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We have calculated the electronic structure of InAs quantum dots embedded in InP as a function of size, using strain dependent eight-band k.p theory in the envelope function approximation. A realistic three-dimensional shape was used for the simulations and the piezoelectric polarization of the system was included. In order to avoid spurious solutions, an extra term was added to the Hamiltonian. P
GaSb/GaAs quantum dot systems are fabricated using MBE under various growth modes. The as-grown samples are studied with in situ synchrotron radiation XPS covering the As 3d, Sb 4d and Ga 3d core levels and the valence band region. The XPS spectra show dramatic changes with the growth modes, reflecting changes in the local electronic structure and chemical environments of the surface and interface
We demonstrate that a Ni-Mn oxide partially inverted spinel (Ni1-pMnv)[NivMn2-v]O-4 having inversion degree v approximate to 0.8 and produced by a modified polymeric precursor method exhibits behaviour previously reported only in monophased samples. The structure of the specimen was determined using Rietveld analysis of X-ray and neutron powder diffraction data, showing that at room temperature th
In 2015, the PHENIX collaboration has measured very forward (η>6.8) single spin asymmetries of inclusive neutrons in transversely polarized proton-proton and proton-nucleus collisions at a center of mass energy of 200 GeV. A previous publication from this dataset concentrated on the nuclear dependence of such asymmetries. In this measurement the explicit transverse momentum dependence of inclusive
A new quantum chemical definition is proposed of the full atomic valence, VA, taking into account both the covalent and ionic parts of the chemical bonds formed by atoms in molecules and crystals. The full atomic valencies, covalencies, and charges on atoms are calculated for nickel–oxygen crystalline compounds in the CNDO band theory approximation. A comparison of the chemical bonding in nickel a
Popular Abstract in Swedish En indikator-jon för en kvantdator Ända sedan transistorn uppfanns 1948 har datorer blivit allt mer kraftfulla. Trots den enorma utveckling som skett finns det fortfarande problem som är för svåra för en dator att lösa. Ett exempel är simulering av stora molekyler, t.ex. proteiner, vilket skulle vara användbart inom medicin och biologi, bland annat för att förutsäga hRare-earth ions doped into a transparent crystal can have optically excited states with coherence times of milliseconds and hyperfine levels with coherence times of hours when cooled down to liquid helium temperatures. This makes them attractive for developing quantum computing hardware. A quantum transistor can be implemented in a rare-earth-ion-doped crystal by utilizing a dipole blockade effe
The unification of quantum mechanics and general relativity has long been elusive. Only recently have empirical predictions of various possible theories of quantum gravity been put to test, where a clear signal of quantum properties of gravity is still missing. The dawn of multi-messenger high-energy astrophysics has been tremendously beneficial, as it allows us to study particles with much higher
We report on low-temperature transport measurements on single and double quantum dots defined using local gates to electrostatically deplete InAs nanowires grown by chemical beam epitaxy. This technique allows us to define multiple quantum dots along a semiconducting nanowire and tune the coupling between them.
Vicerektor forskning, Docent Kontaktinformation E-post: jonas [dot] helgertz [at] ekh [dot] lu [dot] se Telefon: +46 46 222 36 66Organisation Ekonomisk-historiska institutionen Besöksadress: Scheelevägen 15 B, Lund Rumsnummer: Alfa 1:2008 Hämtställe: 10 WebbplatsJonas Helgertz profil i Lunds universitets forskningsportalAndra roller Universitetslektor Ekonomisk demografi Professor Ekonomisk-histor
https://www.ehl.lu.se/jonas-helgertz - 2026-08-04
In the case of a quantum-noise limited detector, signal detection theory suggests that stereoradiographic images can be acquired with one half of the per-image dose needed for a standard radiographic projection, as information from the two stereo images can be combined. Previously, film-screen stereoradiography has been performed using the same per-image dose as in projection radiography, i.e., do
X-ray crystallography is the main source of atomistic information on the structure of proteins. Normal crystal structures are obtained as a compromise between the X-ray scattering data and a set of empirical restraints that ensure chemically reasonable bond lengths and angles. However, such restraints are not always available or accurate for nonstandard parts of the structure, for example substrat
Irradiation-induced phase segregation in mixed methylammonium halide perovskite samples such as methylammonium lead bromide-iodide, MAPb(IxBr1-x)3, is being studied intensively because it limits the efficiency of wide band gap perovskite solar cells. It has been postulated that this phenomenon depends on the intrinsic ionic (in)homogeneity in samples already induced during film formation. A deeper
A detailed flammability evaluation of different materials used in the nuclear power industry is presented as an example of how important are physical observation and detailed analysis in the interpretation of test data. The objective is to provide different criteria that could allow the use of standard test data in fire modeling. So far most fire test data has only been used as an element for rank
Ultracold clouds of dimeric molecules can dissociate into quantum mechanically correlated constituent atoms that are either both bosons or both fermions. We theoretically model the dissociation of two-dimensional anisotropic molecular condensates for which this difference manifests as complementary geometric structures of the dissociated atoms. Atomic bosons are preferentially emitted along the lo
Energy- and angle-resolved photoionization spectra of He irradiated by linearly polarized intense 810 nm laser radiation and several of its XUV odd harmonics are investigated. The angular distribution of the odd-order peaks, produced by single-photon ionization by one harmonic, is, surprisingly, broadened by the IR field. The even-order ones, due to two-colour, two-photon ionization, show at 90° l
