Amy Cassidy

Generalized thermalization in an integrable lattice system.

After a quench, observables in an integrable system may not relax to the standard thermal values, but can relax to the ones predicted by the generalized Gibbs ensemble (GGE) [M. Rigol et al., Phys. Rev. Lett. 98, 050405 (2007)]. The GGE has been shown to accurately describe observables in various one-dimensional integrable systems, but the origin of its success is not fully understood. Here we introduce a microcanonical version of the GGE and provide a justification of the GGE based on a generalized interpretation of the eigenstate thermalization hypothesis, which was previously introduced to explain thermalization of nonintegrable systems. We study relaxation after a quench of one-dimensional hard-core bosons in an optical lattice. Exact numerical calculations for up to 10 particles on 50 lattice sites (≈10(10) eigenstates) validate our approach.

Formation of collective excitations in quasi-one-dimensional metallic nanostructures: Size and density dependence

We investigate theoretically the formation of collective excitations in atomic scale quasi-one dimensional metallic nanostructures. The response of the system is calculated within the linear response theory and random phase approximation. For uniform nanostructures a transition from quantum single particle excitations to classical plasmon scaling is observed, depending on the system length and electron density. We find crucial differences in the scaling behavior for quasi-one dimensional and three-dimensional nanostructures. The presence of an additional modulating on-site potential is shown to localize electrons, leading to the response function that is highly sensitive to the number of electrons at low fillings.

Threshold for Chaos and Thermalization in the One-Dimensional Mean-Field Bose-Hubbard Model

We study the threshold for chaos and its relation to thermalization in the 1D mean-field Bose-Hubbard model, which, in particular, describes atoms in optical lattices. We identify the threshold for chaos, which is finite in the thermodynamic limit, and show that it is indeed a precursor of thermalization. Far above the threshold, the state of the system after relaxation is governed by the usual laws of statistical mechanics.

Conference for Undergraduate Women in Physics: For Students, by Students (abstract)

In January 2006 the first Conference for Undergraduate Women in Physics (CUWP) was organized by students at the University of Southern California. The conference has become an annual event at the university and has expanded to conferences in the Midwest at the University of Michigan and to the East Coast at Yale University. Over 250 undergraduates have attended the CUWP since its inception. We look at the impact of the conferences from survey results taken before and after conference participation. Additionally we discuss the history of the CUWP, how it has evolved, and how it has shaped and been shaped by the institutional climates. We present the future goals and plans for assessing and evaluating the effectiveness of the CUWP.

Successful Proposals, Fund Raising, and Project Leadership

A brief description of the Fundraising, Grant Writing, and Project Leadership workshop at the Third IUPAP International Conference of Women in Physics is presented. The workshop’s purpose was to assist delegates in developing skills in successful proposal writing, fund raising, and project leadership. Handouts and talks were given with information on funding sources in different regions. Talks on grant writing and leadership by Beverly Hartline and J. Grace Lin led to active participation and brainstorming discussions. Based on the discussions a list of recommendations is outlined in this paper. This information is also available at the IUPAP Working Group of Women in Physics website (http://wgwip.df.uba.ar).