27 research outputs found
Photoluminescence Spectra of Quantum Dots: Enhanced Efficiency of the Electron-Phonon Interaction
Reply to "On the cutoff parameter in the translation-invariant theory of the strong coupling polaron"
The present work is a reply to the paper [1]. It is proven that the
argumentation of Ref. [1] is inconsistent. The variational functional for the
polaron ground state energy considered in Ref. [1] contains an incomplete
recoil energy. Since the variational functional of Ref. [1] is incomplete, it
is not proven to provide a variational upper bound for the polaron ground-state
energy. The same conclusion follows also for the bipolaron ground-state energy.Comment: 2 pages, 1 figure, submitted to Solid State Communication
Comments on "Translation-invariant bipolarons and the problem of high-temperature superconductivity"
We comment on the recent results of Refs. [1, 2] on the bipolaron problem
derived using an approximation of Gross - Tulub. It is proved that, contrary to
the claim made in Refs. [1, 2], the bipolaron ground state energy calculated
there in the strong-coupling approximation has not been shown to constitute a
variational upper bound.Comment: 3 pages, 2 figures, submitted to Solid State Communication
Coupled Ripplon-Plasmon Modes in a Multielectron Bubble
In multielectron bubbles, the electrons form an effectively two-dimensional
layer at the inner surface of the bubble in helium. The modes of oscillation of
the bubble surface (the ripplons) are influenced by the charge redistribution
of the electrons along the surface. The dispersion relation for these charge
redistribution modes (`longitudinal plasmons') is derived and the coupling of
these modes to the ripplons is analysed. We find that the ripplon-plasmon
coupling in a multielectron bubble differs markedly from that of electrons a
flat helium surface. An equation is presented relating the spherical harmonic
components of the charge redistribution to those of the shape deformation of
the bubble.Comment: 8 pages, 1 figure, E-mail addresses: [email protected],
[email protected], [email protected], [email protected]
Dynamical properties of the unitary Fermi gas: collective modes and shock waves
We discuss the unitary Fermi gas made of dilute and ultracold atoms with an
infinite s-wave inter-atomic scattering length. First we introduce an efficient
Thomas-Fermi-von Weizsacker density functional which describes accurately
various static properties of the unitary Fermi gas trapped by an external
potential. Then, the sound velocity and the collective frequencies of
oscillations in a harmonic trap are derived from extended superfluid
hydrodynamic equations which are the Euler-Lagrange equations of a
Thomas-Fermi-von Weizsacker action functional. Finally, we show that this
amazing Fermi gas supports supersonic and subsonic shock waves.Comment: 9 pages, 3 figures, invited talk at the International Workshop
"Critical Stability 2011" (Erice, October 2011), to be published in the
journal Few Body System
Reply to "on the cutoff parameter in the translation-invariant theory of the strong coupling polaron"
The present work is a reply to the paper [1]. It is proven that the argumentation of Refs. [1] is inconsistent. The variational functional for the polaron ground state energy considered in Ref. [1] contains an incomplete recoil energy. Since the variational functional of Ref. [1] is incomplete, it is not proven to provide a variational upper bound for the polaron ground-state energy. The same conclusion follows also for the bipolaron ground-state energy
Characterization of self-assembled quantum dots using the phonon-induced features of PL spectra
The luminescence is considered for self-assembled CdSe quantum dots on ZnSe substrate. The spectra of optical phonons are derived for these structures. The PL features due to the LO-phonon-assisted transitions from the remnant-layer exciton state to the quantum-dot exciton state are analyzed. They compare well with the recently obsd. fine structure of PL in self-assembled CdSe quantum dots formed by thermally activated surface reorganization