Sommerfeld Lecture Series (ASC)

Twentyfirst Arnold Sommerfeld Lecture Series, This talk will present an overview of recent progress towards a solution of one

of the grand-challenges of modern science: understanding the properties of

interacting electrons in molecules and solids. After an introduction to the

physics I will argue our theoretical understanding of a basic model system,

the two dimensional Hubbard model, has reached the level that we can say

with confidence that its superconducting properties capture key aspect of the

high-Tc superconductivity in copper-oxide materials. I will then summarize

the current status of our extension of the methods to fully physically realistic

systems, emphasizing the areas of theoretical uncertainty and the prospects

for resolution.

Twentyfirst Arnold Sommerfeld Lecture Series, Superconductivity, the ability of certain materials to conduct electricity with

no resistance whatsoever, has fascinated scientists since its discovery by

Kammerlingh-Onnes in 1911. While much has been understood, the question

of predicting which materials will become superconducting, and at what

temperatures, remains one of the grand challenges of modern materials

theory. This talk will outline the evolution of our understanding as the subject

has progressed from its primitive beginnings through the ''bronze age''

marked by the 1986 discovery of high temperature superconductivity in

copper-oxide compounds to the present-day ''iron age'' of the Fe-As based

superconducting materials. The current status of the theory of the origin of

superconductivity will be described.

Twentieth Arnold Sommerfeld Lecture Series, A combination of ideas originating from Condensed Matter physics, Supersymmetric Field Theory, and AdS/CFT has led to a detailed web of conjectured dualities. These relate the long distance behavior of different short distance theories. These dualities clarify a large number of confusing and controversial issues in Condensed Matter physics and in the study of 2+1 dimensional quantum field theory.

Twentieth Arnold Sommerfeld Lecture Series, Global symmetries and gauge symmetries have played a crucial role in physics. The

idea of duality demonstrates that gauge symmetries can be emergent and might not

be fundamental. During the past decades it became clear that the circle of ideas

about emergent gauge symmetries and duality is central in different branches of

physics including Condensed Matter Physics, Quantum Field Theory, and Quantum

Gravity. We will review these developments, which highlight the unity of physics.

Nineteenth Arnold Sommerfeld Lecture Series, Two of the most amazing ideas in physics are the holographic

principle and quantum error correction. The holographic principle

asserts that all the information contained in a region of space is

encoded on the boundary of the region, albeit in a highly scrambled

form. Quantum error correction is the foundation of our hope that

large-scale quantum computer can be operated to solve hard

problems. I will argue that these two ideas are closely related, and

will describe quantum codes which realize the holographic

principle. These codes provide simplified models of quantum

spacetime, opening new directions in the study of quantum gravity,

though many questions remain.

Nineteenth Arnold Sommerfeld Lecture Series, Aside from enabling revolutionary future technologies, quantum

information science is providing powerful new tools for attacking

deep problems in fundamental physical science. In particular, the

recent convergence of quantum information and quantum gravity is

sparking exciting progress on some old and very hard questions.

Nineteenth Arnold Sommerfeld Lecture Series, The quantum laws governing atoms and other tiny objects seem to

defy common sense, and information encoded in quantum systems

has weird properties that baffle our feeble human minds. John

Preskill will explain why he loves quantum entanglement, the

elusive feature making quantum information fundamentally different

from information in the macroscopic world. By exploiting quantum

entanglement, quantum computers should be able to solve

otherwise intractable problems, with far-reaching applications to

cryptology, materials, and fundamental physical science. Preskill is

less weird than a quantum computer, and easier to understand.

Eighteenth Arnold Sommerfeld Lecture Series, One hundred years ago, D’Arcy Thompson – a nineteenth century

polymath, working at the turn of the twentieth century – wrote a

beautiful monograph, “On Growth and Form”, in which he pondered

the geometry of living forms and how it emerges in the process of

Morphogenesis. Thompson was ahead of his time. Genetics and

Developmental Biology have since come a long way in elucidating

the general and particular aspects of Morphogenesis, uncovering the

key genes and molecules that underlie the process in different

animals and plants. Yet, Thompson’s agenda of understanding how

developmental processes actually specify the geometry of tissues,

limbs and organs is far from complete. A particular challenge is to

bridge the gap between microscopic scales, where molecular

mechanisms operate, and the macroscopic scales of animal “shape

and form”. This challenge offers much for a Theoretical Physicist to

think about. This talk will provide some examples, relating the study

of order in the arrangement of fly wing hairs to ferromagnetism and

uncovering an unexpected wealth of mechanical phenomena in the

study of cellular flows in a fly embryo.

Eighteenth Arnold Sommerfeld Lecture Series, When we think about evolution, it is typically in the context of

natural history, seeking an explanation for the amazing diversity of life. Yet evolution is not only the matter of the past, but an ongoing dynamical process linking the past with the future. Evolutionary

dynamics is particularly apparent in rapidly mutating microbes and

viruses. For example, the virus causing seasonal flu continuously evolves to escape human immunity generated by previous

infections: because of this process, we get the flu again and again.

Can we understand evolutionary dynamics well enough to predict

the future, at least far enough to help with the flu vaccine updates?

This talk will review basic mechanisms of evolutionary dynamics and discuss some of the old and new approaches to evolutionary

forecasting and the challenges that they face. Surprisingly, ideas

from Theoretical Physics can be helpful in understanding

evolutionary dynamics.

Thirteenth ASC Lecture Series, Localization of the eigenfunctions of quantum particles in a random potential was discovered by P.W. Anderson more than 50 years ago in connection with spin relaxation and charge transport in disordered solids. Later experimentally was realized localization of other quantum particles and classical waves: light, microwaves, sound, cold atoms. At the same time it became clear that the domain of applicability of the concept of localization is much broader. In particular, it can be extended to various problems in condensed matter physics that involve not only disorder, but also interaction between quantum particles. We will consider manifestation of the Anderson localization in model systems: interacting Bose and Fermi gases and disordered spin models. This will allow us to discuss such phenomena as superconductor-metal-insulator (superfluid- normal fluid-glass) transitions. In particular, we will introduce a new class of finite-temperature phase transitions that can exist even in one-dimensional systems and manifest themselves in transport rather than equilibrium properties. We will also be able to get some insight on some problems in quantum computational complexity.