# Aktuelle Veranstaltungen

## Kolloquium

Thema:

### Antrittsvorlesung

Datum:

23.05.22

Uhrzeit:

16:15

Ort:

H6

Vortragender:

PD Dr. Wolfgang Unger

Universität Bielefeld

Inhalt:

Ansprechpartner:

Dekan

## Kolloquium Mathematische Physik

Thema:

### tba

Datum:

03.06.22

Uhrzeit:

16:15

Ort:

V4-119

Vortragender:

Elena Vedmedenko

University of Hamburg

Inhalt:

Ansprechpartner:

M. Baake

Thema:

Datum:

30.06.22

Uhrzeit:

14:15

Ort:

D6-135

Vortragender:

Simona Procacci

Universität Bern

Inhalt:

Ansprechpartner:

D. Bödeker

## Seminar Kondensierte Materie

Thema:

### 15:00 Indicators of many-body quantum chaos

Datum:

19.05.22

Uhrzeit:

15:00

Ort:

ZOOM / Konferenzschaltung

Vortragender:

Lea Santos

Yeshiva University, New York

Inhalt:

Quantum chaos, specially when caused by interactions between particles, has experienced a remarkable resurgence in the last decade due to its close relationship with a broad spectrum of problems at the forefront of theoretical and experimental physics. Quantum chaos ensures thermalization, hinders localization, and leads to the fast scrambling of quantum information in many-body quantum systems. In this lecture, I will compare different indicators of quantum chaos associated with the spectrum and eigenstates of many-body quantum systems.

Ansprechpartner:

FOR2692/Jürgen Schnack

## Seminar Mathematische Physik

Thema:

### Many-particles diffusing with resetting: study of the large-deviation properties of the flux distribution

Datum:

05.05.22

Uhrzeit:

16:00

Ort:

D5-153

Vortragender:

Costantino Di Bello

Inhalt:

In this paper we studied a model of noninteracting particles moving on a line following a common dynamics. In particular we considered either a diffusive motion with Poissonian resetting, and a run-and-tumble motion with Poissonian resetting. We were interested in studying the distribution of the random variable $Q_t$ defined as the flux of particles through origin up to time $t$. We used the notation $P(Q,t)$ to identify the probability $\mathbb{P}\{Q_t=Q\}$. We considered particles initially located on the negative half line with a fixed density $\rho$. In fully analogy with disordered systems, we studied both the annealed and the quenched case for initial conditions. In the former case we found that, independently from the specific dynamics, $P_\mathrm{an}(Q,t)$ has a Poissonian shape; while in the latter case, for what concerns the diffusive dynamics with resetting, the large deviation form of the quenched distribution reads $P_\mathrm{qu}(Q,t)\sim \exp\left[-r^2t^2 \Psi_\mathrm{diff}\left(\dfrac{Q}{\rho t}\right)\right]$ with the large deviation function $\Psi_\mathrm{diff}(x)$ exhibiting a discontinuity in the third derivative, hence aiming, despite the simplicity of the model, at the exhistence of a dynamical phase transition. The quenched distribution for the run-and-tumble dynamics, instead, does not exhibit any kind of phase transition. Importance sampling Monte Carlo simulations were performed to prove the analytical results. References: Current fluctuations in noninteracting run-and-tumble particles in one dimension Tirthankar Banerjee, Satya N. Majumdar, Alberto Rosso, and Grégory Schehr, Phys. Rev. E 101, 052101 https://doi.org/10.1103/PhysRevE.101.052101 Current Fluctuations in One Dimensional Diffusive Systems with a Step Initial Density Profile B. Derrida and A. Gerschenfeld, J. Stat. Phys. 137, 978 (2009) https://doi.org/10.1007/s10955-009-9830-1

Ansprechpartner:

Gernot Akemann

## Seminar Bielefeld-Melbourne Zufallsmatrizen

Thema:

### Exponential Functional of the Matrix Brownian Motion, Dufresne Identity and Quantum Scattering

Datum:

25.05.22

Uhrzeit:

09:00

Ort:

ZOOM / Konferenzschaltung

Vortragender:

Aurélien Grabsch

LPTMC, Sorbonne Université

Inhalt:

Exponential functionals of the Brownian motion appear in many different contexts (classical diffusion in random media, quantum scattering, finance,...). I will discuss a recent generalization to the case of matrix Brownian motion. This problem has a natural motivation within the study of quantum scattering on a disordered wire with several conducting channels. I will show that the Wigner-Smith time delay matrix, a fundamental matrix in quantum scattering encoding several characteristic time scales, can be represented as an exponential functional of the matrix BM. I will discuss the relation between this problem of quantum physics and the Dufresne identity, which gives the stationary distribution of such exponential functionals of the BM. Ref: Aurélien Grabsch and Christophe Texier, Wigner-Smith matrix, exponential functional of the matrix Brownian motion and matrix Dufresne identity, J. Phys. A: Math. Theor. 53, 425003 (2020)

Ansprechpartner:

Anas Rahman

• | Druckansicht PDF