Tunneling Systems in Amorphous and Crystalline Solids

Esquinazi, P.

doi:10.1007/978-3-662-03695-2

Cited by 128 publications

(2 citation statements)

References 321 publications

(796 reference statements)

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“…In this equation, Ω 0 is the attempt frequency (assumed to be the same for both wells), d is the spatial distance between the two wells, and m is the mass of the physical entity associated with the TLS (e.g., a molecular mass) [31].…”

Section: A Physical Models Of Tlssmentioning

confidence: 99%

Interacting Defects Generate Stochastic Fluctuations in Superconducting Qubits

Béjanin,

Earnest,

Sharafeldin

et al. 2021

Preprint

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Amorphous dielectric materials have been known to host two-level systems (TLSs) for more than four decades. Recent developments on superconducting resonators and qubits enable detailed studies on the physics of TLSs. In particular, measuring the loss of a device over long time periods (a few days) allows us to investigate stochastic fluctuations due to the interaction between TLSs. We measure the energy relaxation time of a frequency-tunable planar superconducting qubit over time and frequency. The experiments show a variety of stochastic patterns that we are able to explain by means of extensive simulations. The model used in our simulations assumes a qubit interacting with high-frequency TLSs, which, in turn, interact with thermally activated low-frequency TLSs. Our simulations match the experiments and suggest the density of low-frequency TLSs is about three orders of magnitude larger than that of high-frequency ones.

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Section: A Physical Models Of Tlssmentioning

confidence: 99%

Interacting Defects Generate Stochastic Fluctuations in Superconducting Qubits

Béjanin,

Earnest,

Sharafeldin

et al. 2021

Preprint

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“…This condition implies that the minimum relaxation time is achieved by symmetric TLSs (∆ = 0). In dielectric glasses, the main contribution to specific heat and mechanical loss comes from TLSs with energy splitting E = k B T , and their minimum relaxation time is given by [16][17][18] τ min = γ 2 v 5 + 2…”

mentioning

confidence: 99%

Decoupling between propagating acoustic waves and two-level systems in hydrogenated amorphous silicon

Molina-Ruiz,

Jacks,

Queen

et al. 2021

Preprint

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Specific heat measurements of hydrogenated amorphous silicon prepared by hot-wire chemical vapor deposition show a large density of two-level systems at low temperature. Annealing at 200• C, well below the growth temperature, does not significantly affect the already-low internal friction or the sound velocity, but irreversibly reduces the non-Debye specific heat by an order of magnitude at 2 K, indicating a large reduction of the density of two-level systems. Comparison of the specific heat to the internal friction suggests that the two-level systems are uncharacteristically decoupled from acoustic waves, both before and after annealing. Analysis yields an anomalously low value of the coupling constant, which increases upon annealing but still remains anomalously low. The results suggest that the coupling constant value is lowered by the presence of hydrogen.

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Crystal Chemistry and Physical Properties of the Nonmagnetic Kondo Compound HfAs_1.7Se_0.2

et al. 2010

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Single crystals of HfAs(1.7)Se(0.2) are grown by chemical transport reaction and their chemical composition characterized in detail by various analytical methods. Chemical analyses and crystal structure investigations by single-crystal X-ray diffraction as well as powder diffraction with synchrotron radiation reveal a tetragonal PbFCl structure type with strong disorder caused by a significant arsenic deficiency (As(0.9)) on the 2a site and mixed occupancy of the 2c site (As(0.8)Se(0.2)). HfAs(1.7)Se(0.2) is a diamagnetic metal which transforms into a superconducting state at T(c)=0.52 K. Similar to other PbFCl-type arsenide selenides, the title compound displays a magnetic-field-independent -AT(1/2) term in the low-temperature electrical resistivity. This unusual term presumably originates from the electron scattering of structural two-level systems. According to the experimental results, HfAs1.7Se0.2 appears to be a rare example of a nonmagnetic Kondo material.

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Tunneling Systems in Amorphous and Crystalline Solids

Cited by 128 publications

References 321 publications

Interacting Defects Generate Stochastic Fluctuations in Superconducting Qubits

Interacting Defects Generate Stochastic Fluctuations in Superconducting Qubits

Decoupling between propagating acoustic waves and two-level systems in hydrogenated amorphous silicon

Crystal Chemistry and Physical Properties of the Nonmagnetic Kondo Compound HfAs_1.7Se_0.2

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Tunneling Systems in Amorphous and Crystalline Solids

Cited by 128 publications

References 321 publications

Interacting Defects Generate Stochastic Fluctuations in Superconducting Qubits

Interacting Defects Generate Stochastic Fluctuations in Superconducting Qubits

Decoupling between propagating acoustic waves and two-level systems in hydrogenated amorphous silicon

Crystal Chemistry and Physical Properties of the Nonmagnetic Kondo Compound HfAs1.7Se0.2

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Crystal Chemistry and Physical Properties of the Nonmagnetic Kondo Compound HfAs_1.7Se_0.2