What can the tools of quantum information theory teach us about quantum magnets?

by Prof. Nic Shannon (Okinawa Institute of Science and Technology)

Monday Aug 18, 2025, 3:00 PM → 4:30 PM Europe/Stockholm

Albano 2: C2207 - Auditorium 4 (80 seats) (Albano Building 2)

Albano Building 2: C2207 - Auditorium 4

 

zoom link : https://stockholmuniversity.zoom.us/j/67259623527?pwd=bjG5PbKdb4chVtyQsyPS0a3kUTFLYy.1

Meeting ID: 672 5962 3527
 

Fika will be served after the colloquium talk.

 

Abstract: 

The search for unconventional phases of matter remains a central theme in  condensed matter and statistical physics.   However the very things which make  these phases interesting: the absence of conventional order parameters; the emergence of fractional excitations; their topological and entanglement properties, also make them difficult to distinguish in experiment.  This is particularly true of the hunt for quantum spin liquids in quantum magnets: phases viewed as a "holy grail", but which are also notoriously difficult to diagnose, especially in the presence of disorder.  
In this talk we explore how ideas from quantum information could be used to distinguish quantum spin liquids from other competing phases of matter.   We consider two systems where the possibility of finding a quantum spin liquid has been widely discussed: quantum spin chains, and triangular lattice antiferromagnets [1,2].  In both cases, we find that inelastic neutron scattering, interpreted in terms of quantum Fisher information, can be used distinguish quantum spin liquids from states driven by disorder.  We also highlight some of the pitfalls which arise in the naive application of ideas from quantum information to quantum magnets.
These results suggest that, used carefully, the tools of quantum information could offer a powerful way of interpreting the results of both simulation and experiment on quantum magnets.
[1] S. Sabharwal, T. Shimokawa and N. Shannon, Phys. Rev. Res. 7, 023271 (2025)
[2] T. Shimokawa, S. Sabharwal and N. Shannon, arXiv:2505.11874