Browsing by Subject "Disorder"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
Item Open Access Cooling quantum gases with entropy localization(Institute of Physics Publishing, 2017) Ünal, F. Nur; Mueller, Erich J.We study the dynamics of entropy in a time dependent potential and explore how disorder influences this entropy flow. We show that disorder can trap entropy at the edge of the atomic cloud enabling a novel cooling method. We demonstrate the feasibility of our cooling technique by analyzing the evolution of entropy in a one-dimensional Fermi lattice gas with a time dependent superlattice potential.Item Open Access Effect of disorder on the interacting fermi gases in a one-dimensional optical lattice(World Scientific Publishing Co., 2008) Xianlong, G.; Polini, M.; Tosi, M. P.; Tanatar, BilalInteracting two-component Fermi gases loaded in a one-dimensional (1D) lattice and subjected to a harmonic trapping potential exhibit interesting compound phases in which fluid regions coexist with local Mott-insulator and/or band-insulator regions. Motivated by experiments on cold atoms inside disordered optical lattices, we present a theoretical study of the effects of a correlated random potential on these ground-state phases. We employ a lattice version of density-functional theory within the local-density approximation to determine the density distribution of fermions in these phases. The exchange-correlation potential is obtained from the Lieb-Wu exact solution of Fermi-Hubbard model. On-site disorder (with and without Gaussian correlations) and harmonic trap are treated as external potentials. We find that disorder has two main effects: (i) it destroys the local insulating regions if it is suffciently strong compared with the on-site atom-atom repulsion, and (ii) it induces an anomaly in the inverse compressibility at low density from quenching of percolation. For suffciently large disorder correlation length the enhancement in the inverse compressibility diminishes.Item Open Access Investigating dirty crossover through fidelity suscepribility and density of states(World Scientific Publishing, 2014) Khan, A.; Basu, S.; Tanatar, BilalWe investigate the BCS-BEC crossover in an ultracold atomic gas in the presence of disorder. The disorder is incorporated in the mean-field formalism through Gaussian fluctuations. We observe evolution to an asymmetric line-shape of fidelity susceptibility (FS) as a function of interaction coupling with increasing disorder strength which may point to an impending quantum phase transition (QPT). The asymmetric line-shape is further analyzed using the statistical tools of skewness and kurtosis. We extend our analysis to density of states (DOS) for a better understanding of the crossover in the disordered environment.Item Open Access Metamaterials with negative permeability and negative refractive index: Experiments and simulations(Institute of Physics Publishing Ltd., 2007) Özbay, Ekmel; Guven, K.; Aydin, K.We report the transmission characteristics of split-ring resonator and left-handed metamaterials (LHM) in the microwave frequency regime. A left-handed transmission band is observed at the frequencies where both dielectric permittivity and magnetic permeability are negative. The reflection characteristics of ordered and disordered LHMs are studied. The two-dimensional LHM structure is verified to have a negative refractive index. We employed three different methods to observe negative refraction: the beam shift method, refraction through wedge-shaped negative-index metamaterial, and phase-shift experiments.Item Open Access Plasmons and the drag effect in a strong magnetic field(Elsevier B.V., 2002) Manolescu, A.; Tanatar, BilalWe study the effect of magnetoplasmons on the drag resistance in a strong magnetic field, at finite temperatures. The typical magnetic field is about 1 T, and the temperature is up to 10 K. The Landau levels are broadened by disorder, but well separated in energy. We discuss intra-Landau level magnetoplasmons, with low frequencies, below ωc, and inter-Landau level magnetoplasmons (also called Bernstein modes), with high frequencies, close to multiples of ωc. We compare the temperature dependence of the minima and maxima of the Shubnikov-de Haas oscillations of the transresistance.Item Open Access ‘Profane language, horrid oaths and imprecations’: order and the colonial soundscape in the American mid-Atlantic, 1650–1750(Routledge, 2021-08-04) Johnson, DanielOne of the most important developments in the historical discipline in recent years has been the growth of histories of the senses, and studies of sound and soundscapes have made important contributions to this growing field. The relationship between a perennial early modern concern for social order and ‘noise’ has received relatively little attention, however. This article examines the formation of novel soundscapes between the 1650s and 1740s in the North American middle colonies, the most ethnically and culturally diverse region of the English Atlantic world. Placing special emphasis on the region’s two largest cities, New York and Philadelphia, it argues that the mid-Atlantic’s distinctive soundscapes posed significant problems of order for urban and provincial authorities during a period of elite Anglicization. Sound was more than a way to encourage new norms of politeness; it was a source of contestation between different cultural systems. Speech, music and other sounds were also instrumental in processes of class, ethnic and racial formation.