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Artykuły w czasopismach na temat „Landau-Zener System”

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Data publikacji: 6 września 2023

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1

Galeev R.T. "The effect of Landau-Zener transitions on the ac-susceptibility". Physics of the Solid State 63, nr 13 (2022): 1721. http://dx.doi.org/10.21883/pss.2022.13.52312.093.

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A model spin system S=1 with a strongly anisotropic g-factor is considered. Numerical calculations of the response of the system to an alternating magnetic field of low frequency are carried out. The influence of Landau--Zener transitions on the response of the system when it passes through the vicinity of the levels anti-crossing is studied. The ac-susceptibility is calculated and the effect of such transitions on the position of the ac-susceptibility maximum is analyzed. Keywords: level anti-crossing, quantum tunneling of magnetization, Landau--Zener transitions, ac-susceptibility, relaxation of magnetization.

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2

Chen, Jin-Dan, Xue-Da Wen, Guo-Zhu Sun i Yang Yu. "Landau—Zener—Stückelberg interference in a multi-anticrossing system". Chinese Physics B 20, nr 8 (sierpień 2011): 088501. http://dx.doi.org/10.1088/1674-1056/20/8/088501.

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3

Wang Guan-Fang, Liu Bin, Fu Li-Bin i Zhao Hong. "Adiabatic Landau-Zener tunnelling in nonlinear three-level system". Acta Physica Sinica 56, nr 7 (2007): 3733. http://dx.doi.org/10.7498/aps.56.3733.

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4

Imanishi, B., S. Misono i W. Von Oertzen. "Nuclear Landau-Zener promotion in the reactions of the system". Physics Letters B 241, nr 1 (maj 1990): 13–18. http://dx.doi.org/10.1016/0370-2693(90)91478-t.

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5

Faraj, Ali, i Shi Jin. "The Landau-Zener Transition and the Surface Hopping Method for the 2D Dirac Equation for Graphene". Communications in Computational Physics 21, nr 2 (luty 2017): 313–57. http://dx.doi.org/10.4208/cicp.020515.250716a.

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AbstractA Lagrangian surface hopping algorithm is implemented to study the two dimensional massless Dirac equation for Graphene with an electrostatic potential, in the semiclassical regime. In this problem, the crossing of the energy levels of the system at Dirac points requires a particular treatment in the algorithm in order to describe the quantum transition—characterized by the Landau-Zener probability— between different energy levels. We first derive the Landau-Zener probability for the underlying problem, then incorporate it into the surface hopping algorithm. We also show that different asymptotic models for this problem derived in [O. Morandi, F. Schurrer, J. Phys. A:Math. Theor. 44 (2011) 265301]may give different transition probabilities. We conduct numerical experiments to compare the solutions to the Dirac equation, the surface hopping algorithm, and the asymptotic models of [O. Morandi, F. Schurrer, J. Phys. A: Math. Theor. 44 (2011) 265301].

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6

Dashevskaya, Elena I., Evgeny E. Nikitin i Hans-Jürgen Troe. "Uniform Airy Approximation for Nonadiabatic Transitions in a Curve-Crossing Weak-Coupling Case". Zeitschrift für Physikalische Chemie 232, nr 3 (28.03.2018): 311–23. http://dx.doi.org/10.1515/zpch-2017-1025.

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AbstractThis work suggests a connection between Landau-Zener transition probabilities between two crossing potentials in the classically accessible WKB regime and Landau-Lifshitz transition probabilities in the classically inaccessible WKB regime. It is based on the uniform Airy (UAi) approximation which represents a generalization of quantum transition probabilities for linear crossing potentials with constant coupling. The performance of the UAi approximation is tested by comparison with distorted-wave probabilities for an exponential potential model and illustrated for potentials that determine the intersection of twoab initiovibronic potential surfaces of the NO-Ar system.

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7

KRAFT, MATTHIAS, STEPHAN BURKHARDT, RICCARDO MANNELLA i SANDRO WIMBERGER. "LANDAU–ZENER TRANSITIONS IN THE PRESENCE OF HARMONIC NOISE". Fluctuation and Noise Letters 12, nr 02 (czerwiec 2013): 1340005. http://dx.doi.org/10.1142/s0219477513400051.

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We study the influence of off-diagonal harmonic noise on transitions in a Landau–Zener model. We demonstrate that the harmonic noise can change the transition probabilities substantially and that its impact depends strongly on the characteristic frequency of the noise. In the underdamped regime of the noise process, its effect is compared with the one of a deterministic sinusoidally oscillating function. While altering the properties of the noise process allows one to engineer the transitions probabilities, driving the system with a deterministic sinusoidal function can result in larger and more controlled changes of the transition probability. This may be relevant for realistic implementations of our model with Bose–Einstein condensates in noise-driven optical lattices.

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8

MIREA, M. "CONFIGURATION MIXING AND DISSIPATION FROM THE TIME-DEPENDENT PAIRING EQUATIONS". International Journal of Modern Physics E 21, nr 05 (maj 2012): 1250035. http://dx.doi.org/10.1142/s0218301312500358.

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The time-dependent pairing equations are developed to include the Landau–Zener effect and a pair breaking mechanism. The new formalism provide information about the configuration mixing and the dissipation for a dynamical evolution of a nuclear system. A formula for a nonadiabatic cranking inertia is also deduced. Results concerning cluster decay and fission processes are presented.

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9

Галеев, Р. Т. "Влияние переходов Ландау--Зинера на форму ac-восприимчивости". Физика твердого тела 63, nr 11 (2021): 1856. http://dx.doi.org/10.21883/ftt.2021.11.51588.093.

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A model spin system S = 1 with a strongly anisotropic g-factor is considered. Numerical calculations of the response of the system to an alternating magnetic field of low frequency are carried out. The influence of Landau-Zener transitions on the response of the system when it passes through the vicinity of the levels anti-crossing is studied. The ac-susceptibility is calculated and the effect of such transitions on the position of the ac-susceptibility maximum is analyzed.

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10

Liul, M. P., i S. N. Shevchenko. "Rate-equation approach for multi-level quantum systems". Low Temperature Physics 49, nr 1 (styczeń 2023): 96–102. http://dx.doi.org/10.1063/10.0016482.

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Strong driving of quantum systems opens opportunities for both controlling and characterizing their states. For theoretical studying of these systems properties we use the rate-equation formalism. The advantage of such approach is its relative simplicity. We used the formalism for description of a two-level system with further expanding it on a case of a multi-level system. Obtained theoretical results have good agreement with experiments. The presented approach can also be considered as one more way to explore properties of quantum systems and underlying physical processes such as, for instance, Landau–Zener–Stückelberg–Majorana transitions and interference.

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11

Fai, L. C., J. T. Diffo, M. E. Ateuafack, M. Tchoffo i G. C. Fouokeng. "Dynamics of a Landau–Zener non-dissipative system with fluctuating energy levels". Physica B: Condensed Matter 454 (grudzień 2014): 157–64. http://dx.doi.org/10.1016/j.physb.2014.07.081.

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12

Jipdi, M. N., L. C. Fai i M. Tchoffo. "Quantum system driven by incoherent a.c fields: Multi-crossing Landau Zener dynamics". Physics Letters A 380, nr 43 (październik 2016): 3665–71. http://dx.doi.org/10.1016/j.physleta.2016.08.044.

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13

Liu, Xuan-Zuo, Dong-Ping Tian i Bo Chong. "Transition time of nonlinear Landau–Zener model in adiabatic limit". Modern Physics Letters B 30, nr 15 (9.06.2016): 1650194. http://dx.doi.org/10.1142/s0217984916501943.

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The impact of nonlinear interaction on the loop structure of lower energy level and on the time evolution curve of canonical momentum which corresponds to the lower eigenstate are analyzed respectively. We find that the curve changes from single-valued to multi-valued as nonlinear interaction grows. The fascinating part is that the time range delimited by turning points in the loop of energy level and the period between two inflexion points on the multi-valued part of the evolution curve of canonical momentum are the same. Therefore, we propose a characteristic time in the transition process of nonlinear Landau–Zener model in adiabatic limit. Last, the physical meaning of the transition time as a measure of how much time the system experiences a structural change which directly results in the breakdown of adiabaticity is discussed.

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14

Filippov, Sergey N. "Quantum dynamics intervened by repeated nonselective measurements". International Journal of Quantum Information 15, nr 08 (grudzień 2017): 1740027. http://dx.doi.org/10.1142/s0219749917400275.

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We derive the theory of open quantum system dynamics intervened by a series of nonselective measurements. We analyze the cases of time-independent and time-dependent Hamiltonian dynamics between the measurements and find the approximate master equation in the stroboscopic limit. We also consider a situation, in which the measurement basis changes in time, and illustrate it by nonselective measurements in the basis of diabatic states of the Landau–Zener model.

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15

Sinitsyn, N. A. "Exact transition probabilities in a 6-state Landau–Zener system with path interference". Journal of Physics A: Mathematical and Theoretical 48, nr 19 (23.04.2015): 195305. http://dx.doi.org/10.1088/1751-8113/48/19/195305.

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16

Hosseini, Mehdi, i Farrokh Sarreshtedari. "Investigation of the laser controlled Landau–Zener mechanism in a coupled quantum system". Journal of the Optical Society of America B 34, nr 10 (12.09.2017): 2097. http://dx.doi.org/10.1364/josab.34.002097.

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17

Qin, Xiao-Ke. "How to control the coherent oscillations in Landau–Zener–Stueckelberg dynamics of three-level system". Modern Physics Letters B 30, nr 09 (10.04.2016): 1650149. http://dx.doi.org/10.1142/s0217984916501499.

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Coherent pulse is used to control and measure the quantum state of three-level system in double quantum dots. We analyze the coherent oscillations in Landau–Zener–Stueckelberg (LZS) dynamics by the adiabatic-impulse model, which simplifies the applied pulse as an optical interference device. Under the designed “hat-shape” pulse, the sweeping speed through each avoid crossing can be tuned independently. The coherent oscillations in LZS dynamics of three-level system are optimized by the control pulse. Moreover, we can filter out the coherent oscillations with the unexpected frequency and only keep the coherent oscillations with the frequency we are interested in.

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18

Ekengoue, C. M., C. Kenfack-Sadem, J. E. Danga, G. N. Bawe, A. El Moussaouy, O. Mommadi, L. Belamkadem i L. C. Fai. "Polariton condensate and Landau-Zener-Stückelberg interferometry transition in multilayer transition metal dichalcogenides". Physica Scripta 97, nr 2 (13.01.2022): 025801. http://dx.doi.org/10.1088/1402-4896/ac4718.

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Abstract This paper gives a detailed description of a high-performance polariton condensate for a quantum mechanical two-level system (TLS). We propose a transition metal dichalcogenides (TMDs) setup and theoretically carry out the spectroscopy of these polariton condensates. Through theoretical and numerical analysis, we obtain many features in two dimensional (2D) multilayer TMDs. We compute the energy of the system and the Landau-Zener-Stückelberg (LZS) quantum tunneling probability under the effect of a sequence of laser light. At certain critical 2D TMDs parameters, the system exhibits a multi-crossing scenario in a privileged position of 2D multilayer TMDs. We predict the consecutive modulations and highlight the conservation of the LZS interference patterns mapped from the 2D TMDs system. At weak coupling regime, a successful conversion of interferometry signals is identified for some values of laser frequency. We explain such a result as a valley sensitive cavity rate model due to coherent exchange and incoherent scattering, meaning that polariton condensate is formed in the valley around the Brillouin zone. The latter is used quantitatively and qualitatively to achieve high-precision measurements beyond that of its elementary constituents. The obtained results confirm that M o S e 2 has the highest sensitivity to radiation field as compared to other 2D multilayer TMDs materials. Therefore, M o S e 2 stands as an appropriate candidate among other 2D TMDs to form polariton condensates.

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19

Nkambule, Sifiso M., Sibusiso N. Zwane i Oscar N. Mabuza. "Low collision energy mutual neutralization reaction of He⁺ and H⁻". Journal of Physics Communications 6, nr 3 (1.03.2022): 035008. http://dx.doi.org/10.1088/2399-6528/ac5f5f.

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Abstract A Semi-classical Landau-Zener model is employed to theoretically study mutual neutralization in the collisions of 4He+ and H−/D−. The model includes ten covalent states and an ion-pair state of 2Σ+ symmetry for the HeH molecular system. Here the assumption is that only two states are interacting at a given internuclear position. In the diabatic representation, the nuclear dynamics relevant for mutual neutralization is modelled for collision energies below 100 eV. The mutual neutralization reaction cross section and final states distribution are computed and compared with previous theoretical and experimental results.

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20

Pidaparthi, Subhash, i Craig Lent. "Exponentially Adiabatic Switching in Quantum-Dot Cellular Automata". Journal of Low Power Electronics and Applications 8, nr 3 (7.09.2018): 30. http://dx.doi.org/10.3390/jlpea8030030.

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We calculate the excess energy transferred into two-dot and three-dot quantum dot cellular automata systems during switching events. This is the energy that must eventually be dissipated as heat. The adiabaticity of a switching event is quantified using the adiabaticity parameter of Landau and Zener. For the logically reversible operations of WRITE or ERASE WITH COPY, the excess energy transferred to the system decreases exponentially with increasing adiabaticity. For the logically irreversible operation of ERASE WITHOUT COPY, considerable energy is transferred and so must be dissipated, in accordance with the Landauer Principle. The exponential decrease in energy dissipation with adiabaticity (e.g., switching time) distinguishes adiabatic quantum switching from the usual linear improvement in classical systems.

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21

Li, Zhiyuan, Danyu Li, Mengmeng Li, Xiaopei Yang, Shuqing Song, Zhikun Han, Zhen Yang i in. "Quantum State Transfer via Multi‐Passage Landau–Zener–Stückelberg Interferometry in a Three‐Qubit System". physica status solidi (b) 257, nr 1 (8.10.2019): 1900459. http://dx.doi.org/10.1002/pssb.201900459.

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22

Ateuafack, M. E., J. T. Diffo i L. C. Fai. "Dynamics of a Landau–Zener transitions in a two-level system driven by a dissipative environment". Physica B: Condensed Matter 483 (luty 2016): 37–43. http://dx.doi.org/10.1016/j.physb.2015.12.012.

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23

Wang, L. C., X. L. Huang i X. X. Yi. "Landau-Zener transition of a two-level system driven by spin chains near their critical points". European Physical Journal D 46, nr 2 (12.10.2007): 345–49. http://dx.doi.org/10.1140/epjd/e2007-00286-2.

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24

Khon, Yu A. "Nonadiabatically Driven Subcritical Crack Nucleation in Solids". Physical Mesomechanics 26, nr 4 (sierpień 2023): 434–42. http://dx.doi.org/10.1134/s1029959923040057.

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Abstract This paper discusses a subcritical crack nucleation mechanism in a brittle solid within a real range of applied stress. A medium deformed by uniaxial tension is considered as an open nonequilibrium system of nuclei and electrons. Structural relaxation of the medium begins with the excitation of dynamic displacements during nonadiabatic Landau–Zener transitions. Dynamic displacements induce the instability of the medium to the longitudinal displacement wave. The kinetics of structural relaxation is described by two nonlinear parabolic kinetic equations for dynamic order parameters. Conditions are derived for the existence of localized solutions (autosolitons). The excitation of autosolitons leads to local elongation and cross-sectional reduction of the specimen. The resulting neck is a subcritical crack.

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25

Belousov, Yury, Igor Chernousov i Vladimir Man’ko. "Pseudo-Qutrit Formed by Two Interacting Identical Spins (s = 1/2) in a Variable External Magnetic Field". Entropy 25, nr 5 (26.04.2023): 716. http://dx.doi.org/10.3390/e25050716.

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An analytical solution is obtained for the problem of two interacting, identical but separated spin 1/2 particles in a time-dependent external magnetic field, in a general case. The solution involves isolating the pseudo-qutrit subsystem from a two-qubit system. It is shown that the quantum dynamics of a pseudo-qutrit system with a magnetic dipole–dipole interaction can be described clearly and accurately in an adiabatic representation, using a time-dependent basis set. The transition probabilities between the energy levels for an adiabatically varying magnetic field, which follows the Landau–Majorana–Stuckelberg–Zener (LMSZ) model within a short time interval, are illustrated in the appropriate graphs. It is shown that for close energy levels and entangled states, the transition probabilities are not small and strongly depend on the time. These results provide insight into the degree of entanglement of two spins (qubits) over time. Furthermore, the results are applicable to more complex systems with a time-dependent Hamiltonian.

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26

ANGELOPOULOU, P., S. BASKOUTAS, A. JANNUSSIS, R. MIGNANI i V. PAPATHEOU. "NON-HERMITIAN TUNNELING OF OPEN QUANTUM SYSTEMS". International Journal of Modern Physics B 09, nr 17 (30.07.1995): 2083–104. http://dx.doi.org/10.1142/s0217979295000823.

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We discuss some aspects of the time picture of tunneling for open quantum systems described by non-Hermitian (NH) Hamiltonians. The concept of sojourn time for such systems is introduced in the framework of the biorthonormal formalism. Due to the various definitions of probability density in the non-Hermitian case, we get three different sojourn times, two real and one complex. We consider as model of a dissipative NH system the complex, generalized parametric oscillator, for which we derive the exact expressions of the three sojourn times in terms of the Wei-Norman characteristic functions entering the non-unitary evolution operators. The special case of the inverted Caldirola-Kanai oscillator with complex friction parameter is investigated for an initial extended wavepacket. We also discuss the Landau-Zener-like transitions of the NH parametric oscillator, i.e. the dissipative tunneling through a dynamical barrier due to the perturbative effect of the damping.

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27

Bykov, A. A., I. S. Strygin, E. E. Rodyakina i S. A. Vitkalov. "Zener Tunneling between the Landau Levels in a Two-Dimensional Electron System with One-Dimensional Periodic Modulation". JETP Letters 108, nr 2 (lipiec 2018): 121–26. http://dx.doi.org/10.1134/s0021364018140035.

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28

Danileiko, M. V., V. I. Romanenko i L. P. Yatsenko. "Landau-Zener transitions and population transfer in a three-level system driven by two delayed laser pulses". Optics Communications 109, nr 5-6 (lipiec 1994): 462–66. http://dx.doi.org/10.1016/0030-4018(94)90499-5.

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29

Miao, Kevin C., Alexandre Bourassa, Christopher P. Anderson, Samuel J. Whiteley, Alexander L. Crook, Sam L. Bayliss, Gary Wolfowicz i in. "Electrically driven optical interferometry with spins in silicon carbide". Science Advances 5, nr 11 (listopad 2019): eaay0527. http://dx.doi.org/10.1126/sciadv.aay0527.

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Interfacing solid-state defect electron spins to other quantum systems is an ongoing challenge. The ground-state spin’s weak coupling to its environment not only bestows excellent coherence properties but also limits desired drive fields. The excited-state orbitals of these electrons, however, can exhibit stronger coupling to phononic and electric fields. Here, we demonstrate electrically driven coherent quantum interference in the optical transition of single, basally oriented divacancies in commercially available 4H silicon carbide. By applying microwave frequency electric fields, we coherently drive the divacancy’s excited-state orbitals and induce Landau-Zener-Stückelberg interference fringes in the resonant optical absorption spectrum. In addition, we find remarkably coherent optical and spin subsystems enabled by the basal divacancy’s symmetry. These properties establish divacancies as strong candidates for quantum communication and hybrid system applications, where simultaneous control over optical and spin degrees of freedom is paramount.

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30

Hari, Lysianne. "PROPAGATION OF SEMICLASSICAL WAVE PACKETS THROUGH AVOIDED EIGENVALUE CROSSINGS IN NONLINEAR SCHRÖDINGER EQUATIONS". Journal of the Institute of Mathematics of Jussieu 15, nr 2 (20.10.2014): 319–65. http://dx.doi.org/10.1017/s1474748014000346.

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We study the propagation of wave packets for a one-dimensional system of two coupled Schrödinger equations with a cubic nonlinearity, in the semiclassical limit. Couplings are induced by the nonlinearity and by the potential, whose eigenvalues present anavoided crossing: at one given point, the gap between them reduces as the semiclassical parameter becomes smaller. For data which are coherent states polarized along an eigenvector of the potential, we prove that when the wave function propagates through the avoided crossing point there are transitions between the eigenspaces at leading order. We analyze the nonlinear effects, which are noticeable away from the crossing point, but see that in a small time interval around this point the nonlinearity’s role is negligible at leading order, and the transition probabilities can be computed with the linear Landau–Zener formula.

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31

Хомицкий, Д. В., i Н. А. Запруднов. "Спин-зависимое туннелирование в двойной квантовой точке в режиме "медленной" эволюции". Физика и техника полупроводников 56, nr 10 (2022): 973. http://dx.doi.org/10.21883/ftp.2022.10.53958.9875.

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The tunneling and spin dynamics is studied for the hole states in a GaAs-based double quantum dot in the presence of strong spin-orbit coupling and periodic electric field. The regimes of tunneling with the spin flip are considered for the “slow” evolution when the field frequency is lower than the other energy parameters of the stationary part of the Hamiltonian. It is found that the under such conditions the spin flip tunneling may take place at both resonant and non-resonant regimes with respect to the Zeeman level splitting. In the latter case the driving frequency may be lower compared to the resonance one, and the system dynamics resembles the Landau-Zener-Stückelberg-Majorana interference effects arising during the dynamic level passage in isolated quantum dots.

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32

Grumer, J., i P. S. Barklem. "Excitation and charge transfer in low-energy hydrogen atom collisions with neutral manganese and titanium". Astronomy & Astrophysics 637 (maj 2020): A28. http://dx.doi.org/10.1051/0004-6361/201937434.

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Data for inelastic processes due to hydrogen atom collisions with manganese and titanium are needed for accurate modeling of the corresponding spectra in late-type stars. In this work excitation and charge transfer in low-energy Mn+H and Ti+H collisions have been studied theoretically using a method based on an asymptotic two-electron linear combination of an atomic orbitals model of ionic-covalent interactions in the neutral atom-hydrogen-atom system, together with the multichannel Landau-Zener model to treat the dynamics. Extensive calculations of charge transfer (mutual neutralization, ion-pair production), excitation and de-excitation processes in the two collisional systems are carried out for all transitions between covalent states dissociating to energies below the first ionic limit and the dominating ionic states. Rate coefficients are determined for temperatures in the range 1000–20 000 K in steps of 1000 K. Like for earlier studies of other atomic species, charge transfer processes are found to lead to much larger rate coefficients than excitation processes.

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33

Maroufian, Arash, Mehdi Hosseini i Fatemeh Ahmadinouri. "Effect of the next-nearest-neighbor's interaction on the population transfer in a four-particle Landau-Zener system". OSA Continuum 4, nr 2 (19.01.2021): 290. http://dx.doi.org/10.1364/osac.416739.

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34

Levi, Andrea C. "Free Will with Afterthoughts: A Quasichemical Model". Journal of Theoretical Chemistry 2013 (17.12.2013): 1–9. http://dx.doi.org/10.1155/2013/902423.

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A model of free will is proposed, appealing to the similarity with simple, two-body chemical reactions where the energy curves for the reagents and for the products cross. The system at the crossing point has a freedom of choice to perform the reaction or not. The Landau-Zener formula, corresponding to the opportunity of meeting twice the crossing point, is interpreted as free will with an afterthought and generalized to the cases when a subject thinks about a choice n times. If the probability distribution pn of afterthoughts is known, the probability of a final yes decision is given. The results are generalized to situations where a preference for or against a change exists or where the freedom is only partial, has to fight with conditioning factors, and possibly decreases with increasing instances of free choice.

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35

Fouokeng, G. C., M. Tchoffo, S. Moussiliou, J. C. Ngana Kuetche, Lukong Cornelius Fai i Massou Siaka. "Effect of Noise on the Decoherence of a Central Electron Spin Coupled to an Antiferromagnetic Spin Bath". Advances in Condensed Matter Physics 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/526205.

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We analyze the influence of a two-state autocorrelated noise on the decoherence and on the tunneling Landau-Zener (LZ) transitions during a two-level crossing of a central electron spin (CES) coupled to a one dimensional anisotropic-antiferomagnetic spin, driven by a time-dependent global external magnetic field. The energy splitting of the coupled spin system is found through an approach that computes the noise-averaged frequency. At low magnetic field intensity, the decoherence (or entangled state) of a coupled spin system is dominated by the noise intensity. The effects of the magnetic field pulse and the spin gap antiferromagnetic material used suggest to us that they may be used as tools for the direct observation of the tunneling splitting through the LZ transitions in the sudden limit. We found that the dynamical frequencies display basin-like behavior decay with time, with the birth of entanglement, while the LZ transition probability shows Gaussian shape.

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36

Barklem, P. S. "Excitation and charge transfer in low-energy hydrogen atom collisions with neutral oxygen". Astronomy & Astrophysics 610 (luty 2018): A57. http://dx.doi.org/10.1051/0004-6361/201731968.

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Excitation and charge transfer in low-energy O+H collisions is studied; it is a problem of importance for modelling stellar spectra and obtaining accurate oxygen abundances in late-type stars including the Sun. The collisions have been studied theoretically using a previously presented method based on an asymptotic two-electron linear combination of atomic orbitals (LCAO) model of ionic-covalent interactions in the neutral atom-hydrogen-atom system, together with the multichannel Landau-Zener model. The method has been extended to include configurations involving excited states of hydrogen using an estimate for the two-electron transition coupling, but this extension was found to not lead to any remarkably high rates. Rate coefficients are calculated for temperatures in the range 1000–20 000 K, and charge transfer and (de)excitation processes involving the first excited S-states, 4s.5So and 4s.3So, are found to have the highest rates.

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37

Barklem, P. S. "Excitation and charge transfer in low-energy hydrogen atom collisions with neutral iron". Astronomy & Astrophysics 612 (kwiecień 2018): A90. http://dx.doi.org/10.1051/0004-6361/201732365.

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Data for inelastic processes due to hydrogen atom collisions with iron are needed for accurate modelling of the iron spectrum in late-type stars. Excitation and charge transfer in low-energy Fe+H collisions is studied theoretically using a previously presented method based on an asymptotic two-electron linear combination of atomic orbitals model of ionic-covalent interactions in the neutral atom-hydrogen-atom system, together with the multi-channel Landau–Zener model. An extensive calculation including 166 covalent states and 25 ionic states is presented and rate coefficients are calculated for temperatures in the range 1000–20 000 K. The largest rates are found for charge transfer processes to and from two clusters of states around 6.3 and 6.6 eV excitation, corresponding in both cases to active 4d and 5p electrons undergoing transfer. Excitation and de-excitation processes among these two sets of states are also significant.

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38

Khomitsky D. V. i Zaprudnov N. A. "Spin-dependent tunneling in a double quantum dot in the "slow" evolution regime". Semiconductors 56, nr 10 (2022): 748. http://dx.doi.org/10.21883/sc.2022.10.55025.9875.

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The tunneling and spin dynamics is studied for the hole states in a GaAs-based double quantum dot in the presence of strong spin-orbit coupling and periodic electric field. The regimes of tunneling with the spin flip are considered for the "slow" evolution when the field frequency is lower than the other energy parameters of the stationary part of the Hamiltonian. It is found that the under such conditions the spin flip tunneling may take place at both resonant and non-resonant regimes with respect to the Zeeman level splitting. In the latter case the driving frequency may be lower compared to the resonance one, and the system dynamics resembles the Landau-Zener-Stuckelberg-Majorana interference effects arising during the dynamic level passage in isolated quantum dots. Keywords: double quantum dot, spin-orbit interaction, Zeeman splitting, tunneling, electric dipole spin resonance.

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39

ZHEN, YIN. "DYNAMIC THEORY OF ELECTRON TRANSFER PROCESS". Modern Physics Letters B 02, nr 05 (czerwiec 1988): 743–52. http://dx.doi.org/10.1142/s0217984988000448.

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Based on time-dependent Hartree-Fork approximation, we have developed a new technique for dealing with non-adiabatic electron transfer process and also obtained the formula for finding consistently the effective adiabatic parameter and the transition probability. Comparing to Landau-Zener theory our results indicate that the transition probability is greatly influenced by the coupling between the electron and the heat-bath. As the initial state of the electron is in the ground state, interaction between the electron and the heat-bath reduces the transition probability between the electron states. This can be explained that the transition probability from covalent to ionic state in a solute reaction system goes down due to the influence of the solvent. As the initial state of the electron is in the excited state, the coupling to the heat-bath acts to enhance the transition probability between the electron states. This can elucidate that desorption probability decreases in the process of the electron stimulated desorption in virtue of the heat-bath.

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40

Mkam Tchouobiap, S. E., J. E. Danga, R. M. Keumo Tsiaze i L. C. Fai. "Coherent nonlinear low-frequency Landau–Zener tunneling induced by magnetic control of a spin qubit in a quantum wire". International Journal of Quantum Information 16, nr 06 (wrzesień 2018): 1850049. http://dx.doi.org/10.1142/s0219749918500491.

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This paper presents nonlinear Landau–Zener (LZ) tunneling of an electron spin in an accelerating optical parabolic potential, manifested in a heterostructure quantum wire subjected to a periodic magnetic field comprising a spike and a homogeneous part. In this context, driving the two states of a pure nonlinear two-level quantum bit (qubit) system through an avoided level crossing can result in nontrivial dynamics, especially with and without considering a parabolic confinement potential characterized by a curvature confinement potential. We report two striking nonadiabatic and adiabatic scenarios in low modulation frequency limit which appear when such strength modulation occurs. Firstly, the changes of the amplitude of the driving field without considering a parabolic confinement potential act as a perturbation which mixes the spin states. Here, the dynamical evolution of the tunneling probabilities of the nonadiabatic populations under investigation is analyzed. Secondly, for strong fields and strong dependence of a parabolic confinement potential, the two diabatic states do not cross but present anti-crossing phenomenon as the time tends to infinity, describing an adiabatic transition. However, if the field strength in a wire is weak enough, the level separation of a qubit state switches abruptly around the crossing point, and LZ tunneling applies to the whole dynamical range, from adiabatic to fully nonadiabatic crossing. Locally, the tunneling process can be seen as a two-level system (TLS) undergoing a Rabi oscillation. These results open new prospects for the use of quantum interferences in spin–based devices.

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41

Volkoff, T. J., i K. B. Whaley. "Distinguishability times and asymmetry monotone-based quantum speed limits in the Bloch ball". Quantum 2 (1.10.2018): 96. http://dx.doi.org/10.22331/q-2018-10-01-96.

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For both unitary and open qubit dynamics, we compare asymmetry monotone-based bounds on the minimal time required for an initial qubit state to evolve to a final qubit state from which it is probabilistically distinguishable with fixed minimal error probability (i.e., the minimal error distinguishability time). For the case of unitary dynamics generated by a time-independent Hamiltonian, we derive a necessary and sufficient condition on two asymmetry monotones that guarantees that an arbitrary state of a two-level quantum system or a separable state of N two-level quantum systems will unitarily evolve to another state from which it can be distinguished with a fixed minimal error probability δ∈[0,1/2]. This condition is used to order the set of qubit states based on their distinguishability time, and to derive an optimal release time for driven two-level systems such as those that occur, e.g., in the Landau-Zener problem. For the case of non-unitary dynamics, we compare three lower bounds to the distinguishability time, including a new type of lower bound which is formulated in terms of the asymmetry of the uniformly time-twirled initial system-plus-environment state with respect to the generator HSE of the Stinespring isometry corresponding to the dynamics, specifically, in terms of ‖[HSE,ρav(τ)]‖1, where ρav(τ):=1τ∫0τdte−iHSEtρ⊗|0⟩E⟨0|EeiHSEt.

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42

Janev, R. K. "Structure of (Nlm)-(N+1,l+1,m) nonadiabatic couplings in (Z1,e,Z2) system and theZ2/Z1range of Landau-Zener coupling". Physical Review A 55, nr 6 (1.06.1997): 4285–89. http://dx.doi.org/10.1103/physreva.55.4285.

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Dan, Xiaohan, Meng Xu, Yaming Yan i Qiang Shi. "Generalized master equation for charge transport in a molecular junction: Exact memory kernels and their high order expansion". Journal of Chemical Physics 156, nr 13 (7.04.2022): 134114. http://dx.doi.org/10.1063/5.0086663.

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We derive a set of generalized master equations (GMEs) to study charge transport dynamics in molecular junctions using the Nakajima–Zwanzig–Mori projection operator approach. In the new GME, time derivatives of population on each quantum state of the molecule, as well as the tunneling current, are calculated as the convolution of time non-local memory kernels with populations on all system states. The non-Markovian memory kernels are obtained by combining the hierarchical equations of motion (HEOM) method and a previous derived Dyson relation for the exact kernel. A perturbative expansion of these memory kernels is then calculated using the extended HEOM developed in our previous work [M. Xu et al., J. Chem. Phys. 146, 064102 (2017)]. By using the resonant level model and the Anderson impurity model, we study properties of the exact memory kernels and analyze convergence properties of their perturbative expansions with respect to the system–bath coupling strength and the electron–electron repulsive energy. It is found that exact memory kernels calculated from HEOM exhibit short memory times and decay faster than the population and current dynamics. The high order perturbation expansion of the memory kernels can give converged results in certain parameter regimes. The Padé and Landau–Zener resummation schemes are also found to give improved results over low order perturbation theory.

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44

Mirea, M. "Landau–Zener Effect in Superfluid Nuclear Systems". Modern Physics Letters A 18, nr 26 (30.08.2003): 1809–17. http://dx.doi.org/10.1142/s021773230301154x.

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The Landau–Zener effect is generalized for many-body systems with pairing residual interactions. The microscopic equations of motion are obtained and the 14C decay of 223Ra spectroscopic factors are deduced. An asymmetric nuclear shape parametrization given by two intersected spheres is used. The single particle level scheme is determined in the frame of the superasymmetric two-center shell model. The deformation energy is computed in the microscopic–macroscopic approximation. The penetrabilities are obtained within the WKB approximation. The fine structure of the cluster decay analyzed in the frame of this formalism gives a very good agreement with the experimental ratio of partial half-lives for transition to the first excited state and to the ground state.

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45

Firica, Gabriel. "Refined Landau-Zener formulae: multilevel systems and applications". Comptes Rendus de l'Académie des Sciences - Series I - Mathematics 325, nr 4 (sierpień 1997): 449–54. http://dx.doi.org/10.1016/s0764-4442(97)85634-0.

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Bouwmeester, D., N. H. Dekker, F. E. v. Dorsselaer, C. A. Schrama, P. M. Visser i J. P. Woerdman. "Observation of Landau-Zener dynamics in classical optical systems". Physical Review A 51, nr 1 (1.01.1995): 646–54. http://dx.doi.org/10.1103/physreva.51.646.

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47

Jakšić, Vojkan, i Jan Segert. "On the Landau–Zener formula for two‐level systems". Journal of Mathematical Physics 34, nr 7 (lipiec 1993): 2807–20. http://dx.doi.org/10.1063/1.530097.

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MARTIN, PH A., i G. NENCIU. "SEMI-CLASSICAL INELASTIC S-MATRIX FOR ONE-DIMENSIONAL N-STATES SYSTEMS". Reviews in Mathematical Physics 07, nr 02 (luty 1995): 193–242. http://dx.doi.org/10.1142/s0129055x95000116.

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A mathematically fully controlled study of the semi-classical S-matrix associated with one-dimensional N-states systems is presented for energies above the barriers. The transmission coefficients are described by an “effective evolution” model which at high energies approaches the usual “common trajectory” model. In the two-states case a refined Landau-Zener formula describing the cross-over regime between avoided and real crossings is obtained.

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49

Hams, Anthony, Hans De Raedt, Seiji Miyashita i Keiji Saito. "Feedback effect on Landau-Zener-Stückelberg transitions in magnetic systems". Physical Review B 62, nr 21 (1.12.2000): 13880–83. http://dx.doi.org/10.1103/physrevb.62.13880.

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Sánchez, M. J., E. Vergini i D. A. Wisniacki. "Characterization of Landau-Zener transitions in systems with complex spectra". Physical Review E 54, nr 5 (1.11.1996): 4812–18. http://dx.doi.org/10.1103/physreve.54.4812.

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