arXiv subjects

I. V. Bondarev

Publications and source records attributed to I. V. Bondarev.

At least 19 recordsLinked to original sources

arXiv2021

Charged bosons made of fermions in a solid state system without Cooper pairing

We report experimental evidence for charged boson states in a solid without Cooper pairing, based on attaching two free carriers to an exciton in a semiconducting system. Theoretical calculations show that this type of complex is stable in bilayer systems next to a parallel metal layer. Our experimental measurements on structures made using two different materials show a new spectral line at the predicted energy, if and only if all the required conditions for this complex are fulfilled, including a parallel metal layer that significantly screens the repulsive interaction between the like-charge carriers, and with the predicted dependence on the distance to the metal layer. This suggests a new path for pursuing room temperature superconductivity without Cooper pairing.

cond-mat.supr-con↗

arXiv2020

Controlled Exciton-Plasmon Coupling in a Mixture of Ultrathin Periodically Aligned Single-Wall Carbon Nanotube Arrays

We study theoretically the in-plane electromagnetic response and the exciton-plasmon interactions for an experimentally feasible carbon nanotube (CN) film systems composed of parallel aligned periodic semiconducting CN arrays embedded in an ultrathin finite-thickness dielectric. For homogeneous single-CN films, the intertube coupling and thermal broadening bring the exciton and interband plasmon resonances closer together. They can even overlap due to the inhomogeneous broadening for films composed of array mixtures with a slight CN diameter distribution. In such systems the real part of the response function is negative for a broad range of energies (negative refraction band), and the CN film behaves as a hyperbolic metamaterial. We also show that for a properly fabricated two-component CN film, by varying the relative weights of the two constituent CN array components one can tune the optical absorption profile to make the film transmit or absorb light in the neighborhood of an exciton absorption resonance on-demand.

cond-mat.mes-hall↗

arXiv2016

Configuration space method for calculating binding energies of exciton complexes in quasi-1D/2D semiconductors

A configuration space method is developed for binding energy calculations of the lowest energy exciton complexes (trion, biexciton) in spatially confined quasi-1D semiconductor nanostructures such as nanowires and nanotubes. Quite generally, trions are shown to have greater binding energy in strongly confined structures with small reduced electron-hole masses. Biexcitons have greater binding energy in less confined structures with large reduced electron-hole masses. This results in a universal crossover behavior, whereby trions become less stable than biexcitons as the transverse size of the quasi-1D nanostructure increases. The method is also capable of evaluating binding energies for electron-hole complexes in quasi-2D semiconductors such as coupled quantum wells and bilayer van der Walls bound heterostructures with advanced optoelectronic properties.

cond-mat.mes-hall↗

arXiv2015

One-dimensional transport in hybrid metal-semiconductor nanotube systems

We develop an electron transport theory for the hybrid system of a semiconducting carbon nanotube that encapsulates a one-atom-thick metallic wire. The theory predicts Fano resonances in electron transport through the system, whereby the interaction of electrons on the wire with nanotube plasmon generated near-fields blocks some of the wire transmission channels to open up the new coherent plasmon-mediated channel in the nanotube forbidden gap outside the wire transmission band. Such a channel makes the entire hybrid system transparent in the energy domain where neither wire, nor nanotube is indivudually transparent. This effect can be used to manipulate by the electron charge transfer in hybrid nanodevices built on metal-semiconductor nanotube systems.

cond-mat.mes-hall↗

arXiv2014

Plasmon enhanced Raman scattering effect for an atom near a carbon nanotube

Quantum electrodynamics theory of the resonance Raman scattering is developed for an atom in a close proximity to a carbon nanotube. The theory predicts a dramatic enhancement of the Raman intensity in the strong atomic coupling regime to nanotube plasmon near-fields. This resonance scattering is a manifestation of the general electromagnetic surface enhanced Raman scattering effect, and can be used in designing efficient nanotube based optical sensing substrates for single atom detection, precision spontaneous emission control, and manipulation.

cond-mat.mes-hall↗

arXiv2014

Relative stability of excitonic complexes in quasi-one-dimensional semiconductors

A configuration space approach is developed to uncover generic stability peculiarities for the lowest energy neutral and charged exciton complexes (biexciton and trion) in quasi-one-dimensional semiconductors. Trions are shown to be more stable than biexcitons in strongly confined structures with small reduced electron-hole masses. Biexcitons are more stable in less confined structures with large reduced electron-hole masses. In semiconducting carbon nanotubes, in particular, the trion binding energy is shown to be greater than that of the biexciton by a factor ~1.4 decreasing with diameter, thus revealing the general physical principles that underlie recent experimental observations.

cond-mat.mes-hall↗

arXiv2013

Possibility for exciton Bose-Einstein condensation in carbon nanotubes

We demonstrate a possibility for exciton Bose-Einstein condensation in individual small-diameter (~1-2 nm) semiconducting carbon nanotubes. The effect occurs under the exciton-interband-plasmon coupling controlled by an external electrostatic field applied perpendicular to the nanotube axis. It requires fields ~1 V/nm and temperatures below 100 K that are experimentally accessible. The effect offers a testing ground for fundamentals of condensed matter physics in one dimension and opens up perspectives to develop tunable coherent polarized light source with carbon nanotubes.

cond-mat.mes-hall↗

arXiv2012

Temperature dependent graphene suspension due to thermal Casimir interaction

Thermal effects contributing to the Casimir interaction between objects are usually small at room temperature and they are difficult to separate from quantum mechanical contributions at higher temperatures. We propose that the thermal Casimir force effect can be observed for a graphene flake suspended in a fluid between substrates at the room temperature regime. The properly chosen materials for the substrates and fluid induce a Casimir repulsion. The balance with the other forces, such as gravity and buoyancy, results in a stable temperature dependent equilibrium separation. The suspended graphene is a promising system due to its potential for observing thermal Casimir effects at room temperature.

cond-mat.mes-hall↗

arXiv2012

Effects of Spatial Dispersion on the Casimir Force between Graphene Sheets

The Casimir force between graphene sheets is investigated with emphasis on the effect from spatial dispersion using a combination of factors, such as a nonzero chemical potential and an induced energy gap. We distinguish between two regimes for the interaction - T=0 $K$ and $T\neq 0$ $K$. It is found that the quantum mechanical interaction (T=0 $K$) retains its distance dependence regardless of the inclusion of dispersion. The spatial dispersion from the finite temperature Casimir force is found to contribute for the most part from $n=0$ Matsubara term. These effects become important as graphene is tailored to become a poor conductor by inducing a band gap.

cond-mat.mes-hall↗

arXiv2012

Single wall carbon nanotubes as coherent plasmon generators

The possibility of low-energy surface plasmon amplification by optically excited excitons in small-diameter single wall carbon nanotubes is theoretically demonstrated. The nonradiative exciton-plasmon energy transfer causes the buildup of the macroscopic population numbers of coherent localized surface plasmons associated with high-intensity coherent local fields formed at nanoscale throughout the nanotube surface. These strong local fields can be used in a variety of new optoelectronic applications of carbon nanotubes, including near-field nonlinear-optical probing and sensing, optical switching, enhanced electromagnetic absorption, and materials nanoscale modification.

cond-mat.mes-hall↗

arXiv2011

Asymptotic exchange coupling of quasi-1D excitons in carbon nanotubes

An analytical expression is obtained for the biexciton binding energy as a function of the inter-exciton distance and binding energy of constituent quasi-one-dimensional excitons in carbon nanotubes. This allows one to trace biexciton energy variation and relevant non-linear absorption under external conditions whereby the exciton binding energy varies. The non-linear absorption lineshapes calculated exhibit characteristic asymmetric (Rabi) splitting as the exciton energy is tuned to the nearest interband plasmon resonance. These results are useful for tunable optoelectronic device applications of optically excited semiconducting carbon nanotubes, including the strong excitation regime with optical non-linearities.

cond-mat.mes-hall↗

arXiv2010

Exciton-Plasmon Interactions in Individual Carbon Nanotubes

We use the macroscopic quantum electrodynamics approach suitable for absorbing and dispersing media to study the properties and role of collective surface excitations --- excitons and plasmons --- in single-wall and double-wall carbon nanotubes. We show that the interactions of excitonic states with surface electromagnetic modes in individual small-diameter (<~1 nm) single-walled carbon nanotubes can result in strong exciton-surface-plasmon coupling. Optical response of individual nanotubes exhibits Rabi splitting ~0.1 eV, both in the linear excitation regime and in the non-linear excitation regime with the photoinduced biexcitonic states formation, as the exciton energy is tuned to the nearest interband surface plasmon resonance of the nanotube. An electrostatic field applied perpendicular to the nanotube axis can be used to control the exciton-plasmon coupling. For double-wall carbon nanotubes, we show that at tube separations similar to their equilibrium distances interband surface plasmons have a profound effect on the inter-tube Casimir force. Strong overlapping plasmon resonances from both tubes warrant their stronger attraction. Nanotube chiralities possessing such collective excitation features will result in forming the most favorable inner-outer tube combination in double-wall carbon nanotubes. These results pave the way for the development of new generation of tunable optoelectronic and nano-electromechanical device applications with carbon nanotubes.

cond-mat.mes-hall↗

arXiv2009

Surface electromagnetic phenomena in pristine and atomically doped carbon nanotubes

The article reviews recent progress in the theoretical understanding of near-field surface electromagnetic phenomena in pristine and atomically doped carbon nanotubes. The phenomena involving strong coupling effects are outlined. They are the optical absorption by single-walled carbon nanotubes doped with single atoms or ions in the frequency range close to the atomic transition frequency, the entanglement of the pair of atomic qubits strongly coupled to a common high-finesse surface photonic mode of the nanotube, and the optical response of the strongly coupled surface exciton-plasmon excitations in pristine semiconducting carbon nanotubes. The phenomena reviewed have a great potential to be exploited for the future development of the nanotube based tunable optoelectronic device applications in areas such as nanophotonics, nanoplasmonics, cavity quantum electrodynamics, and quantum information science.

cond-mat.mes-hall↗

arXiv2009

Strong exciton-plasmon coupling in semiconducting carbon nanotubes

We study theoretically the interactions of excitonic states with surface electromagnetic modes of small-diameter (~1 nm) semiconducting single-walled carbon nanotubes. We show that these interactions can result in strong exciton-surface-plasmon coupling. The exciton absorption line shape exhibits Rabi splitting ~0.1 eV as the exciton energy is tuned to the nearest interband surface plasmon resonance of the nanotube. We also show that the quantum confined Stark effect may be used as a tool to control the exciton binding energy and the nanotube band gap in carbon nanotubes in order, e.g., to bring the exciton total energy in resonance with the nearest interband plasmon mode. The exciton-plasmon Rabi splitting we predict here for an individual carbon nanotube is close in its magnitude to that previously reported for hybrid plasmonic nanostructures artificially fabricated of organic semiconductors on metallic films. We expect this effect to open up paths to new tunable optoelectronic device applications of semiconducting carbon nanotubes.

cond-mat.mes-hall↗

arXiv2007

Exciton-Plasmon Coupling in Carbon Nanotubes

cond-mat.mes-hall↗

arXiv2006

Atomic States Entanglement in Carbon Nanotubes

The entanglement of two atoms (ions) doped into a carbon nanotube has been investigated theoretically. Based on the photon Green function formalism for quantizing electromagnetic field in the presence of carbon nanotubes, small-diameter metallic nanotubes are shown to result in a high degree of the two-qubit atomic entanglement for long times due to the strong atom-field coupling.

cond-mat.mes-hall↗

arXiv2006

Optical absorbtion by atomically doped carbon nanotubes

We analyze optical absorption by atomically doped carbon nanotubes with a special focus on the frequency range close to the atomic transition frequency. We derive the optical absorbtion line-shape function and, having analyzed particular achiral nanotubes of different diameters, predict the effect of absorbtion line splitting due to strong atom-vacuum-field coupling in small-diameter nanotubes. We expect this effect to stimulate relevant experimental efforts and thus to open a path to new device applications of atomically doped carbon nanotubes in modern nanotechnologies.

cond-mat.mes-hall↗

arXiv2004

Nonpolar optical scattering of positronium in magnesium fluoride

We report the results of the analysis of the temperature broadening of the momentum distribution of delocalized Positronium (Ps) in Magnesium Fluoride in terms of optical deformation-potential scattering model (long-wavelength optical phonons). The Ps optical deformation-potential coupling constant $D_{o}$ in MgF$_{2}$ has been determined to be $(1.8\pm0.3)\times10^{9}$ eV/cm. We also show that the Ps momentum distribution is sensitive to second-order phase transitions in those crystals where optical deformation-potential scattering is allowed in one and forbidden in another crystalline phase.

cond-mat.mtrl-sci↗