Theoretical study of interacting electrons in one dimension - ground states and experimental signatures

This dissertation focuses on a theoretical study of interacting electrons in one dimension. The research elucidates the ground state (zero temperature) electronic phase diagram of an aluminum arsenide quantum wire which is an example of an interacting one dimensional electron liquid. Using one dimensional field theoretic methods involving abelian bosonization and the renormalization group we show the existence of a spin gapped quantum wire with electronic ground states such as charge density wave and singlet superconductivity. The superconducting state arises due to the unique umklapp interaction present in the aluminum arsenide quantum wire bandstructure discussed in this dissertation. It is characterized by Cooper pairs carrying a finite pairing momentum. This is a realization of the Fulde-Ferrell-Larkin- Ovchinnikov state which is known to lead to inhomogeneous superconductivity. The dissertation also presents a theoretical analysis of the finite temperature single hole spectral function of the one dimensional electron liquid with gapless spin and charge modes (Luttinger liquid). The hole spectral function is measured in angle resolved photoemission spectroscopy experiments. The results predict a kink in the effective electronic dispersion of the Luttinger liquid. A systematic study of the temperature and interaction dependence of the kink provides an alternative way to detect spincharge separation in one dimensional systems where the peak due to the spin part of the spectral function is suppressed.Comment: Dissertation, Purdue University (2007

Relative entropy in higher spin holography

We examine relative entropy in the context of the higher-spin/CFT duality. We consider 3$d$ bulk configurations in higher spin gravity which are dual to the vacuum and a high temperature state of a CFT with $\mathcal{W}$-algebra symmetries in presence of a chemical potential for a higher spin current. The relative entropy between these states is then evaluated using the Wilson line functional for holographic entanglement entropy. In the limit of small entangling intervals, the relative entropy should vanish for a generic quantum system. We confirm this behaviour by showing that the difference in the expectation values of the modular Hamiltonian between the states matches with the difference in the entanglement entropy in the short-distance regime. Additionally, we compute the relative entropy of states corresponding to smooth solutions in the $SL(2,\mathbb{Z})$ family with respect to the vacuum.Comment: 29 pages. Published version. All relative entropies are calculated with respect to the vacuu

Places of everyday cosmopolitanisms: East-European construction workers in London

This paper illustrates how cosmopolitanisms among East-European construction workers in London are shaped by the localised spatial contexts in which encounters with difference take place. Their cosmopolitan attitudes and behaviours arise from both survival strategies and from a taste for cultural goods, thus challenging the elite/working-class divide in current cosmopolitanism literature. Through semi-structured interviews and participant photographs of 24 East-European construction workers who have arrived in London since the European Union expansion in May 2004, this paper illustrates how these ‘new’ European citizens, develop varying degrees and multitudes of cosmopolitanisms in everyday places such as building sites and shared houses. These cosmopolitanisms are shaped by their transnational histories, nationalistic sentiments, and access to social and cultural capital in specific localised contexts. Thus subjective perceptions of gendered, ethnic, and racial notions of ‘others’ that are carried across national boundaries are reinforced or challenged as their encounters with ‘others’ produce perceptions of marginalisation or empowerment in these places. This paper finally suggests that cosmopolitanism should be understood not simply through class but rather through access to power and capital in everyday localised contexts

Minimal Triangulations of Manifolds

In this survey article, we are interested on minimal triangulations of closed pl manifolds. We present a brief survey on the works done in last 25 years on the following: (i) Finding the minimal number of vertices required to triangulate a given pl manifold. (ii) Given positive integers $n$ and $d$, construction of $n$-vertex triangulations of different $d$-dimensional pl manifolds. (iii) Classifications of all the triangulations of a given pl manifold with same number of vertices. In Section 1, we have given all the definitions which are required for the remaining part of this article. In Section 2, we have presented a very brief history of triangulations of manifolds. In Section 3, we have presented examples of several vertex-minimal triangulations. In Section 4, we have presented some interesting results on triangulations of manifolds. In particular, we have stated the Lower Bound Theorem and the Upper Bound Theorem. In Section 5, we have stated several results on minimal triangulations without proofs. Proofs are available in the references mentioned there.Comment: Survey article, 29 page