Séminaire du LPTMS : Adam Nahum (LPENS)

Quantum dynamics with an observer: the measurement phase transition

Adam Nahum (Laboratoire de Physique de l’Ecole Normale Supérieure)

Onsite seminar + zoom.

Zoom link:
https://cnrs.zoom.us/j/92283605429?pwd=ZTRuWmR4T0dHVWh2M0VRUzhrc2p6QT09

Meeting ID: 922 8360 5429
Passcode: vv58du

In the quantum world, measurements inevitably affect the state of a system, via wavefunction collapse. This means that the dynamics of a system which is continually being monitored by an observer is fundamentally different from the dynamics of a closed system. In particular, for a spatially extended system, local measurements of the degrees of freedom can “compete” with chaotic dynamics: while chaotic dynamics tends to produce complex, entangled quantum wavefunctions, local measurements tend to collapse the wavefunction into something simpler. I will describe how this leads to a dynamical phase transition between a weak monitoring phase, where the state is complex and entangled, and a strong monitoring phase, where the state is simple and “classical”. I will sketch the relevance of this transition to the classical simulation of quantum dynamics, and some theoretical approaches to understanding the transition.

Date/Time : 15/02/2022 - 11:00 - 12:00

Location : Petit amphi, bâtiment Pascal n° 530