The MCQST Colloquium Series features interdisciplinary talks given by visiting international speakers. The monthly colloquium covers topics spanning all MCQST research areas and will be broadcast live via Zoom for audiences worldwide. The main goal of the series is to create the framework for idea exchange, to strengthen links with QST leading groups worldwide, as well as to act as an integral part of the local educational environment.
MCQST Colloquium: X-mas edition with MCQST members Yuhan Liu and Roberto Rizzato
We are excited to invite you to the colloquium talks by Yuhan Liu (MPQ) and Roberto Rizzato (TUM).
Agenda
16:00 | Colloquium talk by Yuhan Liu (MPQ) on "Mathematical Structures of Open Quantum Systems and Mixed-State Phases through the Lens of Tensor Networks"
16:30 | Colloquium talk by Roberto Rizzato (TUM) on “New Spin Platforms for Quantum Sensing: From Nanotubes to Molecular Materials”
17:00 | Get-together and exchange with coffee, plätzchen & glühwein
Mathematical Structures of Open Quantum Systems and Mixed-State Phases through the Lens of Tensor Networks | Yuhan Liu (MPQ)
Understanding quantum phases of matter is a fundamental goal in physics, and the mathematical structures underlying tensor networks play an important role in this endeavor. In this talk, I explore open quantum systems and mixed-state quantum phases through the framework of matrix product density operators (MPDOs). MPDOs at renormalization fixed points (RFPs) are believed to characterize mixed-state phases in one dimension, where nontrivial topological phases have been shown to exist. I address three questions: (1) Can MPDO RFPs be realized as the unique steady state (or as one of a minimally degenerate set of steady states) of a local frustration-free Lindbladian? (2) What mathematical framework describes MPDO RFPs while incorporating anomalous phases? (3) How can we go beyond renormalization fixed points to rigorously establish phase equivalence? Addressing these questions provides new tools for studying open quantum systems and mixed-state quantum phases.
About Yuhan Liu Yuhan obtained her PhD degree from the University of Chicago and is now a postdoctoral researcher at the theory division of Max Planck Institute of Quantum Optics.
New Spin Platforms for Quantum Sensing: From Nanotubes to Molecular Materials | Roberto Rizzato (TUM)
Optically addressable spin defects in three-dimensional covalent crystals are among the most established platforms for quantum sensing. Yet reliably creating and positioning these defects close to chemical and biological targets, while preserving their spin properties, remains challenging. Spin defects in low-dimensional materials offer a complementary route by potentially improving sensor-target interaction. In this talk, I will first introduce spin defects in boron nitride nanotubes, which we use as high-surface-area sensors at room temperature and in liquids. I will then present new results from other low-dimensional materials, extending to molecular systems, that show optically detected magnetic resonance and coherent spin manipulation under ambient conditions. Extending optical spin control to molecular systems could ultimately let us design the spin-active elements of quantum sensors through chemistry.
About Roberto Rizzato Roberto Rizzato is a physical chemist and Research Group Leader in the Department of Chemistry at the Technical University of Munich, where he holds an ERC Consolidator Grant. His research focuses on optically addressable spins in low-dimensional materials. His group develops these systems as quantum sensors and explores their use to enhance magnetic resonance sensitivity.
