RQC Seminar

188th RQC Seminar

• Speaker

  Dr. Marcello Dalmonte
  ( International Centre for Theoretical Physics (ICTP) )

• Date

  13:15-14:15 (1:15 p.m. - 2:15 p.m.), March 31, 2025 (Monday)

• Venue

  Hybrid(ZOOM・ Wako Main Research 3F 345-347 Seminar Room / 研究本館3階 セミナー室 (345-347) (C01))

• Title

  Complexity beyond entanglement - magic of many-body systems

• Inquiries

  norilab_rqc_assist[at]ml.riken.jp

Abstract
Driven by groundbreaking experimental advances, quantum matter is currently entering the era of quantum error correction - where basic forms of computation can be demonstrated in a fault-tolerant manner. From a many-body theory viewpoint, these developments motivate the question: what are states that are challenging to realize in the presence of error correction? Entanglement alone is not informative about state complexity, and in fact, it is a free resource in such situations.

In this talk, I will tackle quantum state complexity of many-body systems under the lens of non-stabilizerness - also known as magic. Magic quantifies the difficulty of realizing states in most error corrected codes, and is thus of fundamental practical importance. However, very little is known about its significance to many-body phenomena. I will present method(s) to measure magic in tensor network simulations, and illustrate a series of applications to many body systems, including its relevance in critical matter and gauge theories, and its relations to entanglement. These results indicate that a large amount of quantum resources are required to generate interesting many-body phenomena under the assumption of error correction.

On the hardware side, I will then show how one can control and alter the property of topological quantum matter - a prototype element of error corrected machines - utilizing cavities. This elucidates how cavities can be in fact helpful in shaping specific quantum correlations, and even generate exotic quasiparticles that make the presence of topological properties manifest.