Zoran Ivic - Academia.edu (original) (raw)

Papers by Zoran Ivic

Chinese Physics B, 2023

We investigate the properties of the excess charge (electron, hole) introduced into a two-strand ... more We investigate the properties of the excess charge (electron, hole) introduced into a two-strand biomolecule. We consider the possibility that the stable soliton excitation can be formed due to interaction of excess charge with the phonon subsystem. The influence of overlap of the molecular orbitals between adjacent structure elements of the macromolecular chain on the soliton properties is discussed. Special attention is paid to the influence of the overlapping of the molecular orbitals between structure elements placed on the different chains. Using the literature values of the basic energy parameters of the two-chain biomolecular structures, possible types of soliton solutions are discussed.

Physical review, Jun 28, 2022

We study quantum features of electromagnetic radiation propagating in the one-dimensional superco... more We study quantum features of electromagnetic radiation propagating in the one-dimensional superconducting quantum metamaterial comprised of an infinite chain of charge qubits placed within two-stripe massive superconducting resonators. The Quantum-mechanical model is derived assuming weak fields and that, at low temperatures, each qubit is either unoccupied (N = 0) or occupied by a single Cooper pair (N = 1). We demonstrate the emergence of two bands of single-photon-qubitbound states with the energies lying outside the photon continuum: highly above and slightly below it. The higher energy band slowly varies with the qubit-photon center of mass quasi-momentum. It becomes practically flat provided that electromagnetic energy is far below the Josephson one, while the latter is small compared to the charging one. The dispersion of the lower band is practically identical to that of free photons. The emergence of bound states may cause radiation trapping indicating its application for the control of photon transport in superconducting qubit-based artificial media.

Physics of Particles and Nuclei, Jul 1, 2020

Chaos Solitons & Fractals, Feb 1, 2021

Abstract We focus on self-induced transparency (SIT) in the propagation of a pulse in a dispersiv... more Abstract We focus on self-induced transparency (SIT) in the propagation of a pulse in a dispersive medium. The latter can be an ordinary optical medium or, more interestingly, a quantum metamaterial. In both cases we consider a sequence of two level atoms each with a characteristic resonant frequency ω 0 . The propagation features are controlled by the ratio of the pulse frequency ω over the dipole resonant frequency, i.e. on the quantity X = ω / ω 0 . We consider analytically two pulse limits, viz. the sharp line limit as well as the inhomogeneouly broadened case. In the first case we find that for pulse frequencies larger than ω 0 , i.e. for X > 1 the SIT pulse may be fully stopped through absorption by the medium provided its time width exceeds a certain critical value. In the latter case of inhomogeneously broadened medium we find no such frequency restrictions provided the pulse is wide enough. As a result an SIT pulse can be arbitrarily arrested by the absorbing medium. This dispersion-induced pulse stopping is a manifestation of the quantum nature of the medium and of possible use in metamaterial applications.

Наносистемы: физика, химия, математика, Apr 27, 2019

We investigate the problem of generating quantum correlations between different sites of a macrom... more We investigate the problem of generating quantum correlations between different sites of a macromolecular chain by vibronic excitation depending on the temperature. The influence of temperature on the model dynamics is taken into account by employing the partial-dressing method based on the modified LangFirsov unitary transformation under the assumption that the chain collective oscillations are in the thermal equilibrium state. To describe quantum correlations between the chain sites in the case of the initial single-vibronic excitation, we use two-time correlation functions of the second order and the logarithmic negativity as the degree of entanglement. We find that at certain temperatures for various model parameters time-stable entanglement can occur in the chain.

Journal of physics, Feb 1, 2018

The properties of the intramolecular vibrational excitation (vibron) in a quasi 1D macromolecular... more The properties of the intramolecular vibrational excitation (vibron) in a quasi 1D macromolecular structure are studied. It is supposed that due to the vibron interaction with optical phonon modes, a vibron might form partially dressed small polaron states. The properties of these states are investigated in dependence on the basic system parameters and temperature of a thermal bath. We also investigate the process of damping of the polaron amplitude as a function of temperature and vibron-phonon coupling strength. Two different regimes of the polaron damping are found and discussed.

Physica D: Nonlinear Phenomena, Apr 1, 2006

Discrete breathers or intrinsic localized modes are nonlinear localized states that appear in sev... more Discrete breathers or intrinsic localized modes are nonlinear localized states that appear in several classical extended systems, such as for instance the Fermi-Paste-Ulam (FPU) model. In order to probe the quantum states that correspond to discrete breathers, we quantize the β-FPU model using boson quantization rules, retain only number conserving terms, and analyze the two-quanta sector of the model. For both attractive and repulsive nonlinearity, we find the occurrence of biphonons in two forms, on-site and nearest-neighbor site, and analyze their properties. We comment on the use of this model as a minimal model for extended molecular and biomolecular systems.

Scientific Reports, Jul 12, 2016

Quantum bits (qubits) are at the heart of quantum information processing schemes. Currently, soli... more Quantum bits (qubits) are at the heart of quantum information processing schemes. Currently, solid-state qubits, and in particular the superconducting ones, seem to satisfy the requirements for being the building blocks of viable quantum computers, since they exhibit relatively long coherence times, extremely low dissipation, and scalability. The possibility of achieving quantum coherence in macroscopic circuits comprising Josephson junctions, envisioned by Legett in the 1980's, was demonstrated for the first time in a charge qubit; since then, the exploitation of macroscopic quantum effects in low-capacitance Josephson junction circuits allowed for the realization of several kinds of superconducting qubits. Furthermore, coupling between qubits has been successfully achieved that was followed by the construction of multiple-qubit logic gates and the implementation of several algorithms. Here it is demonstrated that induced qubit lattice coherence as well as two remarkable quantum coherent optical phenomena, i.e., self-induced transparency and Dicke-type superradiance, may occur during light-pulse propagation in quantum metamaterials comprising superconducting charge qubits. The generated qubit lattice pulse forms a compound "quantum breather" that propagates in synchrony with the electromagnetic pulse. The experimental confirmation of such effects in superconducting quantum metamaterials may open a new pathway to potentially powerful quantum computing. Quantum simulation, that holds promises of solving particular problems exponentially faster than any classical computer, is a rapidly expanding field of research 1-3. The information in quantum computers is stored in quantum bits or qubits, which have found several physical realizations; quantum simulators have been nowadays realized and/or proposed that employ trapped ions 4 , ultracold quantum gases 5 , photonic systems 6 , quantum dots 7 , and superconducting circuits 1,8,9. Solid state devices, and in particular those relying on the Josephson effect 10 , are gaining ground as preferable elementary units (qubits) of quantum simulators since they exhibit relatively long coherence times and extremely low dissipation 11. Several variants of Josephson qubits that utilize either charge or flux or phase degrees of freedom have been proposed for implementing a working quantum computer; the recently anounced, commercially available quantum computer with more than 1000 superconducting qubit CPU, known as D-Wave 2X TM (the upgrade of D-Wave Two TM with 512 qubits CPU), is clearly a major advancement in this direction. A single superconducting charge qubit (SCQ) 12 at milikelvin temperatures behaves effectively as an artificial two-level "atom" in which two states, the ground and the first excited ones, are coherently superposed by Josephson coupling. When coupled to an electromagnetic (EM) vector potential, a single SCQ does behave, with respect to the scattering of EM waves, as an atom in space. Indeed, a "single-atom laser" has been realized with an SCQ coupled to a transmission line resonator ("cavity") 13. Thus, it would be anticipated that a periodic structure of SCQs demonstrates the properties of a transparent material, at least in a particular frequency band. The idea of building materials comprising artificial "atoms" with engineered properties, i.e., metamaterials, and in particular superconducting ones 14 , is currently under active development. Superconducting quantum metamaterials (SCQMMs) comprising a large number of qubits could hopefully maintain quantum coherence for times

Physica B-condensed Matter, Jun 1, 2016

We studied the properties of the intramolecular vibrational excitation (vibron) at finite tempera... more We studied the properties of the intramolecular vibrational excitation (vibron) at finite temperature in a system which consists of two parallel macromolecular chains. It was assumed that vibron interacts exclusively with dispersionless optical phonons and the whole system is considered to be in thermal equilibrium. Particular attention has been paid to the examination of the impact of the temperature and strength of the interchain coupling on the small polaron crossover. For that purpose we employed partial dressing method which enables the study of the degree of the phonon dressing of the vibron excitations in a wide area of system parameter space. We found that in the non-adiabatic regime the degree of dressing as a function of coupling constant continuously increases reflecting the smooth transition of the slightly dressed, practically free vibron, to a heavily dressed one: small polaron. As "adiabaticity" rises this transition becomes increasingly steeper, and finally, in the adiabatic limit, a discontinuous "jump" of the degree of dressing is observed. The interchain coupling manifests itself through the increase of the effective adiabatic parameter of the system.

arXiv (Cornell University), Sep 3, 2019

We study the effects of dispersion in carrier waves on the properties of soliton self-induced tra... more We study the effects of dispersion in carrier waves on the properties of soliton self-induced transparency (SIT) in two level media. We found substantial impact of dispersion effects on typical SIT soliton features. For example, the degree of SIT pulse velocity slowing down (acceleration) is determined by the ratio of the incoming pulse frequency over atomic transition frequency-x = ω/ω0. Specifically, an immediate pulse stopping is predicted for absorbing media when pulse duration time exceeds some critical value. In the sharp line limit stopping may emerge only for frequency ratio above unity, while for the inhomogeneously broadened systems it appears irrespective of the value of x. Analysis performed on the basis of Mcall& Hahn Area theorem implies that pulse stopping is achieved when Ber's absorption coefficient approaches infinity, that is, pulse energy is fully absorbed in the medium. In the case of amplifying media super-luminal motion is predicted as in the case of resonance. However, there is a lowest value in the frequency ratio below which the pulse velocity tends to the sub-luminal region. These new features of the SIT phenomenon open novel ways on how it may be exploited for the control of electromagnetic wave radiation in two-level media. This may be achieved by varying frequency ratio.

arXiv (Cornell University), Apr 10, 2012

We present a study of the physical properties of the vibrational excitation in the one-dimensiona... more We present a study of the physical properties of the vibrational excitation in the one-dimensional macromolecular chains, caused by the interaction with acoustical phonon modes. The influence of the temperature and the basic system parameters on the vibron dressing has been analyzed by employing the simple mean--field approach based on the variational extension of the Lang--Firsov unitary transformation. Applied approach predicts a region in system parameter space where it is possible of the coexistence of the partially dressed (light and mobile) and fully dressed (immobile) vibron states. We found that the boundary of this region depends on system temperature and type of bond among structure elements in macromolecular chain.

Chaos Solitons & Fractals, Dec 1, 2017

We show that the self-induced transparency of optical phonons may appear in a systems consisting ... more We show that the self-induced transparency of optical phonons may appear in a systems consisting of a two level atoms interacting with elastic waves. The presence of the gap in phonon spectrum substantially enhances the pulse delay in respect to the acoustic self induced transparency phenomena. One of the main characteristics of the predicted phenomenon is the appearance of the critical velocity of the selfinduced transparency pulse which, in the absorbing media, represents the upper limit which pulse may reach. Its magnitude is determined by the ratio of the phonon gap and the energy difference of the two level system. This feature opens a new way for the control of the speed of elastic waves. We believe that, in the view of the emerging new quantum technologies relying on creation and trapping of the coherent phonons interacting with artificial atoms, some practical implementations of interest for the storage and manipulation of quantum information may be realised on the basis of our work.

We study quantum features of electromagnetic radiation propagating in a waveguide built of an inf... more We study quantum features of electromagnetic radiation propagating in a waveguide built of an infinite array of super-conducting qubits (SCQ) placed within a resonator comprised of two massive superconductors. Such engineered media, so-called superconducting quantum metamaterials (SCQMM), have a great potential for quantum information processing and communications and devise a comprehensive study of the nature of the “light”-matter interaction. We predict the emergence of novel in-terference effects with possible practical applications. For exam-ple, photons may exhibit a nontrivial dispersion relation such as band edges and band gaps. In this way, QMMs may be viewed as photonic crystals. This, in turn, enriches their potential for practi-cal applications and provides novel means for devising compre-hensive studies of both practical and fundamental aspects of the interaction of artificial atoms and the EM field.

Springer eBooks, 1990

The temperature-dependent behaviour of localized excitons in a linear molecular α-helix chain mod... more The temperature-dependent behaviour of localized excitons in a linear molecular α-helix chain model is investigated. After transforming Davydov’s original Hamiltonian for the α-helix soliton to include Bogoliubov’s variational theorem, the temperature dependence of the “threshold” of solitonic solution is obtained. We also investigated the damping of a soliton under the influence of the thermal bath. The approach is based on the consequent microscopic treatment in context of quantum Langevin equation.

Physica Status Solidi B-basic Solid State Physics, Oct 1, 1986

A perturbation theory is developed for the kinetic coefficient of the electron transfer from dono... more A perturbation theory is developed for the kinetic coefficient of the electron transfer from donor molecules (Dm) to acceptor molecules (Al) along a one-dimensional molecular chain to which Dm and Al are statistically joined. The influence of donors and acceptors to the soliton states is reflexed to the value of corresponding kinetic coefficient. Es wird eine Storungstheorie fur die kinetischen Koeffizienten des Elektronentransfer von Donator-molekulen (Dm) zu Akzeptormolekulen (Al) entlang einer eindimensionalen Molekulkette, mit der Dm und Al statistisch verbunden sind, entwickelt. Der Einflus der Donatoren und Akzeptoren zu den Solitonenzustanden spiegelt sich im Wert des entsprechenden kinetischen Koeffizienten wieder.

2016 10th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics (METAMATERIALS), 2016

Superconducting quantum bits (qubits) are at the heart of quantum information processing schemes ... more Superconducting quantum bits (qubits) are at the heart of quantum information processing schemes since they satisfy the requirements for being the building blocks of viable quantum computers. Here it is shown that quantum coherence, in the form of population inversion pulses, is induced by self-induced transparent electromagnetic pulses propagating in a quantum metamaterial comprising superconducting charge qubits. The experimental confirmation of that effect may open a new pathway to potentially powerful quantum computing.

In this paper, we investigate the possibility of stable migration of charge carriers over long di... more In this paper, we investigate the possibility of stable migration of charge carriers over long distances in DNA-like macromolecular structures in the form of an adiabatic soliton and derive the conditions for the formation of solitons. We find two types of soliton solutions: symmetric and antisymmetric. Comparing the energy of both types of soliton solutions with the energy of free extra charge, we find the region of the system parameters in which the soliton states are more energetically favorable than the states of quasi-free charges. At the same time, which of the two mentioned soliton solutions corresponds to an energetically favorable state depends on the ratio of the energy parameters of the molecular structure.

Chaos, Solitons & Fractals: X, 2019

We introduce a quantum superconducting metamaterial design constituted of flux qubits that operat... more We introduce a quantum superconducting metamaterial design constituted of flux qubits that operate as artificial atoms and analyze the dynamics of an injected electromagnetic pulse in the system. Qubitphoton interaction affects dramatically the nonlinear photon pulse propagation. We find analytically that the well known atomic phenomenon of self induced transparency may occur in this metamaterial as well and may lead to significant control over the optical pulse propagating properties. Specifically, the pulse may be slowed down substantially or even be stopped. These pulse properties depend crucially on the inhomogeneous broadening of the levels of the artificial atoms.