Quantum Spin Glasses & Spin Liquids.  QUANTUM RELAXATION Ising Magnet in a Transverse Magnetic Field (1) Aging in the Spin Glass (2) Erasing Memories.

Slides:

Advertisements

Similar presentations

THE ISING PHASE IN THE J1-J2 MODEL Valeria Lante and Alberto Parola.

Advertisements

One-dimensional approach to frustrated magnets

MR TRACKING METHODS Dr. Dan Gamliel, Dept. of Medical Physics,

Inelastic Magnetic Neutron Scattering on the Spin-Singlet Spin- ½ FCC System Ba 2 YMoO 6 Jeremy P. Carlo Canadian Neutron Beam Centre, National Research.

D-wave superconductivity induced by short-range antiferromagnetic correlations in the Kondo lattice systems Guang-Ming Zhang Dept. of Physics, Tsinghua.

Antoine Georges Olivier Parcollet Nick Read Subir Sachdev Jinwu Ye Mean field theories of quantum spin glasses Talk online: Sachdev.

NMR SPECTROSCOPY.

Samansa Maneshi, Jalani Kanem, Chao Zhuang, Matthew Partlow Aephraim Steinberg Department of Physics, Center for Quantum Information and Quantum Control,

LiHo x Y 1-x F 4 : The road between solid state ion trap and quantum critical ferromagnet Gabriel Aeppli London Centre for Nanotechnology & UCL TexPoint.

Dynamics and thermodynamics of quantum spins at low temperature Andrea Morello Kamerlingh Onnes Laboratory Leiden University UBC Physics & Astronomy TRIUMF.

Compound Torsional Oscillator: Frequency Dependence and Hysteresis of Supersolid 4 He (and Search for Superfluid Sound Mode) Harry Kojima Rutgers University.

Dilute anisotropic dipolar systems as random field Ising ferromagnets In collaboration with: Philip Stamp Nicolas Laflorencie Moshe Schechter University.

 From a single molecule to an ensemble of molecules at T ~0 : Both tunneling rate and decoherence increase  LZ probability: P LZ = 1 – exp[-  (  /ħ)

Quantum phase transitions in anisotropic dipolar magnets In collaboration with: Philip Stamp, Nicolas laflorencie Moshe Schechter University of British.

Phase Diagram of LiHoxY1-xF4 Jeff Quilliam, Chas Mugford, Jan Kycia Department of Physics and Astronomy University of Waterloo Ariel Gomez, Stefan.

LPS Quantum computing lunchtime seminar Friday Oct. 22, 1999.

Prelude: Quantum phase transitions in correlated metals SC NFL.

PCE STAMP Physics & Astronomy UBC Vancouver Pacific Institute for Theoretical Physics QUANTUM GLASSES Talk given at 99 th Stat Mech meeting, Rutgers, 10.

Dilute anisotropic dipolar systems as random field Ising ferromagnets In collaboration with: Philip Stamp, Nicolas Laflorencie Moshe Schechter University.

Strongly Correlated Systems of Ultracold Atoms Theory work at CUA.

Dipole Glasses Are Different from Spin Glasses: Absence of a Dipole Glass Transition for Randomly Dilute Classical Ising Dipoles Joseph Snider * and Clare.

H. C. Ku Department of Physics, National Tsing Hua University, Hsinchu, Taiwan 300, R.O.C. with: B. N. Lin, P. C. Guan, Y. C. Lin, T. Y. Chiu, M. F. Tai.

Long coherence times with dense trapped atoms collisional narrowing and dynamical decoupling Nir Davidson Yoav Sagi, Ido Almog, Rami Pugatch, Miri Brook.

Experimental Investigation of LiHo x Y 1-x F 4 Jan Kycia, Jeff Quilliam, Shuchao Meng, Chas Mugford Department of Physics and Astronomy University of Waterloo.

Coherent Manipulation and Decoherence of S=10 Fe8 Single- Molecule Magnets Susumu Takahashi Physics Department University of California Santa Barbara S.

Optical control of electrons in single quantum dots Semion K. Saikin University of California, San Diego.

Magnetism III: Magnetic Ordering

Magnetic properties of SmFeAsO 1-x F x superconductors for 0.15 ≤ x ≤ 0.2 G. Prando 1,2, P. Carretta 1, A. Lascialfari 1, A. Rigamonti 1, S. Sanna 1, L.

Magnetic properties of a frustrated nickel cluster with a butterfly structure Introduction Crystal structure Magnetic susceptibility High field magnetization.

Lecture schedule October 3 – 7, 2011  #1 Kondo effect  #2 Spin glasses  #3 Giant magnetoresistance  #4 Magnetoelectrics and multiferroics  #5 High.

Relating computational and physical complexity Computational complexity: How the number of computational steps needed to solve a problem scales with problem.

Ying Chen Los Alamos National Laboratory Collaborators: Wei Bao Los Alamos National Laboratory Emilio Lorenzo CNRS, Grenoble, France Yiming Qiu National.

Neutron Scattering from Geometrically Frustrated Antiferromagnets Spins on corner-sharing tetrahedra Paramagnetic phase Long Range Ordered phase (ZnCr.

Critical Phenomena in Random and Complex Systems Capri September 9-12, 2014 Spin Glass Dynamics at the Mesoscale Samaresh Guchhait* and Raymond L. Orbach**

Glass Phenomenology from the connection to spin glasses: review and ideas Z.Nussinov Washington University.

Neutron Scattering of Frustrated Antiferromagnets Satisfaction without LRO Paramagnetic phase Low Temperature phase Spin glass phase Long range order Spin.

Wave Packet Echo in Optical Lattice and Decoherence Time Chao Zhuang U(t) Aug. 15, 2006 CQISC2006 University of Toronto.

Solving Impurity Structures Using Inelastic Neutron Scattering Quantum Magnetism - Pure systems - vacancies - bond impurities Conclusions Collin Broholm*

 Magnetism and Neutron Scattering: A Killer Application  Magnetism in solids  Bottom Lines on Magnetic Neutron Scattering  Examples Magnetic Neutron.

¶ CNISM-Dipartimento di Fisica “A. Volta,” Università di Pavia, Pavia, (Italy) ║ Max Planck Institute for Chemical Physics of Solids, Dresden,

Two Level Systems and Kondo-like traps as possible sources of decoherence in superconducting qubits Lara Faoro and Lev Ioffe Rutgers University (USA)

Sept. 14 th 2004 Montauk, Long Island, NY Jason S. Gardner NIST, Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg,

Thermodynamics of Spin 3 ultra-cold atoms with free magnetization B. Pasquiou, G. Bismut (former PhD students), B. Laburthe-Tolra, E. Maréchal, P. Pedri,

Collaborations: L. Santos (Hannover) Former members: R. Chicireanu, Q. Beaufils, B. Pasquiou, G. Bismut A.de Paz (PhD), A. Sharma (post-doc), A. Chotia.

Finite Temperature Spin Correlations in Quantum Magnets with a Spin Gap Collin Broholm* Johns Hopkins University and NIST Center for Neutron Research *supported.

Order and disorder in dilute dipolar magnets

Magnets without Direction Collin Broholm Johns Hopkins University and NIST Center for Neutron Research  Introduction  Moment Free Magnetism in one dimension.

Magnets without Direction Collin Broholm Johns Hopkins University and NIST Center for Neutron Research  Introduction  Moment Free Magnetism in one dimension.

Collin Broholm Johns Hopkins University and NIST Center for Neutron Research Quantum Phase Transition in a Quasi-two-dimensional Frustrated Magnet M. A.

Single Molecular Magnets

Magnetic Frustration at Triple-Axis  Magnetism, Neutron Scattering, Geometrical Frustration  ZnCr 2 O 4 : The Most Frustrated Magnet How are the fluctuating.

M. Ueda, T. Yamasaki, and S. Maegawa Kyoto University Magnetic resonance of Fe8 at low temperatures in the transverse field.

Slow Dynamics of Magnetic Nanoparticle Systems: Memory effects P. E. Jönsson, M. Sasaki and H. Takayama ISSP, Tokyo University Co-workers: H. Mamiya and.

NMR and The Designing and Manufacturing of an NMR Probe for 109 Ag in Li x Ag 3 V 4 O 11 Cathode Material, for 0.72

Collin Broholm Johns Hopkins University and NIST Center for Neutron Research Quantum Phase Transition in Quasi-two-dimensional Frustrated Magnet M. A.

Frustrated magnetism in 2D Collin Broholm Johns Hopkins University & NIST  Introduction Two types of antiferromagnets Experimental tools  Frustrated.

Neutron Scattering of Frustrated Antiferromagnets Satisfaction without LRO Paramagnetic phase Low Temperature phases Spin glass phase Long range order.

NMR study of a mixed-metal molecular magnet Yutaka FUJII (University of Fukui) Contents  Introduction (Magnetic properties)  Experimental results  1.

Magnets without Direction Collin Broholm Johns Hopkins University and NIST Center for Neutron Research  Introduction  Moment Free Magnetism in one dimension.

Functional Integration in many-body systems: application to ultracold gases Klaus Ziegler, Institut für Physik, Universität Augsburg in collaboration with.

NMR Studies of nanoscale molecular magnets Y. Furukawa Y. Fujiyoshi S. Kawakami K. Kumagai F. Borsa P. Kogerler Hokkaido University (Japan) Pavia University.

Collin Broholm Johns Hopkins University and NIST Center for Neutron Research Quantum Phase Transition in Quasi-two-dimensional Frustrated Magnet M. A.

Quantum effects in Magnetic Salts

An insulating salt as a laboratory for ‘emergent’ quantum phenomena

B4 Single crystal growth of tunable quantum spin systems

Decoherence at optimal point: beyond the Bloch equations

Is LiHoF4 a Quantum Magnet?

NV centers in diamond: from quantum coherence to nanoscale MRI

Hiroyuki Nojiri, Department of Physics, Okayama University

Institute for Theoretical Physics,

Presentation transcript:

Quantum Spin Glasses & Spin Liquids

 QUANTUM RELAXATION Ising Magnet in a Transverse Magnetic Field (1) Aging in the Spin Glass (2) Erasing Memories  HOLE-BURNING in a SPIN LIQUID Dilute “AntiGlass”: Intrinsic Quantum Mechanics (1) Non-Linear Dynamics (2) Coherent Spin Oscillations (3) Quantum Magnet in a Spin Bath S. Ghosh et al., Science 296, 2195 (2002) and Nature 425, 48 (2003). H. Ronnow et al., Science 308, 389 (2005). C. Ancona-Torres et al., unpublished.

LiHo x Y 1-x F 4 Ho 3+ magnetic, Y 3+ inert Ising (g // = 14) Dipolar coupled (long ranged) x = 1 Ferromagnet T C = 1.53 K x ~ 0.5 Glassy FM T C = xT C (x=1) x ~ 0.2 Spin Glass Frozen short-range order x ~ 0.05 Spin Liquid Short-range correlations Å Å

Effect of a Transverse Field with [ H,  z ] ≠ 0

Experimental Setup  ~ H t 2 h ac, Ising axis

T (mK)  (K) Paramagnet Net Moment Glass LiHo 0.20 Y 0.80 F 4 Aging & Memory in the Quantum Spin Glass

Aging in  ac Time Temperature  Cool at constant rate  decreases at fixed temperature Aging reinitialized when cooling resumes

Thermal vs. Quantum Aging Quantum aging More pronounced & crosses hysteresis Quantum rejuvenation Increases to meet the reference curve  ’ (emu/cm 3 ) Temperature (K) Aging Cooling Reference Warming Reference  ’ (emu/cm 3 ) H t (kOe) Aging Decreasing Reference Increasing Reference

Erasing the Memory (1)Quench system into the spin glass and age (2) Small step to a lower H t rejuvenates (3) On warming, system should remember the original state Negative effective aging time 2.5kG2kG2.5kG t1t1 t2t2 t3t3 Time (s)  ’ (emu/cm 3 ) Time (s)  ’ (emu/cm 3 ) Time (s)  ’ (emu/cm 3.)

Time (s)  ’ (emu/cm 3.) Time (s) Grandfather states Greater Erasure with Greater Excursions

The Spin Liquid Examples: CuHpCl, Gd 3 Ga 5 O 12 (3D geometric frustration) Tb 2 Ti 2 O 7, LiHo Y F 4 (quantum fluctuations) SrCu 2 (BO 3 ) 2, Cs 2 CuCl 4 (2D triangular lattice) —Geometric frustration —Quantum fluctuations —Reduced dimensionality No long range order as T  0 Not a spin glass – spins not frozen, fluctuations persist Not a paramagnet – develops short-range correlations Collective behavior What prevents freezing ?

LiHo Y F 4 Addressing Bits in the Spin Liquid Encode Information Excite collective excitations with long coherence times (seconds): Rabi Oscillations Separate competing ground states Use non-linear dynamics to…

Signatures of spin liquid no peak in   no LRO sub-Curie T dependence  correlations T T -1 dc susceptibility

Quantum fluctuations Ising axis HH H  E E -E H  ≠ 0 ––  +  + a  +   +  + b  +  –– E -E H  = 0    

Quantum spin liquid H t = 0H t ≠ 0

 ac narrows with decreasing T  “Antiglass” Dynamic magnetic susceptibility

Scaled susceptibility Relaxation spectral widths : Debye width (1.14 decades in f) single relaxation time if broader… multiple relaxation times e.g. glasses if narrower… not relaxation spectrum FWHM ≤ 0.8 decades in f

Hole Burning * cm -3 spins missing ~ 1% available * Excitations labeled by f pump probe

Simultaneous Encoding Square pump at 3 Hz 9 Hz hole 3 Hz hole

Coherent Oscillations 5Hz Q ~ 50

Brillouin Fit Magnetization Phase ac Excitation Spins per Cluster

Gd 3 Ga 5 O 12 GGG : Geometrically frustrated, Heisenberg AFM exchange coupling Phase diagram P.Schiffer, A. Ramirez, D. A. Huse and A. J. Valentino PRL

Encryption in GGG… …in the liquidbut not in the glass

Decoherence from the (nuclear) Spin Bath

Conclusions Li(Ho,Y)F 4 a model solid state system to test quantum annealing – quantum fluctuations and ground state complexity can be regulated independently Quantum annealing allows search of different minima, speedier optimization and memory erasure in glasses Coherent excitations in spin liquids of hundreds of spins labeled by frequency can encode information: cf. NMR computing Self-assembly common to “hard” quantum systems

S. Ghosh, J. Brooke, R. Parthasarathy, C. Ancona-Torres, T. F. Rosenbaum University of Chicago G. Aeppli University College, London S. N. Coppersmith University of Wisconsin, Madison