Artūras Acus

Artūras Acus
Vilnius University · Institute of Theoretical Physics and Astronomy

Doctor of Philosophy
Geometric (Clifford) algebra ant its application in theoretical physics

About

44
Publications
2,433
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
134
Citations
Introduction
Geometric algebra and its applications in physics
Additional affiliations
January 2019 - present
Vilnius University
Position
  • Lecturer
January 2006 - August 2017
Vilnius Pedagogical University
Position
  • Professor (Assistant)

Publications

Publications (44)
Article
Full-text available
Closed form expressions in real Clifford geometric algebras Cl0,3,Cl3,0,Cl1,2$$ C{l}_{0,3},C{l}_{3,0},C{l}_{1,2} $$, and Cl2,1$$ C{l}_{2,1} $$ are presented in a coordinate‐free form for exponential function when the exponent is a general multivector. The main difficulty in solving the problem is connected with an entanglement (or mixing) of vector...
Preprint
Full-text available
Formulas to calculate multivector exponentials in a base-free representation and in a orthonormal basis are presented for an arbitrary Clifford geometric algebra Cl(p,q). The formulas are based on the analysis of roots of characteristic polynomial of a multivector. Elaborate examples how to use the formulas in practice are presented. The results ma...
Preprint
Full-text available
Closed form expressions for a multivector exponential and logarithm are presented in real Clifford geometric algebras Cl(p,q)when n=p+q=1 (complex and hyperbolic numbers) and n=2 (Hamilton, split and conectorine quaternions). Starting from Cl(0,1) and Cl(1,0) algebras wherein square of a basis vector is either -1 or +1, we have generalized exponent...
Article
Full-text available
Closed form expressions to calculate the exponential of a general multivector (MV) in Clifford geometric algebras (GAs) Clp;q are presented for n = p + q = 3. The obtained exponential formulas were applied to find exact GA trigonometric and hyperbolic functions of MV argument. We have verified that the presented exact formulas are in accord with se...
Preprint
Full-text available
Closed form expressions in a coordinate-free form in real Clifford geometric algebras (GAs) Cl(0,3), Cl(3,0)$, Cl(1,2) and Cl(2,1) are found for exponential function when the exponent is the most general multivector (MV). The main difficulty in solving the problem is connected with an entanglement or mixing of vector and bivector components. After...
Preprint
Full-text available
Closed form expressions to calculate the exponential of a general multivector (MV) in Clifford geometric algebras (GAs) Cl(p,q) are presented for n=p+q=3. The obtained exponential formulas were applied to find exact GA trigonometric and hyperbolic functions of MV argument. We have verified that the presented exact formulas are in accord with series...
Article
Full-text available
A classical system, which is analogous to the quantum one with a backflow of probability, is proposed. The system consists of a chain of masses interconnected by springs and attached by other springs to fixed supports. Thanks to the last springs the cutoff frequency and dispersion appears in the spectrum of waves propagating along the chain. It is sho...
Preprint
Full-text available
A classical system, which is analogous to the quantum one with a backflow of probability, is proposed. The system consists of a chain of masses interconnected by springs, as well attached by other springs to fixed supports. Thanks to the last springs the cutoff frequency and dispersion appears in the spectrum of waves propagating along the chain. I...
Preprint
Full-text available
An algorithm to extract the square root in radicals from a multivector (MV) in real Clifford algebras Cl(p,q) for n=p+q <=3 is presented. We show that in the algebras Cl(3,0), Cl(1,2) and Cl(0,3) there are up to four isolated roots in a case of the most general (generic) MV. The algebra Cl(2,1) makes up an exception and the MV here can have up to 1...
Article
The problem of square root of multivector (MV) in real 3D (n = 3) Clifford algebras Cl3;0, Cl2;1, Cl1;2 and Cl0;3 is considered. It is shown that the square root of general 3D MV can be extracted in radicals. Also, the article presents basis-free roots of MV grades such as scalars, vectors, bivectors, pseudoscalars and their combinations, which may...
Article
Full-text available
The solution of the Liouville equation for the ensemble of free particles is presented and the classical analog to the quantum accelerating Airy wave packet is constructed and discussed. Considering the motion of various classical packets – with an infinite and restricted distribution of velocities of particles – and also the motion of their fronts...
Preprint
Full-text available
The solution of the Liouville equation for the ensemble of free particles is presented and the classical analog to the quantum accelerating Airy wave packet is constructed and discussed. Considering the motion of various classical packets -- with an infinite and restricted distribution of velocities of particles -- and also the motion of their fron...
Preprint
Full-text available
The coordinate-free solutions of the multivector equation $ax+xb=c$ are discussed and presented for the Clifford algebras $Cl_{p,q}$ when $p+q\le 3$.
Article
The algorithm of finding an inverse multivector (MV) numerically and symbolically is of paramount importance in the applied Clifford geometric algebra (GA) \( Cl _{p,q}\). The first general MV inversion algorithm was based on matrix representation of MV. The complexity of calculations and the size of the answer in a symbolic form grow exponentially...
Article
Full-text available
The algorithm of finding inverse multivector (MV) in a symbolic form is of paramount importance in computational Clifford or geometric algebra (GA) $Cl_{p,q}$. The first attempts of inversion of general MV were based on matrix representation of MV basis elements. However, the complexity of such calculations grows exponentially with the dimension $n...
Article
Full-text available
A practical computation method to find the eigenvalues and eigenspinors of quantum mechanical Hamiltonian is presented. The method is based on reduction of the eigenvalue equation to well known geometric algebra rotor equation and, therefore, allows to replace the usual det(H-E)=0 quantization condition by much simple vector norm preserving require...
Article
Full-text available
We continue the discussion on the interaction energy of the axially symmetric Hopfions evaluated directly from the product anzsatz. The Hopfions are given by the projection of Skyrme model solutions onto the coset space SU(2)/U(1). Our results show that if the separation between the constituents is not small, the product ansatz can be considered as...
Article
Full-text available
We theoretically explore atomic Bose-Einstein condensates (BECs) subject to position-dependent spin-orbit coupling (SOC). This SOC can be produced by cyclically Raman coupling four internal atomic ground (or metastable) states in an environment where the detuning from two-photon Raman resonance depends on position. The resulting spin-orbit coupled...
Article
Full-text available
Hamiltonian and eigenstate problem is formulated for a bilayer graphene in terms of Clifford's geometric algebra \textit{Cl}$_{3,1}$. It is shown that such approach allows to perform analytical calculations in a simple way if geometrical algebra rotors are used. The measured quantities are express through spectrum and rotation half-angle of the pse...
Article
A simple method of temperature and electron density measurement in quasi-equilibrium plasma at temperatures below 10 kK from the ratio of mass spectrometric signals of the doubly and singly ionized ions of Ba and Pb has been proposed. High masses of the ions and possibility to select the odd isotopes makes it possible to perform measurements at a l...
Article
Full-text available
We discuss the relation between the solutions of the Skyrme model of lower degrees and the corresponding axially symmetric Hopfions which is given by the projection onto the coset space SU(2)/U(1). The interaction energy of the Hopfions is evaluated directly from the product ansatz. Our results show that if the separation between the constituents i...
Article
Full-text available
We study the effect of the canonical quantization of the rotational mode of the charge Q=1 and Q=2 spinning Hopfions. The axially-symmetric solutions are constructed numerically, it is shown the quantum corrections to the mass of the configurations are relatively large.
Article
We introduce a one-dimensional two-component system with the self-focusing cubic nonlinearity concentrated at a symmetric set of two spots. Effects of the spontaneous symmetry breaking (SSB) of localized modes were previously studied in the single-component version of this system. In this work, we study the evolution (in the configuration space of...
Article
Full-text available
The rational map approximation provides an opportunity to describe light nuclei as classical solitons with baryon number B > 1 in the framework of the Skyrme model. The rational map ansatz yields a possibility of factorization of S3 baryon charge into S1 and S2 parts, the phenomenology of the model being strongly affected by the chosen factorizatio...
Article
Full-text available
Analytical expressions for spectrum, eigenfunctions and dipole matrix elements of a square double quantum well (DQW) are presented for a general case when the potential in different regions of the DQW has different heights and effective masses are different. This was achieved by Gr\"obner basis algorithm which allows to disentangle the resulting co...
Article
Full-text available
The knowledge of exact wave functions is required in calculating physical parameters such as optical dipole moments, scattering matrix elements, or in wave function engineering. In this report we describe how a system of algebraic equations that follows from the Schrödinger equation can be reduced to a Gröbner basis from which the exact wave functi...
Article
Essentially higher ionization degree of small concentrations of elements in inductively coupled plasma in comparison to the ionization of pure elements is emphasized. This conclusion is used to determine the relative dependence of the sensitivity of the inductively coupled plasma mass spectrometer on the atomic mass. The possibility of evaluation o...
Article
We analyse the effect of the canonical quantization of the rotational mode of the O(3)σ-model which includes the Skyrme term. Numerical evidence is presented that the quantum correction to the mass of the rotationally-invariant charge n=1,2 configurations may stabilize the solution even in the limit of vanishing potential. The corresponding range o...
Article
Full-text available
Analysis of the multivariate data distributions can be helpful or directly applicable in pattern recognition tests. Estimate of the volume of the critical region of overlapping distributions is essential in determination of the condence level of classica- tion. Mathematical tools for analysis of the multivariate distributions (included probability,...
Article
Full-text available
The rational map approximation to the solution to the SU(2) Skyrme model with baryon number B=4 is canonically quantized. The quantization procedure leads to anomalous breaking of the chiral symmetry, and exponential fall-off of the energy density of the soliton at large distances. The model is extended to SU(2) representations of arbitrary dimensi...
Article
Full-text available
The ground state configurations of the solution to Skyrme's topological soliton model for systems with baryon number larger than 1 are well approximated with rational map ans\"atze, without individual baryon coordinates. Here canonical quantization of the baryon number 2 system, which represents the deuteron, is carried out in the rational map appr...
Article
Full-text available
The characteristic feature of the ground state configuration of the Skyrme model description of nuclei is the absence of recognizable individual nucleons. The classical skyrmion with baryon number 2 is axially symmetric, and can be approximated by a simple rational map anzats. Quantized version of biskyrmion then can be identified with dibarion if...
Article
Full-text available
The explicit expressions for the electric, magnetic, axial and induced pseudoscalar form factors of the nucleons are derived in the {\it ab initio} quantized Skyrme model. The canonical quantization procedure ensures the existence of stable soliton solutions with good quantum numbers. The form factors are derived for representations of arbitrary di...
Article
Full-text available
Spontaneous symmetry breaking occurs when the symmetry that a physical system possesses, is not preserved for the ground state of the system. Although the procedure of symmetry breaking is quite clear from the mathematical point of view, the physical interpretation of the phenomenon is worth to be better understood. In this note we present a simple...
Article
Full-text available
This paper is a PhD thesis defended at Institute of Theoretical Physics and Astronomy on 18 December, 1998. The following (abbreviated) statements represent the main results of the work: 1.Each of SU(2) representation j yields the different quantum Lagrangian density. As a consequence, theoretical observables depend on representation j which can be...
Article
Full-text available
A constructive realization of Skyrme's conjecture that an effective pion mass ``may arise as a self consistent quantal effect'' based on an ab initio quantum treatment of the Skyrme model is presented. In this quantum mechanical Skyrme model the spectrum of states with $I=J$, which appears in the collective quantization, terminates without any infi...
Article
Full-text available
The Skyrme model is considered quantum mechanically ab initio in various irreducible representations of the SU(2) group. The canonical quantization procedure yields negative mass correction ensuring existence of stabile soliton solution even in chiral limit. The evaluated static properties of nucleons (masses, magnetic moments, radii etc.) are in a...
Article
The representations of general dimension are constructed for the $SU(2)$ Skyrme model, treated quantum mechanically {\it ab initio. } This quantum Skyrme model has a negative mass term correction, that is not present in the classical Hamiltonian. The magnitude of the quantum mechanical mass correction increases with the dimension of the representat...
Article
Full-text available
For the distance learning and scientific cooperation the possibility to run software by Internet is essential. Ideas, algorithms, models and other software can be tested and investigated by everyone. Computer experimentation on the web becomes a natural approach to research and to scientific collaboration. The new field of complexity exhibits the l...
Article
Full-text available
The Skyrme model (1) has been extended to describe classical solitons with baryon number B > 1 by rational map approximation (2). The canon- ical quantization procedure (3) applied to rotational degrees of freedom of 4 He and 16 O nuclei leads to anomalous breaking of the chiral symmetry and exponential falloff of the energy density of the soliton...

Network

Cited By