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At the nanoscale, electrons and atoms perform random thermal motion and can be subject to quantum effects. Can we use the kinetic energy of electrons to do useful work? Can quantum phenomena make energy conversion more efficient? We combine experiment and theory to explore the fundamentals of generating electricity from heat or light, and the use of information to generate work. A device for st
https://www.nano.lu.se/nanoenergy/nanothermodynamics - 2026-10-09
The rotation of a quantum liquid induces vortices to carry angular momentum. When the system is composed of multiple components that are distinguishable from each other, vortex cores in one component may be filled by particles of the other component, and coreless vortices form. Based on evidence from computational methods, here we show that the formation of coreless vortices occurs very similarly
In the thesis, three-dimensionally confined resonant tunneling structures were studied experimentally. Two approaches were used for obtaining quantum confinement: gate-defined lateral constriction of double barrier structures, and epitaxial growth of self-assembled quantum dots. In addition, the thesis deals with the basic development of large-area double barrier resonant tunneling diodes, as a st
The impact of coherence on the nonlinear optical response and stationary transport is studied in quantum cascade laser structures. Nonequilibrium effects such as the pump-probe signals, the spatiotemporally resolved electron density evolution, and the subband population dynamics (Rabi flopping) as well as the stationary current characteristics are investigated within a microscopic density-matrix a
We study the transient dynamics subject to quantum coherence effects of two interacting parallel quantum dots weakly coupled to macroscopic leads. The stationary particle current of this quantum system is sensitive to perturbations much smaller than any other energy scale, specifically compared to the system-lead coupling and the temperature. We show that this is due to the presence of a parity-li
Popular Abstract in Swedish I denna avhandling studeras egenskaper hos tvådimensionella, kvantmekaniska mångpartikelsystem. Studierna utförs med spinndensitetsfunktionalteori (SDFT) med den lokala spinndensitetsapproximationen (LSDA), samt med numerisk exakt diagonalisering. De egenskaper som studeras inkluderar symmetribrytande tillstånd i kvantprickar med få elektroner, gap i inneslutna fåpartik
High-order Harmonic Generation (HHG) is a highly non-linear process in which an atom interacts with a strong laser field. The laser field lowers the atomic potential barrier allowing bound electrons to escape into the continuum through tunnel ionization, propagate, and, with some probability, recombine with the parent ion. As a result, coherent eXtreme UltraViolet (XUV) radiation is emitted in the
The electronic properties of quantum dot (QD) arrays are strongly influenced by the Coulomb interaction of electrons within the dot as well as with those in neighbouring dots. In this paper, we investigate this behaviour taking into account screening by a free electron gas in the vicinity of the QDs. We find pronounced effects for standard capacitance - voltage ( CV) measurements of QD structures
In the present study, entropy generation in rectangular cavities with the same area but different aspect ratios is numerically investigated. The vertical walls of the cavities are at different constant temperatures while the horizontal walls are adiabatic. Heat transfer between vertical walls occurs by laminar natural convection. Based on the obtained dimensionless velocity and temperature values,
In classical thermodynamics energy always flows from the hotter system to the colder one. However, if these systems are initially correlated, the energy flow can reverse, making the cold system colder and the hot system hotter. This intriguing phenomenon is called "anomalous energy flow"and shows the importance of initial correlations in determining physical properties of thermodynamic systems. He
We investigate shot noise of photon-excited electron-hole pairs in open multiterminal, multichannel chaotic dots. Coulomb interactions in the dot are treated self-consistently giving a gauge-invariant expression for the finite frequency correlations. The Coulomb interactions decrease the noise; the strong interaction limit coincides with the noninteracting adiabatic limit. Inelastic scattering and
We present a theory for a mesoscopic turnstile that produces spatially separated streams of electrons and holes along edge states in the quantum Hall regime. For a broad range of frequencies in the nonadiabatic regime the turnstile operation is found to be ideal, producing one electron and one hole per cycle. The accuracy of the turnstile operation is characterized by the fluctuations of the trans
