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D. Dragoman

Publications and source records attributed to D. Dragoman.

7 recordsLinked to original sources
arXiv2018

Ballistic 3-port interferometric logic gates in the quantum Hall regime

We show that a 3-port interferometer, defined by quantum point contacts in a two-dimensional electron gas, and working in the quantum Hall regime, can implement different logic gates at each port depending on the energy of charge carriers and the operating conditions. In all cases the input logic states are encoded in the potentials applied on the quantum point contacts, while the output logic states are encoded in the values of the overall transmission coefficients at each port. In addition, the output of such compact configurations can be reprogrammed by combining two 3-port interferometers.

cond-mat.mes-hall↗
arXiv2012

Graphene-like metallic-on-silicon field effect transistor

In this manuscript, we present a field effect transistor with a channel consisting of a two-dimensional electron gas located at the interface between an ultrathin metallic film of Ni and a p-type Si(111) substrate. We have demonstrated that the two-dimensional electron gas channel is modulated by the gate voltage. The dependence of the drain current on the drain voltage has no saturation region, similar to a field effect transistor based on graphene. However, the transport in this transistor is not ambipolar, as in graphene, but unipolar.

cond-mat.mes-hall↗
arXiv2010

Polarization Optics Analogy of Quantum Wavefunctions in Graphene

Detailed similarities between polarization states of light and ballistic charge carriers in graphene are derived. Based on these, the optical equivalent of quantum wavefunctions, Dirac equation, and the effect of an electrostatic potential are found, and the quantum analog of the refractive index of light and of the optical composition law of reflection coefficients are obtained. The differences between the behavior of quantum wavefunctions in graphene and electromagnetic fields, due to the chiral symmetry of ballistic charge carriers that cannot be mimicked in classical polarization optics, are also evidenced.

cond-mat.mes-hall↗
arXiv2009

Current Oscillations and Negative Resistances in Crossed Carbon Nanotubes Suspended Over a Dielectric Trench

An oscillatory dependence of the drain current on the drain voltage is found in a nanostructure consisting of two crossing semiconductor carbon nanotubes that are suspended over a dielectric trench, which is backed by a doped silicon substrate that acts as a gate. Alternating positive and negative differential resistance regions are generated as a function of the drain source values and can be slightly shifted by the gate voltage. Moreover, the negative differential resistance is retrieved in a large bandwidth, of up to 100 MHz, when the structure is excited with ac signals.

cond-mat.mes-hall↗
arXiv2009

Writing Electronic Devices on Paper with Carbon Nanotube Ink

The normal paper used in any printer is among the cheapest flexible organic materials that exist. We demonstrate that we can print on paper high-frequency circuits tunable with an applied dc voltage. This is possible with the help of an ink containing functionalized carbon nanotubes and water. After the water is evaporated from the paper, the nanotubes remain steadily imprinted on paper, showing a semiconducting behaviour and tunable electrical properties.

cond-mat.mes-hall↗
arXiv2005

The Aharonov-Bohm Effect in the Momentum Space

The Schrodinger formalism of quantum mechanics is used to demonstrate the existence of the Aharonov-Bohm effect in momentum space and set-ups for experimentally demonstrating it are proposed for either free or ballistic electrons.

quant-ph↗