The Experts below are selected from a list of 49653 Experts worldwide ranked by ideXlab platform
Ka Shen - One of the best experts on this subject based on the ideXlab platform.
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spin orbit coupling and linear crossings of dipolar magnons in van der waals antiferromagnets
Physical Review B, 2020Co-Authors: Jie Liu, L Wang, Ka ShenAbstract:A magnon spin-orbit coupling, induced by the Dipole-Dipole Interaction, is derived in monoclinic-stacked bilayer honeycomb spin lattice with perpendicular magnetic anisotropy and antiferromagnetic interlayer coupling. Linear crossings are predicted in the magnon spectrum around the band minimum in $\mathrm{\ensuremath{\Gamma}}$ valley, as well as in the high-frequency range around the zone boundary. The linear crossings in $K$ and ${K}^{\ensuremath{'}}$ valleys, which connect the acoustic and optical bands, can be gapped when the intralayer Dipole-Dipole or Kitaev Interactions exceed the interlayer Dipole-Dipole Interaction, resulting in a phase transition from semimetal to insulator. Our results are useful for analyzing the magnon spin dynamics and transport properties in van der Waals antiferromagnets.
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Spin-orbit coupling and linear crossings of dipolar magnons in van der Waals antiferromagnets
2020Co-Authors: Liu Jie, Wang Lin, Ka ShenAbstract:A magnon spin-orbit coupling, induced by the Dipole-Dipole Interaction, is derived in monoclinic-stacked bilayer honeycomb spin lattice with perpendicular magnetic anisotropy and antiferromagnetic interlayer coupling. Linear crossings are predicted in the magnon spectrum around the band minimum in G valley, as well as in the high frequency range around the zone boundary. The linear crossings in K and K' valleys, which connect the acoustic and optical bands, can be gapped when the intralayer Dipole-Dipole or Kitaev Interactions exceed the interlayer Dipole-Dipole Interaction, resulting in a phase transition from semimetal to insulator. Our results are useful for analyzing the magnon spin dynamics and transport properties in van der Waals antiferromagnet.Comment: 10 page
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dipolar spin waves in uniaxial easy axis antiferromagnets a natural topological nodal line semimetal
Physical Review Research, 2020Co-Authors: Jie Liu, L Wang, Ka ShenAbstract:The authors show that the Dipole-Dipole Interaction drives the magnons in any uniaxial easy-axis antiferromagnet into a topological nodal-line semimetal phase, which hosts surface modes with chirality-momentum locking.
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Dipolar spin waves in uniaxial easy-axis antiferromagnets: A natural topological nodal-line semimetal
'American Physical Society (APS)', 2020Co-Authors: Liu Jie, Wang Lin, Ka ShenAbstract:The existence of the magnetostatic surface spin waves in ferromagnets, known as Damon-Eshbach mode, was recently demonstrated to originate from the topology of the Dipole-Dipole Interaction. In this work, we study the topological characteristics of magnons in easy-axis antiferromagnets with uniaxial anisotropy. The dipolar spin waves are found to be, driven by the Dipole-Dipole Interaction, in a topological nodal-line semimetal phase, which hosts Damon-Eshbach-type surface modes due to the bulk-edge correspondence. The long wavelength character of dipolar spin waves makes our proposal valid for any natural uniaxial easy-axis antiferromagnet, and thus enriches the candidates of topological magnonic materials. In contrast to the nonreciprocal property in ferromagnetic case, the surface modes with opposite momentum coexist at each surface, but with different chiralities. Such a chirality-momentum or spin-momentum locking, similar to that of electronic surface states in topological insulators, offers the opportunity to design novel chirality-based magnonic devices in antiferromagnets
Wenting Zhou - One of the best experts on this subject based on the ideXlab platform.
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resonance Dipole Dipole Interaction between two accelerated atoms in the presence of a reflecting plane boundary
Symmetry, 2018Co-Authors: Wenting Zhou, Roberto Passante, Lucia RizzutoAbstract:We study the resonant Dipole–Dipole Interaction energy between two non-inertial identical atoms, one excited and the other in the ground state, prepared in a correlated Bell-type state, and interacting with the scalar field or the electromagnetic field nearby a perfectly reflecting plate. We suppose the two atoms move with the same uniform acceleration, parallel to the plane boundary, and that their separation is constant during the motion. By separating the contributions of radiation reaction field and vacuum fluctuations to the resonance energy shift of the two-atom system, we show that Unruh thermal fluctuations do not affect the resonance Interaction, which is exclusively related to the radiation reaction field. However, non-thermal effects of acceleration in the radiation-reaction contribution, beyond the Unruh acceleration–temperature equivalence, affect the resonance Interaction energy. By considering specific geometric configurations of the two-atom system relative to the plate, we show that the presence of the mirror significantly modifies the resonance Interaction energy between the two accelerated atoms. In particular, we find that new and different features appear with respect to the case of atoms in the free-space, related to the presence of the boundary and to the peculiar structure of the quantum electromagnetic field vacuum in the locally inertial frame. Our results suggest the possibility to exploit the resonance Interaction between accelerated atoms as a probe for detecting the elusive effects of atomic acceleration on radiative processes.
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resonance Dipole Dipole Interaction between two accelerated atoms in the presence of a reflecting plane boundary
arXiv: Quantum Physics, 2018Co-Authors: Wenting Zhou, Roberto Passante, Lucia RizzutoAbstract:We study the resonant Dipole-Dipole Interaction energy between two uniformly accelerated identical atoms, one excited and the other in the ground state, prepared in a correlated {\em Bell-type} state, and interacting with the scalar field or the electromagnetic field nearby a perfectly reflecting plate. We suppose the two atoms moving with the same uniform acceleration, parallel to the plane boundary, and that their separation is constant during the motion. We separate the contributions of vacuum fluctuations and radiation reaction field to the resonance energy shift of the two-atom system, and show that Unruh thermal fluctuations do not affect the resonance Interaction, which is exclusively related to the radiation reaction field. However, nonthermal effects of acceleration in the radiation-reaction contribution, beyond the Unruh acceleration-temperature equivalence, affect the resonance Interaction energy. By considering specific geometric configurations of the two-atom system relative to the plate, we show that the presence of the mirror significantly modifies the resonance Interaction energy between the two accelerated atoms. In particular, we find that new and different features appear with respect to the case of atoms in the free space, related to the presence of the boundary and to the peculiar structure of the quantum electromagnetic field vacuum in the locally inertial frame. Our results suggest the possibility to exploit the resonance Interaction between accelerated atoms, as a probe for detecting the elusive effects of atomic acceleration on radiative processes.
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vacuum fluctuations and radiation reaction contributions to the resonance Dipole Dipole Interaction between two atoms near a reflecting boundary
Physical Review A, 2018Co-Authors: Wenting Zhou, Lucia Rizzuto, Roberto PassanteAbstract:We investigate the resonance Dipole-Dipole Interaction energy between two identical atoms, one in the ground state and the other in the excited state, interacting with the electromagnetic field in the presence of a perfectly reflecting plane boundary. The atoms are prepared in a correlated (symmetric or antisymmetric) Bell-type state. Following a procedure due to Dalibard et al. [J. Dalibard et al., J. Phys. (Paris) 43, 1617 (1982); J. Phys. (Paris) 45, 637 (1984)], we separate the contributions of vacuum fluctuations and radiation reaction (source) field to the resonance Interaction energy between the two atoms and show that only the source field contributes to the interatomic Interaction, while vacuum field fluctuations do not. By considering specific geometric configurations of the two-atom system with respect to the mirror and specific choices of Dipole orientations, we show that the presence of the mirror significantly affects the resonance Interaction energy and that different features appear with respect to the case of atoms in free space, for example, a change in the spatial dependence of the Interaction. Our findings also suggest that the presence of a boundary can be exploited to tailor and control the resonance Interaction between two atoms, as well as the related energy transfer process. The possibility of observing these phenomena is also discussed.
Mahi R. Singh - One of the best experts on this subject based on the ideXlab platform.
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enhancement of the second harmonic generation in a quantum dot metallic nanoparticle hybrid system
Nanotechnology, 2013Co-Authors: Mahi R. SinghAbstract:We have investigated the second-harmonic generation (SHG) and Dipole–Dipole Interaction in a quantum dot and metallic nanoparticle hybrid system. A strong probe field is applied to create two-photon absorption in the quantum dot and metallic nanoparticle. SHG photons and SHG surface plasmon polaritons are emitted by the quantum dot and metallic nanoparticle, respectively. Induced Dipoles are created in the quantum dot and the metallic nanoparticle due to two-photon absorption and hence both systems interact with each other via the Dipole–Dipole Interaction. It is found that SHG signals produced by the quantum dot and nanoparticle are enhanced by the Dipole–Dipole Interaction and also that the SHG signal can be switched on and off by applying a control field. The theoretical findings of this paper are supported by recent experimental studies. The present hybrid system can be used to fabricate nano-sensors and all-optical nano-switching devices.
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Dipole-Dipole Interaction between a quantum dot and a graphene nanodisk
Physical Review B, 2012Co-Authors: Joel D. Cox, Mahi R. Singh, Godfrey Gumbs, Miguel A. Antón, Fernando CarreñoAbstract:We study theoretically the Dipole-Dipole Interaction and energy transfer in a hybrid system consisting of a quantum dot and graphene nanodisk embedded in a nonlinear photonic crystal. In our model, a probe laser field is applied to measure the energy transfer between the quantum dot and graphene nanodisk, while a control field manipulates the energy transfer process. These fields create excitons in the quantum dot and surface plasmon polaritons in the graphene nanodisk which interact via the Dipole-Dipole Interaction. Here, the nonlinear photonic crystal acts as a tunable photonic reservoir for the quantum dot, and is used to control the energy transfer. We have found that the spectrum of power absorption in the quantum dot has two peaks due to the creation of two dressed excitons in the presence of the Dipole-Dipole Interaction. The energy transfer rate spectrum of the graphene nanodisk also has two peaks due to the absorption of these two dressed excitons. Additionally, energy transfer between the quantum dot and the graphene nanodisk can be switched on and off by applying a pump laser to the photonic crystal or by adjusting the strength of the Dipole-Dipole Interaction. We show that the intensity and frequencies of the peaks in the energy transfer rate spectra can be modified by changing the number of graphene monolayers in the nanodisk or the separation between the quantum dot and graphene. Our results agree with existing experiments on a qualitative basis. The principle of our system can be employed to fabricate nanobiosensors, optical nanoswitches, and energy transfer devices.
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Dipole Dipole Interaction in a quantum dot and metallic nanorod hybrid system
Applied Physics Letters, 2011Co-Authors: Mahi R. Singh, Daniel Schindel, Ali HatefAbstract:We have studied quantum coherence and interference phenomena in a quantum dot (QD)-metallic nanorod (MNR) hybrid system. Probe and control laser fields are applied to the hybrid system. Induced Dipole moments are created in the QD and the MNR, and they interact with each other via the Dipole-Dipole Interaction. Using the density matrix method, it was found that the power spectrum of MNR has two transparent, states and they can be switched to one transparent state by the control field. Ultrafast switching and sensing nanodevices could be produced using this model.
M A Baranov - One of the best experts on this subject based on the ideXlab platform.
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theoretical progress in many body physics with ultracold dipolar gases
Physics Reports, 2008Co-Authors: M A BaranovAbstract:Abstract Recent experimental progress in trapping and cooling of molecular gases boosts interest in the interdisciplinary field of quantum gases with dominant Dipole–Dipole Interactions. An unprecedented level of experimental control together with specific physical properties of Dipole–Dipole Interaction provide a unique possibility to find new physical phenomena and practical applications. In this review, recent achievements in theoretical studies of ultracold dipolar gases, both fermionic and bosonic, are presented. We focus our attention on many-body properties of such systems and discuss how the characteristic features of Dipole–Dipole Interaction, long range and anisotropy, affect their collective behavior and result in novel macroscopic quantum phenomena. The consideration covers spatially homogeneous and trapped cases, and includes analysis of the properties of dipolar gases in both the mean-field regime (dipolar Bose–Einstein condensates and superfluid BCS pairing transition) and in the strongly correlated one (dipolar gases in optical lattices and in rotating traps).
Jie Liu - One of the best experts on this subject based on the ideXlab platform.
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spin orbit coupling and linear crossings of dipolar magnons in van der waals antiferromagnets
Physical Review B, 2020Co-Authors: Jie Liu, L Wang, Ka ShenAbstract:A magnon spin-orbit coupling, induced by the Dipole-Dipole Interaction, is derived in monoclinic-stacked bilayer honeycomb spin lattice with perpendicular magnetic anisotropy and antiferromagnetic interlayer coupling. Linear crossings are predicted in the magnon spectrum around the band minimum in $\mathrm{\ensuremath{\Gamma}}$ valley, as well as in the high-frequency range around the zone boundary. The linear crossings in $K$ and ${K}^{\ensuremath{'}}$ valleys, which connect the acoustic and optical bands, can be gapped when the intralayer Dipole-Dipole or Kitaev Interactions exceed the interlayer Dipole-Dipole Interaction, resulting in a phase transition from semimetal to insulator. Our results are useful for analyzing the magnon spin dynamics and transport properties in van der Waals antiferromagnets.
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dipolar spin waves in uniaxial easy axis antiferromagnets a natural topological nodal line semimetal
Physical Review Research, 2020Co-Authors: Jie Liu, L Wang, Ka ShenAbstract:The authors show that the Dipole-Dipole Interaction drives the magnons in any uniaxial easy-axis antiferromagnet into a topological nodal-line semimetal phase, which hosts surface modes with chirality-momentum locking.