scholarly journals Pomeranchuk instabilities in holographic metals

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Gastón Giordano ◽  
Nicolás Grandi ◽  
Adrián Lugo
Keyword(s):  
Chemical Potential ◽  
Coupled System ◽  
Fermion Mass ◽  
Zero Temperature ◽  
Strongly Coupled ◽  
Weakly Coupled ◽  
Weakly Coupled System ◽  
Nematic Phases ◽  
Simply Connected ◽  
Do So

Abstract We develop a method to detect instabilities leading to nematic phases in strongly coupled metallic systems. We do so by adapting the well-known Pomeranchuk technique to a weakly coupled system of fermions in a curved asymptotically AdS bulk. The resulting unstable modes are interpreted as corresponding to instabilities on the dual strongly coupled holographic metal. We apply our technique to a relativistic 3 + 1-dimensional bulk with generic quartic fermionic couplings, and explore the phase diagram at zero temperature for finite values of the fermion mass and chemical potential, varying the couplings. We find a wide region of parameters where the system is stable, which is simply connected and localized around the origin of coupling space.

Entropy for Strongly Coupled Oscillators

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Dante A. Tufano ◽  
Zahra Sotoudeh
Keyword(s):  
Coupled Oscillators ◽  
Weak Coupling ◽  
Correction Term ◽  
Coupled System ◽  
Symmetric System ◽  
Energy Term ◽  
Asymmetric System ◽  
Strongly Coupled ◽  
Weakly Coupled ◽  
Weakly Coupled System

This paper examines an approach for determining the entropy of coupled oscillators that does not rely on the assumption of weak coupling. The results of this approach are compared to the results for a weakly coupled system. It is shown that the results from each methodology agree in the case of weak coupling, and that a correction term is required for moderate to strong coupling. The correction term is shown to be related to the mixed energy term from the coupling spring as well as the geometry and stiffness of the system. Numerical simulations are performed for a symmetric system of identical coupled oscillators and an asymmetric system of nonidentical oscillators to demonstrate these findings.

Entropy for Strongly Coupled Oscillators

2016 ◽  
Author(s):  
Dante A. Tufano ◽  
Zahra Sotoudeh
Keyword(s):  
Coupled Oscillators ◽  
Weak Coupling ◽  
Correction Term ◽  
Coupled System ◽  
Symmetric System ◽  
Energy Term ◽  
Asymmetric System ◽  
Strongly Coupled ◽  
Weakly Coupled ◽  
Weakly Coupled System

This paper examines an approach to determining the entropy of coupled oscillators that does not rely on the assumption of weak coupling. The results of this approach are compared to the results for a weakly coupled system. It is shown that the results from each methodology agree in the case of weak coupling, and that a correction term is required for moderate to strong coupling. The correction term is shown to be related to the mixed energy term from the coupling spring as well as the geometry and stiffness of the system. Numerical simulations are performed for a symmetric system of identical coupled oscillators and an asymmetric system of nonidentical oscillators to demonstrate these findings.

Probing molecular properties and the role of the environment at the single-molecule level

2006 ◽  
Vol 78 (12) ◽  
pp. 2261-2266 ◽  
Author(s):  
J. Hofkens ◽  
T. D. M. Bell ◽  
A. Stefan ◽  
E. Fron ◽  
K. Müllen ◽  
...  
Keyword(s):  
Single Molecule ◽  
Conformational Changes ◽  
Local Environment ◽  
Coupled System ◽  
Strongly Coupled ◽  
Single Molecule Level ◽  
Weakly Coupled ◽  
Weakly Coupled System ◽  
Donor Acceptor ◽  
First Time

Evidence for intramolecular photoinduced electron transfer (ET) in synthetic systems consisting of a triphenylamine-perylenediimide donor-acceptor dendrimer or a triphenylamine-peryleneimide dendrimer at the ensemble and single-molecule (SM) level is presented. Moreover, for the first time a direct observation of the forward as well as the backward ET step is made in a single emitting entity. Fluctuations in the values of the rate constants for forward and backward ET were observed, induced by the local environment as well as by conformational changes of the dendrimer itself. The results obtained in a weakly coupled system can also be extended to a strongly coupled donor-acceptor system based on peryleneimide and penta-phenylene.

Article

1999 ◽  
Vol 77 (11) ◽  
pp. 1810-1812 ◽  
Author(s):  
Alex D Bain
Keyword(s):  
Spin System ◽  
Coupled System ◽  
Coupled Systems ◽  
Physical Reason ◽  
Strongly Coupled ◽  
System Combination ◽  
First Order ◽  
Weakly Coupled ◽  
Quantum Transitions ◽  
Weakly Coupled Systems

Strongly coupled spin systems provide many curious and interesting effects in NMR spectra, one of which is the presence of unexpected (from a first-order viewpoint) lines. A physical reason is given for the presence of these combination lines. The X part of the spectrum of an ABX spin system is analysed as an example. For an ABX system, it is well known that the AB nuclei give a spectrum consisting of two AB-type spectra, corresponding to the two orientations of the X nucleus. It can also be shown that the X part of the spectrum corresponds to the X nucleus undergoing a transition in the presence of an AB-like spin system. For weakly coupled systems, the four observed lines correspond to the four different orientations of the A and B nuclei. For a strongly coupled system, two additional lines may appear, the combination lines. The resulting six lines correspond to the four spin orientations, plus the two zero-quantum transitions. It is shown that these six lines are such that there is no net excitation of the AB-like spin system associated with the X transitions. There is no AB coherence created directly by a pulse applied to X. AB coherence is created as the system evolves, and this is responsible for many of the curious effects. This is shown to be true for all spin sub-systems, which are weakly coupled to a strongly coupled sub-system.Key words: NMR, strong coupling, second-order spectra, ABX spin system, combination lines, spectral analysis.

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