Wilsonian Renormalization in the 1970s

This paper examines the history of the renormalization group, a cornerstone of contemporary theoretical physics, focusing on the work of Kenneth Wilson (winner of the 1982 Nobel Prize in physics) and affiliated scholars in the 1970s. In particular, it reconstructs how studies of the renormalization group led to formative interactions between two distinct branches of physics, namely particle physics and condensed matter theory. Instead of explaining such intellectual coordination as the result of material and conceptual exchanges, as in Peter Galison’s widely influential discussion of the “trading zone,” my analysis emphasizes the pedagogical labor, social institutions, and political economic conditions that gave the renormalization group its mediating power. To that end, I show how early lectures and fast circulating pre-prints on the renormalization group created a population of physicists in the United States conversant in the rudiments of both condensed matter and particle theory. I then root the formation of a transatlantic network of renormalization group enthusiasts in the geopolitics of the Cold War, showing that the spread of Wilsonian ideas was made possible by a liberal internationalist program of academic exchanges and summer schools sponsored by the US state department and NATO. Finally, I argue that sharp cuts to basic science funding in the United States pushed young physicists seeking jobs in the 1970s to work across specializations, which visibly impacted how renormalization group ideas were interpreted and used—often against the objections of their original progenitors.

Establishing gold and platinum standards to 1 terapascal using shockless compression

New techniques are advancing the frontier of high-pressure physics beyond 1 terapascal, leading to new discoveries and offering stringent tests for condensed-matter theory and advanced numerical methods. However, the ability to absolutely determine the pressure state remains challenging, and well-calibrated pressure-density reference materials are required. We conducted shockless dynamic compression experiments at the National Ignition Facility and the Z machine to obtain quasi-absolute, high-precision, pressure-density equation-of-state data for gold and platinum. We derived two experimentally constrained pressure standards to terapascal conditions. Establishing accurate experimental determinations of extreme pressure will facilitate better connections between experiments and theory, paving the way toward improving our understanding of material response to these extreme conditions.

An introduction to kinks in $\varphi^4$-theory

As a low-energy effective model emerging in disparate fields throughout all of physics, the ubiquitous \varphi^4φ4-theory is one of the central models of modern theoretical physics. Its topological defects, or kinks, describe stable, particle-like excitations that play a central role in processes ranging from cosmology to particle physics and condensed matter theory. In these lecture notes, we introduce the description of kinks in \varphi^4φ4-theory and the various physical processes that govern their dynamics. The notes are aimed at advanced undergraduate students, and emphasis is placed on stimulating qualitative insight into the rich phenomenology encountered in kink dynamics. The appendices contain more detailed derivations, and allow enquiring students to also obtain a quantitative understanding. Topics covered include the topological classification of stable solutions, kink collisions, the formation of bions, resonant scattering of kinks, and kink-impurity interactions.

Correlations between Complexity and Entanglement in a One-Dimensional XY Model

Many people believe that the study of complex quantum systems may be simplified by first analyzing the static and dynamic entanglement present in those systems [Phys. Rev. A 66 (2002) 032110]. In this paper, we attempt to complement such notion by adding an order–disorder quantifier called statistical complexity and studying how it is correlated with the degree of entanglement as measured by the concurrence quantifier. We perform such an analysis with reference to a representative system chosen from condensed matter theory, the so-called X Y model. Some interesting insight is obtained as the concurrence and the complexity become correlated in an unexpected fashion.

ORDER, DISORDER AND PHASE TRANSITIONS IN QUANTUM MANY BODY SYSTEMS

In this paper, I give an overview of some selected results in quantum many body theory, lying at the interface between mathematical quantum statistical mechanics and condensed matter theory. In particular, I discuss some recent results on the universality of transport coecients in lattice models of interacting electrons, with specic focus on the in- dependence of the quantum Hall conductivity from the electron-electron interaction. In this context, the exchange of ideas between mathematical and theoretical physics proved particu- larly fruitful, and helped in clarifying the role played by quantum conservation laws (Ward Identities), together with the decay properties of the Euclidean current-current correlation functions, on the interaction-independence of the conductivity.

Fracton phases of matter

Fractons are a new type of quasiparticle which are immobile in isolation, but can often move by forming bound states. Fractons are found in a variety of physical settings, such as spin liquids and elasticity theory, and exhibit unusual phenomenology, such as gravitational physics and localization. The past several years have seen a surge of interest in these exotic particles, which have come to the forefront of modern condensed matter theory. In this review, we provide a broad treatment of fractons, ranging from pedagogical introductory material to discussions of recent advances in the field. We begin by demonstrating how the fracton phenomenon naturally arises as a consequence of higher moment conservation laws, often accompanied by the emergence of tensor gauge theories. We then provide a survey of fracton phases in spin models, along with the various tools used to characterize them, such as the foliation framework. We discuss in detail the manifestation of fracton physics in elasticity theory, as well as the connections of fractons with localization and gravitation. Finally, we provide an overview of some recently proposed platforms for fracton physics, such as Majorana islands and hole-doped antiferromagnets. We conclude with some open questions and an outlook on the field.

On gauging finite subgroups

We study in general spacetime dimension the symmetry of the theory obtained by gauging a non-anomalous finite normal Abelian subgroup AA of a \GammaΓ-symmetric theory. Depending on how anomalous \GammaΓ is, we find that the symmetry of the gauged theory can be i) a direct product of G=\Gamma/AG=Γ/A and a higher-form symmetry \hat AÂ with a mixed anomaly, where \hat AÂ is the Pontryagin dual of AA; ii) an extension of the ordinary symmetry group GG by the higher-form symmetry \hat AÂ; iii) or even more esoteric types of symmetries which are no longer groups. We also discuss the relations to the effect called the H^3(G,\hat A)H3(G,Â) symmetry localization obstruction in the condensed-matter theory and to some of the constructions in the works of Kapustin-Thorngren and Wang-Wen-Witten.

On the Single Wall Carbon Nanotube Surface Plasmon Stability

The physics of surface plasmons has a long tradition in condensed matter theory but as the dimension of the systems reaches the nano scale, new effects appear. In this work, by calculating the absorption spectra of a single wall carbon nanotube, using time dependent density functional theory, the effect of adding/removing electrons on the surface plasmon energy is studied. It is shown that removing electrons from the single wall carbon nanotube does not affect the surface plasmon energy peak. In contrast, adding electrons to the single wall carbon nanotube will redshift the plasmonic peak energy, an effect that is explained by an increase of the electron effective mass.