Publications (85)
Electron spin manipulation and resonator readout in a double quantum dot nano-electromechanical system
N. Lambert, I. Mahboob, M. Pioro-Ladrière +3
Magnetically coupling a nano-mechanical resonator to a double quantum dot confining two electrons can enable the manipulation of a single electron spin and the readout of the reson…
Electrically tunable three-dimensional g-factor anisotropy in single InAs self-assembled quantum dots
S. Takahashi, R. S. Deacon, A. Oiwa +3
Three-dimensional anisotropy of the Lande g-factor and its electrical modulation are studied for single uncapped InAs self-assembled quantum dots (QDs). The g-factor is evaluated f…
Low-temperature behavior of transmission phase shift across a Kondo correlated quantum dot
S. Takada, M. Yamamoto, C. Bäuerle +5
We study the transmission phase shift across a Kondo correlated quantum dot in a GaAs heterostructure at temperatures below the Kondo temperature (), where the phase…
Two level anti-crossings high up in the single-particle energy spectrum of a quantum dot
C. Payette, D. G. Austing, G. Yu +5
We study the evolution with magnetic field of the single-particle energy levels high up in the energy spectrum of one dot as probed by the ground state of the adjacent dot in a wea…
Transport properties of two laterally coupled vertical quantum dots in series with tunable inter-dot coupling
T. Hatano, S. Amaha, T. Kubo +5
We describe the electronic properties of a double dot for which the lateral coupling between the two vertical dots can be controlled in-situ with a center gate voltage (Vc) and the…
Mesoscopic phase behavior in a quantum dot around crossover between single-level and multilevel transport regimes
S. Takada, M. Yamamoto, C. Bäuerle +3
The transmission phase across a quantum dot (QD) is expected to show mesoscopic behavior, where the appearance of a phase lapse between Coulomb peaks (CPs) as a function of the gat…
Electrically driven single electron spin resonance in a slanting Zeeman field
M. Pioro-Ladriere, T. Obata, Y. Tokura +5
The rapidly rising fields of spintronics and quantum information science have led to a strong interest in developing the ability to coherently manipulate electron spins. Electron s…
Spin bottleneck in resonant tunneling through double quantum dots with different Zeeman splittings
S. M. Huang, Y. Tokura, H. Akimoto +4
We investigated the electron transport property of the InGaAs/GaAs double quantum dots, the electron g-factors of which are different from each other. We found that in a magnetic f…
Co-tunneling spin blockade observed in a three-terminal triple quantum dot
A. Noiri, T. Takakura, T. Obata +4
We prepare a triple quantum dot with a separate contact lead to each dot to study Pauli spin blockade in the tunnel-coupled three dots in a row. We measure the tunneling current fl…
Topological Kagome magnet Co3Sn2S2 thin flakes with high electron mobility and large anomalous Hall effect
M. Tanaka, Y. Fujishiro, M. Mogi +9
Magnetic Weyl semimetals attract considerable interest not only for their topological quantum phenomena but also as an emerging materials class for realizing quantum anomalous Hall…
Stability of the maximum density droplet in quantum dots at high magnetic fields
T. H. Oosterkamp, J. W. Janssen, L. P. Kouwenhoven +3
We have measured electron transport through a vertical quantum dot containing a tunable number of electrons between 0 and 40. Over some region in magnetic field the electrons are s…
Large anisotropy of spin-orbit interaction in a single InAs self-assembled quantum dot
S. Takahashi, R. S. Deacon, K. Yoshida +4
Anisotropy of spin-orbit interaction (SOI) is studied for a single uncapped InAs self-assembled quantum dot (SAQD) holding just a few electrons. The SOI energy is evaluated from an…
Transmission Phase in the Kondo Regime Revealed in a Two-Path Interferometer
S. Takada, C. Bäuerle, M. Yamamoto +9
We report on the direct observation of the transmission phase shift through a Kondo correlated quantum dot by employing a new type of two-path interferometer. We observed a clear $…
Electronic Structure of Multiple Dots
M. Stopa, A. Vidan, T. Hatano +2
We calculate, via spin density functional theory (SDFT) and exact diagonalization, the eigenstates for electrons in a variety of external potentials, including double and triple do…
Measurement of the Transmission Phase of an Electron in a Quantum Two-Path Interferometer
S. Takada, M. Yamamoto, C. Bäuerle +4
A quantum two-path interferometer allows for direct measurement of the transmission phase shift of an electron, providing useful information on coherent scattering problems. In mes…
Two-stage Kondo effect in a quantum dot at high magnetic field
W. G. van der Wiel, S. De Franceschi, J. M. Elzerman +5
We report a strong Kondo effect (Kondo temperature ~ 4K) at high magnetic field in a selective area growth semiconductor quantum dot. The Kondo effect is ascribed to a singlet-trip…
Full control of quadruple quantum dot circuit charge states in the single electron regime
M. R. Delbecq, T. Nakajima, T. Otsuka +4
We report the realization of an array of four tunnel coupled quantum dots in the single electron regime, which is the first required step toward a scalable solid state spin qubit a…
Dephasing in an Aharonov-Bohm interferometer containing a lateral double quantum dot induced by coupling with a quantum dot charge sensor
T. Kubo, Y. Tokura, S. Tarucha
We theoretically investigated the dephasing in an Aharonov-Bohm interferometer containing a lateral double quantum dot induced by coupling with a quantum dot charge sensor. We empl…
Kondo effect out of equilibrium in a mesoscopic device
S. De Franceschi, R. Hanson, W. G. van der Wiel +5
We study the non-equilibrium regime of the Kondo effect in a quantum dot laterally coupled to a narrow wire. We observe a split Kondo resonance when a finite bias voltage is impose…
A >99.9%-fidelity quantum-dot spin qubit with coherence limited by charge noise
J. Yoneda, K. Takeda, T. Otsuka +10
Recent advances towards spin-based quantum computation have been primarily fuelled by elaborate isolation from noise sources, such as surrounding nuclear spins and spin-electric su…
Observation of the Kondo Screening Cloud of Micron Lengths
I. V. Borzenets, J. Shim, J. Chen +5
When a magnetic impurity exists in a metal, conduction electrons form a spin cloud that screens the impurity spin. This basic phenomenon is called the Kondo effect. Contrary to ele…
Gate Adjustable Coherent Three and Four Level Mixing in a Vertical Quantum Dot Molecule
C. Payette, S. Amaha, T. Hatano +6
We study level mixing in the single particle energy spectrum of one of the constituent quantum dots in a vertical double quantum dot by performing magneto-resonant-tunneling spectr…
Stacking-order dependent transport properties of trilayer graphene
S. H. Jhang, M. F. Craciun, S. Schmidmeier +8
We report markedly different transport properties of ABA- and ABC-stacked trilayer graphenes. Our experiments in double-gated trilayer devices provide evidence that a perpendicular…
Molecular states observed in a single pair of strongly coupled self-assembled InAs quantum dots
T. Ota, M. Stopa, M. Rontani +8
Molecular states in a SINGLE PAIR of strongly coupled self-assembled InAs quantum dots are investigated using a sub-micron sized single electron transistor containing just a few pa…
Two-qubit Gate of Combined Single Spin Rotation and Inter-dot Spin Exchange in a Double Quantum Dot
R. Brunner, Y. -S. Shin, T. Obata +6
A crucial requirement for quantum information processing is the realization of multiple-qubit quantum gates. Here, we demonstrate an electron spin based all-electrical two-qubit ga…
Chiral Quasiparticle Tunneling Between Quantum Hall Edges in Proximity with a Superconductor
M. T. Wei, A. W. Draelos, A. Seredinski +10
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 superconductin…
Aharonov-Bohm Oscillations Changed by Indirect Interdot Tunneling via Electrodes in Parallel-Coupled Vertical Double Quantum Dots
T. Hatano, T. Kubo, Y. Tokura +3
Aharonov-Bohm (AB) oscillations are studied for a parallel coupled vertical double quantum dot with a common source and drain electrode. We observe AB oscillations of current via a…
Electro-magnetic Aharonov-Bohm effect in a 2-D electron gas ring
W. G. van der Wiel, Yu. V. Nazarov, S. De Franceschi +5
We define a mesoscopic ring in a 2-dimensional electron gas (2DEG) interrupted by two tunnel barriers, enabling us to apply a well-defined potential difference between the two halv…
Preparation and Readout of Multielectron High-Spin States in a Gate-Defined GaAs/AlGaAs Quantum Dot
H. Kiyama, K. Yoshimi, T. Kato +3
We report the preparation and readout of multielectron high-spin states, a three-electron quartet, and a four-electron quintet, in a gate-defined GaAs/AlGaAs single quantum dot usi…
Magnetically induced chessboard pattern in the conductance of a Kondo quantum dot
M. Stopa, W. G. van der Wiel, S. De Franceschi +2
We quantitatively describe the main features of the magnetically induced conductance modulation of a Kondo quantum dot -- or chessboard pattern -- in terms of a constant-interactio…
Tuneable electronic properties in graphene
M. F. Craciun, S. Russo, M. Yamamoto +1
Novel materials are in great demand for future applications. The discovery of graphene, a one atom thick carbon layer, holds the promise for unique device architectures and functio…
Kondo effect in an integer-spin quantum dot
S. Sasaki, S. De Franceschi, J. M. Elzerman +4
The Kondo effect is a key many-body phenomenon in condensed matter physics. It concerns the interaction between a localised spin and free electrons. Discovered in metals containing…
Fast spin information transfer between distant quantum dots using individual electrons
B. Bertrand, S. Hermelin, S. Takada +6
Transporting ensembles of electrons over long distances without losing their spin polarization is an important benchmark for spintronic devices. It requires usually to inject and t…
Aharonov-Bohm interferometry with a tunnel-coupled wire
A. Aharony, S. Takada, O. Entin-Wohlman +2
Recent experiments [M. Yamamoto et al., Nature Nanotechnology 7, 247 (2012)] used the transport of electrons through an Aharonov-Bohm interferometer and two coupled channels (at bo…
Footprints of hyperfine, spin-orbit, and decoherence effects in Pauli spin blockade
T. Fujita, P. Stano, G. Allison +8
We detect in real time inter-dot tunneling events in a weakly coupled two electron double quantum dot in GaAs. At finite magnetic fields, we observe two characteristic tunneling ti…
Many-body excitations in tunneling current spectra of a few-electron quantum dot
D. V. Melnikov, T. Fujisawa, D. G. Austing +2
Inherent asymmetry in the tunneling barriers of few-electron quantum dots induces intrinsically different tunneling currents for forward and reverse source-drain biases in the non-…
Noise-correlation spectrum for a pair of spin qubits in silicon
J. Yoneda, J. S. Rojas-Arias, P. Stano +5
Semiconductor qubits are appealing for building quantum processors as they may be densely integrated due to small footprint. However, a high density raises the issue of noise corre…
Charge-noise-free Lateral Quantum Dot Devices with Undoped Si/SiGe Wafer
T. Obata, K. Takeda, J. Kamioka +6
We develop quantum dots in a single layered MOS structure using an undoped Si/SiGe wafer. By applying a positive bias on the surface gates, electrons are accumulated in the Si chan…
High Efficiency CVD Graphene-lead (Pb) Cooper Pair Splitter
I. V. Borzenets, Y. Shimazaki, G. F. Jones +4
We demonstrate high efficiency Cooper pair splitting in a graphene-based device. We utilize a true Y-shape design effectively placing the splitting channels closer together: graphe…
Ballistic graphene Josephson junctions from the short to the long regime
I. V. Borzenets, F. Amet, C. T. Ke +9
We investigate the critical current, , of ballistic Josephson junctions made of encapsulated graphene/boron-nitride heterostructures. We observe a crossover from the short to…
A vertical diatomic artificial molecule in the intermediate coupling regime in a parallel and perpendicular magnetic field
F. Ancilotto, D. G. Austing, M. Barranco +4
We present experimental results for the ground state electrochemical potentials of a few electron semiconductor artificial molecule made by vertically coupling two quantum dots, in…
A fast quantum interface between different spin qubit encodings
A. Noiri, T. Nakajima, J. Yoneda +12
Single-spin qubits in semiconductor quantum dots proposed by Loss and DiVincenzo (LD qubits) hold promise for universal quantum computation with demonstrations of a high single-qub…
Electronic transport properties of few-layer graphene materials
S. Russo, M. F. Craciun, T. Khodkov +3
Since the discovery of graphene -a single layer of carbon atoms arranged in a honeycomb lattice - it was clear that this truly is a unique material system with an unprecedented com…
Noise Correlations in a Coulomb Blockaded Quantum Dot
Y. Zhang, L. DiCarlo, D. T. McClure +5
We report measurements of current noise auto- and cross-correlation in a tunable quantum dot with two or three leads. As the Coulomb blockade is lifted at finite source-drain bias,…
Gate tunable parallel double quantum dot in InAs double-nanowire junctions
S. Baba, S. Matsuo, H. Kamata +4
We report fabrication and measurement of a device where closely-placed two parallel InAs nanowires (NWs) are contacted by source and drain normal metal electrodes. Established tech…
Spin configurations in circular and rectangular vertical quantum dots in a magnetic field: Three-dimensional self-consistent simulation
Dmitriy V. Melnikov, Philippe Matagne, Jean-Pierre Leburton +5
The magnetic field dependence of the electronic properties of \textit{real} single vertical quantum dots in circular and rectangular mesas is investigated within a full three-dimen…
Repetitive single electron spin readout in silicon
J. Yoneda, K. Takeda, A. Noiri +5
Single electron spins confined in silicon quantum dots hold great promise as a quantum computing architecture with demonstrations of long coherence times, high-fidelity quantum log…
Electron transport through double quantum dots
W. G. van der Wiel, S. De Franceschi, J. M. Elzerman +3
Electron transport experiments on two lateral quantum dots coupled in series are reviewed. An introduction to the charge stability diagram is given in terms of the electrochemical…
Molecular phases in coupled quantum dots
M. Rontani, S. Amaha, K. Muraki +4
We present excitation energy spectra of few-electron vertically coupled quantum dots for strong and intermediate inter-dot coupling. By applying a magnetic field, we induce ground…
Single-dot spectroscopy via elastic single-electron tunneling through a pair of coupled quantum dots
T. Ota, K. Ono, M. Stopa +7
We study the electronic structure of a single self-assembled InAs quantum dot by probing elastic single-electron tunneling through a single pair of weakly coupled dots. In the regi…
Accurate Model of a Vertical Pillar Quantum Dot
P. A. Maksym, Y. Nishi, D. G. Austing +4
An accurate model of a vertical pillar quantum dot is described. The full three dimensional structure of the device containing the dot is taken into account and this leads to an ef…
Direct Coulomb and Exchange Interaction in Artificial Atoms
S. Tarucha, D. G. Austing, Y. Tokura +2
We determine the contributions from the direct Coulomb and exchange interactions to the total interaction in semiconductor artificial atoms. We tune the relative strengths of the t…
A triangular triple quantum dot with tunable tunnel couplings
A. Noiri, K. Kawasaki, T. Otsuka +9
A two-dimensional arrangement of quantum dots with finite inter-dot tunnel coupling provides a promising platform for studying complicated spin correlations as well as for construc…
Spins in few-electron quantum dots
R. Hanson, L. P. Kouwenhoven, J. R. Petta +2
This review describes the physics of spins in quantum dots containing one or two electrons, from an experimentalist's viewpoint. Various methods for extracting spin properties from…
Double-gated graphene-based devices
S. Russo, M. F. Craciun, M. Yamamoto +2
We discuss transport through double gated single and few layer graphene devices. This kind of device configuration has been used to investigate the modulation of the energy band st…
Lateral electron tunneling through single self-assembled InAs quantum dots coupled to superconducting nanogap electrodes
K. Shibata, C. Buizert, A. Oiwa +2
We have fabricated superconductor-quantum dot-superconductor (SC-QD-SC) junctions by using SC aluminum electrodes with narrow gaps laterally contacting a single self-assembled InAs…
Ellipsoidal deformation of vertical quantum dots
D. G. Austing, S. Sasaki, S. Tarucha +3
Addition energy spectra at 0 T of circular and ellipsoidally deformed few-electron vertical quantum dots are measured and compared to results of model calculations within spin-dens…
Intermediate Low Spin States in a Few-electron Quantum Dot in the Regime
Y. Nishi, P. A. Maksym, D. G. Austing +4
We study the effects of electron-electron interactions in a circular few-electron vertical quantum dot in such a strong magnetic field that the filling factor . We measure…
Non-universal transmission phase behaviour of a large quantum dot
H. Edlbauer, S. Takada, G. Roussely +6
The electron wave function experiences a phase modification at coherent transmission through a quantum dot. This transmission phase undergoes a characteristic shift of when sc…
2-periodic magnetic interference in ballistic graphene Josephson junctions
C. T. Ke, A. W. Draelos, A. Seredinski +11
We investigate supercurrent interference patterns measured as a function of magnetic field in ballistic graphene Josephson junctions. At high doping, the expected -periodic…
Quantum dephasing in a gated GaAs triple quantum dot due to nonergodic noise
M. R. Delbecq, T. Nakajima, P. Stano +8
We extract the phase coherence of a qubit defined by singlet and triplet electronic states in a gated GaAs triple quantum dot, measuring on timescales much shorter than the decorre…
Microwave spectroscopy on a quantum-dot molecule
T. H. Oosterkamp, T. Fujisawa, W. G. van der Wiel +4
Quantum dots are small conductive regions in a semiconductor, containing a variable number of electrons (N=1 to 1000) that occupy well defined discrete quantum states. They are oft…
Geometric blockade in a quantum dot coupled to two-dimensional and three dimensional electron gases
K. Yamada, M. Stopa, T. Hatano +4
We fabricated a quantum dot coupled laterally to a two-dimensional electron gas and vertically to a three-dimensional electron gas in order to investigate the eigenstate dependence…
Electrical control of Kondo effect and superconducting transport in a side-gated InAs quantum dot Josephson junction
Y. Kanai, R. S. Deacon, A. Oiwa +4
We measure the non-dissipative supercurrent in a single InAs self-assembled quantum dot (QD) coupled to superconducting leads. The QD occupation is both tuned by a back-gate electr…
Optimized electrical control of a Si/SiGe spin qubit in the presence of an induced frequency shift
K. Takeda, J. Yoneda, T. Otsuka +9
Electron spins confined in quantum dots are an attractive system to realize high-fidelity qubits owing to their long coherence time. With the prolonged spin coherence time, however…
Contact resistance in graphene-based devices
S. Russo, M. F. Craciun, M. Yamamoto +2
We report a systematic study of the contact resistance present at the interface between a metal (Ti) and graphene layers of different, known thickness. By comparing devices fabrica…
Tuning the electrically evaluated electron Lande g factor in GaAs quantum dots and quantum wells of different well widths
G. Allison, T. Fujita, K. Morimoto +9
We evaluate the Lande g factor of electrons in quantum dots (QDs) fabricated from GaAs quantum well (QW) structures of different well width. We first determine the Lande electron g…
Single Photoelectron Detection after Selective Excitation of Electron-Heavy Hole and Electron-Light Hole Pairs in Double Quantum Dots
K. Morimoto, T. Fujita, G. Allison +9
We demonstrate the real-time detection of single photogenerated electrons in two different lateral double quantum dots made in AlGaAs/GaAs/AlGaAs quantum wells having a thin or a t…
Micro-magnets for coherent control of spin-charge qubit in lateral quantum dots
M. Pioro-Ladriere, Y. Tokura, T. Obata +2
A lateral quantum dot design for coherent electrical manipulation of a two-level spin-charge system is presented. Two micron-size permanent magnets integrated to high-frequency ele…
Few-electron molecular states and their transitions in a single InAs quantum dot molecule
T. Ota, M. Rontani, S. Tarucha +6
We study electronic configurations in a single pair of vertically coupled self-assembled InAs quantum dots, holding just a few electrons. By comparing the experimental data of non-…
Electron Cotunneling in a Semiconductor Quantum Dot
S. De Franceschi, S. Sasaki, J. M. Elzerman +3
We report transport measurements on a semiconductor quantum dot with a small number of confined electrons. In the Coulomb blockade regime, conduction is dominated by cotunneling pr…
Characterization and Suppression of Low-frequency Noise in Si/SiGe Quantum Point Contacts and Quantum Dots
K. Takeda, T. Obata, Y. Fukuoka +5
We report on the effects of a global top gate on low-frequency noise in Schottky gate-defined quantum point contacts (QPCs) and quantum dots (QDs) in a modulation-doped Si/SiGe het…
The Kondo Effect in the Unitary Limit
W. G. van der Wiel, S. De Franceschi, T. Fujisawa +3
We observe a strong Kondo effect in a semiconductor quantum dot when a small magnetic field is applied. The Coulomb blockade for electron tunneling is overcome completely by the Ko…
Kondo effects in a triangular triple quantum dot with lower symmetries
A. Oguri, S. Amaha, Y. Nishikawa +4
The triangular triple quantum dot is an interesting system which can demonstrate various types of the Kondo effects, such as the one due to the local spin S=1 moment caused by the…
Dissociation of vertical semiconductor diatomic artificial molecules
M. Pi, A. Emperador, M. Barranco +4
We investigate the dissociation of few-electron circular vertical semiconductor double quantum dot artificial molecules at 0 T as a function of interdot distance. Slight mismatch i…
Excitation Spectra of Circular Few-Electron Quantum Dots
L. P. Kouwenhoven, T. H. Oosterkamp, M. W. S. Danoesastro +4
We study ground states and excited states in semiconductor quantum dots containing 1 to 12 electrons. For the first time, it is possible to identify the quantum numbers of the stat…
Coherent beam splitting of flying electrons driven by a surface acoustic wave
R. Ito, S. Takada, A. Ludwig +3
We develop a coherent beam splitter for single electrons driven through two tunnel-coupled quantum wires by surface acoustic waves (SAWs). The output current through each wire osci…
Large nuclear Overhauser fields detected in vertically-coupled double quantum dots
J. Baugh, Y. Kitamura, K. Ono +1
We report the electrical induction and detection of dynamic nuclear polarization in the spin-blockade regime of double GaAs vertical quantum dots. The largest Overhauser field obse…
A fault-tolerant addressable spin qubit in a natural silicon quantum dot
K. Takeda, J. Kamioka, T. Otsuka +8
Fault-tolerant quantum operation is a key requirement for the development of quantum computing. This has been realized in various solid-state systems including isotopically purifie…
Excitation spectroscopy of few-electron states in artificial diatomic molecules
T. Hatano, Y. Tokura, S. Amaha +3
We study the excitation spectroscopy of few-electron, parallel coupled double quantum dots (QDs). By applying a finite source drain voltage to a double QD (DQD), the first excited…
Few-Electron Quantum Dot Circuit with Integrated Charge Read-Out
J. M. Elzerman, R. Hanson, J. S. Greidanus +5
We report on the realization of a few-electron double quantum dot defined in a two-dimensional electron gas by means of surface gates on top of a GaAs/AlGaAs heterostructure. Two q…
Fast Electrical Control of Single Electron Spins in Quantum Dots with Vanishing Influence from Nuclear Spins
J. Yoneda, T. Otsuka, T. Nakajima +7
We demonstrate fast universal electrical spin manipulation with inhomogeneous magnetic fields. With fast Rabi frequency up to 127 MHz, we leave the conventional regime of strong nu…
Proposal for a magnetic field induced graphene dot
P. A. Maksym, M. Roy, M. F. Craciun +3
Quantum dots induced by a strong magnetic field applied to a single layer of graphene in the perpendicular direction are investigated. The dot is defined by a model potential which…
Probabilistic teleportation of a quantum dot spin qubit
Y. Kojima, T. Nakajima, A. Noiri +8
Electron spin s in semiconductor quantum dot s have been intensively studied for implementing quantum computation and high fidelity single and two qubit operation s have recently b…
Spontaneous Emission Spectrum in Double Quantum Dot Devices
T. Fujisawa, T. H. Oosterkamp, W. G. van der Wiel +4
A double quantum dot device is a tunable two-level system for electronic energy states. A dc electron current directly measures the rates for elastic and inelastic transitions betw…