literature.…”

Section: -24mentioning

confidence: 99%

“…(3) Any mechanism that couples the spins to the lattice 16 or to themselves 17,25,29 leads to finite frequency noise. However, evaluating Eq.…”

Section: A General Casementioning

confidence: 99%

“…The article is organized as follows: Section II introduces our flux-vector model, and develops a general theory on how flux noise depends on flux vector and the 7,25 and expected location of the spin species causing flux noise. The superconducting wire is made of niobium, the insulator of partially oxidized aluminum (likely amorphous), and the substrate of silicon-dioxide.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Flux-vector model of spin noise in superconducting circuits: Electron versus nuclear spins and role of phase transition

LaForest

Sousa

2015

Phys. Rev. B

Self Cite

View full text Add to dashboard Cite

Superconducting Quantum Interference Devices (SQUIDs) and other superconducting circuits are limited by intrinsic flux noise with spectral density 1/f α with α < 1 whose origin is believed to be due to spin impurities. Here we present a theory of flux noise that takes into account the vectorial nature of the coupling of spins to superconducting wires. We present explicit numerical calculations of the flux noise power (spectral density integrated over all frequencies) for electron impurities and lattice nuclear spins under several different assumptions. The noise power is shown to be dominated by surface electron spins near the wire edges, with bulk lattice nuclear spins contributing ∼ 5% of the noise power in aluminum and niobium wires. We consider the role of electron spin phase transitions, showing that the spin-spin correlation length (describing e.g. the average size of ferromagnetic spin clusters) greatly impacts the scaling of flux noise with wire geometry. Remarkably, flux noise power is exactly equal to zero when the spins are polarized along the flux vector direction, forming what we call a poloidal state. Flux noise is non-zero for other spin textures, but gets reduced in the presence of correlated ferromagnetic fluctuations between the top and bottom wire surfaces, where the flux vectors are antiparallel. This demonstrates that engineering spin textures and/or intersurface correlation provides a method to reduce flux noise in superconducting devices.

show abstract

Section: -24mentioning

confidence: 99%

Section: -24mentioning

confidence: 99%

“…(3) Any mechanism that couples the spins to the lattice 16 or to themselves 17,25,29 leads to finite frequency noise. However, evaluating Eq.…”

Section: A General Casementioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Flux-vector model of spin noise in superconducting circuits: Electron versus nuclear spins and role of phase transition

LaForest

Sousa

2015

Phys. Rev. B

Self Cite

View full text Add to dashboard Cite

show abstract

“…(38) and Table I in Conclusion. For fixed specific inductance and capacitance, these correlators are not proportional to the TL's area; typically, the external-noise effect increases faster than mechanisms [12,13,16] caused by the RKKY interaction between near-interface spins via the superconductor and proportional to the length of the TL. Bacause of this key difference, even weak external noises may give a dominant contribution in long TLs.…”

Section: Introductionmentioning

confidence: 99%

Flux Noise in a Superconducting Transmission Line

Vasko¹

2017

Phys. Rev. Applied

View full text Add to dashboard Cite

We study a superconducting transmission line (TL) formed by distributed LC oscillators and excited by external magnetic fluxes which are aroused from random magnetization (A) placed in substrate or (B) distributed at interfaces of a two-wire TL. Low-frequency dynamics of a random magnetic field is described based on the diffusion Langevin equation with a short-range source caused by (a) random amplitude or (b) gradient of magnetization. For a TL modeled as a two-port network with open and shorted ends, the effective magnetic flux at the open end has non-local dependency on noise distribution along the TL. The flux-flux correlation function is evaluated and analyzed for the regimes (Aa), (Ab). (Ba), and (Bb). Essential frequency dispersion takes place around the inverse diffusion time of random flux along the TL. Typically, noise effect increases with size faster than the area of TL. The flux-flux correlator can be verified both via the population relaxation rate of the qubit, which is formed by the Josephson junction shunted by the TL with flux noises, and via random voltage at the open end of the TL.

show abstract

A NASA perspective on quantum computing: Opportunities and challenges

et al. 2017

View full text Add to dashboard Cite

In the last couple of decades, the world has seen several stunning instances of quantum algorithms that provably outperform the best classical algorithms.For most problems, however, it is currently unknown whether quantum algorithms can provide an advantage, and if so by how much, or how to design quantum algorithms that realize such advantages. Many of the most challenging computational problems arising in the practical world are tackled today by heuristic algorithms that have not been mathematically proven to outperform other approaches but have been shown to be effective empirically. While quantum heuristic algorithms have been proposed, empirical testing becomes possible only as quantum computation hardware is built. The next few years will be exciting as empirical testing of quantum heuristic algorithms becomes more and more feasible. While large-scale universal quantum computers are likely decades away, special-purpose quantum computational hardware has begun to emerge that will become more powerful over time, as well as some small-scale universal quantum computers. * Rupak Biswas

show abstract

Evidence for temperature-dependent spin diffusion as a mechanism of intrinsic flux noise in SQUIDs

Cited by 27 publications

References 23 publications

Flux-vector model of spin noise in superconducting circuits: Electron versus nuclear spins and role of phase transition

Flux-vector model of spin noise in superconducting circuits: Electron versus nuclear spins and role of phase transition

Flux Noise in a Superconducting Transmission Line

A NASA perspective on quantum computing: Opportunities and challenges

Contact Info

Product

Resources

About