The finding of bulk quantum oscillations in the Kondo insulator SmB proved a considerable surprise. Subsequent measurements of bulk quantum oscillations in other correlated insulators including YbB lent support to our discovery of a class of bulk unconventional insulators that host bulk quantum oscillations. Here we perform a series of experiments to examine evidence for the intrinsic character of bulk quantum oscillations in floating zone-grown single crystals of SmB that have been the subject of our quantum oscillation studies. We present results of thermodynamic, transport, and composition analysis experiments on pristine floating zone-grown single crystals of SmB and compare quantum oscillations with metallic LaB and elemental aluminum. These results establish the intrinsic origin of quantum oscillations from the insulating bulk of floating zone-grown SmB. The similarity of the Fermi surface in insulating SmB with the conduction-electron Fermi surface in metallic hexaborides is at the heart of a theoretical mystery.
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http://dx.doi.org/10.1016/j.isci.2020.101632 | DOI Listing |
Materials (Basel)
January 2025
CNR-IOM-Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, 34149 Trieste, Italy.
Hybrid systems consisting of highly transparent channels of low-dimensional semiconductors between superconducting elements allow the formation of quantum electronic circuits. Therefore, they are among the novel material platforms that could pave the way for scalable quantum computation. To this aim, InAs two-dimensional electron gases are among the ideal semiconductor systems due to their vanishing Schottky barrier; however, their exploitation is limited by the unavailability of commercial lattice-matched substrates.
View Article and Find Full Text PDFBiology (Basel)
January 2025
School of Instrumentation Science and Optoelectronic Engineering, Beihang University, Beijing 100191, China.
Neural oscillations observed during semantic processing embody the function of brain language processing. Precise parameterization of the differences in these oscillations across various semantics from a time-frequency perspective is pivotal for elucidating the mechanisms of brain language processing. The superlet transform and cluster depth test were used to compute the time-frequency representation of oscillatory difference (ODTFR) between neural activities recorded by optically pumped magnetometer-based magnetoencephalography (OPM-MEG) during processing congruent and incongruent Chinese semantics.
View Article and Find Full Text PDFEntropy (Basel)
January 2025
Chula Intelligent and Complex Systems Lab, Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
Quantum reservoir computing (QRC) has emerged as a promising paradigm for harnessing near-term quantum devices to tackle temporal machine learning tasks. Yet, identifying the mechanisms that underlie enhanced performance remains challenging, particularly in many-body open systems where nonlinear interactions and dissipation intertwine in complex ways. Here, we investigate a minimal model of a driven-dissipative quantum reservoir described by two coupled Kerr-nonlinear oscillators, an experimentally realizable platform that features controllable coupling, intrinsic nonlinearity, and tunable photon loss.
View Article and Find Full Text PDFEntropy (Basel)
January 2025
Department of Physics and Fujian Provincial Key Laboratory of Low Dimensional Condensed Matter Physics, Xiamen University, Xiamen 361005, China.
We show that the theory of quantum statistical mechanics is a special model in the framework of the quantum probability theory developed by mathematicians, by extending the characteristic function in the classical probability theory to the quantum probability theory. As dynamical variables of a quantum system must respect certain commutation relations, we take the group generated by a Lie algebra constructed with these commutation relations as the bridge, so that the classical characteristic function defined in a Euclidean space is transformed to a normalized, non-negative definite function defined in this group. Indeed, on the quantum side, this group-theoretical characteristic function is equivalent to the density matrix; hence, it can be adopted to represent the state of a quantum ensemble.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Two-dimensional (2D) vibrational spectroscopy is a powerful means of investigating the structure and dynamics of complex molecules in condensed phases. However, even in theory, analysis of 2D spectra resulting from complex inter- and intra-molecular motions using only molecular dynamics methods is not easy. This is because molecular motions comprise complex multiple modes and peaks broaden and overlap owing to various relaxation processes and inhomogeneous broadening.
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