Journal ArticlePhysical Review B · March 15, 2024
There has been a growing interest in hybrid quantum Hall-superconductor devices, driven by the prospect to realize exotic ground states and excitations with non-Abelian exchange statistics. While the existing experiments clearly demonstrate Andreev couplin ...
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Journal ArticlePhysical review letters · October 2023
We perform a systematic study of Andreev conversion at the interface between a superconductor and graphene in the quantum Hall (QH) regime. We find that the probability of Andreev conversion from electrons to holes follows an unexpected but clear trend: th ...
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Journal ArticleNano letters · June 2023
Superconducting diodes are proposed nonreciprocal circuit elements that should exhibit nondissipative transport in one direction while being resistive in the opposite direction. Multiple examples of such devices have emerged in the past couple of years; ho ...
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Journal ArticleScience advances · February 2023
A two-dimensional, anisotropic superconductivity was recently found at the KTaO3(111) interfaces. The nature of the anisotropic superconducting transition remains a subject of debate. To investigate the origins of the observed behavior, we grew ...
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Journal ArticleNano letters · December 2022
The vanishing band gap of graphene has long presented challenges for making high-quality quantum point contacts (QPCs)─the partially transparent p-n interfaces introduced by conventional split gates tend to short circuit the QPCs. This complication has hin ...
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Journal ArticleNano letters · September 2022
The dynamical properties of multiterminal Josephson junctions (MT-JJs) have attracted interest, driven by the promise of new insights into synthetic topological phases of matter and Floquet states. This effort has culminated in the discovery of Cooper mult ...
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Journal ArticleNano letters · November 2021
When a Josephson junction is exposed to microwave radiation, it undergoes the inverse AC Josephson effect─the phase of the junction locks to the drive frequency. As a result, the I-V curves of the junction acquire "Shapiro steps" of quantized ...
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Journal ArticleAIP Advances · April 1, 2021
Establishing ohmic contact to van der Waals semiconductors such as MoS2 is crucial to unlocking their full potential in next-generation electronic devices. Encapsulation of few layer MoS2 with hBN preserves the material’s electronic properties but makes el ...
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Journal ArticleNano letters · October 2020
The AC Josephson effect manifests itself in the form of "Shapiro steps" of quantized voltage in Josephson junctions subject to radiofrequency (RF) radiation. This effect presents an early example of a driven-dissipative quantum phenomenon and is presently ...
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Journal ArticleNature Physics · May 18, 2020
The search for topological excitations such as Majorana fermions has spurred interest in the boundaries between distinct quan- tum states. Here, we explore an interface between two prototypical phases of electrons with conceptually different ground states: ...
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Journal ArticlePhysical Review Research · November 7, 2019
We investigate supercurrent interference patterns measured as a function of magnetic field in ballistic graphene Josephson junctions. At high doping, the expected φ0-periodic "Fraunhofer"pattern is observed, indicating a uniform current distribution. Close ...
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Journal ArticlePhysical Review B · September 10, 2019
We study a two-terminal graphene Josephson junction with contacts shaped to form a narrow constriction, less than 100nm in length. The contacts are made from type-II superconducting contacts and able to withstand magnetic fields high enough to reach the qu ...
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Journal ArticleScience advances · September 2019
We present a study of a graphene-based Josephson junction with dedicated side gates carved from the same sheet of graphene as the junction itself. These side gates are highly efficient and allow us to modulate carrier density along either edge of the junct ...
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Journal ArticlePhysical Review B · March 29, 2019
In this work, we report on hot carrier diffusion in graphene across large enough length scales that the carriers are not thermalized across the crystal. The carriers are injected into graphene at one site and their thermal transport is studied as a functio ...
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Journal ArticleNano letters · February 2019
We investigate the electronic properties of ballistic planar Josephson junctions with multiple superconducting terminals. Our devices consist of monolayer graphene encapsulated in boron nitride with molybdenum-rhenium contacts. Resistance measurements yiel ...
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Journal ArticleMRS Advances · January 1, 2018
Coupling superconductors to quantum Hall edge states is the subject of intense investigation as part of the ongoing search for non-abelian excitations. Our group has previously observed supercurrents of hundreds of picoamperes in graphene Josephson junctio ...
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Journal ArticlePhysical review letters · December 2016
We investigate the critical current I_{C} of ballistic Josephson junctions made of encapsulated graphene-boron-nitride heterostructures. We observe a crossover from the short to the long junction regimes as the length of the device increases. In long balli ...
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Journal ArticleNano letters · August 2016
We present transport measurements on long, diffusive, graphene-based Josephson junctions. Several junctions are made on a single-domain crystal of CVD graphene and feature the same contact width of ∼9 μm but vary in length from 400 to 1000 nm. As the carri ...
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Journal ArticleScience (New York, N.Y.) · May 2016
A promising route for creating topological states and excitations is to combine superconductivity and the quantum Hall (QH) effect. Despite this potential, signatures of superconductivity in the QH regime remain scarce, and a superconducting current throug ...
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ConferenceProceedings of SPIE - The International Society for Optical Engineering · January 1, 2016
Plasmonics in the UV-range constitutes a new challenge due to the increasing demand to detect, identify and destroy biological toxins, enhance biological imaging, and characterize semiconductor devices at the nanometer scale. Silver and aluminum have an ef ...
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Journal ArticleNano letters · February 2015
The nonoxidizing catalytic noble metal rhodium is introduced for ultraviolet plasmonics. Planar tripods of 8 nm Rh nanoparticles, synthesized by a modified polyol reduction method, have a calculated local surface plasmon resonance near 330 nm. By attaching ...
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Journal ArticleACS nano · August 2014
The coexistence of semiconducting and metallic single-walled carbon nanotubes (SWNTs) during synthesis is one of the major bottlenecks that prevent their broad application for the next-generation nanoelectronics. Herein, we present more understanding and d ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · February 18, 2014
We study tunneling through a resonant level connected to two dissipative bosonic baths: one is the resistive environment of the source and drain leads, while the second comes from coupling to potential fluctuations on a resistive gate. We show that several ...
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Journal ArticleNano letters · January 2014
DNA origami is a novel self-assembly technique allowing one to form various two-dimensional shapes and position matter with nanometer accuracy. We use DNA origami templates to engineer surface-enhanced Raman scattering substrates. Specifically, gold nanopa ...
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Journal ArticlePhysical review letters · July 2013
We examine the nature of the transitions between the normal and superconducting branches in superconductor-graphene-superconductor Josephson junctions. We attribute the hysteresis between the switching (superconducting to normal) and retrapping (normal to ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · June 21, 2013
The resonant-level model represents a paradigmatic quantum system which serves as a basis for many other quantum impurity models. We provide a comprehensive analysis of the nonequilibrium transport near a quantum phase transition in a spinless dissipative ...
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Journal ArticleNature Physics · January 1, 2013
A quantum phase transition is an abrupt change between two distinct ground states of a many-body system, driven by an external parameter. In the vicinity of the quantum critical point (QCP) where the transition occurs, a new phase may emerge that is determ ...
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Journal ArticlePLoS One · 2013
The computational complexity of the brain depends in part on a neuron's capacity to integrate electrochemical information from vast numbers of synaptic inputs. The measurements of synaptic activity that are crucial for mechanistic understanding of brain fu ...
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Journal ArticleNature · August 2012
A Luttinger liquid is an interacting one-dimensional electronic system, quite distinct from the 'conventional' Fermi liquids formed by interacting electrons in two and three dimensions. Some of the most striking properties of Luttinger liquids are revealed ...
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Journal ArticleIEEE Transactions on Applied Superconductivity · June 14, 2012
We fabricate superconductor-graphene-superconductor Josephson junctions with superconducting regions made of lead (Pb). The critical current through graphene may be modulated by the external magnetic field; the resulting Fraunhofer interference pattern sho ...
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Journal ArticleJ Appl Phys · April 1, 2012
This paper discusses several methods for manufacturing ultra-sharp probes, with applications geared toward, but not limited to, scanning microscopy (STM, AFM) and intra-cellular recordings of neural signals. We present recipes for making tungsten, platinum ...
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ConferenceJournal of Physics: Conference Series · January 1, 2012
We investigate tunneling through a resonant level formed in a carbon nanotube quantum dot contacted by resistive metal wires. These contacts create a dissipative environment for the electrons tunneling across the nanotube, thus suppressing the tunneling ra ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · November 8, 2011
Hysteretic I-V (current-voltage) curves are studied in narrow Al nanowires. The nanowires have a cross section as small as 50 nm2. We focus on the retrapping current in a down-sweep of the current, at which a nanowire re-enters the superconducting state fr ...
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Journal ArticlePhysical review letters · September 2011
An aluminum nanowire switches from superconducting to normal as the current is increased in an upsweep. The switching current (I(s)) averaged over upsweeps approximately follows the depairing critical current (I(c)) but falls below it. Fluctuations in I(s) ...
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Journal ArticlePhysical review letters · September 2011
We report on graphene-based Josephson junctions with contacts made from lead. The high transition temperature of this superconductor allows us to observe the supercurrent branch at temperatures up to ∼2 K, at which point we can detect a small, but nonzero, ...
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Journal ArticleNano letters · August 2011
We present a novel method for producing complex metallic nanostructures of programmable design. DNA origami templates, modified to have DNA binding sites with a uniquely coded sequence, were adsorbed onto silicon dioxide substrates. Gold nanoparticles func ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · October 18, 2010
The concept of the "Kondo box" describes a single spin, antiferromagnetically coupled to a quantum dot with a finite level spacing. Here, a Kondo box is formed in a carbon nanotube interacting with a localized electron. We investigate the spins of its firs ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · June 22, 2009
We measure tunneling through a single quantum level in a carbon nanotube quantum dot connected to resistive metal leads. For the electrons tunneling to/from the nanotube, the leads serve as a dissipative environment, which suppresses the tunneling rate. In ...
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Journal ArticleJETP Letters · April 1, 2009
In this paper, we present the results of helium temperature transport measurements through carbon nanotubes using an AFM conductive tip as a mobile gate for creation of a local distributive Coulomb potential. In semiconducting nanotubes we observe shifting ...
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Journal ArticleApplied Physics Letters · September 2008
We describe a method to pattern SiO2 surfaces with colloidal gold nanoparticles by e-beam lithography and selective nanoparticle deposition. The simple technique allows us to deposit nanoparticles in continuous straight lines, just one nanoparticle wide an ...
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Journal ArticlePhysica B: Condensed Matter · April 1, 2008
We study the evolution of conductance regimes in carbon nanotubes with doubly degenerate orbitals ("shells") by controlling the contact transparency within the same sample. For sufficiently open contacts, Kondo behavior is observed for 1, 2, and 3 electron ...
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Journal ArticlePhysical review letters · February 2008
We present numerical renormalization group calculations for the zero-bias conductance of quantum dots made from semiconducting carbon nanotubes. These explain and reproduce the thermal evolution of the conductance for different groups of orbitals, as the d ...
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Journal ArticleJournal of the American Chemical Society · January 2008
The simple helical motif of double-strand DNA (dsDNA) has typically been judged to be uninteresting for assembly in DNA-based nanotechnology applications. In this letter, we demonstrate construction of superstructures consisting of heterogeneous DNA motifs ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · October 25, 2007
We find that electrons in single-wall carbon nanotubes may propagate substantial distances (tens of nanometers) under metal contacts. We perform four-probe transport measurements of the nanotube conductance and observe significant deviations from the stand ...
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Journal ArticleApplied Physics Letters · August 10, 2007
The authors describe conductive tip atomic force microscope used for imaging carbon nanotubes at low temperatures. The instrument allows them to measure the tip-nanotube conductance while performing the topographic scan of the nanotubes on a nonconductive ...
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Journal ArticlePhysical review letters · August 2007
We study the evolution of conductance regimes in carbon nanotubes with doubly degenerate orbitals (shells) by controlling the contact transparency within the same sample. For sufficiently open contacts, Kondo behavior is observed for 1, 2, and 3 electrons ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · June 25, 2007
We study the SU(4) Kondo effect in carbon nanotube quantum dots, where doubly degenerate orbitals form four-electron "shells." The SU(4) Kondo behavior is investigated for one, two, and three electrons in the topmost shell. While the Kondo state of two ele ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · November 6, 2006
The quantum-mechanical orbitals in carbon nanotube quantum dots are doubly degenerate over a large number of states. We argue that this experimental observation indicates that electrons are reflected without mode mixing at the nanotube-metal contacts. Two ...
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Journal ArticleApplied Physics Letters · July 28, 2006
We report on the electrical conductivity measurement of silver nanowires templated on native X-bacteriophage and synthetic double-stranded DNA molecules. After an electroless chemical deposition, the metallized DNA wires have a diameter down to 15 nm and a ...
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Journal ArticleApplied Physics Letters · 2006
We report on the electrical conductivity
measurement of silver nanowires templated on
native λ-bacteriophage and synthetic double-
stranded DNA molecules. After an electroless
chemical deposition, the metallized DNA wires
have a diameter down to 1 ...
Cite
Journal ArticleNano Letters · March 2005
We present a DNA nanostructure, the three-
helix bundle (3HB), which consists of three
double helical DNA domains connected by six
immobile crossover junctions such that the
helix axes are not coplanar. The 3HB motif
presents a triangular cross-section ...
Cite
Journal ArticleNanotechnology · July 2004
We report on the self-assembly of one- and
two-dimensional DNA scaffolds,
which serve as templates for the targeted
deposition of ordered nanoparticles
and molecular arrays. TheDNAnanostructures
are easy to reprogram, and
we demonstrate two distinct con ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · September 15, 2002
Subsurface charge accumulation imaging is a cryogenic scanning probe technique that has recently been used to spatially probe incompressible strips formed in a two-dimensional electron system (2DES) at high magnetic fields. In this paper, we present a deta ...
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Journal ArticleNano Letters · August 1, 2002
Single Walled carbon nanotubes (SWNTs) were grown directly on flat substrates using chemical vapor deposition (CVD) method with carbon monoxide and hydrogen mixture as feeding gas. Comparing with other CVD methods, this new approach yields higher efficienc ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · March 15, 2002
Using charge-accumulation imaging, we measure the charge flow across an incompressible strip and follow its evolution with magnetic field. The strip runs parallel to the edge of a gate deposited on the sample and forms at positions where an exact number of ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · January 1, 2002
Using charge-accumulation imaging, we measure the charge flow across an incompressible strip and follow its evolution with magnetic field. The strip runs parallel to the edge of a gate deposited on the sample and forms at positions where an exact number of ...
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Journal ArticleScience · July 7, 2000
A scanning probe technique was used to obtain a high-resolution map of the random electrostatic potential inside the quantum Hall liquid. A sharp metal tip, scanned above a semiconductor surface, sensed charges in an embedded twodimensional (2D) electron g ...
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Journal ArticlePhysica E: Low-Dimensional Systems and Nanostructures · January 1, 2000
The two-dimensional electron gas (2DEG) in the quantum Hall regime close to integer filling factors was studied. In a smooth potential gradient, low-compressibility strips corresponding to integer Landau level filling factors are observed. These strips tur ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · 2000
Using subsurface charge accumulation scanning microscopy, we image strips of low compressibility corresponding to several integer quantum Hall filling factors. We study in detail the strips at Landau level filling factors ν=2 and 4. The observed strips app ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · January 1, 1999
We compare the photoluminescence spectra of the negatively and positively charged excitons in GaAs quantum wells. We use a structure which enables us to observe both complexes within the same sample. We find that their binding energy and Zeeman splitting a ...
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Journal ArticlePhysica B: Condensed Matter · December 2, 1998
We report on time-resolved photoluminescence studies of charged and neutral excitons in a modulation doped GaAs quantum well under resonant excitation and high magnetic field. The radiative lifetime of the charged exciton is rather short, 60 ps at zero fie ...
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Journal ArticlePhysica B: Condensed Matter · June 17, 1998
Shake-up processes in the photoluminescence spectra of a two-dimensional electron gas in a GaAs/AlGaAs quantum well at high magnetic fields are studied at a range of filling factors. We find that when the electrons occupy only the lowest Landau level these ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · January 1, 1998
We study the dynamics of the charged and neutral excitons in a modulation-doped GaAs quantum well by time-resolved photoluminescence under a resonant excitation. The radiative lifetime of the charged exciton is found to be surprisingly short, 60 ps. This t ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · January 1, 1997
We observe shakeup processes in the photoluminescence spectra of a two-dimensional electron gas in a (Formula presented) quantum well at high magnetic fields. We find that when the electrons occupy only the lowest Landau level these processes are strongly ...
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Journal ArticleSurface Science · July 20, 1996
We implement optical spectroscopy to study charged excitons in modulation-doped GaAs/AlGaAs quantum wells. We report the first observation of the positively charged exciton and of the triplet state of the negatively charged exciton. Applying a gate voltage ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · January 1, 1996
We report on shakeup processes in the luminescence spectra of a negatively charged exciton ((Formula presented)) at moderate magnetic fields. These processes manifest themselves as a series of low-energy satellite peaks emerging from the negatively charged ...
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Journal ArticlePhysical Review B - Condensed Matter and Materials Physics · January 1, 1996
We report the observation of the positively charged exciton and of the triplet state of the negatively charged exciton in modulation doped GaAs quantum wells. Applying a gate voltage at high magnetic fields we find that the photoluminescence line of the tw ...
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Journal ArticleIl Nuovo Cimento D · November 1, 1995
We implement optical spectroscopy to study charged excitons (trions) in modulation-doped GaAs/AlGaAs quantum wells. We observe for the first time several new trions: the positively charged exciton, the light-hole negatively charged exciton and the triplet ...
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Journal Articlephysica status solidi (b) · January 1, 1995
Time‐resolved four‐wave mixing is used to study electron scattering in modulation‐doped GaAs quantum wells in high magnetic fields up to 8T. A strong increase in dephasing times in strong magnetic fields is observed and attributed to a decrease in the scat ...
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Journal ArticlePhysical Review Letters · January 1, 1995
We report on optical measurements of a two-dimensional electron gas near the metal-insulator transition. We observe the appearance of excitons and negatively charged excitons, X-, at the onset of the transition. The fact that these excitons appear at a rel ...
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Journal ArticlePhysical Review B · January 1, 1994
We present time-resolved differential-absorption data for GaAs quantum wells, in which temporal oscillations originating in a biexcitonic pairing appear. We interpret the oscillations within a four-level model of the exciton-biexciton system, and discuss t ...
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Journal ArticlePhysical Review B · January 1, 1993
We present a model for the nonlinear optical response of quantum wells, which includes biexcitons. We show that within this model, the interaction of two laser pulses, mediated by the nonlinear susceptibility, results in oscillations and in coupling betwee ...
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Conference
In multi-terminal Josephson junctions, the superconducting coupling is established between each pair of contacts across a common normal channel. The state of such junction is described by N-1 independent phase differences between pairs of contacts, where N ...
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Conference
There has been a growing interest to the materials with broken time-reversal and inversion symmetry, which can support non-reciprocal superconducting currents [1]. This search for an intrinsic superconducting diode has so far resulted in devices that typic ...
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Conference
There has been a growing interest to the materials with broken time-reversal and inversion symmetry, which can support non-reciprocal superconducting currents [1]. This search for an intrinsic superconducting diode has so far resulted in devices that typic ...
Open AccessCite