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  • 1.
    Aydin, Alhun
    et al.
    Istanbul Technical University, Energy Institute.
    Sisman, Altug
    Istanbul Technical University, Energy Institute.
    Discrete Density of States2016In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 380, p. 1236-1240Article in journal (Refereed)
    Abstract [en]

    By considering the quantum-mechanically minimum allowable energy interval, we exactly count number of states (NOS) and introduce discrete density of states (DOS) concept for a particle in a box for various dimensions. Expressions for bounded and unbounded continua are analytically recovered from discrete ones. Even though substantial fluctuations prevail in discrete DOS, they’re almost completely flattenedout after summation or integration operation. It’s seen that relative errors of analytical expressions of bounded/unbounded continua rapidly decrease for high NOS values (weak confinement or high energy conditions), while the proposed analytical expressions based on Weyl’s conjecture always preserve their lower error characteristic.

  • 2.
    Aydin, Alhun
    et al.
    Istanbul Technical University, Energy Institute.
    Sisman, Altug
    Istanbul Technical University, Energy Institute.
    Discrete Nature of Thermodynamics in Confined Ideal Fermi Gases2014In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 378, p. 2001-2007Article in journal (Refereed)
    Abstract [en]

    Intrinsic discrete nature in thermodynamic properties of Fermi gas appears in strongly confined and degenerate conditions. For a rectangularconfinement domain, thermodynamic properties of an ideal Fermi gas are expressed in their exact summation forms. For 1D, 2D and 3D nanodomains; variations of both number of particles and internal energy per particle with chemical potential are examined. It is shown that theirrelation with chemical potential exhibits a discrete nature which allows them to take only some definite values. Furthermore, quasi-irregularoscillatory-like sharp peaks are observed in heat capacity. New nano devices can be developed based on these behaviors.

  • 3.
    aydin, Alhun
    et al.
    Istanbul Technical University, Energy Institute.
    Sisman, Altug
    Istanbul Technical University, Energy Institute.
    Quantum oscillations in confined and degenerate Fermi gases. I. Half-vicinity model2018In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 382, p. 1807-1812Article in journal (Refereed)
    Abstract [en]

    We propose an analytical model for the prediction and accurate calculation of size and density dependent quantum oscillations in thermodynamic and transport properties of confined and degenerate Fermi gases. Our model considers only half-vicinity states of Fermi level. We show that the half-vicinity model quite accurately estimates quantum oscillations depending on confinement and degeneracy. Periods of quantum oscillations are even analytically expressed for one-dimensional case. Furthermore, similarities between functional behaviors of total occupancy variance and conventional density of states functions at Fermi level are discussed.

  • 4.
    Aydin, Alhun
    et al.
    Istanbul Technical University, Energy Institute .
    Sisman, Altug
    Istanbul Technical University, Energy Institute .
    Quantum oscillations in confined and degenerate Fermi gases. II. The phase diagram and applications of half-vicinity model2018In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 382, p. 1813-1817Article in journal (Refereed)
    Abstract [en]

    For part I see DOI: 10 .1016 /j.physleta.2018.02.006. Size and density dependent quantum oscillations appear in Fermi gases under strong confinement and degeneracy conditions. We provide a universal recipe that explicitly separates oscillatory regime from non-oscillatory (stationary) one. A phase diagram representing stationary and oscillatory regimes on degeneracy-confinement space is proposed. Analytical expressions of phase transition interfaces are derived. The critical point, which separates entirely stationary and oscillatory regions, is determined and its dependencies on aspect ratios are examined for anisometric domains. Accuracy of the half-vicinity model and the phase diagram are verified through the quantum oscillations in electronic heat capacity and its ratio to entropy.

  • 5.
    Aydin, Alhun
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Istanbul Tech Univ, Energy Inst, Nano Energy Res Grp, Istanbul, Turkey.
    Sisman, Altug
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Istanbul Tech Univ, Energy Inst, Nano Energy Res Grp, Istanbul, Turkey.
    Quantum shape effects and novel thermodynamic behaviors at nanoscale2019In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 383, no 7, p. 655-665Article in journal (Refereed)
    Abstract [en]

    Thermodynamic properties of confined systems depend on sizes of the confinement domain due to quantum nature of particles. Here we show that shape also enters as a control parameter on thermodynamic state functions. By considering specially designed confinement domains, we demonstrate how shape effects alone modify Helmholtz free energy, entropy and internal energy of a confined system. We propose an overlapped quantum boundary layer method to analytically predict quantum shape effects without even solving Schrödinger equation or invoking any other mathematical tools. Thereby we reduce a thermodynamic problem into a simple geometric one and reveal the profound link between geometry and thermodynamics. We report also a torque due to quantum shape effects. Furthermore, we introduce isoformal, shape preserving, process which opens the possibility of a new generation of thermodynamic cycles operating at nanoscale with unique features.

  • 6.
    BECKMAN, O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    LUNDGREN, L
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    NORDBLAD, P
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    SANDLUND, L
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    SVEDLINDH, P
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    LUNDSTROM, T
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    RUNDQVIST, S
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    SPECIFIC-HEAT AND MAGNETIC-SUSCEPTIBILITY OF SINGLE-PHASE YBA2CU3O71987In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 125, p. 425-428Article in journal (Refereed)
  • 7. Borman, V. D.
    et al.
    Johansson, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Skorodumova, Natalia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Tronin, I. V.
    Tronin, V. N.
    Troyan, V. I.
    Diffusion and particle mobility in 1D system2006In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 359, no 5, p. 504-508Article in journal (Refereed)
    Abstract [en]

    The transport properties of one-dimensional (1D) systems have been studied theoretically. Contradictory experimental results on molecular transport in quasi-1D systems, such as zeolite structures, when both diffusion transport acceleration and the existence of the diffusion mode with lower particle mobility (single-file diffusion (< x(2)> similar to t(1/2))) have been reported, are consolidated in a consistent model. Transition from the single-file diffusion mode to an Einstein-like diffusion < x(2)> similar to t with diffusion coefficient increasing with the density has been predicted to occur at large observation times.

  • 8.
    Brown, Harvey R.
    et al.
    Sub-Faculty of Philosophy, Oxford Univ., UK.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Bacciagaluppi, Guido
    Sub-Faculty of Philosophy, Oxford Univ., UK.
    Remarks on identical particles in de Broglie-Bohm theory1999In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 251, no 4, p. 229-235Article in journal (Refereed)
    Abstract [en]

    It is argued that the topological approach to the (anti-) symmetrisation condition for the quantum state of a collection of identical particles, defined in the "reduced" configuration space, is particularly natural from the perspective of de Broglie-Bohm pilot-wave theory.

  • 9.
    Cooray, Vernon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Cooray, Gerald
    Dept of Clinical Neuroscience, Karolinska Institutet, Stockholm.
    Dwyer, Joseph
    Florida Institute of Technology, Melbourne, FL, USA.
    On the possibility of phosphenes being generated by the energetic radiation from lightning flashes and thunderstorms2011In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 375, no 42, p. 3704-3709Article in journal (Refereed)
    Abstract [en]

    After the first report of this phenomenon by Apollo 11 astronauts, experiments conducted in space and on the ground confirmed the creation of phosphenes by the interaction of energetic radiation with the human visual system. The aim of this Letter is to show that the energetic radiation generated in the form of X-rays, gamma rays, electrons and neutrons by thunderstorms and lightning is strong enough for the creation of phosphenes in humans. It is also pointed out that some of the visual observations reported during thunderstorms might be attributable to phosphenes excited by this energetic radiation.

  • 10.
    Ericsson, Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Pomp, S
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, H
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Traneus, E
    Comment on "Piezonuclear decay of thorium" [Phys. Lett. A 373 (2009) 1956]2009In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 373, no 41, p. 3795-3796Article in journal (Refereed)
  • 11.
    Ericsson, Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Pomp, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sjöstrand, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Traneus, E.
    Raysearch AB, Stockholm.
    Piezonuclear reactions - do they really exist?2010In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 374, no 5, p. 750-753Article in journal (Refereed)
    Abstract [en]

    In a number of recent articles in this journal F. Cardone and collaborators have claimed the observation of several striking nuclear phenomena which they attribute to "piezonuclear reactions". One such claim [F. Cardone, R. Mignani, A. Petrucci, Phys. Lett. A 373 (2009) 1956] is that subjecting a solution of 228Th to cavitation leads to a "transformation" of thorium nuclei that is 104 times faster than the normal nuclear decay for this isotope. In a "Comment" [G. Ericsson, S. Pomp, H. Sjöstrand, E. Traneus, Phys. Lett. A 373 (2009) 3795] to the thorium work, we have criticized the evidence provided for this claim. In a "Reply" [F. Cardone, R. Mignani, A. Petrucci, Phys. Lett. A 373 (2009) 3797] Cardone et al. answer only some minor points but avoid addressing the real issue. The information provided in their Reply displays a worrying lack of control of their experimental situation and the data they put forward as evidence for their claims. We point out several shortcomings and errors in the described experimental preparations, set-up and reporting, as well as in the data analysis. We conclude that the evidence presented by Cardone et al. is insufficient to justify their claims of accelerated thorium decay (by "piezonuclear reactions" or otherwise).

  • 12.
    Ericsson, Marie
    et al.
    Centre for Quantum Computation, DAMTP, University of Cambridge, UK.
    Kult, David
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry, Quantum Chemistry.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry, Quantum Chemistry.
    Åberg, Johan
    Centre for Quantum Computation, DAMTP, Cambridge, UK.
    Nodal free geometric phases: concept and application to geometric quantum computation2008In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 372, no 5, p. 596-599Article in journal (Refereed)
    Abstract [en]

    Nodal free geometric phases are the eigenvalues of the final member of a parallel transporting family of unitary operators. These phases are gauge invariant, always well defined, and can be measured interferometrically. Nodal free geometric phases can be used to construct various types of quantum phase gates.

  • 13.
    Ericsson, Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry, Quantum Chemistry.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry, Quantum Chemistry.
    Quantum computation using the Aharonov-Casher set up2002In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 303, no 1, p. 7-10Article in journal (Refereed)
    Abstract [en]

    It is argued that the Aharonov-Casher set up could be used as the basic building block for quantum computation. We demonstrate explicitly in this scenario one- and two-qubit phase shift gates that are fault tolerant to deformations of the path when encircling two sites of the computational system around each other.

  • 14.
    Filipp, Stefan
    et al.
    Atominstitut, Vienna, Austria .
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Off-diagonal quantum holonomy along density operators2005In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 342, no 3, p. 205-212Article in journal (Refereed)
    Abstract [en]

    Uhlmann's concept of quantum holonomy for paths of density operators is generalised to the off-diagonal case providing insight into the geometry of state space when the Uhlmann holonomy is undefined. Comparison with previous off-diagonal geometric phase definitions is carried out and an example comprising the transport of a Bell-state mixture is given.

  • 15.
    Gürkan, Nilhan
    et al.
    Department of Industrial Engineering, Gediz University, Menemen-Izmir, Turkey.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Realization of a holonomic quantum computer in a chain of three-level systems2015In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 379, no 47-48, p. 3050-3053Article in journal (Refereed)
    Abstract [en]

    Holonomic quantum computation is the idea to use non-Abelian geometric phases to implement universal quantum gates that are robust to fluctuations in control parameters. Here, we propose a compact design for a holonomic quantum computer based on coupled three-level systems. The scheme does not require adiabatic evolution and can be implemented in arrays of atoms or ions trapped in tailored standing wave potentials. 

  • 16.
    Ioannidou, Theodora
    et al.
    Aristotle Univ Thessaloniki, Sch Engn, Fac Civil Engn, Thessaloniki 54249, Greece..
    Niemi, Antti J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics. Univ Tours, Federat Denis Poisson, CNRS UMR 6083, Lab Math & Phys Theor, F-37200 Tours, France.;Beijing Inst Technol, Dept Phys, Beijing 100081, Peoples R China..
    Poisson hierarchy of discrete strings2016In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 380, no 3, p. 333-336Article in journal (Refereed)
    Abstract [en]

    The Poisson geometry of a discrete string in three dimensional Euclidean space is investigated. For this the Frenet frames are converted into a spinorial representation, the discrete spinor Frenet equation is interpreted in terms of a transfer matrix formalism, and Poisson brackets are introduced in terms of the spinor components. The construction is then generalised, in a self-similar manner, into an infinite hierarchy of Poisson algebras. As an example, the classical Virasoro (Witt) algebra that determines reparametrisation diffeomorphism along a continuous string, is identified as a particular sub-algebra, in the hierarchy of the discrete string Poisson algebra.

  • 17.
    Karabetoglu, Sevan
    et al.
    Istanbul Technical University, Energy Institute.
    Sisman, Altug
    Istanbul Technical University, Energy Institute.
    Thermosize effects in semiconductors2017In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 381, p. 2704-2708Article in journal (Refereed)
    Abstract [en]

    A thermosize junction consists of two different sized structures made using the same material. Classical and quantum thermosize effects (CTSEs and QTSEs), which are opposite to each other, induce a thermosize potential in a thermosize junction. A semi-analytical method is proposed to calculate thermosize potentials in wide ranges of degeneracy and confinement by considering both CTSEs and QTSEs in thermosize junctions made using semiconductors. Dependencies of thermosize potential on temperature, size, and degeneracy are examined. It is shown that a potential difference in millivolt scale can be induced as a combined effect of CTS and QTS. The highest potential is obtained in nondegenerate limit where the full analytical solution is obtained. The model can be used to design semiconductor thermosize devices for a possible experimental verification of CTSEs and QTSEs, which may lead to new nano energy conversion devices.

  • 18.
    Larsson, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Noncyclic mixed state phase in SU(2) polarimetry2003In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 315, no 1-2, p. 12-15Article in journal (Refereed)
    Abstract [en]

    We demonstrate that Pancharatnam's relative phase for mixed spin-1/2 states in noncyclic SU(2) evolution can be measured polarimetrically.

  • 19.
    Liberman, M. A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Kiverin, A. D.
    Ivanov, M. F.
    On detonation initiation by a temperature gradient for a detailed chemical reaction models2011In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 375, no 17, p. 1803-1808Article in journal (Refereed)
    Abstract [en]

    The evolution from a temperature gradient to a detonation is investigated for combustion mixture whose chemistry is governed by a detailed chemical kinetics. We show that a detailed chemical reaction model has a profound effect on the spontaneous wave concept for detonation initiation by a gradient of reactivity. The evolution to detonation due to a temperature gradient is considered for hydrogen-oxygen and hydrogen-air mixtures at different initial pressures. It is shown that the minimal length of the temperature gradient for which a detonation can be ignited is much larger than that predicted from a one-step chemical model.

  • 20.
    Liberman, M. A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Kuznetsov, M.
    Ivanov, A.
    Matsukov, I.
    Formation of the preheated zone ahead of a propagating flame and the mechanism underlying the deflagration-to-detonation transition2009In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 373, no 5, p. 501-510Article in journal (Refereed)
    Abstract [en]

    The Letter presents analytical, numerical and experimental studies of the mechanism underlying the deflagration-to-detonation transition (DDT). Insight into how, when, and where DDT occurs is obtained by analyzing analytically and by means of multidimensional numerical simulations dynamics of a flame accelerating in a tube with no-slip walls. It is shown that the deflagration-to-detonation transition exhibits three separate stages of evolution corroborating majority experimental observations. During the first stage flame accelerates and generates shocks far ahead of the flame front. During the second stage the flame slows down, shocks are formed in the immediate proximity of the flame front and the preheated zone ahead of the flame front is created. The third stage is self-restructuring of the steep temperature profile within the flame, formation of a reactivity gradient and the actual formation of the detonation wave itself. The mechanism for the detonation wave formation, given an appropriate formation of the preheated zone, seems to be universal and involves a reactivity gradient formed from the initially steep flame temperature profile in the presence of the preheated zone. The developed theory and numerical simulations are found to be well consistent with extensive experiments of the DDT in hydrogen-oxygen and ethylene-oxygen mixtures in tubes with smooth and rough walls.

  • 21. Music, Denis
    et al.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Schneider, Jochen M.
    Electronic structure and lattice dynamics of CaPd3B studied by first-principles methods2006In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 356, no 3, p. 251-254Article in journal (Refereed)
    Abstract [en]

    Using first-principles methods, we have studied the electronic structure and lattice dynamics of CaPd3B and compared them to isostructural MgNi3C- CaPd3B possesses less electronic states at the Fermi level, but more phonon modes at low frequencies, than MgNi3C. According to the phonon density of states, low frequency acoustic modes are dominated by Pd states, corresponding to Ni in MgNi3C. Furthermore, these Pd modes show soft phonons, which may be significant for second-order phase transitions. Based on the comparison to MgNi3C, we suggest that the properties of these two compounds may be similar.

  • 22.
    NORDBLAD, P
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    SVEDLINDH, P
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    SANDLUND, L
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    LUNDGREN, L
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    COEXISTENCE OF AGING STATES IN SPIN-GLASSES1987In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 120, p. 475-478Article in journal (Refereed)
  • 23.
    Sisman, Altug
    et al.
    Berlin Technical University, Thermodynamic Institute.
    Muller, Ingo
    Berlin Technical University, Thermodynamic Institute.
    The Casimir-like size effects in ideal gases2004In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 320, p. 360-366Article in journal (Refereed)
    Abstract [en]

    The wave character of atoms can produce Casimir-like size effects in gases confined in a narrow box. Thus the pressure tensoris not isotropic anymore and size difference becomes a driving force for isothermal diffusion by a permeable wall. Such sizeeffects give rise to “thermosize effects” similar to thermoelectric effects.

  • 24.
    Sisman, Altug
    et al.
    Istanbul Technical University, Energy Institute.
    Ozturk, Z Fatih
    Istanbul Technical University, Energy Institute.
    Firat, Coskun
    Istanbul Technical University, Energy Institute.
    Quantum boundary layer: a non-uniform density distribution of an ideal gas in thermodynamic equilibrium2007In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 362, p. 16-20Article in journal (Refereed)
    Abstract [en]

    Density distribution of an ideal Maxwellian gas confined in a finite domain is not uniform even in thermodynamic equilibrium. Near to theboundaries, there is a layer in which the density goes to zero. Existence of this boundary layer explains the shape and size dependence of thethermodynamic quantities in nano scale.

  • 25.
    Sjöqvist, Erik
    Department of Mathematical Sciences, University of Durham, UK, Sub-Faculty of Philosophy, Oxford University, UK.
    A quantum mechanical angle anholonomy1997In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 226, no 1-2, p. 14-16Article in journal (Refereed)
    Abstract [en]

    It is shown that adiabatic averaging for a de Broglie-Bohm particle moving on a ring guided by a slowly changing wave function leads to an anholonomic shift.

  • 26.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry, Quantum Chemistry.
    Anandan–Aharonov–Casher oscillations in a simply connected region2000In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 270, no 1-2, p. 10-13Article in journal (Refereed)
    Abstract [en]

    An entanglement effect between the spin and spatial degrees of freedom of an electrically neutral spin-1/2 particle in a planar electric field is predicted. This nonclassical effect is manifested as spatial interference oscillations in a force free simply connected region of space. It is suggested that these oscillations provide an experimentally accessible analogue of Anandan's "quantum solenoid effect'' [Phys. Lett. A 164 (1992) 369], The effect could be tested with spin polarised atoms.

  • 27.
    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.

  • 28.
    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.

  • 29.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala universitet.
    Nonadiabatic holonomic single-qubit gates in off-resonant Λ systems2016In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 380, no 1-2, p. 65-67Article in journal (Refereed)
    Abstract [en]

    We generalize nonadiabatic holonomic quantum computation in a resonant Λ configuration proposed in [New J. Phys. 14 (2012) 103035] to the case of off-resonant driving lasers. We show that any single-qubit holonomic gate can be realized by separately varying the detuning, amplitude, and phase of the lasers. 

  • 30.
    Sjöqvist, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry, Quantum Chemistry.
    Proposed interferometry test of noncyclic geometric phase2001In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 286, no 1, p. 4-6Article in journal (Refereed)
    Abstract [en]

    An interferometric test of the geometric phase in noncyclic spin-1/2 precession is proposed. It is shown that the resulting interference shift depends only on the noncyclic geometric phase for any opening angle on the Bloch sphere as well as for any degree of polarisation.

  • 31.
    Sjöqvist, Erik
    et al.
    Sub-Fuculty of Philosophy, Oxford University, Department of Mathematical Sciences, University of Durham.
    Brown, Harvey R.
    Sub-Faculty of Philosophy, Oxford Univ., UK.
    Carlsen, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry, Quantum Chemistry.
    Galilean noninvariance of geometric phase1997In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 229, no 5, p. 273-278Article in journal (Refereed)
    Abstract [en]

    It is shown that generally geometric phase in nonrelativistic quantum mechanics is not Galilean invariant. It appears, however, that in none of the actual experiments performed to date on geometric phase is the measured phase frame dependent.

  • 32.
    Sjöqvist, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry, Quantum Chemistry.
    Carlsen, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry, Quantum Chemistry.
    Fractional statistics in Bohm's theory1995In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 202, no 2-3, p. 160-166Article in journal (Refereed)
    Abstract [en]

    We introduce fractional statistics in Bohm's formulation of quantum mechanics.

  • 33.
    Sjöqvist, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry, Quantum Chemistry.
    Åberg, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry, Quantum Chemistry.
    Weak cloning of an unknown quantum state2006In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 354, no 5-6, p. 396-398Article in journal (Refereed)
    Abstract [en]

    The impossibility to clone an unknown quantum state is a powerful principle to understand the nature of quantum mechanics, especially within the context of quantum computing and quantum information. This principle has been generalized to quantitative statements as to what extent imperfect cloning is possible. We delineate an aspect of the border between the possible and the impossible concerning quantum cloning, by putting forward an entanglement-assisted scheme for simulating perfect cloning in the context of weak measurements. This phenomenon we call weak cloning of an unknown quantum state.

  • 34.
    SVEDLINDH, P
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    GRANBERG, P
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    LUNDGREN, L
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    NORDBLAD, P
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    CHEN, HS
    Bell.
    THERMAL MAGNETIC FLUCTUATIONS IN METALLIC SPIN-GLASSES1987In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 121, p. 237-240Article in journal (Refereed)
  • 35. Vayanganie, S.P.A.
    et al.
    Cooray, Vernon
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Rahman, Mahbubur
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Hettiarachchi, Pasan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Diaz, Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Fernando, M.
    On the occurrence of ‘bead lightning’ phenomena in long laboratory sparks2016In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 380, no 7-8, p. 816-821Article in journal (Refereed)
    Abstract [en]

    The formation of bead lightning, where the lightning channel appears to break up into luminous fragments, is still an object of speculation. Here we report similar observations in laboratory discharges. Analysis of time resolved photographs shows that the discharge channel exhibits a 'bead pattern' in the decaying stage of the discharge and the occurrence of loops in the channel sections where the bead pattern is observed. This result presents the first evidence that the rapid cooling of non-uniform channel sections could lead to the formation of beads. It is suggested that periodically occurring non-uniform channel sections could explain the bead pattern of lightning discharges.

  • 36. 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.

  • 37. Yang, Zongxian
    et al.
    Lu, Zhansheng
    Luo, Gaixia
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Oxygen vacancy formation energy at the Pd/CeO2(111) interface2007In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 369, no 1-2, p. 132-139Article in journal (Refereed)
    Abstract [en]

    The atomic and electronic structure of Pd adsorption on the unreduced and reduced ceria (111) surfaces is studied using first principles projector-augmented-wave (PAW) method based density functional theory (DFT) within generalized gradient approximation (GGA) and with the inclusion of on-site Coulomb interaction (GGA + U). It is found that there exist different adsorption features for Pd on different surfaces (unreduced and reduced): (1) on the unreduced CeO2(111) surface, Pd prefers to be adsorbed on the O-bridge site (O2-site); (2) on the reduced CeO2(111) surface, the adsorption is much stronger than that on the unreduced CeO2(111) surface; (3) the formation of an oxygen vacancy is easier at the Pd/CeO2(111) interface than that on the clean CeO2(111) surface, indicating that the Pd adatom enhances the oxygen storage capacity (OSC) of ceria, and the interaction between the palladium catalyst and the ceria support enhances the lower temperature activity of the catalyst. The mechanisms for this promotion in the OSC of ceria at the Pd/ceria interface are discussed.

  • 38. Yang, Zongxian
    et al.
    Yu, Xiaohu
    Lu, Zhansheng
    Li, Shunfang
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Oxygen vacancy pairs on CeO2(110): A DFT + U study2009In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 373, no 31, p. 2786-2792Article in journal (Refereed)
    Abstract [en]

    Oxygen vacancy pairs have been suggested to play a role in the reduction of NO molecules on ceria and for the oxidation processes of reducible rare-earth oxides. The formation energy of the oxygen vacancy pairs and the changes in the structural and electronic properties of the ceria (110) surface with oxygen vacancy pairs are investigated using density-functional theory (DFT + U) methodology within the generalized gradient approximation. It is found that the excess electrons localize on the Ce ions neighbouring the vacancies, and the most stable structure for the oxygen vacancy pairs on the ceria (110) surface is at next-nearest-neighbour site.

  • 39. Zaoui, A.
    et al.
    Belabbes, A.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ferhat, M.
    Interplay between lattice dynamics and the low-pressure phase of simple cubic polonium2011In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 375, no 15, p. 1695-1697Article in journal (Refereed)
    Abstract [en]

    Low-pressure structural properties of simple cubic polonium are explored through first-principles density-functional theory based relativistic total energy calculations using pseudopotentials and plane-wave basis set, as well as linear-response theory. We have found that Po undergoes structural phase transition at low pressure near 2 GPa, where the element transforms from simple cubic to a mixture of two trigonal phases namely, hR1 (alpha = 86 degrees) and hR2 (alpha = 97.9 degrees) structures. The lattice dynamics calculations provide strong support for the observed phase transition, and show the dynamical stability (instability) of the hR2 (hR1) phase.

1 - 39 of 39
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