- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Simple eigenvalue-self-consistent ΔˉGW0
摘要： We show that a rigid scissors-like GW self-consistency approach, labeled here ˉ?GW0, can be trivially implemented at zero additional cost for large scale one-shot G0W 0 calculations. The method significantly improves one-shot G0W 0 and for large systems is very accurate. ˉ?GW0 is similar in spirit to evGW 0 where the self-consistency is only applied on the eigenvalues entering Green’s function, while both W and the eigenvectors of Green’s function are held fixed. ˉ?GW0 further assumes that the shift of the eigenvalues is rigid scissors-like so that all occupied states are shifted by the same amount and analogously for all the unoccupied states. We show that this results in a trivial modification of the time-dependent G0W 0 self-energy, enabling an a posteriori self-consistency cycle. The method is applicable for our recent stochastic-GW approach, thereby enabling self-consistent calculations for giant systems with thousands of electrons. The accuracy of ˉ?GW0 increases with the system size. For molecules, it is up to 0.4-0.5 eV away from coupled-cluster single double triple (CCSD(T)), but for tetracene and hexacene, it matches the ionization energies from both CCSD(T) and evGW 0 to better than 0.05 eV. For solids, as exemplified here by periodic supercells of semiconductors and insulators with 6192 valence electrons, the method matches evGW 0 quite well and both methods are in good agreement with the experiment.
关键词： quasiparticle energies,large systems,self-consistency,stochastic approach,GW approximation
更新于2025-09-10 09:29:36
-
Enhancing nanomechanical squeezing by atomic interactions in a hybrid atom-optomechanical system
摘要： In a hybrid atom-optomechanical system, the optical coupling of a mechanical mode of a nanomembrane in an optical cavity with a distant interacting atom gas permits highly nonclassical quantum many-body states. We show that the mechanical mode can be squeezed by the backaction of internal excitations of the atoms in the gas. A Bogoliubov approach reveals that these internal excitations form a fluctuating environment of quasiparticle excitations for the mechanical mode with a gaped spectral density. Nanomechanical squeezing arises due to quasiparticle excitations in the interacting atom gas when the mechanical frequency is close to resonance with the internal atomic transitions. Interestingly, nanomechanical squeezing is enhanced by atom-atom interactions.
关键词： Bogoliubov approach,atom-optomechanical system,quasiparticle excitations,nanomechanical squeezing,atom-atom interactions
更新于2025-09-09 09:28:46
-
Electronic properties of Pb islands on graphene: Consequences of a weak interface coupling from a combined STM and <i>ab initio</i> study
摘要： By means of scanning tunneling microscopy and spectroscopy, we investigate the electronic properties of lead islands (width 5–100 nm, thickness 5–25 monolayers) deposited by molecular beam epitaxy on twisted graphene layers grown on SiC(000-1). We ?nd that elastic scattering processes govern the local density of states probed at the surface of the Pb islands, inducing (i) the well-known quantum well states due to electron con?nement in the direction perpendicular to the surface and (ii) spatial in-plane periodic modulations related to quasiparticle interferences off the island edges. Through a quantitative analysis of these effects, compared with ab initio calculations for a two-dimensional Pb slab, we conclude that the lead islands grown on the surface of graphene can be considered as freestanding from the point of view of their electronic structure, leaving the surrounding graphene layer unperturbed. Accordingly, low bias tunneling spectra show evidence of a sizable interface resistance. Nevertheless, we suggest that the transparency of the interface, which can be estimated from its resistance, is good enough to induce superconductivity within the underlying graphene layer by proximity effect with the Pb islands.
关键词： lead islands,graphene,quantum well states,quasiparticle interferences,interface resistance,superconductivity,scanning tunneling microscopy,proximity effect,spectroscopy
更新于2025-09-09 09:28:46
-
[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018) - Nagoya (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Terahertz Quasiparticle Acceleration: From Electron-Hole Collisions To Lightwave Valleytronics
摘要： Intense lightwaves can accelerate quasiparticles inside solids. This strong-field light-matter interaction results in the emission of high-harmonic or high-order sideband radiation. While the former process relies on a complex coupling between simultaneously driven interband polarization and intraband currents, high-order sidebands originate from a ballistic acceleration of the quasiparticles within the bands. This mechanism allows for the implementation of a quasiparticle collider in order to study those entities in close analogy to conventional collision experiments. Accelerating electrons and holes in a monolayer of transition metal dichalcogenides extends this scheme to internal quantum degrees of freedom. Our experiments show a lightwave-induced switching of the valley pseudospin, paving the way to ultimately fast valleytronics.
关键词： valley pseudospin,terahertz,high-harmonic generation,lightwave valleytronics,electron-hole collisions,quasiparticle acceleration,high-order sideband radiation,transition metal dichalcogenides
更新于2025-09-04 15:30:14
-
Renormalized Spectrum of Three-Level Localized Quasiparticle Interacting with Polarization Phonons at Cryogenic Temperature
摘要： Based on the generalized method of Feynman–Pines diagram technique, a new method of calculation of the mass operator in the Fourier image of Green’s function is proposed for the system of a three-level localized quasiparticle interacting with polarization phonons at T = 0 K. The revealed main class of diagrams gives the opportunity to write the renormalized mass operator in a form of continuous branch chain fraction with typical links. Such presentation allows effective accounting of multi-phonon processes. It is shown that the renormalized energy spectrum contains the complexes of bound-to-phonon states of the quasiparticle. These complexes essentially differ for the resonant and non-resonant systems.
关键词： Spectrum,Quasiparticle,Phonon,Mass operator,Green’s function
更新于2025-09-04 15:30:14