The Experts below are selected from a list of 76137 Experts worldwide ranked by ideXlab platform
Zhao Liu - One of the best experts on this subject based on the ideXlab platform.
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quantum entanglement as a diagnostic of phase Transitions in disordered fractional quantum hall liquids
Physical Review Letters, 2016Co-Authors: Zhao Liu, R N BhattAbstract:We investigate the disorder-driven phase Transition from a fractional quantum Hall state to an Anderson insulator using quantum entanglement methods. We find that the Transition is Signaled by a sharp increase in the sensitivity of a suitably averaged entanglement entropy with respect to disorder-the magnitude of its disorder derivative appears to diverge in the thermodynamic limit. We also study the level statistics of the entanglement spectrum as a function of disorder. However, unlike the dramatic phase-Transition Signal in the entanglement entropy derivative, we find a gradual reduction of level repulsion only deep in the Anderson insulating phase.
R N Bhatt - One of the best experts on this subject based on the ideXlab platform.
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quantum entanglement as a diagnostic of phase Transitions in disordered fractional quantum hall liquids
Physical Review Letters, 2016Co-Authors: Zhao Liu, R N BhattAbstract:We investigate the disorder-driven phase Transition from a fractional quantum Hall state to an Anderson insulator using quantum entanglement methods. We find that the Transition is Signaled by a sharp increase in the sensitivity of a suitably averaged entanglement entropy with respect to disorder-the magnitude of its disorder derivative appears to diverge in the thermodynamic limit. We also study the level statistics of the entanglement spectrum as a function of disorder. However, unlike the dramatic phase-Transition Signal in the entanglement entropy derivative, we find a gradual reduction of level repulsion only deep in the Anderson insulating phase.
P K Madhu - One of the best experts on this subject based on the ideXlab platform.
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enhancement of the central Transition Signal in static and magic angle spinning nmr of quadrupolar nuclei by frequency swept fast amplitude modulated pulses
Chemical Physics Letters, 2004Co-Authors: Thomas Brauniger, Kannan Ramaswamy, P K MadhuAbstract:Abstract We here report on using fast amplitude-modulated (FAM) pulse trains with constantly incremented pulse durations (SW-FAM) for Signal enhancement in one-dimensional nuclear magnetic resonance spectra of quadrupolar nuclei with half-integer spin. In such systems, a FAM pulse train leads to a redistribution of populations across the spin levels, which results in a substantial gain for the central-Transition Signal. Compared to fixed-duration FAM pulse trains, SW-FAM delivers about the same Signal enhancement for spinning samples, but gives much better performance in the static case. This is demonstrated for several compounds, observing the nuclei 23 Na ( I =3/2), 27 Al ( I =5/2), and 45 Sc ( I =7/2).
Alexander J Vega - One of the best experts on this subject based on the ideXlab platform.
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mas nmr spin locking of half integer quadrupolar nuclei
Journal of Magnetic Resonance, 1992Co-Authors: Alexander J VegaAbstract:The spin dynamics of single-resonance spin locking of half-integer quadrupolar nuclei under static and magic-angle-spinning conditions is investigated. The MAS spin-locking mechanism of the central-Transition coherence of nuclei with large quadrupolar coupling constants is nontrivial owing to the time dependence of the first-order quadrupole splitting, Q, in rotating samples. The nature of the spin locking is determined by the rate of change of Q at its zero crossings. The passages range from adiabatic to sudden depending on the relative magnitudes of the RF amplitude, the quadrupole frequency, and the rotor frequency. In the intermediate case the spin-lock efficiency is greatly reduced. In the adiabatic limit the central-Transition coherence is demagnetized in the first half of each rotor period and remagnetized at the end of the period, giving rise to an echo-like time dependence of the Signal. Central-Transition Signal can be created by adiabatic magnetization in an MAS spinlock experiment without a preparatory excitation pulse. A qualitative theoretical description is given for spin 32. Experimental results are presented for 23Na in NaC103.
Thomas Brauniger - One of the best experts on this subject based on the ideXlab platform.
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enhancement of the central Transition Signal in static and magic angle spinning nmr of quadrupolar nuclei by frequency swept fast amplitude modulated pulses
Chemical Physics Letters, 2004Co-Authors: Thomas Brauniger, Kannan Ramaswamy, P K MadhuAbstract:Abstract We here report on using fast amplitude-modulated (FAM) pulse trains with constantly incremented pulse durations (SW-FAM) for Signal enhancement in one-dimensional nuclear magnetic resonance spectra of quadrupolar nuclei with half-integer spin. In such systems, a FAM pulse train leads to a redistribution of populations across the spin levels, which results in a substantial gain for the central-Transition Signal. Compared to fixed-duration FAM pulse trains, SW-FAM delivers about the same Signal enhancement for spinning samples, but gives much better performance in the static case. This is demonstrated for several compounds, observing the nuclei 23 Na ( I =3/2), 27 Al ( I =5/2), and 45 Sc ( I =7/2).