scholarly journals Laplacian-Level Quantum Hydrodynamic Theory for Plasmonics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Henrikh M. Baghramyan ◽  
Fabio Della Sala ◽  
Cristian Ciracì
Keyword(s):  
Hydrodynamic Theory ◽  
Quantum Hydrodynamic

scholarly journals Plasmonic quantum effects on single-emitter strong coupling

Nanophotonics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1821-1833 ◽  
Author(s):  
Cristian Ciracì ◽  
Radoslaw Jurga ◽  
Muhammad Khalid ◽  
Fabio Della Sala
Keyword(s):  
Strong Coupling ◽  
Quantum Effects ◽  
Hydrodynamic Theory ◽  
Strong Coupling Regime ◽  
Efficient Tool ◽  
Metallic Particles ◽  
Plasmonic Structures ◽  
Classical Models ◽  
Quantum Hydrodynamic ◽  
Fluorescent Molecules

AbstractCoupling between electromagnetic cavity fields and fluorescent molecules or quantum emitters can be strongly enhanced by reducing the cavity mode volume. Plasmonic structures allow light confinement down to volumes that are only a few cubic nanometers. At such length scales, nonlocal and quantum tunneling effects are expected to influence the emitter interaction with the surface plasmon modes, which unavoidably requires going beyond classical models to accurately describe the electron response at the metal surface. In this context, the quantum hydrodynamic theory (QHT) has emerged as an efficient tool to probe nonlocal and quantum effects in metallic nanostructures. Here, we apply state-of-the-art QHT to investigate the quantum effects on strong coupling of a dipole emitter placed at nanometer distances from metallic particles. A comparison with conventional local response approximation (LRA) and Thomas-Fermi hydrodynamic theory results shows the importance of quantum effects on the plasmon-emitter coupling. The QHT predicts qualitative deviation from LRA in the weak coupling regime that leads to quantitative differences in the strong coupling regime. In nano-gap systems, the inclusion of quantum broadening leads to the existence of an optimal gap size for Rabi splitting that minimizes the requirements on the emitter oscillator strength.

Quantum nonlocal polarizability of spherical metal nanoparticles

2016 ◽  
Vol 30 (09) ◽  
pp. 1650048 ◽  
Author(s):  
Afshin Moradi
Keyword(s):  
Boundary Conditions ◽  
Plasma Waves ◽  
Hydrodynamic Theory ◽  
Explicit Calculation ◽  
Metallic Nanoparticle ◽  
The Poisson Equation ◽  
Longitudinal Plasma ◽  
Quantum Hydrodynamic ◽  
Spherical Metal Nanoparticles ◽  
Quantum Boundary Conditions

An explicit calculation of the quantum nonlocal (QNL) polarizability of a metallic nanoparticle is presented, where two quantum longitudinal plasma waves are excited. The QNL generalization of the classical Clausius–Mossotti factor of the system is derived, by means of the quantum hydrodynamic theory in conjunction with the Poisson equation and applying the appropriate additional quantum boundary conditions.

scholarly journals Quantum Gases of Dipoles, Quadrupoles and Octupoles in Gross–Pitaevskii Formalism with Form Factor

2020 ◽  
Vol 5 (4) ◽  
pp. 61
Author(s):  
Artem A. Alexandrov ◽  
Alina U. Badamshina ◽  
Stanislav L. Ogarkov
Keyword(s):  
Form Factor ◽  
Gaussian Approximation ◽  
Form Factors ◽  
Quantum Gases ◽  
Hydrodynamic Theory ◽  
Bose Gases ◽  
Probe Wave ◽  
Quantum Hydrodynamic ◽  
Bogoliubov Excitations

Here, classical and quantum field theory of dipolar, axisymmetric quadrupolar and octupolar Bose gases is considered within a general approach. Dipole, axisymmetric quadrupole and octupole interaction potentials in the momentum representation are calculated. These results clearly demonstrate attraction and repulsion areas in corresponding gases. Then the Gross–Pitaevskii (GP) equation, which plays a key role in the present paper, is derived from the corresponding functional. The zoology of the form factors appearing in the GP equation is studied in details. The proper classes for the description of spatially non-uniform condensates form factors are chosen. In the Thomas–Fermi approximation a general solution of the GP equation with a quasilocal form factor is obtained. This solution has an interesting form in terms of a double rapidly converging series that universally includes all the interactions considered. Plots of condensate density functions for the exponential-trigonometric form factor are given. For the sake of completeness, in this paper we consider the GP equation with an optical lattice potential in the limit of small condensate densities. This limit does not distinguish between dipolar, quadrupolar and octupolar gases. An important analysis of the condensate stability, in other words the study of condensate excitations, is also performed in this paper. In the Gaussian approximation (from the Gross–Pitaevskii functional), a functional describing the perturbations of the condensate is derived in detail. This problem is an analog of the Bogolubov transformation used in the study of quantum Bose gases in operator formalism. For a probe wave function in the form of a plane wave, a spectrum of (Bogoliubov) excitations was obtained, from which an equation describing the threshold momentum for the emergence of instability was derived. An important result of this paper is the dependence of the threshold on the momentum of a stationary condensate. For completeness of the presentation, the approximating expression in the form of a rapidly converging series is obtained for the corresponding dependence, and plots of the corresponding series for the exponential-trigonometric form factor are given. Finally, in the conclusion a quantum hydrodynamic theory for dipolar, axisymmetric quadrupolar and octupolar gases is briefly presented, giving a clue to the experimental determination of the form factors.

The Uncertainty Principle Derived by The Finite Transmission Speed of Light and Information

2014 ◽  
Vol 3 (3) ◽  
pp. 257-266 ◽  
Author(s):  
Piero Chiarelli
Keyword(s):  
Uncertainty Principle ◽  
Large Scale ◽  
Uncertainty Relations ◽  
Speed Of Light ◽  
Energy Fluctuation ◽  
Hydrodynamic Analogy ◽  
Non Local ◽  
Minimum Uncertainty ◽  
Quantum Hydrodynamic ◽  
Transmission Speed

This work shows that in the frame of the stochastic generalization of the quantum hydrodynamic analogy (QHA) the uncertainty principle is fully compatible with the postulate of finite transmission speed of light and information. The theory shows that the measurement process performed in the large scale classical limit in presence of background noise, cannot have a duration smaller than the time need to the light to travel the distance up to which the quantum non-local interaction extend itself. The product of the minimum measuring time multiplied by the variance of energy fluctuation due to presence of stochastic noise shows to lead to the minimum uncertainty principle. The paper also shows that the uncertainty relations can be also derived if applied to the indetermination of position and momentum of a particle of mass m in a quantum fluctuating environment.

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