Nuclear Quadrupole Moments as a Microscopic Probe to Study the Motion of Atomic Tunneling Systems in Amorphous Solids

Bartkowiak, M.; Bazrafshan, M.; Fischer, C. E.; Fleischmann, A.; Enss, C.

doi:10.1103/physrevlett.110.205502

Cited by 12 publications

(13 citation statements)

References 24 publications

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“…3 presenting the frequency standard deviation σ f : it grows as we cool. This resembles what has been reported on superconducting cavities, and attributed to TLSs present in the constitutive materials 48 ; here, it would be the TLSsgenerating frequency shifts from strain-coupling 37,38,51 . Details on the statistical analysis can be consulted in Supplementary Note 3.…”

Section: Resultssupporting

confidence: 84%

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A macroscopic object passively cooled into its quantum ground state of motion beyond single-mode cooling

et al. 2021

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The nature of the quantum-to-classical crossover remains one of the most challenging open question of Science to date. In this respect, moving objects play a specific role. Pioneering experiments over the last few years have begun exploring quantum behaviour of micron-sized mechanical systems, either by passively cooling single GHz modes, or by adapting laser cooling techniques developed in atomic physics to cool specific low-frequency modes far below the temperature of their surroundings. Here instead we describe a very different approach, passive cooling of a whole micromechanical system down to 500 μK, reducing the average number of quanta in the fundamental vibrational mode at 15 MHz to just 0.3 (with even lower values expected for higher harmonics); the challenge being to be still able to detect the motion without disturbing the system noticeably. With such an approach higher harmonics and the surrounding environment are also cooled, leading to potentially much longer mechanical coherence times, and enabling experiments questioning mechanical wave-function collapse, potentially from the gravitational background, and quantum thermodynamics. Beyond the average behaviour, here we also report on the fluctuations of the fundamental vibrational mode of the device in-equilibrium with the cryostat. These reveal a surprisingly complex interplay with the local environment and allow characteristics of two distinct thermodynamic baths to be probed.

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Section: Resultssupporting

confidence: 84%

“…16,56 ). The unexpected properties of the fluctuations reported here call for theoretical input on both thermodynamics and the constitutive matter 37,43,51,57 . As for superconducting mesoscopic electronic devices 49 , TLS are certainly the key to the understanding of the complex microscopic environment interacting with the mechanical mode.…”

Section: Discussionmentioning

confidence: 74%

A macroscopic object passively cooled into its quantum ground state of motion beyond single-mode cooling

et al. 2021

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“…3 presenting the frequency standard deviation σ f : it grows as we cool. This resembles what has been reported on superconducting cavities, and attributed to TLSs present in the constitutive materials [52]; here, it would be the TLSs generating frequency shifts from strain-coupling [42,43,55]. Details on the statistical analysis can be consulted in Supplementary Information.…”

supporting

confidence: 71%

A macroscopic object passively cooled into its quantum ground state of motion: beyond single-mode cooling

Cattiaux,

Golokolenov,

Kumar

et al. 2021

Preprint

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“…Although from a qualitative point of view this picture is certainly reasonable and appealing, in practice one has to see whether in a real glass-forming system such DWPs with the right characteristics are indeed present. Through experiments, it is very difficult to obtain microscopic information about the properties of the TSs since they do not give direct access to the relevant information (distribution of barrier heights, asymmetry, nature of the motion of the participating particles, and so on (but see the attempts in [64,65])). Thus at present the only promising approach to make progress in this field are atomistic computer simulations.…”

Section: Bas Glassmentioning

confidence: 99%

Realistic tunnelling states for the magnetic effects in non-metallic real glasses

Jug

Bonfanti

Kob

2015

Philosophical Magazine

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The discovery of magnetic and compositional effects in the low temperature properties of multicomponent glasses has prompted the need to extend the standard two-level systems (2LSs) tunneling model. A possible extension [1] assumes that a subset of tunneling quasi-particles is moving in a threewelled potential (TWP) associated with the ubiquitous inhomogeneities of the disordered atomic structure of the glass. We show that within an alternative, cellular description of the intermediate-range atomic structure of glasses the tunneling TWP can be fully justified. We then review how the experimentally discovered magnetic effects can be explained within the approach where only localized atomistic tunneling 2LSs and quasi-particles tunneling in TWPs are allowed. We discuss the origin of the magnetic effects in the heat capacity, dielectric constant (real and imaginaryi parts), polarization echo and SQUID magnetization in several glassy systems. We conclude by commenting on a strategy to reveal the mentioned tunneling states (2LSs and TWPs) by means of atomistic computer simulations and discuss the microscopic nature of the tunneling states in the context of the potential energy landscape of glass-forming systems.arXiv:1508.02424v1 [cond-mat.dis-nn] 10 Aug 2015 1 IntroductionThe physics of glasses, especially at low temperatures, continues to attract considerable interest. At low temperatures glasses are believed to be characterized by low-energy excitations going under the name of tunneling systems, or states (TSs) which are normally described in terms of double-welled potentials (DWPs) and two-level systems (2LSs) with energy asymmetry and tunneling barrier uniformly distributed in the amorphous solid [2,3]. Little is still known about the nature of the TSs, but the general consensus is still that the intermediate-range atomic structure of glasses is well described by Zachariasen's 1932 continuous random network model [4,5] (thus, homogeneously disordered like for a liquid) and the 2LSs arise out of two slightly similar, localized atomic configurations. With this characterization the 2LSs have been employed in the 1970s and 80s to explain with some success the anomalies in the properties of glasses at low temperatures. Recently, the field has been witnessing a renaissance since the discovery that there are unexpected magnetic effects in insulating glasses [6,7,8,9] and that the TSs are responsible for the decoherence of phase qubits made of superconducting Josephson-junctions [10,11,12,13,14]. The 2LSs are thought to be ubiquitous in the junction's tunneling barrier which, though very thin, is considered to be amorphous and described by Zachariasen-Warren's model [4,5]. On the other hand, the low-temperature glasses have also been studied as a paradigm where to conduct research on the physics of aging so common to many disordered systems out of equilibrium [15,16]. In this context, the relevant degrees of freedom have also been described in terms of 2LSs, with some success [17]. Yet, deviations from the behaviour pred...

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Nuclear Quadrupole Moments as a Microscopic Probe to Study the Motion of Atomic Tunneling Systems in Amorphous Solids

Cited by 12 publications

References 24 publications

A macroscopic object passively cooled into its quantum ground state of motion beyond single-mode cooling

A macroscopic object passively cooled into its quantum ground state of motion beyond single-mode cooling

A macroscopic object passively cooled into its quantum ground state of motion: beyond single-mode cooling

Realistic tunnelling states for the magnetic effects in non-metallic real glasses

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