Sommerfeld Lecture Series (ASC) LudwigMaximiliansUniversität München

 Science

Every semester the Arnold Sommerfeld Center for Theoretical Physics invites a distinguished theoretical physicist in order to present a short series of lectures with increasing level of specialization. Usually it includes a public talk for a general audience, a theory colloquium and a specialized seminar.

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Theory Colloquium: Scaling Down the Laws of Thermodynamics
Thermodynamics provides a robust conceptual framework and
set of laws that govern the exchange of energy and matter.
Although these laws were originally articulated for macroscopic
objects, nanoscale systems also exhibit “thermodynamiclike”
behavior – for instance, biomolecular motors convert chemical
fuel into mechanical work. To what extent can the laws of
thermodynamics be scaled down to apply to individual
microscopic systems, and what new features emerge at the
nanoscale? I will describe some of the recent progress and
challenges associated with addressing these questions. 
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Statistical Physics Seminar: Quantum Impulse Control
The quantum adiabatic theorem governs the evolution of a
wavefunction under a slowly timevarying Hamiltonian. I will
consider the opposite limit of a Hamiltonian that is varied
impulsively: a strong perturbation U(x,t) is applied over a time
interval of infinitesimal duration e>0. When the strength of the
perturbation scales like 1/eˆ2, there emerges an interesting
dynamical behavior characterized by an abrupt displacement of
the wave function in coordinate space. I will solve for the
evolution of the wavefunction in this situation. Remarkably, the
solution involves a purely classical construction, yet describes
the quantum evolution exactly, rather than approximately. I will
use these results to show how appropriately tailored impulses
can be used to control the behavior of a quantum wavefunction. 
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Public Lecture: Adventures of an Idea – the Life and Travels of Maxwell’s Demon
In a letter written in 1867, James Clerk Maxwell described a
hypothetical creature: a “neatfingered being” capable of
separating fast molecules from slow ones. Maxwell mused that
such a creature would seem to violate the second law of
thermodynamics, which had recently been enunciated by
Rudolf Clausius and is now a pillar of our understanding of the
natural world. Over the past century and a half, that hypothetical creature – Maxwell’s demon – has wandered through
the thoughts of eminent scientists, has appeared in research
articles and popular cultural references, and in recent years has
been observed in laboratory experiments. Along the way, the
mischievous devil has sharpened our understanding of the
second law of thermodynamics, exposing a deep relationship
between physics and information. I will give an overview of the
questions raised and the lessons learned from contemplating
Maxwell’s demon, and I will summarize our current understanding of this topic. This story highlights the importance of
imagination and whimsy in scientific discovery. 
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Theory Colloquium: When a Symmetry Breaks
Spontaneous Symmetry Breaking is a very universal concept applicable for a wide range of subjects: crystal, superfluid, neutron stars, Higgs boson, magnets, and many others. Yet there is a variety in the spectrum of gapless excitations even when the symmetry breaking patterns are the same. We unified all known examples of internal symmetries in a singleline Lagrangian of the lowenergy effective theory. In addition, we now have a better understanding of what happens with spacetime symmetries, and predict gaps for certain states
exactly based on symmetries alone. 
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Public Lecture: Quantum Universe
Where do we come from? Science is making progress on this ageold question of humankind. The Universe was once much smaller than the size of an atom. Small things mattered in the small Universe, where quantum physics dominated the scene.
To understand the way the Universe is today, we have to solve remaining major puzzles. The Higgs boson that was discovered recently is holding our body together from evaporating in a nanosecond. But we still do not know what exactly it is. The
mysterious dark matter is holding the galaxy together, and we would not have been born without it. But nobody has seen it directly. And what is the very beginning of the Universe? 
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Fields and Strings Seminar: What is dark matter?
I review what we know about dark matter right now and some hints about its nature. In particular, I discuss candidates away from the conventional WIMP (Weakly Interactive Massive Particle) paradigm.