Presents a technique to directly excite Luttinger liquid collective modes in carbon nanotubes at gigahertz frequencies. By modeling the nanotube as a nano-transmission line with distributed kinetic and magnetic inductance as well as distributed quantum and electrostatic capacitance, we calculate the complex frequency-dependent impedance for a variety of measurement geometries. Exciting voltage waves on the nano-transmission line is equivalent to directly exciting the yet-to-be observed one-dimensional plasmons, the low energy excitation of a Luttinger liquid. Our technique has already been applied to two-dimensional plasmons and should work well for one-dimensional plasmons. Tubes of length 100 microns must be grown for gigahertz resonance frequencies. Ohmic contact is not necessary with our technique; capacitive contacts can work. Our modeling has applications in potentially terahertz nanotube transistors and RF nanospintronics.

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Luttinger liquid theory as a model of the gigahertz electrical properties of carbon nanotubes

We present quantitative predictions of the performance of nanotubes and nanowires as antennas, including the radiation resistance, the input reactance and resistance, and antenna efficiency, as a function of frequency and nanotube length. Particular attention is paid to the quantum capacitance and kinetic inductance. We develop models for both far-field antenna patterns as well as near-field antenna-to-antenna coupling. In so doing, we also develop a circuit model for a transmission line made of two parallel nanotubes, which has applications for nanointerconnect technology. Finally, we derive an analog of Hallen's integral equation appropriate for single-walled carbon nanotube antennas

Quantitative theory of nanowire and nanotube antenna performance

Throughout physics, stable composite objects are usually formed by way of attractive forces, which allow the constituents to lower their energy by binding together. Repulsive forces separate particles in free space. However, in a structured environment such as a periodic potential and in the absence of dissipation, stable composite objects can exist even for repulsive interactions. Here we report the observation of such an exotic bound state, which comprises a pair of ultracold rubidium atoms in an optical lattice. Consistent with our theoretical analysis, these repulsively bound pairs exhibit long lifetimes, even under conditions when they collide with one another. Signatures of the pairs are also recognized in the characteristic momentum distribution and through spectroscopic measurements. There is no analogue in traditional condensed matter systems of such repulsively bound pairs, owing to the presence of strong decay channels. Our results exemplify the strong correspondence between the optical lattice physics of ultracold bosonic atoms and the Bose–Hubbard model—a link that is vital for future applications of these systems to the study of strongly correlated condensed matter and to quantum information.

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Repulsively bound atom pairs in an optical lattice.

Experimentalists have observed the predicted half-integer quantum Hall effect using the topological insulator BiSbTeSe2, which exhibits topological surface states at room temperature, with each surface contributing a half quantum of Hall conductance.

/pdf/observation-of-topological-surface-state-quantum-hall-effect-2w1c0tnh9i.pdf

Observation of topological surface state quantum Hall effect in an intrinsic three-dimensional topological insulator

https://iopscience.iop.org/article/10.1088/2053-1583/aaf836/pdf

A roadmap for electronic grade 2D materials

Electron transport in a quantum wire with leads is investigated with actual Coulomb interaction taken into account The latter includes both the direct interaction of electrons with each other and their interaction via the image charges induced in the leads Exact analytical solution of the problem is found with the use of the bosonization technique for one-dimensional electrons and the three-dimensional Poisson equation for the electric field The Coulomb interaction is shown to change significantly the electron density distribution along the wire as compared with the Luttinger-liquid model with short-range interactions In dc and low-frequency regimes, the Coulomb interaction causes the charge density to increase strongly in the vicinity of the contacts with the leads The quantum wire impedance shows an oscillating behavior versus the frequency caused by the resonances of the charge waves The Coulomb interaction produces a frequency-dependent renormalization of the charge-wave velocity

https://arxiv.org/pdf/cond-mat/9803383.pdf

Electron transport in a quantum wire with realistic Coulomb interaction

Growth of Bi2Te3 films and other phases of Bi-Te system by MOVPE

Metalorganic vapor phase epitaxy growth of ternary tetradymite Bi2Te3−xSex compounds

It is shown that in one-dimensional mesoscopic structures the electron-electron interaction leads to qualitatively new effects in the dynamic conductivity which are best manifested in the frequency dependence of the impedance. Interelectronic repulsion increases the resistance and narrows the resonance dips of the resistance at transit frequencies. Interelectronic attraction gives rise to resonance peaks of the resistance against a high-conductivity background. These effects are due to the reflection of bosonic excitations of a Luttinger liquid from the boundaries of a quantum channel with current-lead electrodes and to resonances of these excitations over the length of the channel.

Dynamic conductivity of interacting electrons in open mesoscopic structures

Optimization of growth conditions allows us to grow mirror-like hexagonal ZnCdS layers and CdSSe/ZnCdS quantum well (QW) structures on CdS(0001) and ZnCdS(0001) substrates by MOVPE. ZnCdS epilayers with high cathodoluminescence (CL) intensity at room temperature (RT) have also been obtained. An intense QW emission line has been observed in CdS/ZnCdS QW structures. With increasing excitation intensity the line shifted to shorter wavelength, which is a manifestation of an internal piezoelectric effect. An additional short-wavelength line appears in low-temperature CL spectra of CdSSe/ZnCdS QW structures due to localization of charge carriers by nonuniformity of alloy composition or QW thickness.

B.S. Shchamkhalova

Papers

Electron transport in a quantum wire with realistic Coulomb interaction

Growth of Bi2Te3 films and other phases of Bi-Te system by MOVPE

Metalorganic vapor phase epitaxy growth of ternary tetradymite Bi2Te3−xSex compounds

Dynamic conductivity of interacting electrons in open mesoscopic structures

Hexagonal ZnCdS epilayers and CdSSe/ZnCdS QW structures on CdS(0001) and ZnCdS(0001) substrates grown by MOVPE