The MCQST Colloquium Series features interdisciplinary talks given by visiting international speakers. The monthly colloquium covers topics spanning all MCQST research units 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: Xie Chen

We are excited to invite you to the colloquium talk by Xie Chen (Caltech). You can join us in-person at the Max Planck Institute of Quantum Optics at the above address, or online via the Zoom link below:

https://lmu-munich.zoom.us/j/99897798115
Meeting ID: 998 9779 8115
Passcode: mcqst2023

Talk Information

Quantum circuit and the hierarchy of many-body entanglement

Entanglement in many-body quantum systems is notoriously hard to characterize due to the exponentially many parameters involved to describe the state. On the other hand, we are usually not interested in all the microscopic details of the entanglement pattern but only some of its global features. It turns out, quantum circuits of different levels of complexity provide a useful way to establish a hierarchy among many-body entanglement structures. A circuit of a finite depth generates only short range entanglement which is in the same gapped phase as an unentangled product state. A linear depth circuit on the other hand can lead to chaos beyond thermal equilibrium. In this talk, we discuss how to reach the interesting regime in between that contains nontrivial gapped orders. This is achieved using the Sequential Quantum Circuit - a circuit of linear depth but with each layer acting only on one subregion in the system. We discuss how the Sequential Quantum Circuit can be used to generate nontrivial gapped states with long range correlation or long range entanglement, perform renormalization group transformation in foliated fracton order, and create defect excitations inside the bulk of a higher dimensional topological state.

About the speaker

Xie Chen is a Professor of Theoretical Physics at the California Institute of Technology. Dr. Chen obtained her Ph.D. degree from MIT in 2012 and was a Miller research fellow at the University of California, Berkeley before joining Caltech in 2014. Dr. Chen is a condensed matter theorist studying emergent phenomena in strongly interacting quantum many-body systems. She received the New Horizons in Physics Prize from the Breakthrough Foundation in 2020 and was named a Simons Investigator in 2021.