TY - Generic
T1 - Utility of the inverse partial fluorescence for electronic structure studies of battery materials
JF - Applied Physics Letters
Y1 - 2012
A1 - H. Wadati
A1 - A. J. Achkar
A1 - D.G. Hawthorn
A1 - T.Z. Regier
A1 - M. P. Singh
A1 - Truong, K. D.
A1 - P. Fournier
A1 - G. Chen
A1 - T. Mizokawa
A1 - G.A. Sawatzky
KW - electronic structure
KW - fluorescence
KW - secondary cells
KW - X-ray absorption spectra
ER -
TY - Generic
T1 - Magnetic properties and phonon behavior of Pr[sub 2]NiMnO[sub 6] thin films
JF - Applied Physics Letters
Y1 - 2011
A1 - M. P. Singh
A1 - Truong, K. D.
A1 - S. Jandl
A1 - P. Fournier
KW - ferromagnetic materials; magnetic epitaxial layers; magnetic transition temperature; magnetisation; nickel compounds; praseodymium compounds; pulsed laser deposition; Raman spectra; spin-phonon interactions
ER -
TY - Generic
T1 - Evidence of substrate induced charge order quenching, insulator metal transition, and colossal magnetoresistance in polycrystalline Pr[sub 0.58]Ca[sub 0.42]MnO[sub 3] thin films
JF - Applied Physics Letters
Y1 - 2010
A1 - Vasudha Agarwal
A1 - R. Prasad
A1 - M. P. Singh
A1 - P. K. Siwach
A1 - Amit Srivastava
A1 - P. Fournier
A1 - H. K. Singh
KW - calcium compounds
KW - charge-ordered states
KW - colossal magnetoresistance
KW - ferromagnetic materials
KW - ground states
KW - hysteresis
KW - magnetic moments
KW - magnetic thin films
KW - magnetoelectric effects
KW - metal-insulator transition
KW - metamagnetism
KW - praseodymium compounds
KW - spin glasses
ER -
TY - Generic
T1 - Multiferroic double perovskites: Opportunities, issues, and challenges
JF - Journal of Applied Physics
Y1 - 2010
A1 - M. P. Singh
A1 - Truong, K. D.
A1 - S. Jandl
A1 - P. Fournier
KW - ferromagnetic materials
KW - ground states
KW - magnetoelectric effects
KW - multiferroics
KW - pulsed laser deposition
KW - spin-phonon interactions
ER -
TY - Generic
T1 - Phase formation, phonon behavior, and magnetic properties of novel ferromagnetic La[sub 3]BAlMnO[sub 9] (B = Co or Ni) triple perovskites
JF - Journal of Applied Physics
Y1 - 2010
A1 - M. P. Singh
A1 - Truong, K. D.
A1 - S. Jandl
A1 - P. Fournier
KW - aluminium compounds
KW - cobalt compounds
KW - ferromagnetic materials
KW - lanthanum compounds
KW - magnetic thin films
KW - magnetic transition temperature
KW - magnetisation
KW - magnetoelectric effects
KW - manganese compounds
KW - multiferroics
KW - spin-phonon interactions
KW - superexchange interactions
ER -
TY - Generic
T1 - Growth, magnetic properties, and Raman scattering of La[sub 2]NiMnO[sub 6] single crystals
JF - Journal of Applied Physics
Y1 - 2009
A1 - M. N. Iliev
A1 - M. M. Gospodinov
A1 - M. P. Singh
A1 - J. Meen
A1 - Truong, K. D.
A1 - P. Fournier
A1 - S. Jandl
KW - crystal defects
KW - crystal growth from solution
KW - ferromagnetic materials
KW - lanthanum compounds
KW - magnetisation
KW - nickel compounds
KW - Raman spectra
ER -
TY - Generic
T1 - Influence of Ni/Mn cation order on the spin-phonon coupling in multifunctional La[sub 2]NiMnO[sub 6] epitaxial films by polarized Raman spectroscopy
JF - Physical Review B
Y1 - 2009
A1 - Truong, K. D.
A1 - M. P. Singh
A1 - S. Jandl
A1 - P. Fournier
KW - Brillouin zones
KW - ferromagnetic materials
KW - lanthanum compounds
KW - long-range order
KW - magnetic epitaxial layers
KW - magnetisation
KW - nickel compounds
KW - soft modes
KW - spin-phonon interactions
ER -
TY - Generic
T1 - Long-range Ni/Mn structural order in epitaxial double perovskite La[sub 2]NiMnO[sub 6] thin films
JF - Physical Review B
Y1 - 2009
A1 - M. P. Singh
A1 - Truong, K. D.
A1 - S. Jandl
A1 - P. Fournier
KW - Brillouin zones
KW - crystal symmetry
KW - ferromagnetic-paramagnetic transitions
KW - lanthanum compounds
KW - lattice constants
KW - long-range order
KW - magnetic epitaxial layers
KW - magnetisation
KW - nickel compounds
KW - Raman spectra
KW - solid-state phase transformations
KW - X-ray diffraction
ER -
TY - Generic
T1 - Stabilization and functional properties of La[sub 3]NiAlMnO[sub 9] and La[sub 3]CoAlMnO[sub 9] magnetoelectric triple perovskites
JF - Applied Physics Letters
Y1 - 2009
A1 - M. P. Singh
A1 - Truong, K. D.
A1 - S. Jandl
A1 - P. Fournier
KW - aluminium compounds
KW - cobalt compounds
KW - electron spin polarisation
KW - ferromagnetic materials
KW - lanthanum compounds
KW - magnetic thin films
KW - magnetic transitions
KW - magnetoelectric effects
KW - nickel compounds
KW - permittivity
KW - phonons
KW - pulsed laser deposition
ER -
TY - Generic
T1 - Terahertz magnetotransport measurements in underdoped Pr[sub 2 - x]Ce[sub x]CuO[sub 4] and comparison with angle-resolved photoemission
JF - Physical Review B
Y1 - 2009
A1 - Jenkins, G. S.
A1 - Schmadel, D. C.
A1 - Bach, P. L.
A1 - R.L. Greene
A1 - Béchamp-Laganière, X.
A1 - Roberge, G.
A1 - P. Fournier
A1 - Drew, H. D.
KW - carrier relaxation time
KW - cerium compounds
KW - copper compounds
KW - Fermi surface
KW - galvanomagnetic effects
KW - high-temperature superconductors
KW - praseodymium compounds
ER -
TY - Generic
T1 - Anomalously large ferromagnetic Curie temperature of epitaxial Bi[sub 2]CoMnO[sub 6] thin films
JF - Applied Physics Letters
Y1 - 2008
A1 - M. P. Singh
A1 - Truong, K. D.
A1 - P. Fournier
A1 - Rauwel, P.
A1 - E. Rauwel
A1 - L.P. Carignan
A1 - D. Ménard
KW - bismuth compounds
KW - cobalt compounds
KW - coercive force
KW - ferromagnetic materials
KW - lanthanum compounds
KW - magnetic hysteresis
KW - magnetic structure
KW - magnetic thin films
KW - magnetoelastic effects
KW - strontium compounds
ER -
TY - Generic
T1 - Quantum reference frames and deformed symmetries
JF - Phys. Rev. D
Y1 - 2008
A1 - F. Girelli
A1 - Poulin, D.
KW - Foundations
KW - Gravity
KW - Reference frame
AB - In the context of constrained quantum mechanics, reference systems are used to construct relational observables that are invariant under the action of the symmetry group. Upon measurement of a relational observable, the reference system undergoes an unavoidable measurement ``back-action" that modifies its properties. In a quantum-gravitational setting, it has been argued that such a back-action may produce effects that are described at an effective level as a form of deformed (or doubly) special relativity. We examine this possibility using a simple constrained system that has been extensively studied in the context of quantum information. While our conclusions support the idea of a symmetry deformation, they also reveal a host of other effects that may be relevant to the context of quantum gravity, and could potentially conceal the symmetry deformation.
ER -
TY - Generic
T1 - The Variational Cluster Approximation for Hubbard Models: Practical Implementation
JF - High Performance Computing Systems and Applications, 2008. HPCS 2008. 22nd International Symposium on
Y1 - 2008
A1 - D. Sénéchal
KW - correlated electron systems
KW - frequency- wavevector integrals
KW - high-temperature superconductors
KW - Hubbard model
KW - integral equations
KW - lattice sites
KW - lattice theory
KW - molecular electronic states
KW - organic superconductors
KW - organic superconductorsHubbard models
KW - Sans titre
KW - senechal
KW - variational cluster approximation
ER -
TY - Generic
T1 - Collective modes of CP[sup 3] skyrmion crystals in quantum Hall ferromagnets
JF - Physical Review B (Condensed Matter and Materials Physics)
Y1 - 2007
A1 - René Côté
A1 - D. B. Boisvert
A1 - Bourassa, J.
A1 - Boissonneault, M.
A1 - H. A. Fertig
KW - FERROMAGNETISM
KW - ground states
KW - phonons
KW - quantum Hall effect
KW - RPA calculations
KW - skyrmions
KW - spin systems
KW - tunnelling
KW - two-dimensional electron gas
KW - Zeeman effect
ER -
TY - Generic
T1 - Different roles of cerium substitution and oxygen reduction in transport in Pr[sub 2 - x]Ce[sub x]CuO[sub 4] thin films
JF - Physical Review B
Y1 - 2007
A1 - J. Gauthier
A1 - S. Gagné
A1 - J. Renaud
A1 - M.-È. Gosselin
A1 - P. Fournier
A1 - P. Richard
KW - annealing
KW - antiferromagnetism
KW - carrier density
KW - cerium compounds
KW - doping
KW - frustration
KW - high-temperature superconductors
KW - hole mobility
KW - laser ablation
KW - praseodymium compounds
KW - quasiparticles
KW - superconducting thin films
KW - vacancies (crystal)
ER -
TY - Generic
T1 - Evidence of bidomain structure in double-perovskite La[sub 2]CoMnO[sub 6] thin films
JF - Applied Physics Letters
Y1 - 2007
A1 - M. P. Singh
A1 - S. Charpentier
A1 - Truong, K. D.
A1 - P. Fournier
KW - cobalt compounds
KW - ferromagnetic materials
KW - insulating thin films
KW - lanthanum compounds
KW - magnetic domains
KW - magnetic epitaxial layers
KW - magnetic transitions
KW - MAGNETORESISTANCE
ER -
TY - Generic
T1 - Fluctuations and topological transitions of quantum Hall stripes: Nematics as anisotropic hexatics
JF - Physical Review B (Condensed Matter and Materials Physics)
Y1 - 2007
A1 - A. M. Ettouhami
A1 - Doiron, C. B.
A1 - René Côté
KW - fluctuations
KW - Landau levels
KW - melting
KW - phase diagrams
KW - quantum Hall effect
KW - two-dimensional electron gas
KW - Wigner crystal
ER -
TY - Generic
T1 - Magnetodielectric effect in double perovskite La[sub 2]CoMnO[sub 6] thin films
JF - Applied Physics Letters
Y1 - 2007
A1 - M. P. Singh
A1 - Truong, K. D.
A1 - P. Fournier
KW - cobalt compounds
KW - Curie temperature
KW - dielectric thin films
KW - ferromagnetic materials
KW - lanthanum compounds
KW - magnetoelectric effects
KW - paramagnetic materials
KW - permittivity
ER -
TY - Generic
T1 - Relational time for systems of oscillators
JF - Int. J. Quant. Info.
Y1 - 2006
A1 - Milburn, G. J.
A1 - Poulin, D.
KW - Foundations
KW - Gravity
KW - Quantum Theory
KW - Reference frame
AB - Using an elementary example based on two simple harmonic oscillators, we show how a relational time may be defined that leads to an approximate Schrödinger dynamics for subsystems, with corrections leading to an intrinsic decoherence in the energy eigenstates of the subsystem.
ER -
TY - Generic
T1 - Toy model for a relational formulation of quantum theory
JF - Int. J. of Theor. Phys.
Y1 - 2006
A1 - Poulin, D.
KW - Foundations
KW - Gravity
KW - Measurement
KW - Quantum Theory
KW - Reference frame
AB - In the absence of an external frame of reference –- i.e. in background independent theories such as general relativity –- physical degrees of freedom must describe {\em relations} between systems. Using a simple model, we investigate how such a relational quantum theory naturally arises by promoting reference systems to the status of dynamical entities. Our goal is twofold. First, we demonstrate using elementary quantum theory how any quantum mechanical experiment admits a purely relational description at a fundamental level. Second, we describe how the original ``non-relational" theory approximately emerges from the fully relational theory when reference systems become semi-classical. Our technique is motivated by a Bayesian approach to quantum mechanics, and relies on the noiseless subsystem method of quantum information science used to protect quantum states against undesired noise. The relational theory naturally predicts a fundamental decoherence mechanism, so an arrow of time emerges from a time-symmetric theory. Moreover, our model circumvents the problem of the ``collapse of the wave packet" as the probability interpretation is only ever applied to diagonal density operators. Finally, the physical states of the relational theory can be described in terms of ``spin networks" introduced by Penrose as a combinatorial description of geometry, and widely studied in the loop formulation of quantum gravity. Thus, our simple bottom-up approach (starting from the semi-classical limit to derive the fully relational quantum theory) may offer interesting insights on the low energy limit of quantum gravity.
ER -
TY - Generic
T1 - Environment as a Witness: Selective Proliferation of Information and Emergence of Objectivity
JF - Physical Review A
Y1 - 2005
A1 - Ollivier, H.
A1 - Poulin, D.
A1 - Zurek, W. H.
KW - Decoherence
KW - Foundations
KW - Quantum Theory
AB - We study the role of the information deposited in the environment of an open quantum system in course of the decoherence process. Redundant spreading of information –- the fact that some observables of the system can be independently ``read-off'' from many distinct fragments of the environment –- is investigated as the key to effective objectivity, the essential ingredient of ``classical reality''. This focus on the environment as a communication channel through which observers learn about physical systems underscores importance of quantum Darwinism –- selective proliferation of information about ``the fittest states'' chosen by the dynamics of decoherence at the expense of their superpositions –- as redundancy imposes the existence of preferred observables. We demonstrate that the only observables that can leave multiple imprints in the environment are the familiar pointer observables singled out by environment-induced superselection (einselection) for their predictability. Many independent observers monitoring the environment will therefore agree on properties of the system as they can only learn about preferred observables. In this operational sense, the selective spreading of information leads to appearance of an objective ``classical reality'' from within quantum substrate.
ER -
TY - Generic
T1 - Macroscopic Observables
JF - Physical Review A
Y1 - 2005
A1 - Poulin, D.
KW - Decoherence
KW - Emergent
KW - Foundations
KW - Quantum Theory
KW - Renormalization
AB - We study macroscopic observables defined as the total value of a physical quantity over a collection of quantum systems. We show that previous results obtained for infinite ensemble of identically prepared systems lead to incorrect conclusions for finite ensembles. In particular, exact measurement of a macroscopic observable significantly disturbs the state of any finite ensemble. However, we show how this disturbance can be made arbitrarily small when the measurement are of finite accuracy. We demonstrate a general tradeoff between state disturbance and measurement coarseness as a function of the size of the ensemble. Using this tradeoff, we show that the histories generated by any sequence of finite accuracy macroscopic measurements always generate a consistent family in the absence of large scale entanglement, for sufficiently large ensembles. Hence, macroscopic observables behave ``classically" provided that their accuracy is coarser than the quantum correlation length-scale of the system. The role of these observable is also discussed in the context of NMR quantum information processing and bulk ensemble quantum state tomography.
ER -
TY - Generic
T1 - Objective properties from subjective quantum states: Environment as a witness
JF - Physical Review Letters
Y1 - 2004
A1 - Ollivier, H.
A1 - Poulin, D.
A1 - Zurek, W. H.
KW - Decoherence
KW - Foundations
KW - Quantum Theory
AB - We study the emergence of objective properties in open quantum systems. In our analysis, the environment is promoted from a passive role of reservoir selectively destroying quantum coherence, to an active role of amplifier selectively proliferating information about the system. We show that only preferred pointer states of the system can leave a redundant and therefore easily detectable imprint on the environment. Observers who–-as it is almost always the case–-discover the state of the system indirectly (by probing a fraction of its environment) will find out only about the corresponding pointer observable. Many observers can act in this fashion independently and without perturbing the system: they will agree about the state of the system. In this operational sense, em preferred pointer states exist objectively.
ER -
TY - Generic
T1 - Compatibility of quantum states
JF - Physical Review A
Y1 - 2003
A1 - Poulin, D.
A1 - Blume–Kohout, R.
KW - Foundations
AB - We introduce a measure of the compatibility between quantum states–-the likelihood that two density matrices describe the same object. Our measure is motivated by two elementary requirements, which lead to a natural definition. We list some properties of this measure, and discuss its relation to the problem of combining two observers' states of knowledge.
ER -
TY - Generic
T1 - Classicality of Quantum Information Processing
JF - Physical Review A
Y1 - 2001
A1 - Poulin, D.
KW - Foundations
AB - The ultimate goal of the classicality program is to quantify the amount of quantumness of certain processes. Here, classicality is studied for a restricted type of process: quantum information processing (QIP). Under special conditions, one can force some qubits of a quantum computer into a classical state without affecting the outcome of the computation. The minimal set of conditions is described and its structure is studied. Some implications of this formalism are the increase of noise robustness, a proof of the quantumness of mixed state quantum computing and a step forward in understanding the very foundation of QIP.
ER -
TY - Generic
T1 - The complex magnetic behavior and the role of dynamic structural fluctuations in La[sub 1.2]Sr[sub 1.8]Mn[sub 2]O[sub 7] crystals
JF - The 7th joint MMM-intermag conference on magnetism and magnetic materials
Y1 - 1998
A1 - R.P. Sharma
A1 - P. Fournier
A1 - R.L. Greene
A1 - T. Venkatesan
A1 - J. F. Mitchell
A1 - D. Miller
KW - channelling
KW - ferromagnetic materials
KW - FERROMAGNETISM
KW - giant magnetoresistance
KW - ION CHANNELING
KW - Jahn-Teller effect
KW - lanthanum compounds
KW - LANTHANUM OXIDES
KW - magnetic anisotropy
KW - magnetic transitions
KW - MAGNETIZATION
KW - MAGNETORESISTANCE
KW - MANGANESE OXIDES
KW - neutron diffraction
KW - paramagnetic materials
KW - PARAMAGNETISM
KW - PEROVSKITES
KW - strontium compounds
KW - STRONTIUM OXIDES
KW - TEMPERATURE DEPENDENCE
ER -