The Kondo effect and superconductivity are both prime examples of many-body phenomena. Here we report transport measurements on a carbon nanotube quantum dot coupled to superconducting leads that show delicate interplay between effects. We demonstrate the does not destroy correlations when temperature, which varies for different single-electron states, exceeds gap energy.

We explore the electric-field effect of carbon nanotubes (NTs) in electrolytes. Due to large gate capacitance, Fermi energy shifts order +/- 1 V can be induced, enabling tune NTs from p n-type. Consequently, resistance changes are measured. At zero voltage hole doped air with E_F ? 0.3-0.5 eV, corresponding a doping level 10^{13} cm^{-2}. Hole-doping increases electrolyte. This (oxidation) is most likely caused by adsorption oxygen and cations

We have measured the differential conductance of individual multiwall carbon nanotubes. Coulomb blockade and energy level quantization are observed. The electron levels nearly fourfold degenerate (including spin) their evolution in magnetic field (Zeeman splitting) agrees with a g factor 2. In zero sequential filling states evolves spin S according to = 0-->1/2-->0.... A Kondo enhancement is observed when number electrons on tube odd.

We report resonant multiple Andreev reflections in a multiwall carbon nanotube quantum dot coupled to superconducting leads. The position and magnitude of the subharmonic gap structure is found depend strongly on level positions single-electron states which are adjusted with gate electrode. discuss theoretical model device compare calculated differential conductance experimental data.

We have studied tunneling of electrons into multiwall carbon nanotubes (NTs) in NT-gold and NT-NT junctions, the latter created by atomic force microscope manipulation. The conductance goes to zero as energy (temperature bias) is reduced, functional form consistent with a power law. exponents depend upon sample geometry. relationship between these results theories for ballistic disordered metals discussed.

We demonstrate charge pumping in semiconducting carbon nanotubes by a traveling potential wave. From the observation of nanotube insulating state we deduce that transport occurs packets being carried along By tuning side gate, either electron or hole can be realized. Prospects for realization based single-electron pumps are discussed.

Scanning tunneling microscope spectroscopy is used to study in detail the electronic band structure of carbon nanotubes as well locally investigate features interesting topological sites such nanotube ends and bends. From a large number measurements density-of-states (DOS) can be classified, according predictions, either semiconducting (two-third total tubes) or metallic (one-third). The energy subband separations DOS compare reasonably theoretical calculations. At ends, spatially resolved...

We investigate radio-frequency (rf) reflectometry in a tunable carbon nanotube double quantum dot coupled to resonant circuit. By measuring the in-phase and quadrature components of reflected rf signal, we are able determine complex admittance as function energies single-electron states. The measurements found be good agreement with theoretical model device incoherent limit. In addition being fundamental interest, our results present an important step forward towards noninvasive charge spin...

We report a simple and high yield method for fabricating multiple nanogaps simultaneously by an electroless gold plating technique using solution which consists of common medical liquid iodine tincture L(+)-ascorbic acid (vitamin C). The distance between the electrodes (33nm in average) on SiO2∕Si substrate was decreased selective deposition onto surface electrodes. By plating, we fabricated below 5nm width with 41% process yield. also demonstrated Coulomb blockade effect...

We investigate charge pumping in carbon nanotube quantum dots driven by the electric field of a surface acoustic wave. find that, at small driving amplitudes, pumped current reverses polarity as conductance is tuned through Coulomb blockade peak using gate electrode. study behavior function wave amplitude, frequency, and direction develop model which our results can be understood resulting from adiabatic redistribution between leads on nanotube.

We report Pauli spin blockade in a carbon nanotube double quantum dot defined by tunnel barriers at the contacts and structural defect nanotube. observe pronounced current suppression for negative source-drain bias voltages, which is investigated both symmetric asymmetric coupling of dots to leads. The measured differential conductance agrees well with theoretical model system spin-blockade regime, allows us estimate occupation probabilities relevant singlet triplet states. This work shows...

We make use of spin selection rules to investigate the electron system a carbon nanotube double quantum dot. Measurements transport as function magnetic field and energy detuning between dots reveal an intricate pattern state evolution. demonstrate that complete set measurements can be understood by taking into account interplay spin-orbit interaction single impurity coupled The detection tunability this coupling are important for manipulation in nanotubes.

We investigate a tunable two-impurity Kondo system in strongly correlated carbon nanotube double quantum dot, accessing the full range of charge regimes. In regime where both dots contain an unpaired electron, approaches model. At zero magnetic field interdot coupling disrupts physics and local singlet state arises, but we are able to tune crossover screened phase by application field. All results show good agreement with numerical renormalization group study device.

We report low-temperature transport spectroscopy of a graphene quantum dot fabricated by atomic force microscope nanolithography. The excellent spatial resolution the allows us to reliably fabricate dots with short constrictions less than 15 nm in length. Transport measurements demonstrate that device is dominated single over wide gate range. electron spin system investigated applying an in-plane magnetic field. results are consistent Landé g-factor ∼2 but no regular filling sequence...

We report on electrical resistance measurements of single multiwalled carbon nanotubes (MWNTs) in different environments (ambient air, H2, O2 and the electrolytes LiClO4, KCl, KMnO4 H3PO3). The gate dependence is studied using back-gating, electrochemical gating gates evaporated directly onto (NTs). MWNTs at room temperature are p-doped. Upon changing environment a change doping state inferred from linear resistance. effect contacts negligible our experiments. p-doping proposed to originate...

We investigate atomic force microscope nanolithography of single and bilayer graphene. In situ tip current measurements show that cutting graphene is not driven. Using a combination transport scanning electron microscopy we while indentations accompanied by appear in the lattice for range voltages, real cuts are characterized strong reduction above threshold voltage. The reliability flexibility technique demonstrated fabrication, measurement, modification, remeasurement nanodevices with...

In the context of quantum information processing, carbon nanotubes allow accurate control electronic charge, spin, and valley degrees freedom, in an atomically perfect isotopically pure material. Using rf reflectometry to measure capacitance, authors study a nanotube charge qubit with encoded electron's position. By manipulating states microwaves, they are able directly coherence qubit. Their technique allows operation at sweet spot where device is first-order insensitive noise, for much...

Au nanoparticle single-electron transistors with metal-bridged top-gates and nanogap electrodes were fabricated using two consecutive electron beam lithography electroless plating steps. The top-gate suspended above plated electrodes. nanoparticles (5.2 nm in diameter) chemisorbed between the after fabrication. Clear Coulomb diamonds observed at 9 K. gate capacitance Cg of was 99 zF, which is 10 times larger than that a similar device only side-gate

We demonstrate single-electron pumping in a gate-defined carbon nanotube double quantum dot. By periodic modulation of the potentials two dots, we move system around charge triple points and transport exactly one electron or hole per cycle. investigate as function frequency amplitude observe good current quantization up to frequencies 18 MHz where rectification effects cause mechanism break down.

Abstract Recent years have seen great progress in our understanding of the electronic properties nanomaterials which at least one dimension measures less than 100 nm. However, contacting true nanometer scale materials such as individual molecules or nanoparticles remains a challenge even state-of-the-art nanofabrication techniques electron-beam lithography resolution few nm best. Here we present fabrication and measurement technique that allows high sensitivity bandwidth readout discrete...

We investigate charge pumping in semiconducting carbon nanotubes by a travelling potential wave on the surface of piezoelectric quartz substrate. estimate magnitude and profile as its passes show how this results packets. By tuning side gate, transport either electron or hole packets can be realized, reversing direction current. furthermore discuss specific device which current shows distinct plateau function gate voltage, amplitude frequency. Interestingly, appears at value ef, where e is f...

We present electrical transport and Raman measurements on individual single-wall carbon nanotubes filled with the paramagnetic metallofullerene Sc@C82. find nearly all devices to be metallic p-type conductors, which we tentatively attribute bandstructure modification of by encapsulated Sc@C82 molecules. At low temperatures peapod behave as quantum dots is shown coherent over distances at least ∼100 nm. Kondo features are observed lowest measurement 50 mK. Our results fundamental interest...

We investigate mesoscopic Josephson-junction arrays created by patterning superconducting disks on monolayer graphene, concentrating the high-$T/{T}_{c}$ regime of these devices and phenomena which contribute to glass state in diffusive arrays. observe features magnetoconductance at rational fractions flux quanta per array unit cell, we attribute formation flux-quantized vortices. The applied fields occur are well described Ginzburg-Landau simulations that take into account number cells...

Abstract Radiofrequency reflectometry can provide fast and sensitive electrical read-out of charge spin qubits in quantum dot devices coupled to resonant circuits. In situ frequency tuning impedance matching the resonator circuit using voltage-tunable capacitors (varactors) is needed optimize sensitivity, but performance conventional semiconductor- ferroelectric-based varactors degrades substantially millikelvin temperature range relevant for solid-state devices. Here we show that strontium...