Article
Quantum Science & Technology
Shi Jin, Xiantao Li, Nana Liu
Summary: This paper discusses the solution of the time-dependent Schrodinger equation in the semi-classical regime, considering the multiple-scale behavior and the impact of a small parameter. Quantum analogues of pseudo-spectral methods on classical computers are explored, and estimates on the gate counts are obtained. It is found that the number of required qubits scales logarithmically, and when physical observables are the desired outcomes, the gate complexity is reduced.
Article
Mathematics, Applied
Constantino Tsallis, Henrique Santos Lima, Ugur Tirnakli, Deniz Eroglu
Summary: This paper numerically studies the thermal transport in d=1,2,3 dimensions of classical inertial nearest-neighbor XY ferromagnet. The expression of thermal conductance is found to be related to the system size L and temperature T, and inversely proportional to the thermal conductance in the infinite system size limit. These findings contribute to the understanding of the thermal conductivity of materials.
PHYSICA D-NONLINEAR PHENOMENA
(2023)
Article
Physics, Fluids & Plasmas
Luigi Barletti, Paolo Bordone, Lucio Demeio, Elisa Giovannini
Summary: This study investigates the impact of the reduction of correlation length on a one-dimensional scattering problem through numerical simulations. The results indicate that a decrease in correlation length leads to broadening and flattening of the Wigner function, resulting in reduced reflection at low energies and reduced transmission at high energies.
Article
Mechanics
Yusuke Shibasaki, Minoru Saito, Ken Judai
Summary: Generalized statistical mechanics based on q-Gaussian is an effective theoretical framework for analyzing non-equilibrium systems. In this study, an alternative method based on the Loewner equation is introduced to convert the multiplicative Langevin dynamics into an equilibrium system obeying the conventional microcanonical ensemble. The fluctuations and dissipation properties of the converted system are discussed, revealing a novel connection between q-generalized and Boltzmann-Gibbs statistical mechanics.
JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT
(2023)
Article
Physics, Multidisciplinary
Augusto C. L. Moreira, Celso P. de Melo
Summary: In this study, we demonstrate that the classical master equation (CME) treatment and the elastic scattering (ES) approach yield equivalent results for a system consisting of two states/one level under certain approximations. However, when considering more states and/or levels, the predictions of these two approaches deviate. The CME and ES approaches capture the same physics in the transport process under specific conditions, but their predictions differ in other situations.
Article
Optics
S. Fedorov, N. N. Rosanov, I. A. Aleksandrov, R. Popov, D. A. Tumakov, A. Dadeko, E. A. Vashukevich, A. Baeva
Summary: The study focuses on analyzing weak quantum fluctuations of a spatial soliton in a laser with fast saturable absorption, potentially with the presence of weak holding radiation. By linearizing the master Heisenberg-Langevin equation and constructing the solution based on the spectral expansion in eigenfunctions, the mean values of the squared fluctuations of the soliton's center coordinates and momentum are determined using the discrete spectrum of the evolution operator. A comparison is made with similar fluctuations in driven interferometers with Kerr non-linearity of the medium.
LASER PHYSICS LETTERS
(2021)
Article
Computer Science, Interdisciplinary Applications
Clemens Willers, Oliver Kamps
Summary: Modeling non-Markovian time series using the generalized Langevin equation (GLE) and Bayesian estimation is a promising approach in various fields. This study presents an efficient implementation of Bayesian estimation for GLE by using a piecewise constant approximation of the model's drift and diffusion functions. This method reduces the numerical cost and allows for the consideration of trend effects. The capabilities of the method and model are illustrated using an example from turbulence.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Physics, Multidisciplinary
Augusto C. L. Moreira, Juliana A. B. da Silva
Summary: In this work, we demonstrate that in the non-interacting limit, the classical master equation (CME) with electron transfer rates obtained via Fermi golden rule and the elastic scattering approach are equivalent. This finding provides a theoretical basis for incorporating elastic mechanisms into quantum transport, allowing the description of weak and strong quantum transport regimes within the same theory.
Article
Optics
Massimo Frigerio, Claudia Benedetti, Stefano Olivares, Matteo G. A. Paris
Summary: The study introduces a minimal set of physically motivated postulates that the Hamiltonian of a continuous-time quantum walk should satisfy for properly representing the quantum counterpart of a classical random walk on a given graph. It is found that there are infinitely many quantum Hamiltonians that meet these conditions, which offer novel degrees of freedom for quantum enhanced protocols. The on-site energies and phases of the off-diagonal elements in the Hamiltonian are shown to be unconstrained on the quantum side, providing potential for control and manipulation in quantum walks.
Article
Physics, Multidisciplinary
Ko Sanders
Summary: The article investigates the properties of solutions of the semi-classical Einstein-Klein-Gordon system with a cosmological constant Lambda, by analyzing the choice of parameters and renormalization constants to determine the set of solutions, while also characterizing the features of quasi-free solutions.
ANNALES HENRI POINCARE
(2022)
Article
Chemistry, Multidisciplinary
Simon Huppert, Thomas Ple, Sara Bonella, Philippe Depondt, Fabio Finocchi
Summary: This paper reviews methods for simulating nuclear quantum effects using generalized thermal baths. The baths simulate quantum features through non-Markovian stochastic dynamics, and have been successful in various systems. The paper discusses the characteristics and applications of generalized baths, as well as the issues related to zero-point energy leakage. It also presents a recently proposed adaptive quantum thermal bath scheme to mitigate this problem and concludes with further development opportunities and challenges.
APPLIED SCIENCES-BASEL
(2022)
Article
Quantum Science & Technology
Saachi Mutreja, Walter O. Krawec
Summary: This paper investigates a mediated semi-quantum key distribution protocol and proposes improvements and extensions to enhance the protocol's efficiency and noise tolerance. The protocol enables the sharing of a secret key among users who have limited quantum abilities, using only the capability to detect or reflect qubits, with the assistance of a quantum server controlled by the adversary.
QUANTUM INFORMATION PROCESSING
(2022)
Article
Automation & Control Systems
Ugo Boscain, Eugenio Pozzoli, Mario Sigalotti
Summary: This paper studies the controllability problem for a symmetric-top molecule in both classical and quantum rotational dynamics using three orthogonal electric fields interacting with its electric dipole. Different controllability characteristics are observed based on the dipole position, resulting in the emergence of quantum symmetry in quantum dynamics without a classical counterpart. The approximate controllability of the symmetric-top Schriidinger equation is established using a Lie-Galerkin method based on blockwise approximations.
SIAM JOURNAL ON CONTROL AND OPTIMIZATION
(2021)
Article
Physics, Particles & Fields
Sandip Chowdhury, Kunal Pal, Kuntal Pal, Tapobrata Sarkar
Summary: This study demonstrates how to solve common issues in the conformal version by using appropriate disformal transformations to introduce quantum effects into gravitational theory.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Multidisciplinary
Wan Qing Wu, Chen Yang Sun
Summary: This study proposes a semi-quantum key distribution protocol that allows a quantum user to distribute different private keys to two classical users simultaneously. By using Bell-state measurement, particles can be detected simultaneously and generate different raw keys. The protocol can be extended to multi-party communication scheme and significantly reduces communication complexity in large-scale communication networks.
FRONTIERS IN PHYSICS
(2022)
Review
Chemistry, Multidisciplinary
Ferdinand Evers, Amnon Aharony, Nir Bar-Gill, Ora Entin-Wohlman, Per Hedegard, Oded Hod, Pavel Jelinek, Grzegorz Kamieniarz, Mikhail Lemeshko, Karen Michaeli, Vladimiro Mujica, Ron Naaman, Yossi Paltiel, Sivan Refaely-Abramson, Oren Tal, Jos Thijssen, Michael Thoss, Jan M. van Ruitenbeek, Latha Venkataraman, David H. Waldeck, Binghai Yan, Leeor Kronik
Summary: This article provides a critical overview of the theory of the chirality-induced spin selectivity (CISS) effect and reviews its applications in electron processes. It discusses the latest developments in the understanding of the CISS effects in electron transmission, electron transport, and chemical reactions, and identifies the remaining challenges and research opportunities.
ADVANCED MATERIALS
(2022)
Article
Physics, Multidisciplinary
Fei Gao, Dongzhe Li, Cyrille Barreteau, Mads Brandbyge
Summary: All-electrical writing and reading of spin states can be achieved in molecular spinterfaces by depositing FeTPP molecules, and a feasible three-terminal setup to probe the spin state is proposed. In addition, we demonstrate how FeTPP modifies the quantum transport of non-spin polarized BG.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Mehdi Bouatou, Cyril Chacon, Aleksander Bach Lorentzen, Huu Thoai Ngo, Yann Girard, Vincent Repain, Amandine Bellec, Sylvie Rousset, Mads Brandbyge, Yannick J. Dappe, Jerome Lagoute
Summary: This study demonstrates the realization of nanopatterning of nitrogen dopants in graphene by using a submonolayer of self-assembled physisorbed molecules as a resist during post-synthesis nitrogen doping process. The resulting domains with different nitrogen concentrations enable the formation of n-n' and p-n junctions in graphene. The electronic properties of the junctions were measured at the atomic scale using scanning tunneling microscopy, revealing an intrinsic width of approximately 7 nm corresponding to a sharp junction regime.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Physical
Liangguang Jia, Fei Gao, Yu Zhang, Yaoyao Chen, Baofei Hou, Zeping Huang, Quanzhen Zhang, Xu Wu, Liwei Liu, Shiwu Gao, Mads Brandbyge, Hong-Jun Gao, Yeliang Wang
Summary: This study reports the influence of defects in vdW crystals on the local atomic configurations and interlayer coupling. The findings show that Se vacancies in few-layer NbSe2 can cause atomic distortions and generate in-gap states in single-layer NbSe2. Moreover, these vacancies lead to a significant suppression of interlayer coupling in the bilayer system.
Article
Physics, Condensed Matter
Sofia Sanz, Nick Papior, Geza Giedke, Daniel Sanchez-Portal, Mads Brandbyge, Thomas Frederiksen
Summary: We theoretically study electron interference in a Mach-Zehnder-like geometry formed by four parallel pairs of zigzag graphene nanoribbons. By adjusting the interribbon separation, each intersection can function as an electron beam splitter or mirror, allowing for tuneable circuitry with interfering pathways. We evaluate the electron transport properties of these eight-terminal devices and identify pairs of terminals subject to self-interference. The proposed devices have potential applications as magnetic field sensors, detectors of phase shifts induced by local scatterers, and for the study of quantum entanglement.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Chemistry, Multidisciplinary
Cesar Moreno, Xabier Diaz de Cerio, Manuel Vilas-Varela, Maria Tenorio, Ane Sarasola, Mads Brandbyge, Diego Pena, Aran Garcia-Lekue, Aitor Mugarza
Summary: Recent advances in surface-assisted synthesis have demonstrated the ability to create highly anisotropic nanoporous graphene structures by laterally coupling arrays of nanometer wide graphene nanoribbons. In this study, a new nanoporous graphene structure was synthesized in which the interribbon electronic coupling can be controlled by phenylene bridges. The versatility of this structure arises from the multiple configurations of phenylene cross-coupling and the twist angle, which can be altered by interaction with the substrate and other external stimuli.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Physics, Multidisciplinary
Xiaocui Wu, Nicolas Neel, Mads Brandbyge, Joerg Kroeger
Summary: The abstraction of pyrrolic hydrogen from a single phthalocyanine on graphene turns the molecule into a sensitive probe for graphene phonons. The inelastic electron transport measured with a scanning tunneling microscope across the molecular adsorbate and graphene becomes strongly enhanced for a graphene out-of-plane acoustic phonon mode. Supporting density functional and transport calculations elucidate the underlying physical mechanism.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Fei Gao, Rodrigo E. E. Menchon, Aran Garcia-Lekue, Mads Brandbyge
Summary: Recently, researchers have combined porphyrin units with graphene nanoribbons (Por-GNR) to create various structures. In this study, the authors use first-principles calculations to investigate the properties of two experimentally feasible Por-GNR hybrids. They find that one of the hybrids has a small band gap and can be used as electrodes in devices. By embedding a Fe atom in the porphyrin, a spin-polarized ground state is achieved. The authors examine the spin transport properties of a 2-terminal setup involving a Fe-Por-GNR between Por-GNR electrodes and observe a Fano anti-resonance feature. They also demonstrate how mechanical strain or chemical adsorption can induce spin-crossover, leading to different spin states. These findings provide valuable insights for the development of carbon-based spintronics and chemical sensing applications.
COMMUNICATIONS PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Aleksander Bach Lorentzen, Mehdi Bouatou, Cyril Chacon, Yannick J. Dappe, Jerome Lagoute, Mads Brandbyge
Summary: Recent studies have shown the spatial control of nitrogen dopant concentration in graphene using a molecular mask. This technique enables the creation of ballistic electron optics-like structures and has implications for current focusing and quantized conductance.
Article
Materials Science, Multidisciplinary
Victor Rosendal, Walber H. Brito, Milan Radovic, Alla Chikina, Mads Brandbyge, Nini Pryds, Dirch H. Petersen
Summary: This study maps the energy landscape of octahedral tilting in Strontium niobate using density functional theory calculations, and finds that compressive strain induces tilting around the out-of-plane axis, while tensile strain induces tilting around the in-plane axes. The competition between in-phase and out-of-phase tilting in SrNbO3 allows for tuning the thermoelectric and optical properties. The study also shows how the tilt angle and mode affect the Seebeck coefficient and the plasma frequency due to changes in the band structure.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Lei-Lei Nian, Bo Zheng, Jing-Tao Lue
Summary: We propose a scheme to achieve arbitrary photon statistics in a circuit quantum electrodynamics (cQED) system. By tuning inelastic electron tunneling processes, antibunched, bunched, superthermal, and coherent photon emissions can be achieved. The scheme also allows for the observation of quantum correlation between cavities and the transition from quantum to classical behavior.
Article
Chemistry, Multidisciplinary
Cesar Moreno, Xabier Diaz de Cerio, Manuel Vilas-Varela, Maria Tenorio, Ane Sarasola, Mads Brandbyge, Diego Pena, Aran Garcia-Lekue, Aitor Mugarza
Summary: Recent advances in surface-assisted synthesis have shown that graphene nanoribbons can be coupled laterally to form nanoporous graphene structures. This graphene nanoarchitecture consists of weakly coupled semiconducting nanochannels with electron propagation characterized by interchannel quantum interferences. By utilizing phenylene bridges, the electronic coupling between the nanoribbons in the nanoporous graphene structure can be controlled, providing versatility through different phenylene cross-coupling configurations and twist angles. Simulation results demonstrate the ability to switch on/off or modulate the interribbon coupling using the chemical or conformational knob. Molecular bridges offer efficient tools for engineering quantum transport and anisotropy in carbon-based 2D nanoarchitectures.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Materials Science, Multidisciplinary
Wen-Hao Mao, Man-Yu Shang, Jing-Tao Lue
Summary: We investigate the non-Hermitian collective dynamics of spatially separated edge carbon dimer vibrations in armchair graphene nanoribbons, which are mediated by coherent and dissipative coupling to nonequilibrium electron transport. We demonstrate that the indirect coupling between two dimers crucially depends on gating and source-drain bias. In particular, we analyze the competition between two distinct energy transfer mechanisms from nonequilibrium electrons to vibrations, namely deterministic work done by nonconservative current-induced force and stochastic Joule heating. Our findings suggest that armchair graphene nanoribbons could be promising candidates for experimental exploration of nonconservative current-induced forces in nanoconductors.
Article
Materials Science, Multidisciplinary
Shi-Ping Ding, Miao Liang, Zhen Ma, Jing-Tao Lu, Jin-Hua Gao
Summary: Due to the observed superconductivity in alternating twisted trilayer graphene, researchers have recently shown great interest in this material. By replacing one or several single-layered graphene in the trilayer structure with multilayer graphene, a double-twisted multilayer graphene is obtained. The researchers theoretically illustrate that if the double-twisted multilayer graphene possesses mirror symmetry along the z direction like the trilayer graphene, a mirror symmetry decomposition occurs, resulting in the exact decoupling of the system into two subsystems with opposite parity. This mirror symmetry decomposition provides a clear interpretation of the novel features in the moire band structures of the double-twisted multilayer graphene, and also predicts the existence of superconductivity in a specific configuration of the system.
Article
Materials Science, Multidisciplinary
Lei-Lei Nian, Shiqian Hu, Long Xiong, Jing-Tao Lu, Bo Zheng
Summary: A nonlinear QD-cQED setup is proposed to enhance photon-to-electron conversion by utilizing quantum phase transition. It is found that there is an increased energy transfer from photon to electron systems near the phase transition, leading to an enhancement in photocurrent.
