Publications (40)
Mean-field limit of the random flux model
B. Kramer, D. Belitz, M. Batsch
The problem of non--interacting electrons on a square lattice subject to a random magnetic flux is mapped onto a one--dimensional model with infinitely many orbitals per site. Link…
Energy-level statistics and localization of 2d electrons in random magnetic fields
M. Batsch, L. Schweitzer, B. Kramer
Using the method of energy-level statistics, the localization properties of electrons moving in two dimensions in the presence of a perpendicular random magnetic field and addition…
Scaling Behavior of Level Statistics in Quantum Hall Regime
Y. Ono, T. Ohtsuki, B. Kramer
The scaling property of level statistics in the quantum Hall regime, i.e. 2D disordered electron systems subject to strong magnetic fields, is analyzed numerically in the light of…
Numerical study on Anderson transitions in three-dimensional disordered systems in random magnetic fields
T. Kawarabayashi, B. Kramer, T. Ohtsuki
The Anderson transitions in a random magnetic field in three dimensions are investigated numerically. The critical behavior near the transition point is analyzed in detail by means…
Critical level statistics at the Anderson transition in four-dimensional disordered systems
I. Kh. Zharekeshev, B. Kramer
The level spacing distribution is numerically calculated at the disorder-induced metal--insulator transition for dimensionality d=4 by applying the Lanczos diagonalisation. The cri…
Non-universal power laws in transport properties of one-dimensional quantum dots
T. Kleimann, J. Stockburger, M. Sassetti +1
We investigate discrepancies between recent experimental results on transport through one-dimensional quantum dots and universal power laws predicted by an idealized Luttinger Liqu…
Phase diagram of localization in a magnetic field
T. Droese, M. Batsch, I. Kh. Zharekeshev +1
The phase diagram of localization is numerically calculated for a three-dimensional disordered system in the presence of a magnetic field using the Peierls substitution. The mobili…
Phonons and Phonon Confinement in Transport through Double Quantum Dots
S. Debald, T. Vorrath, T. Brandes +1
We calculate the electron-phonon interaction coefficients for surface acoustic waves and for phonons in free standing quantum wells. These are used to derive the inelastic current…
Scaling of Level Statistics at the Disorder-Induced Metal-Insulator Transition
I. Kh. Zharekeshev, B. Kramer
The distribution of energy level separations for lattices of sizes up to 282828 sites is numerically calculated for the Anderson model. The results show one-paramet…
Scaling of level statistics at the metal-insulator transition
I. Kh. Zharekeshev, B. Kramer
Using the Anderson model for disordered systems the fluctuations in electron spectra near the metal--insulator transition were numerically calculated for lattices of sizes up to 28…
Spin polarization in a T-shape conductor induced by strong Rashba spin-orbit coupling
M. Yamamoto, T. Ohtsuki, B. Kramer
We investigate numerically the spin polarization of the current in the presence of Rashba spin-orbit interaction in a T-shaped conductor proposed by A.A. Kiselev and K.W. Kim (Appl…
A heat-wave of accretion energy traced by masers in the G358-MM1 high-mass protostar
R. A. Burns, K. Sugiyama, T. Hirota +20
High-mass stars are thought to accumulate much of their mass via short, infrequent bursts of disk-aided accretion. Such accretion events are rare and difficult to observe directly…
Transport in quantum wires with impurities at finite temperatures
T. Kleimann, M. Sassetti, B. Kramer
The temperature dependence of Coulomb blockade peaks of a one dimensional quantum dot is calculated. The Coulomb interaction is treated microscopically using the Luttinger liquid m…
Negative differential conductance induced by spin-charge separation
F. Cavaliere, A. Braggio, J. T. Stockburger +2
Spin-charge states of correlated electrons in a one-dimensional quantum dot attached to interacting leads are studied in the non-linear transport regime. With non-symmetric tunnel…
High output data rates with PCInt on the EVN MkIV data processor
H. J. van Langevelde, H. Verkouter, S. Parsley +3
The EVN MkIV data processor is being equipped with a high data output capability, called PCInt. In its next phase it will allow very high data output rates, up to 160 Mb/s. This fu…
Spin effects in transport through non-Fermi liquid quantum dots
F. Cavaliere, A. Braggio, M. Sassetti +1
The current-voltage characteristic of a one dimensional quantum dot connected via tunnel barriers to interacting leads is calculated in the region of sequential tunneling. The spin…
Anderson transitions in three-dimensional disordered systems with randomly varying magnetic flux
T. Kawarabayashi, B. Kramer, T. Ohtsuki
The Anderson transition in three dimensions in a randomly varying magnetic flux is investigated in detail by means of the transfer matrix method with high accuracy. Both, systems w…
Spin and rotational symmetries in unrestricted Hartree Fock states of quantum dots
U. De Giovannini, F. Cavaliere, R. Cenni +2
Ground state energies are obtained using the unrestricted Hartree Fock method for up to four interacting electrons parabolically confined in a quantum dot subject to a magnetic fie…
Transport properties of quantum dots in the Wigner molecule regime
F. Cavaliere, U. De Giovannini, M. Sassetti +1
The transport properties of quantum dots with up to N=7 electrons ranging from the weak to the strong interacting regime are investigated via the projected Hartree-Fock technique.…
Nonlinear Transport Properties of Quantum Dots
W. Pfaff, D. Weinmann, W. Haeusler +3
The influence of excited levels on nonlinear transport properties of a quantum dot weakly coupled to leads is studied using a master--equation approach. A charging model for the do…
Theory of measuring the "Luttinger-g" of a one-dimensional quantum dot
T. Kleimann, F. Cavaliere, M. Sassetti +1
We study electron transport through a quantum dot in a Tomonaga-Luttinger liquid with an inhomogeneity induced either by a non-uniform electron interaction or by the presence of tu…
Random Network Models and Quantum Phase Transitions in Two Dimensions
B. Kramer, T. Ohtsuki, S. Kettemann
An overview of the random network model invented by Chalker and Coddington, and its generalizations, is provided. After a short introduction into the physics of the Integer Quantum…
The Mesoscopic Quantum-Hall-Insulator Transition
S. Kettemann, B. Kramer, T. Ohtsuki
Sharp localization transitions of chiral edge states in disordered quantum wires, subject to strong magnetic field, are shown to be driven by crossovers from two- to one-dimensiona…
New selection rules for resonant Raman scattering on quantum wires
E. Mariani, M. Sassetti, B. Kramer
The bosonisation technique is used to calculate the resonant Raman spectrum of a quantum wire with two electronic sub-bands occupied. Close to resonance, the cross section at frequ…
Wigner Molecules in Nanostructures
K. Jauregui, W. Haeusler, B. Kramer +1
The one-- and two-- particle densities of up to four interacting electrons with spin, confined within a quasi one--dimensional ``quantum dot'' are calculated by numerical diagonali…
Decay rate and renormalized frequency shift of a quantum wire Wannier exciton in a planar microcavity
Yueh-Nan Chen, Der-San Chuu, T. Brandes +1
The superradiant decay rate and frequency shift of a Wannier exciton in a one-dimensional quantum wire are studied. It is shown that the dark mode exciton can be examined experimen…
Charge and spin addition energies of one dimensional quantumn dot
T. Kleimann, M. Sassetti, B. Kramer +1
We derive the effective action for a one dimensional electron island formed between a double barrier in a single channel quantum wire including the electron spin. Current and energ…
Dynamics of a large-spin-boson system in the strong coupling regime
T. Vorrath, T. Brandes, B. Kramer
We investigate collective effects of an ensemble of biased two level systems interacting with a bosonic bath in the strong coupling regime. The two level systems are described by a…
Crossover from critical orthogonal to critical unitary statistics at the Anderson transition
M. Batsch, L. Schweitzer, I. Kh. Zharekeshev +1
We report a novel scale-independent, Aharonov-Bohm flux controlled crossover from critical orthogonal to critical unitary statistics at the disorder induced metal insulator transit…
Phonon Cavity Models for Quantum Dot Based Qubits
T. Vorrath, S. Debald, B. Kramer +1
Phonon cavities are believed to be the next step towards a control of dephasing in semiconductor quantum dot `qubits'. In this paper, we discuss two models for phonon cavities - a…
VLBI observations of the G25.65+1.05 water maser superburst
R. A. Burns, G. Orosz, O. Bayandina +23
This paper reports observations of a 22 GHz water maser `superburst' in the G25.65+1.05 massive star forming region, conducted in response to an alert from the Maser Monitoring Org…
Control of Dephasing and Phonon Emission in Coupled Quantum Dots
S. Debald, T. Brandes, B. Kramer
We predict that phonon subband quantization can be detected in the non-linear electron current through double quantum dot qubits embedded into nano-size semiconductor slabs, acting…
Transport through a one-dimensional quantum dot
T. Kleimann, M. Sassetti, G. Cuniberti +1
We examine the effects of long-range interactions in a quantum wire with two impurities. We employ the bosonization technique and derive an effective action for the system. The eff…
Crossover of Level Statistics between Strong and Weak Localization in Two Dimensions
I. Kh. Zharekeshev, M. Batsch, B. Kramer
We investigate numerically the statistical properties of spectra of two-dimensional disordered systems by using the exact diagonalization and decimation method applied to the Ander…
Spin-pairing instabilities at the coincidence of two Landau levels
E. Mariani, N. Magnoli, F. Napoli +2
The effect of interactions near the coincidence of two Landau levels with opposite spins at filling factor 1/2 is investigated. By mapping to Composite Fermions it is shown that th…
Dynamics of a large spin with weak dissipation
T. Vorrath, T. Brandes, B. Kramer
We investigate the generalization of the spin-boson model to arbitrary spin size. The Born-Markov approximation is employed to derive a master equation in the regime of small coupl…
Negative differential conductance in quantum dots in theory and experiment
M. C. Rogge, F. Cavaliere, M. Sassetti +2
Experimental results for sequential transport through a lateral quantum dot in the regime of spin blockade induced by spin dependent tunneling are compared with theoretical results…
Composite Fermions with Spin at
B. Kramer, N. Magnoli, E. Mariani +3
The model of Composite Fermions for describing interacting electrons in two dimensions in the presence of a magnetic field is described. In this model, charged Fermions are combine…
Spin projected unrestricted Hartree-Fock ground states for harmonic quantum dots
U. De Giovannini, F. Cavaliere, R. Cenni +2
We report results for the ground state energies and wave functions obtained by projecting spatially unrestricted Hartree Fock states to eigenstates of the total spin and the angula…
Tomonaga-Luttinger features in the resonant Raman spectra of quantum wires
B. Kramer, M. Sassetti
The differential cross section for resonant Raman scattering from the collective modes in a one dimensional system of interacting electrons is calculated non-perturbatively using t…