Mathematisches Oberseminar: Quantenmechanische Vielteilchensysteme und relativistische Quantentheorie
In the summer term 2020 from
Dr. Dirk Deckert,
Prof. Dr. Detlef Dürr
and
Prof. Dr. Peter Pickl
The seminar is usually on Wednesdays, 16:15h, starting on the 22th of April and will take place on Zoom. Please contact us for the session link if you are interested to join.
Organizer: Manuela Feistl
News:
Updates may be distributed on short notice by mail to all people on an internal list. People interested in should contact
Dr. Dirk Deckert,
Prof. Dr. Detlef Dürr
or
Prof. Dr. Peter Pickl.
Talks
Date 
Room 
Title 
Speaker 

Wed 22.04.20, 16:15 
B004 
Heisenberg Uncertainty Principle

Serj Aristarhov

Wed 29.04.20, 16:15 
B004 
Vlasov for shortrange potentials
I will present a probabilistic proof of the mean field limit and propagation of chaos of an Nparticle systems in three dimensions with compactly supported pair potentials. In particular, for typical initial data, we show convergence of the empirical distributions to solutions of the VlasovPoisson system with deltalike interactions.

Manuela Feistl

Wed 06.05.20, 16:15 
B004 
Quantum measurements of time
We propose a timeofarrival operator in quantum mechanics
by conditioning on a quantum clock. This allows us to bypass some of
the problems of previous proposals, and to obtain a Hermitian time of
arrival operator whose probability distribution arises from the Born
rule and which has a clear physical interpretation. The same procedure
can be employed to measure the "time at which some event happens" for
arbitrary events (and not just specifically for the arrival time of a
particle).

Lorenzo Maccone

Wed 13.05.20, 16:15 
B004 
Through the Big Bang of the Newtonian Universe
I show that the threeparticle E = P = L = 0 Newtonian universe can be evolved through the points of triple collision â€“ the Big Bang of the threeparticle E = P = L = 0 Newtonian universe. The result is essentially based on a description of the systemâ€™s dynamics on shape phase space, the relational phase space of the system. Explicitly, I show that the shape, i.e. angular, degrees of freedom can be evolved uniquely through the points of total collision. This holds
for almost all collision solutions. One such solution on shape phase space corresponds to two solutions on absolute phase space, one which ends at and one which begins at a total collision, â€˜glued togetherâ€™ via the unique evolution of the shape degrees of freedom. That way, the Newtonian singularity is passed. Eventually, I sketch the eternal evolution of a threeparticle E = P = L = 0 Newtonian universe with a Big Bang: there is a triple collision, i.e. a Big
Bang, at the midpoint of that evolution while the particles separate, typically into a Kepler pair and a single particle, and fly off in both time directions away from that point.

Dr. Paula Reichert

Wed 20.05.20, 16:15 
B004 
Arrival time POVMs from absorbing boundary conditions

Siddhant Das

Wed 27.05.20, 16:15 
B004 
QuasiParticles

Umut

Wed 03.06.20, 16:15 
B004 
Geometric construction of the phase of QED

Markus NÃ¶th

Wed 10.06.20, 16:15 
B004 
Momentum measurement in QM

Felix Feist

Wed 17.06.20, 16:15 
B004 
The sound of collapse
In some collapse models, like the GhirardiRiminiWeber model, there are real objective quantum jumps. These spontaneous jumps have empirical consequences, making such models deviate from quantum mechanics. I will argue that the predictions of collapse models in general are not specific enough to deviate from quantum mechanics taken as a general approach, but only from its instantiation in the Standard Model. I will discuss one example I find particularly
surprising: a collapse model in which the jumps are so violent that they can be heard. It seems that in this context, one can know for sure that there are genuine stochastic jumps, at odds with the sort of general indistinguishably I seem to claim exists in general. But it's not the case. And I think understanding what goes on is a good way to grasp much better the role played (and not played) by decoherence in the resolution of the measurement problem.

Dr. Antoine Tilloy

Wed 24.06.20, 16:15 
B004 
A functional central limit theorem for a dynamical system

Anne FrÃ¶mel

Wed 01.07.20, 16:15 
B004 
The trajectories of the SchrÃ¶dinger equation
I will discuss the properties of the set of trajectories that are obtained from a fixed initial state by varying the potential in the SchrÃ¶dinger equation.
This is related to the control problem, i.e. driving the system to a target state, which turns out to be impossible for "typical" target states using bounded potentials.

Dr. Jonas Lampart

Wed 08.07.20, 16:15 
B004 
Typicality
Abstract: Why does time seem to have a direction in a universe governed by timesymmetric fundamental laws? Why do we remember the past but not the future? Why does it seem like we can influence the future but not the past? Many physicists (and some philosophers) believe that the epistemic and causal asymmetries can be reduced to the thermodynamic one. The talk will present an approach based on the concept of typicality and an analysis causal reasoning in a universe with entropic arrow.

Dr. Dustin Lazarovici

Wed 15.07.20, 16:15 
B004 
Time evolution of phase space regions
I compare the time evolution of phase space regions for the model of a gas in the box, a gas without box and the Newtonian gravitational Nbody system (N particles in infinite Euclidean space attracting each other according to the Newtonian force law). I analyze the (reduced) Liouville measure, draw the distinction between the space of solutions and the space in which the trajectories lie, and show how the identification of dynamically similar trajectories enables us to get rid of the divergence of the measure.

Dr. Paula Reichert
