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191.
Vitalii Semin 《Europhysics letters》2020,130(1)
The non-Markovian generalization of a stochastic Schrödinger equation of diffusion type is considered. Generalization is performed by adding to the system Hamiltonian new stochastic terms some of which are correlated with the environment. The advantage of such an approach is ensuring the complete positivity of the density operator at any time. We illustrate the approach by the example of two interacting qubits in noisy laser fields.https://doi.org/10.1209/0295-5075/130/10003 相似文献
192.
本文以分析变深度螺旋槽止推轴承为例介绍了边界元法在润滑力学研究领域中的应用,以及相应的边界条件的处理方法,同时还讨论了轴承的尺寸参数对其性能参数的影响。 相似文献
193.
It is one of the peculiar features of quantum physics that some sets of measurements are incompatible in the sense that they cannot be performed simultaneously. Incompatibility is an important quantum resource as it enables Bell nonlocality and steering. Here we show that incompatibility is crucial also in certain communication tasks; we prove that quantum random access code performs better than its classical counterpart only when incompatible quantum measurements are used in the decoding task. As a consequence,evaluating the average success probability for quantum random access code provides a semi-device-independent test for the detection of quantum incompatibility. We further demonstrate that any incompatible pair of projective measurements gives an advantage over all classical strategies. Finally,we establish a connection between the maximal average success probability for quantum random access code and earlier quantities introduced to assess incompatibility.https://doi.org/10.1209/0295-5075/130/50001 相似文献
194.
A. K. Malviya;N. Tiwari 《Europhysics letters》2020,132(4)
A vectorial Boolean function takes multi-bit input and produces a multi-bit output. According to the input parameters,a vectorial Boolean function can be linear or non-linear. Non-linear vectorial Boolean functions have high importance in information theory and cryptology. Finding a linear approximation of a non-linear vectorial Boolean function is of high significance in these areas. Assuming that the quantum access to a vectorial Boolean function is provided,we present a quantum computing approach which can find the best linear approximation of the non-linear vectorial Boolean functions. The presented quantum approach is exponentially better than any known solution on the factors of querying the function,quantum circuit depth and memory requirements.https://doi.org/10.1209/0295-5075/132/40001 相似文献
195.
In this contribution,we investigate the interaction between electric and magnetic fields with an electric quadrupole moment of a spinless particle moving in an elastic medium which has a topological defect (screw dislocation). By considering this interaction,the Schrödinger equation is exactly solved by using the analytical method. Thus,the eigenfunction and energy eigenvalues for two configurations are found. Meanwhile,by observing a shift in the angular momentum quantum number,the energy eigenvalues and the wave function of the system are modified,due to the screw dislocation in the medium.https://doi.org/10.1209/0295-5075/132/60005 相似文献
196.
Based on quantum thermodynamic processes, we make a quantum-mechanical (QM) extension of the typical heat engine cycles, such as the Carnot, Brayton, Otto, Diesel cycles, etc., with no introduction of the concept of temperature. When these QM engine cycles are implemented by an ideal gas confined in an arbitrary power-law trap, a relation between the quantum adiabatic exponent and trap exponent is found. The differences and similarities between the efficiency of a given QM engine cycle and its classical counterpart are revealed and discussed.https://doi.org/10.1209/0295-5075/111/20006 相似文献
197.
Qi Tong;Shaofan Li 《Europhysics letters》2015,110(6)
We proposed a novel multiscale molecular-dynamics model in order to apply macroscale boundary conditions to microscale molecular systems, which is difficult for classical molecular dynamics. Unlike in statistical mechanics, in which macroscale quantities such as temperature and pressure are collected from molecular information, the proposed approach is a reversed procedure to find optimal molecular states when macroscale conditions such as traction are enforced. The model is originated from Parrinello-Rahman molecular dynamics but extends it to solve finite-size, inhomogeneous molecular-dynamics problems by generalizing the representative volume element to a “material point” in continuum mechanics. An example of compressing a nickel nanowire is presented to demonstrate the capacity of the method to simulate localized phase transition in a finite-size molecular system, which validates the effectiveness of the method.https://doi.org/10.1209/0295-5075/110/60005 相似文献
198.
A one-dimensional long-range model of classical rotators with an extended degree of complexity, as compared to paradigmatic long-range systems, is introduced and studied. Working at constant density, in the thermodynamic limit one can prove the statistical equivalence with the Hamiltonian mean-field (HMF) model and α -HMF: a second-order phase transition is indeed observed at the critical energy threshold . Conversely, when the thermodynamic limit is performed at infinite density (while keeping the length of the hosting interval L constant), the critical energy is modulated as a function of L . At low energy, a self-organized collective crystal phase is reported to emerge, which converges to a perfect crystal in the limit . To analyze the phenomenon, the equilibrium one-particle density function is analytically computed by maximizing the entropy. The transition and the associated critical energy between the gaseous and the crystal phase is computed. Molecular dynamics show that the crystal phase is apparently split into two distinct regimes, depending on the energy per particle ε . For small ε , particles are exactly located on the lattice sites; above an energy threshold , particles can travel from one site to another. However, does not signal a phase transition but reflects the finite time of observation: the perfect crystal observed for corresponds to a long-lasting dynamical transient, whose lifetime increases when the approaches zero.https://doi.org/10.1209/0295-5075/111/30011 相似文献
199.
Violation of the Leggett-Garg inequality (LGI) implies quantum phenomena. In this light we establish that Moreva et al. 's (Phys. Rev. A , 89 (2014) 052122) experiment demonstrating Page-Wootters' mechanism (Page D. N. and Wootters W. K., Phys. Rev. D , 27 (1983) 2885; Wootters W. K., Int. J. Theor. Phys. , 23 (1984) 701). falls in the quantum domain. An observer outside a 2-photons world does not detect any change in the 2-photons state, i.e. , there is no time parameter for the outside observer. But an observer attached to one of the photons sees the other photon evolving and this means that there is an “internal” time. The LGI is violated for the clock photon whose state evolves with the internal time as measured by the system photon. Conditional probabilities in this 2-photons system are computed for both sharp and unsharp measurements. The conditional probability increases for entangled states as obtained by Page and Wootters for both ideal and also unsharp measurements.https://doi.org/10.1209/0295-5075/116/40007 相似文献
200.
We determine the phase diagram for a generalisation of two- and three-dimensional hard spheres: a classical system with three-body interactions realised as a hard cut-off on the mean-square distance for each triplet of particles. Quantum versions of this model are important in the context of the unitary Bose gas, which is currently under close theoretical and experimental scrutiny. In two dimensions, the three-body hard-core model possesses a conventional atomic liquid phase and a peculiar solid phase formed by dimers. These dimers interact effectively as hard disks. In three dimensions, the solid phase consists of isolated atoms that arrange in a simple-hexagonal lattice.https://doi.org/10.1209/0295-5075/109/20003 相似文献