Conveners
Theoretical
- Frederik Scholtz (National Institute for Theoretical Physics)
Theoretical
- Jean Cleymans ()
Theoretical
- Dieter Heiss ()
Theoretical
- Steven Karataglidis ()
Theoretical
- Jan Greben ()
Theoretical
- Moritz Braun ()
Theoretical
- Robert de Mello Koch ()
Description
Theoretical and Computational Physics
A symmetrized and dynamical density matrix renormalization group is used to study 1-dimensional extended Peierls-Hubbard model at half-filling. We have investigated the optical conductivity spectrum and electro-absorption spectrum for low-lying optical exciton with strong, intermediate and weak coupling parameter sets for the on-site and neighbor interactions. We were able to capture the...
The origin of numerical errors, which in certain cases lead to complete failure of the direct method for solving the 1-dimensional Marchenko integral equation, are investigated. Bargmann and block potentials, for which exact analytical expressions exist, are used to compare the accuracy of numerical results. In particular, numerical results from the Nystrom method are compared to those...
The pressure induced B3-B1 phase transition has been studied using both density functional theory (DFT) and quantum Monte Carlo (QMC) methods. We present results obtained using the local density approximation (LDA), PW91-GGA generalized gradient approximation, hybrid density functionals and QMC. The changes in the equation of state has also been investigated using the different functionals...
Understanding the magnetic effects of ultra-dense, cold nuclear matter is of particular importance when investigating the magnetic properties of dense matter systems such as neutron stars. One property that we are interested in is the possibility of generating a magnetic field in nuclear matter as the central density increases. We investigate this possibility by employing a relativistic,...
The theory of continuous measurement provides a tool to monitor the evolution of the wave function of a single quantum system in real time. We derive the master equation in the non-selective regime for the dynamics of the wave function of a particle in an external potential which is subject to continuous measurement of position. In the derivation we view continuous measurement as the limit...
We investigate the scattering of a wave-packet off a soliton in the (1+1) dimensional kink model. We solve the classical, time-dependent field equation numerically subject to the initial condition that the wave-packet is widely separated from the kink soliton at very early times and propagates towards the soliton. After some time the wave-packet interacts with the static soliton and...
Quantum walks of particles obeying bose statistics are introduced. In such a quantum walks the conditional shift operation is performed with the single coin tossing for the whole lattice. An explicit form for the transition probabilities in a single step is derived. This allow to describe the evolution of an arbitrary state and an arbitrary number of steps. This model easily embrace the...
GEANT 4 is a C++ library developed by CERN to simulate particle physics experiments. However, GEANT 4 can be also be used for other applications that need not have anything to do with particle or high-energy physics. Here we discuss an application of GEANT 4 that simulates the EMU Spectrometer for Muon Spin Relaxation measurements at the ISIS facility in the Rutherford Appleton Laboratory....
The spectrum of a carbon nanotube in a strong enough magnetic field (>50T for a 3nm nanotube) revealed an almost dispersionless band at the Fermi energy. The formation of Landau levels has been theoretically and experimentally investigated. In experimental studies the existence of Landau levels is indirectly derived from longitudinal conductance measurements. We will show that a more direct...
Ab initio density functional calculations within the generalised gradient approximation (GGA) have been carried out on a wide range of phases and stoichiometries for the platinum-titanium (Pt-Ti) and iridium-titanium (Ir-Ti) alloy systems, using the Vienna Ab Initio Simulation Package (VASP). The elastic constants and elastic moduli are calculated and the electronic structure and density...
Reactions involving four particles, either in the entrance or final channel, are quite involved when computing observables in comparison to three-body reactions. Yet these reactions are of interest in studying reactions of astrophysical interest, such as hep process, which is essential for describing the quantitative solar model. At lower solar energies, it is difficult to measure the...
One-Way Quantum computing is based on the preparation of certain entangled states of several particles, which are subsequently individually measured. The measurements serve to process information as well as to read out the final result of the computation. The implementation with OAM carrying photons is based on the usage of qubits (only two OAM values are relevant) but is a first step...
Quantum Cryptography, one aspect of which is Quantum Key Distri- bution (QKD), provides the only physically secure and proven method for the transmission of a secret key between two distant parties, Alice and Bob. The goal of QKD is to guarantee that a possible eavesdropper (Eve), with access to the communication channel is unable to obtain useful information about the message. The...
Ground-state properties of three-nucleon systems consisting of one and two hyperons are studied with the integro-differential equations approach. The Hamiltonian of the systems is constructed with semi-realistic nucleon-nucleon interactions and phenomenological nucleon-hyperon interactions. The results obtained for the ground-state energies and root-mean-square radii are compared with the...
Models with extra spacial dimensions offer a new way to address outstanding problems in and beyond the standard model. In such models the Planck scale in the bulk can be of the order of the electro-weak symmetry breaking scale. This allows the coupling strength of gravity to increase to a size similar to the other interactions, opening the way to the unification of gravity and the gauge...
N=4 SYM theory has been extensively studied in the planar limit. A very significant result of this study is a map from the planar dilatation operator to the Hamiltonian of an integrable spin chain. In this talk we consider a large N (but not planar) limit of the theory. This is a considerably more complicated problem since non-planar corrections need to be summed. This summation is...
ABJM theory is an N=6 Superconformal Chern-Simons theory with gauge group U(N)XU(N). This gauge theory has been extensively studied in the planar limit. Motivated by similar results for N=4 SYM, the planar dilatation operator of ABJM theory has been mapped to the Hamiltonian of an integrable system. Recently, it has been argued that there are large N (but not planar) limits of N=4 SYM...
A new correspondence between type IIA string theory on AdS4×CP3 and an N=6 Super Chern-Simons-matter theory was proposed by Aharony, Bergman, Jafferis and Maldacena (ABJM) in 2008. We construct the D4-brane giant graviton, extended and moving in the complex projective space, which is dual to a subdeterminant operator in ABJM theory. This dynamically stable configuration factorizes at...
N=4 SYM theory has been extensively studied in the planar limit. An important result is that the planar dilatation operator can be mapped to the Hamiltonian of an integrable system. In this talk we study certain large N (but not planar) limits of the theory. We argue that the dilatation operator remains integrable: it reduces to a set of decoupled harmonic oscillators. This challenges...
An entangled bipartite Gaussian state is coupled to two thermal reservoirs, one for each particle. A harmonic oscillation is allowed between the two particles. The reservoirs are assumed to have different temperatures and to be coupled to the particles with different coupling strengths. This allows for a realistic situation where a bipartite state may be shared between two parties who...
Decoherence indicates the process that a quantum system undergoes through the interaction with an external environment. The central issue and one of the greatest challenges in Nanotechnology and Quantum Information Processing is the way to control or delay the destructive effect of the environment on qubit coherence. For this reason, a qubit interacting with a reservoir of bosons...
The transfer of energy and information in quantum networks plays an important role in both quantum communication and quantum computation. The quantum system inevitably interacts with the surrounding environment, and such interaction leads to dissipation and decoherence, which are processes typically associated with a destruction of quantum coherence in the system. However, recently evidence...
Quantum Random Walks have been introduced almost 20 years by Y. Aharonov et al. [Phys. Rev. A, 48(2):1687–1690, 1993] and have found wide applications in quantum computing. As is often the case in quantum theory, Quantum Walks differ strongly from classical random walks. In joint work of S. Attal, C. Sabot, F. Petruccione and I. Sinayskiy the concept of Open Quantum Random Walks was...
We find non-local but non-signaling probabilities satisfying the 'nonlocality without inequality’ arguments for multiple two-level systems. Maximum probability of success of these arguments are obtained in the framework of a generalized nonlocal theory. Interestingly, for two two-level systems, the probability of success of these arguments converge to a common maximum in this framework....
Ground-state properties of three-nucleon and four-nucleon systems are studied with the angular-momentum-projected and parity-projected antisymmetrized molecular dynamics. The Hamiltonian of the systems is constructed with semi-realistic nucleon-nucleon interactions. The results obtained for the ground-state energies, root-mean-square radii and magnetic dipole moments are compared with the...
The angular-momentum-projected and parity-projected antisymmetrized molecular dynamics is used to analyse the charge and magnetic form factors of the three-nucleon systems. Non-relativistic nuclear charge and current operators with relativistic corrections are employed. The Hamiltonian of the nuclear systems is described with a semi-realistic nucleon-nucleon potential. The results...
During the last 15 years there has been considerable interest in density matrix based methods for electronic structure calculations. The “difficult” problem of ensuring idempotency conservation of the density matrix through an appropriate purification scheme as well as the use of the “nearsightedness” and associated sparsity of the density matrix to achieve linear scaling with system size...
Physics is one of the most digitally-intensive areas of modern research and has traditionally led the development of tools to increase the efficiency and capability of research activities. The integration of the tools necessary for today's competitive physics research projects, from HPC centres to data resources, metadata catalogues, and services to enable collaboration in virtual...
The electro-magnetic field is expanded in a bilinear series consisting of products of quark creation and annihilation operators. This bilinear form is suggested by the equations of motion for the electromagnetic field and provides a very powerful quantum representation, which is devoid of many of the technical problems associated with standard quantization. In this approach the energy of...
Problems involving bound states of few particles can be solved exactly since the number of degrees of freedom are small. Several methods in this direction exist. One of these is the Integro-differential equation approximation method (IDEA). These few-body methods have been succesfully applied to obtained bound and scattering states for three- and four-body problems for nuclear and molecular...
Analytical equations of motion, in the form dxi ⁄ dt = fi(x,t), are derived for a damped harmonically driven triple plane pendulum. This form of the equations clearly displays the nature of the non-linear coupling and provides a basis for physical interpretation. The equations also facilitate the derivation of the Jacobian...
Efficient and reliable methods to solve effective three dimensional Schroedinger equations are an important ingredient for both density functional as well as Hartree Fock methods used to calculate the properties of molecules and solids. In order to judge the accuracy of popular methods such as using Gaussian basis functions or smooth pseudo potentials it is desirable to use a method that...
We devise a hierarchy of computational algorithms to enumerate the microstates of a system comprising N independent, distinguishable particles. An important challenge is to cope with integers that increase exponentially with system size, and which very quickly become too large to be addressed by the computer. A related problem is that the computational time for the most obvious brute-force...
One of the striking features of particle production at high beam energies is the near equal abundance of matter and antimatter in the central rapidity region. In this paper we would like to study how this symmetry is reached as the beam energy is increased. In particular we quantify explicitly the energy dependence of the approach to matter/antimatter symmetry. Expectations are...
A systematic strategy for the algebraic calculation of density functionals consists in coding information about the density and the energy into polynomials of the degrees of freedom of the wave functions. Density functionals and Kohn-Sham potentials are then obtained by standard elimination procedures of such degrees of freedom between the polynomials. Numerical examples illustrate the formalism.
The present observational data strongly suggest that Einstein's gravity must be modified, one of the popular modifications being provided by superstring ideas. In view of the mathematical problems of the string theory, other, much simpler, modifications of gravity that affect only the gravitational sector (not touching other interactions) are also popular. One of them is based on...
A short resume about the nature of EPs followed by a discussion about their ubiquitous occurrence in a great variety of physical problems. EPs feature in quantum phase transition, quantum chaos, they produce dramatic effects in multichannel scattering, specific time dependence and more. In nuclear physics they are associated with instabilities and affect approximation schemes. EPs could...
