Related papers: Collective excitations and quantum incompressibili…
Measurements and a theoretical interpretation of the excitation spectrum of a two-electron quantum dot fabricated on a parabolic Ga[Al]As quantum well are reported. Experimentally, excited states are found beyond the well-known lowest…
A fully microscopic theory for the spontaneous emission from semiconductors is discussed. The theory is evaluated for a quantum-well system and the role of excitonic and unbound electron-hole-pair contributions to the emission is analyzed.…
In crowded systems, particle currents can be mediated by propagating collective excitations which are generated as rare events, are localized and have a finite lifetime. The theoretical description of such excitations is hampered by the…
We apply a voltage pulse to electrically excite the incompressible region of a two-dimensional electron liquid in the $\nu=2/3$ fractional quantum Hall state and investigate the collective excitations in both the edge and bulk via…
Excitons, the bosonic quasiparticle emerging from Coulomb interaction between electrons and holes, will undergo a Bose-Einstein condensation(BEC) and transition into a superfluid state with global phase coherence at low temperatures. An…
We study the ground state of a bilayer system of dipolar bosons with dipoles oriented by an external field perpendicularly to the two parallel planes. By decreasing the interlayer distance, for a fixed value of the strength of the dipolar…
Bilayer electron-hole systems undergo excitonic condensation when the distance d between the layers is smaller than the typical distance between particles within a layer. All excitons in this condensate have a fixed dipole moment which…
We show that the excitation spectrum of interacting electrons at filling factor $\nu=\nu^*/(2\nu^*+1)$ is well described in terms of non-interacting composite fermions at filling factor $\nu^*$, but does not have a one-to-one correspondence…
We report on an effective gauge theory of double-layer quantum Hall systems, that is constructed via bosonization from the response of incompressible states without referring to composite bosons and fermions. It is pointed out that…
We compare the response of five different models of two interacting electrons in a quantum dot to an external short lived radial excitation that is strong enough to excite the system well beyond the linear response regime. The models…
Collective, low-energy excitations in quasi-two-dimensional d-wave superconductors are analyzed. While the long-range Coulomb interaction shifts the charge-density-wave and phase modes up to the plasma energy, the spin-density-wave…
We investigate the electron addition spectrum in a class of Hubbard-like models which describe arrays of coupled quantum dots. Interdot tunneling leads to a sequence of two phase transitions separating a region of collective Coulomb…
Conditions at which a quasi-one-dimensional (1D) electron system can be considered as a quantum liquid of impenetrable charged particles are theoretically analyzed. In the presence of an inert, neutralizing background, a motion of…
This paper considers a system of two parallel quantum Hall layers with total filling factor $0$ or $1$. When the distance between the layers is small enough, electrons and holes in opposite layers form inter-layer excitons, which have a…
Collective modes of bilayered superconducting superlattices (e.g., YBCO) are investigated within the conserving gauge-invariant ladder diagram approximation including both the nearest interlayer single electron tunneling and the…
We report electrical transport measurements on GaAs/AlGaAs based electron-hole bilayers. These systems are expected to make a transition from a pair of weakly coupled two-dimensional systems to a strongly coupled exciton system as the…
We report magnetotransport measurements on bilayer GaAs hole systems with unequal hole concentrations in the two layers. At magnetic fields where one layer is in the integer quantum Hall state and the other has bulk extended states at the…
In a quantum dot with dozens of electrons, an approximation beyond Tamm-Dankoff is used to construct the quantum states with an additional electron-hole pair, i.e. the "excitonic" states. The lowest states mimic the non-interacting…
Time-dependent density functional theory (TDDFT) within the linear response regime provides a solid mathematical framework to capture excitations. The accuracy of the theory, however, largely depends on the approximations for the…
The influence of a random field induced by impurities, boundary irregularities etc. on the superfluidity of a quasi-two-dimensional (2D) system of spatially indirect excitons in coupled quantum wells is studied. The interaction between…