AQP Seminar: Monitored Quantum Transport: How Weak Measurements Shape Chaos and Localization

Monitored Quantum Transport: How Weak Measurements Shape Chaos and Localization

Jakub Tworzydlo (University of Warsaw, Poland)
 

Abstract: The framework of "monitored quantum dynamics"—where coherent unitary evolution is interspersed with continuous weak measurements—has recently emerged as a powerful tool for exploring open quantum systems. This talk will introduce the fundamentals of weak measurement and monitoring, demonstrating how quantum channels can be used to continuously extract partial information from a system while introducing a tunable rate of decoherence. We will then explore the profound consequences of this monitored transport in two foundational paradigms of mesoscopic physics. First, in a disordered one-dimensional conductor, we will show how continuously monitoring local scattering events suppresses the phase coherence responsible for Anderson localization. This measurement-induced decoherence replaces the typical exponential decay of transmission with a diffusive 1/L tail, while remarkably preserving the binomial distribution of the full counting statistics. Second, we will apply random-matrix theory to chaotic quantum dots, illustrating how monitoring a subset of closed modes brings the system locally out of equilibrium and breaks reciprocity, which fundamentally modifies its electrical conductance and current-voltage relations.

This event is supported by InstituteQ, Finland's National Quantum Institute. InstituteQ serves as an umbrella organisation coordinating quantum research, education, business development, and innovation activities throughout the country. InstituteQ member organisations include: Aalto University, CSC – IT Center for Science, Tampere University, The University of Eastern Finland, The University of Helsinki, The University of Jyväskylä, The University of Oulu, The University of Turku, and VTT Technical Research Centre of Finland.