title: Using thermal boundary conditions to engineer the quantum state of a bulk magnet.
abstract: The degree of contact between a system and the external environment can alter dramatically its proclivity to quantum mechanical modes of relaxation. We show that controlling the thermal coupling of cubic-centimeter-sized crystals of the Ising magnet LiHo(x)Y(1-x)F4 to a heat bath can be used to tune the system between a glassy state dominated by thermal excitations over energy barriers and a state with the hallmarks of a quantum spin liquid. Application of a magnetic field transverse to the Ising axis introduces both random magnetic fields and quantum fluctuations, which can retard and speed the annealing process, respectively, thereby providing a mechanism for continuous tuning between the destination states. The nonlinear response of the system explicitly demonstrates quantum interference between internal and external relaxation pathways.
authors.affiliation: The James Franck Institute and Department of Physics, The University of Chicago, Chicago, IL 60637.
authors.forename: M A
authors.initials: MA
authors.lastname: Schmidt
authors.forename: D M
authors.initials: DM
authors.lastname: Silevitch
authors.forename: G
authors.initials: G
authors.lastname: Aeppli
authors.forename: T F
authors.initials: TF
authors.lastname: Rosenbaum
mesh_terms: D002616:Chemical Engineering / Q000379:methods*; D059346:Magnets / Q000737:chemistry*; D008956:Models, Chemical; D011789:Quantum Theory; D013696:Temperature
keywords: adiabatic quantum computing; quantum annealing; quantum information; quantum magnetism; random fields