Theory of Quantum Matter Unit (Nic Shannon)

Theory of Quantum Matter

 
This is particularly true if you put a large number of quantum particles in the same place - for example Helium atoms condensed into a liquid, electrons deep inside metal oxides, or cold atoms in an optical trap.
 
In all of these cases, the assembled particles write their own, local, laws of physics, through the way in which they interact with one another.  The consequences are dramatic, and include the superfluidity of liquid Helium, the magnetism and superconductivity of electrons in oxides, and quantum coherent Bose condensates found in cold atoms.   
 
The Theory of Quantum Matter group uses a wide range of numerical and analytic techniques to explore these phenomena.  Our goal is to develop new theoretical approaches to quantum matter, and to guide the discovery of new quantum phases.  To this end, we work closely with experimental physicists, and chemists developing new quantum materials.
 
Interests represented in the group include the behaviour of quantum magnets; topological aspects of quantum matter; statistical mechanics; multferroics; the theoretical understanding of water; and the application of machine learning to problems in many-body physics.  
 
Much of our recent research has focused on frustrated magnets - systems torn between one choice and another.  The way in which these materials resolve their difficulties has proved a constant source of beautiful, and unexpected, new ideas.
 
You can read more about this work in our Annual Reports, as well as in the papers listed on our Publications page.
 

Selected Recent Publications

"Rank-2 U(1) spin liquid on the breathing pyrochlore lattice"
Han Yan, Owen Benton, Ludovic D.C. Jaubert and Nic Shannon
Phys. Rev. Lett. 124, 127203 (2020)

"Identification of emergent constraints and hidden order in frustrated magnets using tensorial kernel methods of machine learning"
Jonas Greitemann, Ke Liu, Ludovic D.C. Jaubert, Han Yan, Nic Shannon and Lode Pollet
Phys. Rev. B 100, 174408 (2019)

"Negative thermal expansion in the plateau state of a magnetically-frustrated spinel"
L. Rossi, A. Bobel, S. Wiedmann, R. Küchler, Y. Motome, K. Penc, N. Shannon, H. Ueda, and B. Bryant
Phys. Rev. Lett. 123, 027205 (2019)

"Quantum spin ice with frustrated transverse exchange: from pi-flux phase to nematic quantum spin liquid"
Owen Benton, L. D. C. Jaubert, Rajiv Singh, Jaan Oitmaa, Nic Shannon
Phys. Rev. Lett. 121, 067201 (2018)

"Experimental signatures of emergent quantum electrodynamics in a quantum spin ice"
Romain Sibille, Nicolas Gauthier, Han Yan, Monica Ciomaga Hatnean, Jacques Ollivier, Barry Winn, Geetha Balakrishnan, Michel Kenzelmann, Nic Shannon, Tom Fennell
Nature Physics 14, 711-715 (2018)

"Competing spin liquids and hidden spin-nematic order in spin ice with frustrated transverse exchange"
Mathieu Taillefumier, Owen Benton, Han Yan, Ludovic Jaubert and Nic Shannon
Phys. Rev. X 7, 041057 (2017)

"Theory of multiple-phase competition in pyrochlore magnets with anisotropic exchange, with application to Yb2Ti2O7, Er2Ti2O7 and Er2Sn2O7"
Han Yan, Owen Benton, L.D.C. Jaubert and Nic Shannon
Phys. Rev. B 95, 094422 (2017)

"From pinch points to pinch lines: a new spin liquid on the pyrochlore lattice"
Owen Benton, L. D. C. Jaubert, Han Yan and Nic Shannon
Nature Communications 7, 11572 (2016)