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Lazic S.,Paul Drude Institute For Festkorkperelektronik | Lazic S.,Autonomous University of Madrid | Violante A.,Paul Drude Institute For Festkorkperelektronik | Cohen K.,Hebrew University of Jerusalem | And 3 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

Excitons, quasiparticles consisting of electron-hole pairs bound by the Coulomb interaction, are a potential medium for the processing of photonic information in the solid state. Information processing via excitons requires efficient techniques for the transport and manipulation of these uncharged particles. We have carried out a detailed investigation of the transport of excitons in GaAs quantum wells by surface acoustic waves. Based on these results, we introduce here a concept for the interconnection of multiple remote exciton systems based on the long-range transport of dipolar excitons by a network of configurable interconnects driven by acoustic wave beams. By combining this network with electrostatic gates, we demonstrate an integrated exciton multiplexer capable of interconnecting, gating, and routing exciton systems separated by millimeter distances. The multiplexer provides a scalable platform for the manipulation of exciton fluids with potential applications in information processing. © 2014 American Physical Society.


Buyukkose S.,MESA Institute for Nanotechnology | Hernandez-Minguez A.,Paul Drude Institute For Festkorkperelektronik | Vratzov B.,NTandD Nanotechnology and Devices | Somaschini C.,Paul Drude Institute For Festkorkperelektronik | And 4 more authors.
Nanotechnology | Year: 2014

The oscillating piezoelectric fields accompanying surface acoustic waves are able to transport charge carriers in semiconductor heterostructures. Here, we demonstrate high-frequency (above 1 GHz) acoustic charge transport in GaAs-based nanowires deposited on a piezoelectric substrate. The short wavelength of the acoustic modulation, smaller than the length of the nanowire, allows the trapping of photo-generated electrons and holes at the spatially separated energy minima and maxima of conduction and valence bands, respectively, and their transport along the nanowire with a well defined acoustic velocity towards indium-doped recombination centers. © 2014 IOP Publishing Ltd.


Boucher P.,Paul Drude Institute For Festkorkperelektronik | Boucher P.,Ecole Polytechnique - Palaiseau | Rauwerdink S.,Paul Drude Institute For Festkorkperelektronik | Tahraoui A.,Paul Drude Institute For Festkorkperelektronik | And 3 more authors.
Applied Physics Letters | Year: 2014

We demonstrate a ring resonator for gigahertz surface acoustic waves (SAWs) consisting of a Ge waveguide on a silicon chip. SAWs generated by interdigital transducers on a section of the waveguide are guided over a curved path and detected by a second interdigital transducers. The structure of the GHz waveguide modes mapped using high resolution interferometry compares well with elastic calculations. The acoustic propagation properties as well as the potential applications of these semiconductor-based resonators are discussed. © 2014 AIP Publishing LLC.


Santos P.V.,Paul Drude Institute For Festkorkperelektronik | Schumann T.,Paul Drude Institute For Festkorkperelektronik | Oliveira Jr. M.H.,Paul Drude Institute For Festkorkperelektronik | Lopes J.M.J.,Paul Drude Institute For Festkorkperelektronik | Riechert H.,Paul Drude Institute For Festkorkperelektronik
Applied Physics Letters | Year: 2013

We report on the piezoelectric excitation and acoustic charge transport by gigahertz surface acoustic waves (SAWs) in epitaxial monolayer graphene (EG) on SiC. The GHz SAWs frequencies were generated by interdigital transducers fabricated on a piezoelectric island on the SiC substrate. Acoustic transport studies in a Hall bar geometry show that the propagating SAW field transports carriers in EG, the transport direction being determined by the direction of the acoustic beam. Carrier transport is driven by drift in the piezoelectric field induced by the SAW in EG. © 2013 AIP Publishing LLC.


Violante A.,Paul Drude Institute For Festkorkperelektronik | Hey R.,Paul Drude Institute For Festkorkperelektronik | Santos P.V.,Paul Drude Institute For Festkorkperelektronik
Physical Review B - Condensed Matter and Materials Physics | Year: 2015

We report on the coherent control and transport of indirect-exciton (IX) spins in GaAs double quantum well (DQW) nanostructures. The spin dynamics was investigated by optically generating spins using a focused, circularly polarized light spot and by probing their spatial distribution using spatially and polarization resolved photoluminescence spectroscopy. Optically injected IX spins precess while moving over distances exceeding 20μm from the excitation spot with a precession length that depends on the spin transport direction as well as on the bias applied across the DQW structure. This behavior is attributed to the spin precession in the effective magnetic field induced by the spin-orbit interaction. From the dependence of the spin dynamics on the transport direction, bias, and external magnetic fields we directly determined the Dresselhaus and Rashba electron spin splitting coefficients for the DQW structure. The precession dynamics is essentially independent of the IX density, thus indicating that the long spin lifetimes are not associated with IX collective effects. The long IX lifetimes, together with the negligible contribution of holes to the spin dynamics, are rather attributed to spatial separation of the electron and hole wave functions by the electric field, which reduces the electron-hole exchange interaction. If extended to the single-exciton regime, the present results on coherent spin precession over long transport distances as well as the control of the spin vector using electric and magnetic fields open the way for the application of IX spins in quantum information processing. © 2015 American Physical Society.


Hernandez-Minguez A.,Paul Drude Institute For Festkorkperelektronik | Biermann K.,Paul Drude Institute For Festkorkperelektronik | Lazic S.,Paul Drude Institute For Festkorkperelektronik | Hey R.,Paul Drude Institute For Festkorkperelektronik | Santos P.V.,Paul Drude Institute For Festkorkperelektronik
Applied Physics Letters | Year: 2010

Time-resolved Kerr reflectometry (TRKR) is used to investigate the long-range transport of spins by surface acoustic waves in undoped GaAs (110) quantum wells. TRKR measurements under an applied magnetic field demonstrate the coherent precession of the optically generated electron spin during acoustic transport over several micrometers and yield information about the relaxation processes for moving spins. © 2010 American Institute of Physics.


Hernandez-Minguez A.,Paul Drude Institute For Festkorkperelektronik | Biermann K.,Paul Drude Institute For Festkorkperelektronik | Hey R.,Paul Drude Institute For Festkorkperelektronik | Santos P.V.,Paul Drude Institute For Festkorkperelektronik
Physical Review Letters | Year: 2012

Spin dephasing via the spin-orbit interaction (SOI) is a major mechanism limiting the electron spin lifetime in III-V zincblende quantum wells (QWs). The dephasing can be suppressed in GaAs(111) quantum wells by applying an electric field. The suppression has been attributed to the compensation of the intrinsic SOI associated with the bulk inversion asymmetry of the GaAs lattice by a structural induced asymmetry SOI term induced by an electric field. We provide direct experimental evidence for this mechanism by demonstrating the transition between the bulk inversion asymmetry-dominated to a structural induced asymmetry-dominated regime via photoluminescence measurements carried out over a wide range of applied fields. Spin lifetimes exceeding 100 ns are obtained near the compensating electric field, thus making GaAs(111) QWs excellent candidates for the electrical storage and manipulation of spins. © 2012 American Physical Society.

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