Ultrafast optical rotations of electron spins in quantum dots (2009)
Greilich, A., Economou, Sophia E., Spatzek, S., Yakovlev, D. R., Reuter, D., Wieck, A. D., ...
Coherent manipulation of quantum bits (qubits) on time scales much shorter than the coherence time is a key prerequisite for quantum information processing. Electron spins in quantum dots (QDs) are...
Crystal-orientation dependant spin dephasing for 2D and bulk electrons in GaAs wires (2009)
Denega, S. Z., Last, T., Liu, J., Slachter, A., Rizo, P. J., ...
We report the observation of spin dephasing anisotropy for quasi-1D electron ensembles in wires etched into a GaAs/AlGaAs heterojunction system. Time-resolved Kerr rotation measurements show...
Rizo, P. J., Pugzlys, A., Slachter, A., Denega, S. Z., Reuter, D., Wieck, A. D., ...
We present time-resolved Kerr rotation measurements of electron spin dynamics in a GaAs/AlGaAs heterojunction system that contains a high-mobility two-dimensional electron gas (2DEG). Due to the...
Chen, J. C. H., Klochan, O., Micolich, A. P., Hamilton, A. R., Martin, T. P., Ho, L. H., ...
We study the Zeeman spin-splitting in hole quantum wires oriented along the $[011]$ and $[01\bar{1}]$ crystallographic axes of a high mobility undoped (100)-oriented AlGaAs/GaAs heterostructure. Our...
Spin noise of electrons and holes in self-assembled quantum dots (2009)
Crooker, S. A., Brandt, J., Sandfort, C., Greilich, A., Yakovlev, D. R., Reuter, D., ...
We measure the frequency spectra of random spin fluctuations, or "spin noise", in ensembles of (In,Ga)As/GaAs quantum dots (QDs) at low temperatures. We employ a spin noise spectrometer based on a...
Evidence for localization and 0.7 anomaly in hole quantum point contacts (2009)
Komijani, Y., Csontos, M., Shorubalko, I., Ihn, T., Ensslin, K., Meir, Y., ...
Quantum point contacts implemented in p-type GaAs/AlGaAs heterostructures are investigated by low-temperature electrical conductance spectroscopy measurements. Besides one-dimensional conductance...
Quantized magnetic confinement in quantum wires (2009)
Tarasov, A., Hugger, S., Xu, Hengyi, Cerchez, M., Heinzel, T., Zozoulenko, I. V., ...
Ballistic quantum wires are exposed to longitudinal profiles of perpendicular magnetic fields composed of a spike (magnetic barrier) and a homogeneous part. An asymmetric magnetoconductance peak as a...
Kurtze, H., Yakovlev, D. R., Reuter, D., Wieck, A. D., Bayer, M.
The population dynamics of bright and dark excitons confined in (In,Ga)As/GaAs quantum dots have been studied as function of magnetic field by two-color pump-probe spectroscopy at cryogenic...
A combinatorial passivation study of Ta–Ti alloys (2009)
Mardare, A. I., Savan, A., Ludwig, A., Wieck, A. D., Hassel, A. W.
Non-local Aharonov-Bohm conductance oscillations in an asymmetric quan-tum ring (2008)
Buchholz, S. S., Fischer, S. F., Kunze, U., Reuter, D., Wieck, A. D.
We investigate ballistic transport and quantum interference in a nanoscale quantum wire loop fab-ricated as a GaAs/AlGaAs field-effect heterostructure. Four-terminal measurements of current and...
Collective single mode precession of electron spins in a quantum dot ensemble (2008)
Greilich, A., Spatzek, S., Yugova, I. A., Akimov, I. A., Yakovlev, D. R., Efros, Al. L., ...
We show that the spins of all electrons, each confined in a quantum dot of an (In,Ga)As/GaAs dot ensemble, can be driven into a single mode of precession about a magnetic field. This regime is...
Rizo, P. J., Pugžlys, A., Liu, J., Reuter, D., Wieck, A. D., Van Der Wal, C. H., ...
A compact cryogenic Kerr microscope for operation in the small volume of high-field magnets is described. It is suited for measurements both in Voigt and Faraday configuration. Coupled with a pulsed...
Observation of excited states in a p-type GaAs quantum dot (2008)
Komijani, Y., Csontos, M., Ihn, T., Ensslin, K., Reuter, D., Wieck, A. D.
A quantum dot fabricated by scanning probe oxidation lithography on a p-type, C-doped GaAs/AlGaAs heterostructure is investigated by low temperature electrical conductance measurements. Clear Coulomb...
Effect of disorder on the quantum coherence in mesocopic wires (2008)
Niimi, Y., Baines, Y., Capron, T., Mailly, D., Wieck, A. D., ...
We present phase coherence time measurements in quasi one-dimensional mesoscopic wires made from high mobility two dimensional electron gas. By implanting gallium ions into a GaAs/AlGaAs...
Magnetic barrier induced conductance fluctuations in quantum wires (2008)
Hugger, S., Xu, Hengyi, Tarasov, A., Cerchez, M., Heinzel, T., Zozoulenko, I. V., ...
Quasi-ballistic semiconductor quantum wires are exposed to localized perpendicular magnetic fields, also known as magnetic barriers. Pronounced, reproducible conductance fluctuations as a function of...
Tunable ballistic rectification in a density-modulated two-dimensional-system (2008)
Ganczarczyk, A., Notthoff, C., Geller, M., Lorke, A., Reuter, D., Wieck, A. D.
We demonstrate tunable rectification in a density-modulated two-dimensional electron gas (2DEG). The density modulation is induced by two surface gates, running in parallel along a narrow strip of...
Sassine, S., Krupko, Yu., Kvon, Z. D., Murali, R., Martin, K. P., ...
We report on experimental evidence of directed electron transport, induced by external linear-polarized microwave irradiation, in a two-dimensional spatially-periodic asymmetrical system called...
Kaiser, F. J., Kohler, S., Hänggi, P., Malecha, M., Ebbecke, J., Wixforth, A., ...
Two strongly coupled quantum dots are theoretically and experimentally investigated. In the conductance measurements of a GaAs based low-dimensional system additional features to the Coulomb blockade...
Spin Accumulation and Spin Relaxation in a Large Open Quantum Dot (2008)
Koop, E. J., Van Wees, B. J., Reuter, D., Wieck, A. D., Van Der Wal, C. H.
We report electronic control and measurement of an imbalance between spin-up and spin-down electrons in micron-scale open quantum dots. Spin injection and detection was achieved with quantum point...
coupled quantum dot systems (2008)
J. Phys, Condens Matter, M Malecha, J Ebbecke, H W Schumacher, A D Wieck
investigations of Coulomb blockade in
Low temperature dephasing in irradiated metallic wires (2007)
Capron, T., Niimi, Y., Baines, Y., Mailly, D., Melnikov, A., ...
We present phase coherence time measurements in quasi-one-dimensional Ag wires implanted with Ag$^{+}$ ions with an energy of $100 keV$. The measurements have been carried out in the temperature...
Hysteretic magnetotransport in p-type AlGaAs heterostructures with In/Zn/Au ohmic contacts (2007)
Grbic, B., Leturcq, R., Ihn, T., Ensslin, K., Blatter, G., Reuter, D., ...
The two-terminal magneto-conductance of a hole gas in C-doped AlGaAs/GaAs heterostructures with ohmic contacts consisting of alloyed In/Zn/Au displays a pronounced hysteresis of the conductance...
Hole transport in p-type GaAs quantum dots and point contacts (2007)
Grbic, B., Leturcq, R., Ihn, T., Ensslin, K., Reuter, D., Wieck, A. D.
Strong spin-orbit interaction characteristic for p-type GaAs systems, makes such systems promising for the realization of spintronic devices. Here we report on transport measurements in...
Koop, E. J., Lerescu, A. I., Liu, J., Van Wees, B. J., Reuter, D., Wieck, A. D., ...
The conductance of a quantum point contact (QPC) shows several features that result from many-body electron interactions. The spin degeneracy in zero magnetic field appears to be spontaneously lifted...
Persistence of the 0.7 anomaly of quantum point contacts in high magnetic fields (2007)
Koop, E. J., Lerescu, A. I., Liu, J., Van Wees, B. J., Reuter, D., Wieck, A. D., ...
The spin degeneracy of the lowest subband that carries one-dimensional electron transport in quantum point contacts appears to be spontaneously lifted in zero magnetic field due to a phenomenon that...
Quantum dot as thermal rectifier (2007)
Scheibner, R., Koenig, M., Reuter, D., Wieck, A. D., Buhmann, H., Molenkamp, L. W.
We report the observation of thermal rectification in a semiconductor quantum dot, as inferred from the asymmetric line shape of the thermopower oscillations. The asymmetry is observed at high...
Charge and spin dynamics in a two dimensional electron gas (2006)
Pugzlys, A, Rizo, P J, Ivanin, K, Slachter, A, Reuter, D, Wieck, A D, ...
A number of time resolved optical experiments probing and controlling the spin and charge dynamics of the high mobility two-dimensional electron gas in a GaAs/AlGaAs heterojunction are discussed....
Scheibner, R., Novik, E. G., Borzenko, T., Koenig, M., Reuter, D., Wieck, A. D., ...
We have studied the temperature dependent thermopower of gate-defined, lateral quantum dots in the Coulomb blockade regime using an electron heating technique. The line shape of the thermopower...
Scaling of the low temperature dephasing rate in Kondo systems (2006)
Mallet, F., Ericsson, J., Mailly, D., Unlubayir, S., Reuter, D., Melnikov, A., ...
We present phase coherence time measurements in quasi-one-dimensional Ag wires doped with Fe Kondo impurities of different concentrations $n_s$. Due to the relatively high Kondo temperature...
Specific Heat of a Fractional Quantum Hall System (2006)
Schulze-Wischeler, F., Zeitler, U., Zobeltitz, C. V., Hohls, F., Reuter, D., Wieck, A. D., ...
Using a time-resolved phonon absorption technique, we have measured the specific heat of a two-dimensional electron system in the fractional quantum Hall effect regime. For filling factors $\nu =...
Dolgopolov, V. T., Deviatov, E. V., Khrapai, V. S., Reuter, D., Wieck, A. D., Wixforth, A., ...
We investigate the ground state competition at the transition from the spin unpolarized to spin ordered phase at filling factor $\nu=2/3$ in single layer heterostructure and at $\nu=2$ in double...
Deviatov, E. V., Kapustin, A. A., Dolgopolov, V. T., Lorke, A., Reuter, D., Wieck, A. D.
We experimentally investigate transport across the incompressible stripe at the sample edge in the fractional quantum Hall effect regime at bulk filling factors $\nu=2/3$ and $\nu=2/5$. We obtain the...
Deviatov, E. V., Kapustin, A. A., Dolgopolov, V. T., Lorke, A., Reuter, D., Wieck, A. D.
We experimentally study equilibration between edge states, co-propagating at the edge of the fractional quantum Hall liquid, at high initial imbalances. We find an anomalous increase of the...
Experimental investigation of the edge states structure at fractional filling factors (2005)
Deviatov, E. V., Dolgopolov, V. T., Lorke, A., Wegscheider, W., Wieck, A. D.
We experimentally study electron transport between edge states in the fractional quantum Hall effect regime. We find an anomalous increase of the transport across the 2/3 incompressible fractional...
Mueller, T., Wuertz, A., Lorke, A., Reuter, D., Wieck, A. D.
We utilize a time-periodic ratchet-like potential modulation imposed onto a two-dimensional electron system inside a GaAs/Al$_x$Ga$_{1-x}$As heterostructure to evoke a net dc pumping current. The...
Electrical read-out of the local nuclear polarization in the quantum Hall effect (2005)
Würtz, A., Müller, T., Lorke, A., Reuter, D., Wieck, A. D.
It is demonstrated that the now well-established `flip-flop' mechanism of spin exchange between electrons and nuclei in the quantum Hall effect can be reversed. We use a sample geometry which...
Coulomb-interaction induced incomplete shell filling in the hole system of InAs quantum dots (2005)
Reuter, D., Kailuweit, P., Wieck, A. D., Zeitler, U., Wibbelhoff, O. S., Meier, C., ...
We have studied the hole charging spectra of self-assembled InAs quantum dots in perpendicular magnetic fields by capacitance-voltage spectroscopy. From the magnetic field dependence of the...
Optical orientation of electron spins in GaAs quantum wells (2004)
Pfalz, S., Winkler, R., Nowitzki, T., Reuter, D., Wieck, A. D., Haegele, D., ...
We present a detailed experimental and theoretical analysis of the optical orientation of electron spins in GaAs/AlAs quantum wells. Using time and polarization resolved photoluminescence excitation...
Magnetotransport in C-doped AlGaAs heterostructures (2004)
Grbic, B., Ellenberger, C., Ihn, T., Ensslin, K., Reuter, D., Wieck, A. D.
High-quality C-doped p-type AlGaAs heterostructures with mobilities exceeding 150 000 cm$^2$/Vs are investigated by low-temperature magnetotransport experiments. We find features of the fractional...
Phonon Excitations of Composite Fermion Landau Levels (2004)
Schulze-Wischeler, F., Hohls, F., Zeitler, U., Reuter, D., Wieck, A. D., Haug, R. J.
Phonon excitations of fractional quantum Hall states at filling factors nu = 1/3, 2/5, 4/7, 3/5, 4/3, and 5/3 are experimentally shown to be based on Landau level transitions of Composite Fermions....
Magnetization of a two-dimensional electron gas with a second filled subband (2003)
Schaapman, M. R., Zeitler, U., Christianen, P. C. M., Maan, J. C., Reuter, D., Wieck, A. D., ...
We have measured the magnetization of a dual-subband two-dimensional electron gas, confined in a GaAs/AlGaAs heterojunction. In contrast to two-dimensional electron gases with a single subband, we...
Phase measurements using Two-Channel Fano Interference in a Semiconductor Quantum Dot (2003)
Fuhner, C., Keyser, U. F., Haug, R. J., Reuter, D., Wieck, A. D.
We investigate a lateral semiconductor quantum dot with a large number of electrons in the semi-open Fano regime. In transport measurements we observe three stable series of Fano resonances with...
Deviatov, E. V., Wurtz, A., Lorke, A., Melnikov, M. Yu., Dolgopolov, V. T., Reuter, D., ...
Using a quasi-Corbino geometry to directly study electron transport between spin-split edge states, we find a pronounced hysteresis in the I-V curves, originating from slow relaxation processes. We...
Resonant Rayleigh scattering dynamics of excitons in single quantum wells (2003)
Langbein, W., Woggon, U., Savona, V., Zimmermann, R., Reuter, D., Wieck, A.D., ...
The resonant Rayleigh scattering dynamics of excitons in single GaAs quantum wells is investigated. The deviation of the measured intensity from the ideal ensemble average is analyzed as a function...
Hopping Conductivity Beyond The Percolation Regime Probed By Shot-Noise Measurements (2002)
Camino, F. E., Kuznetsov, V. V., Mendez, E. E., Gershenson, M. E., Reuter, D., Schafmeister, P., ...
We have observed suppression of shot noise in the variable-range hopping regime for a two-dimensional electron gas whose localization length, xi, is controlled by a gate voltage. We have found that...
Flux-quantum-modulated Kondo conductance in a multielectron quantum dot (2002)
Fuhner, C., Keyser, U. F., Haug, R. J., Reuter, D., Wieck, A. D.
We investigate a lateral semiconductor quantum dot with a large number of electrons in the limit of strong coupling to the leads. A Kondo effect is observed and can be tuned in a perpendicular...
Regul, J., Keyser, U. F., Paesler, M., Hohls, F., Zeitler, U., Haug, R. J., ...
We use the all-diamond tip of an atomic force microscope for the direct engraving of high quality quantum point contacts in GaAs/AlGaAs-heterostructures. The processing time is shortened by two...
Transport and Lifetime Enhancement of Photoexcited Spins in GaAs by Surface Acoustic Waves (2001)
Eshlaghi, S., Santos, P. V., Sogawa, T., Wieck, A. D., Zhang, S. K.
Suter, Dieter, Eshlaghi, Soheyla, Meier, Cedrik, Reuter, D., Wieck, A. D.
The implantation-induced intermixing depth profile for 100 keV Ga + ions was determined by photoluminescence measurements on a series of samples containing quantum wells at variable depth from the...
Electron-Assisted Hopping in Two Dimensions (1999)
Gershenson, M. E., Khavin, Yu. B., Reuter, D., Schafmeister, P., Wieck, A. D.
We have studied the non-ohmic effects in the conductivity of a two-dimensional system which undergoes the crossover from weak to strong localization with decreasing electron concentration. When the...