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  • 151.
    Pietzsch, A.
    et al.
    MAX-lab, Lund University, Box 118, S-221 00 Lund, Sweden.
    Sun, Y. -P
    Department of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, S-106 91 Stockholm, Sweden.
    Hennies, Franz
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Rinkevicius, Z.
    Department of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, S-106 91 Stockholm, Sweden.
    Karlsson, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Schmitt, T.
    Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
    Strocov, V. N.
    Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
    Andersson, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Kennedy, B.
    MAX-lab, Lund University, Box 118, S-221 00 Lund, Sweden.
    Schlappa, J.
    Institute for Methods and Instrumentation in Synchrotron Radiation Research G-I2, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany.
    Foehlisch, A.
    Institute for Methods and Instrumentation in Synchrotron Radiation Research G-I2, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany.
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Gel'mukhanov, F.
    Department of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, S-106 91 Stockholm, Sweden.
    Spatial Quantum Beats in Vibrational Resonant Inelastic Soft X-Ray Scattering at Dissociating States in Oxygen2011In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 106, no 15, p. 153004-1-153004-4Article in journal (Refereed)
    Abstract [en]

    Resonant inelastic soft x-ray scattering (RIXS) spectra excited at the 1 sigma(g) -> 3 sigma(u) resonance in gas-phase O-2 show excitations due to the nuclear degrees of freedom with up to 35 well-resolved discrete vibronic states and a continuum due to the kinetic energy distribution of the separated atoms. The RIXS profile demonstrates spatial quantum beats caused by two interfering wave packets with different momenta as the atoms separate. Thomson scattering strongly affects both the spectral profile and the scattering anisotropy.

  • 152. Pitonak, Michal
    et al.
    Aquilante, Francesco
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Hobza, Pavel
    Neogrady, Pavel
    Noga, Jozef
    Urban, Miroslav
    Parallelized implementation of the CCSD(T) method in molcas using optimized virtual orbitals space and cholesky decomposed two-electron integrals2011In: Collection of Czechoslovak Chemical Communications, ISSN 0010-0765, E-ISSN 1212-6950, Vol. 76, no 6, p. 713-742Article in journal (Refereed)
    Abstract [en]

    Parallelized implementation of the coupled cluster singles doubles with non-iterative triples in the MOLCAS program suite is described. The code benefits from the Cholesky decomposition of two-electron integrals and the algorithm is particularly designed for calculations using reduced optimized virtual orbital space. Different aspects of parallelization and its efficiency are discussed based on our recent successful calculations for medium sized molecules involving more than 1000 basis functions.

  • 153. Robb, Mike
    et al.
    Siegbahn, Per
    Lindh, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Foreword: Special Issue, A Celebration of the Scientific Achievements of Bjorn O. Roos2011In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 111, no 13, p. 3255-3255Article in journal (Refereed)
  • 154.
    Rudolfsson, Pierre
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Relative state measures of correlations in bipartite quantum systems2012In: Quantum information & computation, ISSN 1533-7146, Vol. 12, no 1-2, p. 119-137Article in journal (Refereed)
    Abstract [en]

    Everett's concept of relative state can be viewed as a map that contains information about correlations between measurement outcomes on two quantum systems. We demonstrate how geometric properties of the relative state map can be used to develop operationally well-defined measures of the total correlation in bipartite quantum systems of arbitrary state space dimension. These measures are invariant under local unitary transformations and non-increasing under local operations. We show that some known correlation measures have a natural interpretation in terms of relative states.

  • 155. Sabin, John R.
    et al.
    Brändas, Erkki J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Preface2009In: Advances in Quantum Chemistry / [ed] J. Sabin, E. Brändas, Academic Press, 2009, p. ix-Chapter in book (Other (popular science, discussion, etc.))
  • 156. Saenz, Alejandro
    et al.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Effect of final-state interactions in allowed beta decays .II. Reliability of the beta-decay spectrum for T-21997In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 56, no 4, p. 2162-2184Article in journal (Refereed)
  • 157. Saenz, Alejandro
    et al.
    Jonsell, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Improved molecular final-state distribution of HeT+ for the beta-decay process of T-22000In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 84, no 2, p. 242-245Article in journal (Refereed)
    Abstract [en]

    An improved theoretical final-state distribution of HeT+ (and HeH+) resulting front the beta decay of molecular tritium T-2 (HT) is presented to accommodate the needs of increased accuracy in the analysis of ongoing and future tritium neutrino-mass experiments. The previously available theoretical spectrum has been improved in many respects, and adopted approximations have been validated.

  • 158. Saenz, Alejandro
    et al.
    Weyrich, Wolf
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    The first Born approximation and absolute scattering cross sections1996In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 29, no 1, p. 97-113Article in journal (Refereed)
    Abstract [en]

    The problem of bringing experimental electron-scattering cross sections to the absolute scale using the so-called Lassettre theorem is addressed. Experimental data that have been measured by electron-scattering experiments for different incident energies (in the range of 100 to 600 eV) and have been normalized on the basis of this theorem are compared with absolute cross sections that have been calculated within the first Born approximation by means of the complex-scaling method. The agreement is not found to be satisfactory even for the smallest values of momentum transfer. This, however, is a contradiction to Lassettre's theorem. A new normalization procedure for the experimental data is suggested that has yielded good agreement between the present calculated and the measured data even for a comparatively large range of momentum transfer. This indicates an extended range of validity of the first Born approximation.

  • 159. Sala, Xavier
    et al.
    Ertem, Mehmed Z.
    Vigara, Laura
    Todorova, Tanya K.
    Chen, Weizhong
    Rocha, Reginaldo C.
    Aquilante, Francesco
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Cramer, Christopher J.
    Gagliardi, Laura
    Llobet, Antoni
    The cis-[Ru-II(bpy)(2)(H2O)(2)](2+) Water-Oxidation Catalyst Revisited2010In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 49, no 42, p. 7745-7747Article in journal (Refereed)
  • 160. Schapiro, Igor
    et al.
    Ryanzantsev, Mikhail Nikolaevich
    Frutos, Luis Manuel
    Ferré, Nicolas
    Lindh, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Olivucci, Massimo
    The Ultrafast Photoisomerizations of Rhodopsin and Bathorhodopsin Are Modulated by Bond Length Alternation and HOOP Driven Electronic Effects2011In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 133, no 10, p. 3354-3364Article in journal (Refereed)
    Abstract [en]

    Rhodopsin (Rh) and bathorhodopsin (bathoRh) quantum-mechanics/molecular-mechanics models based on ab initio multiconfigurational wave functions are employed to look at the light induced π-bond breaking and reconstitution occurring during the RhfbathoRh and bathoRhfRh isomerizations. More specifically, semiclassical trajectory computations are used to compare the excited (S1) and ground (S0) state dynamics characterizing the opposite steps of the Rh/bathoRh photochromic cycle during the first 200 fs following photoexcitation. We show that the information contained in these data provide an unprecedented insight into the sub-picosecond π-bond reconstitution process which is at the basis of the reactivity of the protein embedded 11-cis and all-trans retinal chromophores.More specifically, the data point to the phase and amplitude of the skeletal bond length alternation stretchingmode as the key factor switching the chromophore to a bonding state. It is also confirmed/found that the phase and amplitude of the hydrogen-out-of-plane mode controls the stereochemical outcome of the forward and reverse photoisomerizations.

  • 161.
    Schnadt, Joachim
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Department of Physics and Materials Science, Physics I. Physics V.
    Brühwiler, Paul A.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Department of Physics and Materials Science, Physics I. Physics V.
    Patthey, Luc
    O'Shea, James N.
    Södergren, Sven
    Department of Physical Chemistry. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Department of Physics and Materials Science, Physics I. Physics V.
    Odelius, Michael
    Persson, Petter
    Department of Quantum Chemistry. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Department of Physics and Materials Science, Physics I. Physics V.
    Siegbahn, Hans
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Department of Physics and Materials Science, Physics I. Physics V. Fysik I.
    Lunell, Sten
    Department of Quantum Chemistry. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Department of Physics and Materials Science, Physics I. Physics V.
    Mårtensson, Nils
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Department of Physics and Materials Science, Physics I. Physics V.
    Experimental evidence for sub-3-fs charge transfer from an aromatic adsorbate to a semiconductor2002In: Nature, ISSN 0028-0836, Vol. 418, no 6898, p. 620-623Article in journal (Refereed)
    Abstract [en]

    The ultrafast timescale of electron transfer processes is crucial to their role in many biological systems and technological devices. In dye-sensitized solar cells(1-4), the electron transfer from photoexcited dye molecules to nanostructured semiconductor

  • 162.
    Shiotani, Masaru
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Lund, Anders
    Linköpings universitet.
    Lunell, Sten
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Williams, Ffrancon
    Department of Chemistry, University of Tennessee.
    Structures of the hexafluorocyclopropane, octafluorocyclobutane, and decafluorocyclopentane radical anions probed by experimental and computational studies of anisotropic electron spin resonance (ESR) spectra2007In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 111, no 2, p. 321-338Article in journal (Refereed)
    Abstract [en]

    Anisotropic electron spin resonance (ESR) spectra are reported for the radical anions of hexafluorocyclopropane (c-C3F6-), octafluorocyclobutane (c-C4F8-), and decafluorocyclopentane (c-C5F10-) generated via gamma-irradiation in plastically crystalline tetramethylsilane (TMS) and rigid 2-methyltetrahydrofuran (MTHF) matrices. By combining the analysis of these experimental ESR spectra involving anisotropic hyperfine (hf) couplings with a series of quantum chemical computations, the geometrical and electronic structure of these unusual perfluorocycloalkane radical anions have been characterized more fully than in previous studies that considered only the isotropic couplings. Unrestricted Hartree-Fock (UHF) computations with the 6-311+G(d,p) basis set predict planar ring structures for all three radical anions, the ground electronic states being (2)A(2)" for c-C3F6- (D-3h symmetry), (2)A(2u) for c-C4F8- (D-4h), and (2)A(2)" for c-C5F10- (D-5h), in which the respective six, eight, and ten F-19-atoms are equivalent by symmetry. A successful test of the theoretical computation is indicated by the fact that the isotropic F-19 hf couplings computed by the B3LYP method with the 6-311+G(2df,p) basis set for the optimized geometries are in almost perfect agreement with the experimental values: viz., 19.8 mT (exp) vs 19.78 mT (calc) for c-C3F6-; 14.85 mT (exp) vs 14.84 mT (calc) for c-C4F8-; 11.6 mT (exp) vs 11.65 mT (calc) for c-C5F10-. Consequently, the same computation method has been applied to calculate the almost axially symmetric anisotropic F-19 hf couplings for the magnetically equivalent F-19 atoms: (-4.90 mT, -4.84 mT, 9.75 mT) for c-C3F6-, (-3.54 mT, -3.48 mT, 7.02 mT) for c-C4F8-, and (-2.62 mT, -2.56 mT, 5.18 mT) for c-C5F10-. ESR spectral simulations performed using the computed principal values of the hf couplings and the spatial orientations of the F-19 nuclei as input parameters reveal an excellent fit to the experimental anisotropic ESR spectra of c-C3F6-, c-C4F8-, and c-C5F10-, thereby providing a convincing proof of the highly symmetric D-nh structures that are predicted for these negative ions. Furthermore, using the computed F-19 principal values and their orientations, the effective F-19 anisotropic hf couplings along the molecular symmetry axes were evaluated for c-C3F6- and c-C4F8- and successfully correlated with the positions of the characteristic outermost features in both the experimental and calculated anisotropic spectra. In addition, the electronic excitation energies and oscillator strengths for the c-C3F6-, c-C4F8-, and c-C5F10- radical anions were computed for the first time using time-dependent density functional theory (TD-DFT) methods.

  • 163.
    Shiotani, Masaru
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Persson, Petter
    Physics, Department of Quantum Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Quantum Chemistry.
    Lunell, Sten
    Physics, Department of Quantum Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry. Quantum Chemistry.
    Lund, Anders
    Williams, Ffrancon
    Structures of Tetrafluorocyclopropene, Hexafluorocyclobutene, Octafluorocyclopentene and Related Perfluoroalkene Radical Anions Revealed by ESR Spectroscopic and Computational Studies2006In: Journal of Physical Chemistry A, Vol. 110, p. 6307-Article in journal (Refereed)
  • 164. Siegbahn, Per
    et al.
    Lindh, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Bjorn O. Roos: 1937-2010 Mentor, Colleague, Innovator2011In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 111, no 13, p. 3256-3259Article in journal (Refereed)
  • 165.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    A new phase in quantum computation2008In: Physics, ISSN 1943-2879, Vol. 1, no 35Article, review/survey (Other academic)
    Abstract [en]

    Large-scale quantum computers are hard to construct because quantum systems easily lose their coherence through interaction with the environment. Researchers have tried to avoid this problem by using geometric phase shifts in the design of quantum gates to perform information processing. Experiments and simulations have shown that these gates may be tolerant to certain types of faults, and may therefore be useful for robust quantum computation.

  • 166.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Book review of 'More than one mystery: explorations in quantum interference' by M.P. Silverman1996In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 58, no 5, p. 535-535Article, book review (Other academic)
  • 167.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Entanglement-induced geometric phase of quantum states2010In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 374, no 13-14, p. 1431-1433Article in journal (Refereed)
    Abstract [en]

    The concept of relative state is used to introduce geometric phases that originate from correlations in states of composite quantum systems. In particular, we identify an entanglement-induced geometric phase in terms of a weighted average of geometric phase factors associated with a decomposition that define the entanglement of formation. An explicit procedure to calculate the entanglement-induced geometric phase for qubit pairs is put forward. We illustrate it for maximally entangled mixed states (MEMS) of two qubits.

  • 168.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Geometric phase in weak measurements2006In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 359, no 3, p. 187-189Article in journal (Refereed)
    Abstract [en]

    Pancharatnam's geometric phase is associated with the phase of a complex-valued weak value arising in a certain type of weak measurement in pre- and post-selected quantum ensembles. This makes it possible to test the nontransitive nature of the relative phase in quantum mechanics, in the weak measurement scenario.

  • 169.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Pancharatnam revisited2002In: Quantum Theory: Reconsideration of Foundations / [ed] Andrei Khrennikov, 2002, p. 343-Conference paper (Other academic)
    Abstract [en]

    Some recent ideas concerning Pancharatnam's prescription of relative phase between quantal states are delineated. Generalisations to mixed states and entangled two-photon states are discussed. An experimental procedure to test the geometric phase as a Pancharatnam relative phase is described. We further put forward a spatial split-beam dual to Pancharatnam's relative phase.

  • 170.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Reply to Comment on `Locality and topology in the molecular Aharonov-Bohm effect'2003In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 91, no 4, p. 048902-048902Article in journal (Refereed)
    Abstract [en]

    A Reply to the Comment by R. Resta in [Phys. Rev. Lett. 91, 048901 (2003)] on the Letter in [Phys. Rev. Lett. 89, 210401 (2002)].

  • 171.
    Sjöqvist, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Filipp, Stefan
    Institut für Theoretische Physik, TU-Wien, Austria.
    Off-diagonal mixed state phases in unitary evolution2003In: Foundations of probability and physics - 2, 2003, p. 545-555Conference paper (Other academic)
    Abstract [en]

    Off-diagonal mixed state phases based upon a concept of orthogonality adapted to unitary evolution and a proper normalisation condition are introduced. Some particular instances are analysed and parallel transport leading to the off-diagonal mixed state geometric phase is delineated. A complete experimental realisation of the off-diagonal mixed state geometric phases in the qubit case using polarisation-entangled two-photon interferometry is proposed.

  • 172.
    Sjöqvist, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Rahaman, Ramij
    Selmer Center, Department of Informatics, University of Bergen, Bergen N5020, Norway .
    Basu, Urna
    Theoretical Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Kolkata 700 064, India .
    Basu, Banasri
    Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700 108, India .
    Berry phase and fidelity susceptibility of the three-qubit Lipkin–Meshkov–Glick ground state2010In: Journal of Physics A: Mathematical and General, ISSN 0305-4470, E-ISSN 1361-6447, Vol. 43, no 35, p. 354026-Article in journal (Refereed)
    Abstract [en]

    Berry phases and quantum fidelities for interacting spins have attracted considerable attention, particularly in relation to entanglement properties of spin systems and quantum phase transitions. These efforts mainly focus either on spin pairs or the thermodynamic infinite spin limit, while studies of the multi-partite case of a finite number of spins are rare. Here we analyze Berry phases and quantum fidelities of the ground state of a Lipkin–Meshkov–Glick model consisting of three spin-1/2 particles (qubits). We find explicit expressions for the Berry phase and fidelity susceptibility of the full system as well as the mixed-state Berry phase and partial-state fidelity susceptibility of its one- and two-qubit subsystems. We demonstrate a realization of a nontrivial magnetic monopole structure associated with local, coordinated rotations of the three-qubit system around the external magnetic field.

  • 173.
    Sjöqvist, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Tong, Dianmin
    Dept. of Physics, Shandong University, China.
    Andersson, Mauritz
    Dept. of Applied Physics, KTH.
    Hessmo, Björn
    Centre for Quantum Technologies, NUS, Singapore.
    Johansson, Markus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Singh, Kuldip
    Centre for Quantum Technologies, NUS, Singapore.
    Non-Adiabatic Holonomic Quantum Computation2012In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 14, article id 103035Article in journal (Refereed)
    Abstract [en]

    We develop a non-adiabatic generalization of holonomic quantum computation in which high-speed universal quantum gates can be realized using non-Abelian geometric phases. We show how a set of non-adiabatic holonomic one- and two-qubit gates can be implemented by utilizing optical transitions in a generic three-level Λ configuration. Our scheme opens up the possibility of realizing universal holonomic quantum computation on qubits characterized by short coherence time.

  • 174. Srnec, Martin
    et al.
    Aquilante, Francesco
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Ryde, Ulf
    Rulisek, Lubomir
    Reaction Mechanism of Manganese Superoxide Dismutase Studied by Combined Quantum and Molecular Mechanical Calculations and Multiconfigurational Methods2009In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 113, no 17, p. 6074-6086Article in journal (Refereed)
    Abstract [en]

    Manganese superoxide dismutases (MnSODs) are enzymes that convert two molecules of the poisonous superoxide radical into molecular oxygen and hydrogen peroxide. During the reaction, the manganese ion cycles between the Mn2+ and Mn3+ oxidation states and accomplishes its enzymatic action in two half-cycles (corresponding to the oxidation and reduction of O-2(center dot-)). Despite many experimental and theoretical studies dealing with SODs, including quantum chemical active-site-model studies of numerous variants of the reaction mechanisms, several details of MnSOD enzymatic action are still unclear. In this study, we have modeled and compared four reaction pathways (one associative, one dissociative, and two second-sphere) in a protein environment using the QM/MM approach (combined quantum and molecular mechanics calculations) at the density functional theory level. The results were complemented by CASSCF/CASPT2/MM single-point energy calculations for the most plausible models to account properly for the multireference character of the various spin multiplets. The results indicate that the oxidation of O-2(center dot-) to O-2 most likely occurs by an associative mechanism following a two-state (quartet-octet) reaction profile. The barrier height is estimated to be less than 25 kJ.mol(-1). On the other hand, the conversion of O-2(center dot-) to H2O2 is likely to take place by a second-sphere mechanism, that is, without direct coordination of the superoxide radical to the manganese center. The reaction pathway involves the conical intersection of two quintet states, giving rise to an activation barrier of similar to 60 kJ.mol(-1). The calculations also indicate that the associative mechanism can represent a competitive pathway in the second half-reaction with the overall activation barrier being only slightly higher than the activation barrier in the second-sphere mechanism. The activation barriers along the proposed reaction pathways are in very good agreement with the experimentally observed reaction rates of SODs (k(cat) approximate to 10(4)-10(5) s(-1)).

  • 175.
    Strambi, Angela
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Durbeej, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Excited-state modeling of the astaxanthin dimer predicts a minor contribution from exciton coupling to the bathochromic shift in crustacyanin2009In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 113, no 15, p. 5311-5317Article in journal (Refereed)
    Abstract [en]

    The >0.50 eV bathochromic shift of the absorption by the carotenoid astaxanthin in crustacyanin, the carotenoprotein responsible for the coloration of lobster shell, is believed to result from ground-state polarization of the chromophore and/or exciton coupling between the two chromophores of each protein subunit. Here, the contribution of exciton   coupling to the shift is quantified using quantum chemical calculations that do not rely on the dipole-dipole approximation but rather consider the full astaxanthin dimer in the geometry relevant for the protein-bound state. Employing a variety of methods, it is found that the exciton coupling amounts to 0.04 eV only. Furthermore, even when more closely aggregated dimers than the one in the protein are considered, the predicted couplings remain small (0.05-0.09 eV). These findings demonstrate that the bathochromic shift cannot be explained in terms of exciton coupling. It is therefore argued that polarization is likely to be the dominant mechanism, a notion supported by the fact that calculations carried out at the same levels of theory identify a scenario (hydrogen bonding with a histidine residue) whose contribution to the shift vastly exceeds that of exciton coupling.

  • 176. Sun, Y-P
    et al.
    Pietzsch, A.
    Hennies, Franz
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Rinkevicius, Z.
    Karlsson, Hans O.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Schmitt, T.
    Strocov, V. N.
    Andersson, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Kennedy, B.
    Schlappa, J.
    Föhlisch, A.
    Gel'mukhanov, F.
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Internal symmetry and selection rules in resonant inelastic soft x-ray scattering2011In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 44, no 16, p. 161002-Article in journal (Refereed)
    Abstract [en]

    Resonant inelastic soft x-ray scattering spectra excited at the dissociative 1 sigma(g) -> 3 sigma(u) resonance in gas-phase O(2) are presented and discussed in terms of state-of-the-art molecular theory. A new selection rule due to internal spin coupling is established, facilitating a deep analysis of the valence excited final states. Furthermore, it is found that a commonly accepted symmetry selection rule due to orbital parity breaks down, as the core hole and excited electron swap parity, thereby opening the symmetry forbidden 3 sigma(g) decay channel.

  • 177.
    Suter, HU
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Quantum Chemistry. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. QUANTUM CHEMISTRY.
    Engels, B
    Lunell, S
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Quantum Chemistry. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Was H-2(-) observed in solid H-2? A theoretical answer2001In: ADVANCES IN QUANTUM CHEMISTRY, ISSN 0065-3276, Vol. 40, p. 133-142Article in journal (Refereed)
  • 178. Söderhjelm, Pär
    et al.
    Aquilante, Francesco
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Ryde, Ulf
    Calculation of Protein-Ligand Interaction Energies by a Fragmentation Approach Combining High-Level Quantum Chemistry with Classical Many-Body Effects2009In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 113, no 32, p. 11085-11094Article in journal (Refereed)
    Abstract [en]

    We have developed a method to estimate accurate interaction energies between a full protein and a bound ligand. It is based oil the recently proposed PMISP (polarizable multipole interaction with supermolecular pairs) method (Soderhjelm, P.; Ryde, U. J. Phys. Chem. A 2009, 113. 617), which treats electrostatic interaction by multipoles up to quadrupoles, induction by anisotropic polarizabilities, and nonclassical interactions by explicit quantum mechanical (QM) calculations, using a fragmentation approach. For a whole protein, electrostatics and induction are treated the same way, but for the nonclassical interactions, a Lennard-Jones term from a standard molecular mechanics (MM) force field (e.g., Amber) is used outside a certain distance from the ligand (4-7 angstrom). This QM/MM variant of the PMISP method is carefully tested by varying this distance. Several approximations related to the classical interactions are also evaluated. It is found that one can speed up the calculation by using density functional theory to compute multipoles and polarizabilities but that a proper treatment of polarization is important. As a demonstration of the method, the interaction energies of two ligands bound to avidin are calculated at the MP2/aug-cc-pVTZ level, with an expected relative error of 1-2%.

  • 179.
    Thunström, Patrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Åberg, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Adiabatic approximation for weakly open systems2005In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. A72, no 022328, p. 022328-1-022328-13Article in journal (Refereed)
    Abstract [en]

    We generalize the adiabatic approximation to the case of open quantum systems, in the joint limit of slow change and weak open system disturbances. We show that the approximation is “physically reasonable” as under wide conditions it leads to a completely positive evolution, if the original master equation can be written on a time-dependent Lindblad form. We demonstrate the approximation for a non-Abelian holonomic implementation of the Hadamard gate, disturbed by a decoherence process. We compare the resulting approximate evolution with numerical simulations of the exact equation.

  • 180.
    Tidström, Jonas
    et al.
    School of Information and Communication Technology, KTH, Sweden.
    Ericsson, Marie
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Andersson, Mauritz
    School of Information and Communication Technology, KTH, Sweden.
    Open system effects on slow light and electromagnetically induced transparency2011In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 44, no 13, p. 135501-Article in journal (Refereed)
    Abstract [en]

    The coherence properties of a three-level $\Lambda$-system influenced by a Markovian environment are analyzed. A coherence vector formalism is used and a vector form of the Lindblad equation is derived. Together with decay channels from the upper state, open system channels acting on the subspace of the two lower states are investigated, i.e., depolarization, dephasing, and amplitude damping channels. We derive an analytic expression for the coherence vector and the concomitant optical susceptibility, and analyze how the different channels influence the optical response. This response depends non-trivially on the type of open system interaction present, and even gain can be obtained. We also present a geometrical visualization of the coherence vector as an aid to understand the system response.

  • 181.
    Tong, D. M.
    et al.
    Dept. of Physics, NUS, Singapore.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Kwek, L. C.
    Dept. of Physics, NUS, Singapore.
    Oh, C. H.
    Dept. of Physics, NUS, Singapore.
    Erratum: Kinematic Approach to the Mixed State Geometric Phase in Nonunitary Evolution [Phys. Rev. Lett. 93, 080405 (2004)]2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 95, p. 249902-249902Article in journal (Other academic)
  • 182. Toriyama, Kazumi
    et al.
    Okazaki, Masaharu
    Jansson, Magnus
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Quantum Chemistry. Department of Physics. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Kvantkemi.
    Lund, Anders
    Lunell, Sten
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Quantum Chemistry. Department of Physics. Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry. Kvantkemi.
    Isotope effect on the J-T distortion of partially deuteriated benzene cation radicals: an experimental EPR and theoretical DFT study2004In: Physical Chemistry and Chemical Physics: PCCP, Vol. 6, no 1658Article in journal (Refereed)
  • 183. Vanne, Yulian
    et al.
    Saenz, Alejandro
    Dalgarno, Alex
    Forrrey, Robert
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Jonsell, Svante
    Doubly Excited Autoionizing States of H2 converging to the H(n=2) + H(n' = 2) Limit2006In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 73, no 6, p. 062706-Article in journal (Refereed)
    Abstract [en]

    A numerical investigation of the doubly excited states of H2 converging to the H(n=2)+H(n=2) limit was performed. Special emphasis was put on the accurate description of the range of intermediate internuclear distances in order to correctly connect the short range with the asymptotic van der Waals regime where perturbation theory is applicable. The present nonperturbative calculation extends to internuclear separations R=200a0 and is sufficiently accurate to achieve a connection between the two extreme regimes without any need for an interpolation procedure. The high precision of the ab initio results revealed a long range dipole-quadrupole interaction that had been omitted in two earlier calculations. In addition to revised first-order perturbation theory results the leading second-order term varying as R−6 was obtained. The impact of the present findings for cold H(n=2) collisions is briefly discussed.

  • 184. Vigo-Aguiar, J.
    et al.
    Brändas, Erkki J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Mathematical and computational tools in theoretical chemistry2009In: Journal of Mathematical Chemistry, ISSN 0259-9791, E-ISSN 1572-8897, Vol. 48, no 1, p. 1-2Article in journal (Other academic)
  • 185. Voronin, A. Yu.
    et al.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Resonant phenomena in antihydrogen-hydrogen scattering2008In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 77, no 2, p. 022505-Article in journal (Refereed)
    Abstract [en]

    We present a treatment of cold hydrogen-antihydrogen collisions based on the asymptotic properties of atom-antiatom interactions. We derive general formulas for the elastic and inelastic cross sections and for the scattering lengths and analyze their sensitivity to the parameters characterizing the inelasticity of the collision process. Given the inelasticity, we obtain bounds for the complex scattering length. We investigate the influence of strong nuclear forces and the isotope effects in H (H) over bar and D (H) over bar collisions and demonstrate enhancement of these effects due to the presence of the near-threshold narrow H (H) over bar (D (H) over bar) states. The values of the elastic and inelastic cross sections with simultaneous account of rearrangement and strong forces are presented. General expressions for the (complex) energies of the near-threshold H (H) over bar states are obtained.

  • 186.
    Voronin, Alexei
    et al.
    Lebedev Physical Institute, Moscow.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Hyperfine transitions in ultracold  hydrogen: antihydrogen collisions2009In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 80, no 1, p. 010502-Article in journal (Refereed)
    Abstract [en]

    We consider the hyperfine transitions in ultracold collisions of  hydrogen (H) and antihydrogen ((H) over bar) atoms. The cross sections for transitions between various spin states are calculated. We show that hyperfine transitions in (H) over bar -H collisions are basically driven by the strong force between proton and antiproton.

  • 187. Voronin, Alexei
    et al.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Quantum Reflection of Ultracold Antihydrogen from a Conducting Surface2005In: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616, Vol. 796, no 1, p. 280-284Article in journal (Refereed)
  • 188.
    Voronin, Alexei
    et al.
    Lebedev Physical Institute, Moscow.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Spin-exchange in hydrogen-antihydrogen collisions2009In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 42, no 12, p. 125204-Article in journal (Refereed)
    Abstract [en]

    We consider spin exchange in ultracold collisions of hydrogen (H) and antihydrogen ((H) over bar) atoms. The cross sections for transitions between various hyperfine states are calculated. We show that the process of spin exchange in (H) over bar -H collisions is basically driven by the strong force between a proton and an antiproton.

  • 189. Voronin, Alexei
    et al.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Nesvizhevsky, Valery
    Gravitational quantum states of Antihydrogen2011In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 83, p. 032903-Article in journal (Refereed)
    Abstract [en]

    We present a theoretical study of the motion of the antihydrogen atom ((H) over bar) in the gravitational field of Earth above a material surface. We predict that the (H) over bar atom, falling in the gravitational field of Earth above a material surface, would settle into long-lived quantum states. We point out a method of measuring the difference in the energy of (H) over bar in such states. The method allows for spectroscopy of gravitational levels based on atom-interferometric principles. We analyze the general feasibility of performing experiments of this kind. We point out that such experiments provide a method of measuring the gravitational force (Mg) acting on (H) over bar and that they might be of interest in the context of testing the weak equivalence principle for antimatter.

  • 190. Voronin, Alexei
    et al.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Zygelman, Bernard
    Interaction of ultracold antihydrogen with a conducting wall2005In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 72, no 6, p. 062903/1-062903/11Article in journal (Refereed)
    Abstract [en]

    We investigate the interaction of ultracold antihydrogen with a conducting surface, focusing on the phenomenon of quantum reflection. We calc. the reflection probability as a function of incident atom energy. We find that, for ground-state H atoms (with T<10-5 K), the probability of reflection is R.simeq.1-kb, where k is the momentum of the atom and b=2174.0 a.u. is a const. detd. solely by the van der Waals-Casimir tail of the atom-wall interaction. We show that quantum reflection, which suppresses the direct contact of ultracold atoms with the surface, allows for the possibility of confinement and storage of sufficiently cold antihydrogen atoms. We calc. the lifetime of H atoms enclosed in between solid walls. We develop a theory of H in a waveguide and propose some applications, notably the measurement of retardation corrections in the long-range component of the antiatom-wall potential. We demonstrate the existence of quantized states for antihydrogen atoms falling onto conducting surface in the gravitational field of Earth. We calc. the lifetime of ultracold H in its lowest gravitational state and obtain t=(Mgb/2h)-1.simeq.0.1 s, where Mg is a gravitational force acting on the antiatom. We propose that measurement of this lifetime may provide a new test for the gravitational properties of antimatter.

  • 191. Wallenius, Jan
    et al.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Excited States of Muonic Helium Hydride Ions and Their Possible Impact on Muon Reactivation1999In: Hyperfine Interactions, ISSN 0304-3843, E-ISSN 1572-9540, Vol. 118, no 1-4, p. 223-228Article in journal (Refereed)
  • 192. Wallenius, Jan
    et al.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Formation of metastable dt mu molecules in t mu(2s)-D-2 collision1996In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 54, no 2, p. 1171-1182Article in journal (Refereed)
    Abstract [en]

    The formation process of metastable dt mu molecules in D-2-T-2 mixtures is investigated. The dt mu molecule exhibits a series of three-body resonances embedded in the t mu+d scattering continuum just below the t mu(2s)+d threshold, These states can-be for

  • 193.
    Wallenius, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Impact of the side-path model on the muon cycling rate density dependence in D-T mixtures1996In: Hyperfine Interactions, ISSN 0304-3843, E-ISSN 1572-9540, Vol. 101-102, no 1, p. 293-300Article in journal (Refereed)
    Abstract [en]

    The side-path model previously suggested by us allows for muon transferfrom tritiumto deuterium via intermediate dtµ* resonances formed in tµ(2s)-D2 collisions. Taking this effect into account, the density dependence of the muon cycling rate in D-T mixtures at low temperatures is analysed. Compared with cascade models where only one-sided transfer is present, the predicted density dependence of λc is in better agreement with measurements.

  • 194. Wallenius, Jan
    et al.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Meta Stable States of Muonic Molecules and Their Impact on Muon Catalysed Fusion Cycle1997In: Ann. Est. Phys. Soc., Vol. 42, p. 1996-Article in journal (Refereed)
  • 195. Wallenius, Jan
    et al.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Muon Transfer in dmu + H_2 Collisions1999In: Hyperfine Interactions, ISSN 0304-3843, E-ISSN 1572-9540, Vol. 119, no 1-4, p. 165-171Article in journal (Refereed)
  • 196. Wallenius, Jan
    et al.
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Muon transfer via meta-stable dtμ molecules and the kinetics of μCF1995In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 206, no 1-2, p. 73-80Article in journal (Refereed)
    Abstract [en]

    We have considered details of the lower stages of the muon cascade following formation of highly excited muonic atoms in D,-T, mixtures. We show that when the muon reaches the n = 2 states of the muonic atom, an important modification of the hitherto accepted cascade model takes place. Our new theory predicts that fast (A,+. = 10” s-l) formation of metastable dt p * in tp(2s)-D, collisions and their further decay into tp(ls) + d or dp.(ls) + t together constitute a deexcitation process quickly depleting the n = 2 levels of muonic atoms. The decay into dp(ls) can be seen as a muon transfer from the t ~(2s) to d ~(1s) via an intermediate resonant state of dt CL. This process provides an efficient mechanism for muon return from the tritium to deuterium atom which enhances the population of dp(ls), thereby slowing down the cycling rate of the muon and quenching the fusion yield. This new understanding may help to further optimise physical conditions in order to maximise the fusion yield.

  • 197. Wallenius, Jan
    et al.
    Jonsell, Svante
    Kino, Yasushi
    Froelich, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Muonic Atom Deexcitation via Formation of Metastable Molecular States: in Light of Experimental Verification2001In: Hyperfine Interactions, ISSN 0304-3843, E-ISSN 1572-9540, Vol. 138, no 1-4, p. 285-288Article in journal (Other (popular science, discussion, etc.))
  • 198. Wang, Dong
    et al.
    Hansson, Tony
    Larson, Åsa
    Karlsson, Hans O.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Larson, Jonas
    Quantum interference structures in trapped-ion dynamics beyond the Lamb-Dicke and rotating wave approximations2008In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 77, no 5, p. 053808-1-053808-11Article in journal (Refereed)
    Abstract [en]

    We apply wave-packet methods to study an ion-trap system imposing neither the rotating wave nor the Lamb-Dicke approximations. By this approach we show the existence of states with restricted phase-space evolution as a genuine consequence of quantum interference between wave-packet fractions. A particular instance of such a state oscillates between maximal entanglement and pure disentanglement between the constitute subsystems, where the characteristic crossover time is very rapid. Over longer time periods the dynamics of these states exhibits collapse-revival patterns with well-resolved fractional revivals in autocorrelation, inversion, and entanglement.

  • 199. Wang, Dong
    et al.
    Larson, Åsa
    Hansson, Tony
    Karlsson, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Molecular quantum wave-packet splitting and revivals in shared phase space2009In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 79, no 2, p. 023402-Article in journal (Refereed)
    Abstract [en]

    The evolution of a molecular wave packet created by an ultrashort laser pulse in a system of two coupled bound states is investigated by quantum dynamics calculations and semiclassical theory. Under suitable dynamical quantum interference conditions, the wave packet may be split into two separable fractions that move in different but partially overlapping regions of the energetically available phase space. Each wave-packet part can be individually addressed in the divided parts of the molecular phase space, and they are shown to go through separate long-term collapse-revival cycles analogous to those of wave packets moving in single anharmonic potentials. In a pump-probe scheme, the dynamics of the system would look very different depending on what internuclear distances are probed. The regular dynamics observable in the separated parts of the phase space takes on a quite irregular appearance in the regions that are shared by the wave-packet components. The wave-packet regularity is shown to depend sensitively on the pump pulse wavelength, which is a reflection of the energy range over which the quantum interference conditions are maintained. These conditions, as well as the wave-packet fraction revival times, are well reproduced by semiclassical theory.

  • 200. Wang, Dong
    et al.
    Larson, Åsa
    Karlsson, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Hansson, Tony
    Molecular quantum wavepacket revivals in coupled electronic states2007In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 449, no 4-6, p. 266-271Article in journal (Refereed)
    Abstract [en]

    Large-amplitude revivals of molecular wavepackets in two coupled electronic states were obtained in quantum dynamical calculations. The revivals occurred in both bound and predissociative systems with a pattern analogous to that of wavepackets in single anharmonic potentials. Essential for their appearance was dynamical interference of wavepacket fractions moving along diabatic and adiabatic paths. The full revival period of the coupled system was shown to be given by an average of those of the diabatic and adiabatic states weighted in proportion to the wavepacket splitting ratio at the potential curve crossing.

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