### Conveners

#### Theoretical and Computational Physics: Session 1

- Thomas Konrad (UKZN)

#### Theoretical and Computational Physics: Session 2

- Alan Cornell (University of Johannesburg)

#### Theoretical and Computational Physics: Session 3

- William Horowitz (University of Cape Town)

#### Theoretical and Computational Physics

- There are no conveners in this block

#### Theoretical and Computational Physics

- There are no conveners in this block

#### Theoretical and Computational Physics

- There are no conveners in this block

#### Theoretical and Computational Physics

- There are no conveners in this block

Open quantum walks (OQWs) have been introduced as a type of quantum walks which are entirely driven by the dissipative interaction with external environments and are defined in terms of discrete completely positive trace-preserving maps on graphs [1]. Recently, a quantum optical scheme for the experimental realization of OQWs was proposed [2]. In the proposed scheme, a two-level atom plays the...

Emerging quantum technologies rely principally on quantum phenomena such as superposition and entanglement for their unique capabilities. To this end, it is essential to develop well-defined and efficient protocols to produce and further exercise control over states of quantum bits that exhibit desired quantum mechanical traits. From a pure separable multipartite state, a control sequence,...

The theoretical framework behind modern-day quantum optics has been successful in explaining a number of interesting phenomena. However, since it is traditionally formulated using ordinary quantum mechanics and Fourier optics, it cannot account for relativistic notions such as different reference frames (including non-inertial ones) or curved classical gravitational backgrounds. In an attempt...

Traditionally, quantum key distribution (QKD) is used for sharing secret key between two distant authorized participants with unconditional security. Here, we extend the reach of QKD by proposing a reference frame independent quantum key distribution (RFI-QKD) which allows three legitimate parties to share the common secret keys without any alignment of reference frames in their quantum...

In this contribution, we present the results of calculations for the ground state energy of H2+ employing Sinc functions as a basis set as discussed for a number of

examples in [1]. The modifications required to the basis functions to make them suitable for calculating the ground state energy of H2+ as well as the application of the cusp factor formulism [2] are outlined. Finally the...

Molecular machines, known as motor proteins, walk along configurations of filamentous proteins which make up the cytoskeleton of a cell. These motor proteins, for example kinesins, are responsible for transporting a variety of cargoes within the cell. The arrival of the cargoes at specific locations within the cell are imperative for the successful execution of various cellular processes,...

We present our latest findings on the status of factorization in heavy ion collisions. In the first microsecond of the universe, space was filled with deconfined nuclear matter at a temperature of a trillion degrees. These conditions are recreated thousands of times a second at experiments in the US and Europe in which large nuclei such as gold and lead are collided at nearly the speed of...

We present predictions for the suppression and angular distribution of B and D mesons in $\sqrt{s}=5.5$ TeV Pb+Pb collisions at the LHC for central, semi-central and peripheral collisions. Ultrarelativistic heavy-ion collisions produce an enormous amount of energy, resulting in the formation of a quark-gluon plasma (QGP). Studying the behaviour of particles (e.g. heavy quarks) propagating...

We study the relic density and astrophysical constraints of an effective model featuring top-philic scalar dark matter and a heavy T-channel mediator. The addition of a dimension-five contact term which is common to BSM scenarios modifies the available parameter space, and the model features interplay between the associated Wilson coefficient and Yukawa parameter in producing the correct relic...

One of the biggest problems in particle physics today, is understanding the nature of dark matter. If dark mesons exist, their evolution and hadronization procedure are currently little constrained. They could decay promptly and result in a very SM QCD like jet structure, even though the original decaying particles are dark sector ones; they could behave as semi-visible jets; or they could...

In an era where high energy particle physics is having to transition from a theory-driven to a data-driven approach, the traditional method of performing specific searches off of theory models may be inefficient. Contur (Constraints On New Theories Using Rivet) was designed as a means to quickly exclude BSM models based off the many LHC measurements currently contained in Rivet. Focusing on...

Random numbers are used extensively in both cryptography and simulation, but are difficult to generate reliably using classical methods. We investigate random number generation on the ibmq_16_melbourne quantum processor, a 15-qubit superconducting quantum computer. By applying simple post-processing techniques to the random bits generated, we were able to extract a sample of random bits which...

In this work, a brief review of a new form of scalar-tensor theories of gravity, known as gravitational scalar-tensor theories (GST) in which the action is composed of the Ricci scalar and its first and second derivatives is made. Some of the cosmological applications that have been investigated in these new theories are discussed considering different models corresponding to the first...

The accelerated expansion of the universe and the rotational dynamics of galaxies have become part of the mysteries of the physical world and have had theorists working tirelessy for the past years. There is no consensus on what is causing these observable effects: whether it is the the unknown dark energy and dark matter or it is the breaking down of our currently accepted theory of gravity,...

The quasinormal modes (QNMs) of a black hole (BH) may be identified as a class of damped, classical oscillations in spacetime, emergent as part of the late-stage response to a perturbation of the compact body. In the weak-field limit, the radial behaviour of these oscillations can be modelled as a wave equation whose potential varies to represent different fields. The choice of computational...

Previously, we have discussed Bell correlations in a relativistic setting and the possibility of using these to detect weak forces between particles. Now a theoretical description of quantum entanglement in terms of relativistic quantum mechanics is presented. Essentially, in non-relativistic quantum mechanics, entanglement leads to a non-local correlation between 2 particles. This was shown...

Inspired by the dual correspondence between measurement and preparation procedures, we discuss inequalities for observables of local realistic models which are violated according to the predictions of quantum mechanics, thus demonstrating the inability of classical physics to reproduce all quantum predictions (Bell's theorem). Such Bell inequalities test the statistical correlation between...

The recent paper by google [1] claiming to achieve quantum supremacy in quantum computing has risen a lot of interest. While there seems to be lot of questions regarding the validity of their claims of achieving quantum supremacy and comparison with the classical time frames in calculating the same quantity, it seems that there is little doubt they indeed perform computation using quantum...

In today’s growing field of quantum communication, a major quest is trying to increase the bandwidth of information that can be sent. An interesting avenue is looking at nonlinear optical processes which also allows one to incorporate the spatial degrees of freedom of light. A widely used nonlinear process is spontaneous parametric down conversion (SPDC), which is a source for entangled...

High energy heavy ion collisions such as those at the Relativistic Heavy Ion Collider (RHIC), Brookhaven National Laboratory (BNL), Long Island, NY and those at the Large Hadron Collider (LHC), CERN, Geneva have produced a new state of matter called Quark-Gluon Plasma (QGP). This QGP filled the entire early Universe for a few microseconds (~10 μs) after the Big Bang. This state of matter is...

We present for the first time a quantitative

analysis of multiple gluon emission in hard

scattering events in the soft and collinear

emission limit. These calculations specifically

include the non-trivial, non-Abelian QCD

corrections. We base our numerics on derivations

using the spinor helicity formalism, a natural framework for

evaluating tree-level Feynman diagrams in...

A exploratory study of dark photons in a search for dark matter is presented, where a dark photon is a hypothetical dark matter particle. A dark photon may be detected through its kinetic mixing with the general photon, in which it then couples weakly to electrically charged particles and allows a non-gravitational window into the detection of dark matter. We will be considering the...

The interactions of O2 and H2O with mineral surfaces are the major factors that determine the oxidation and wettability behaviour of minerals. This study employed the first-principles density functional theory to explore the bonding behaviour, adsorption energies and electronic properties directly related to the reactivity of O2 and H2O with geversite (100) mineral surface. The oxidation of...

Neutron stars provide a laboratory environment where we can study nuclear matter under extreme conditions of super-density, super magnetic field as well as super-gravity. This is a laboratory where the four forces of nature namely, gravity, the weak force, electromagnetism and the strong force can be studied. Studying nuclear matter under extreme conditions in neutron stars can be used to...

Hematite has attracted research interest for many years due to its application in water splitting. Despite their desirable optical band gap and other attractive features, there are great challenges for the implementation of hematite-based photoelectrochemical cells for water splitting. Doping with transition metals have shown to be a practical solution to overcome some of the limitations faced...

Physics-informed neural networks (PINNs) have recently emerged in machine learning as a tool for solving differential equations governing various physics phenomena. The present research will apply them specifically to solving black hole perturbation equations – differential equations describing quasinormal modes (QNMs) induced on the surface of a black hole by perturbing fields. Generally,...

In deeply inelastic lepton-nucleus scattering, hadron-nucleus and heavy-ion collisions; multiple scatterings of energetic partons in the nuclear medium lead to a broadening of the average jet transverse momentum. This jet broadening phenomenon offers a useful tool for probing the properties of nuclear media, including the quark-gluon plasma formed in high-energy heavy-ion collisions. Many...

In this paper, we have analysed the latest data from NO$\nu$A and T2K with the Lorentz invariance violation along with the standard oscillation hypothesis. We have found that the NO$\nu$A data cannot distinguish between the two hypotheses at $1\, \sigma$ confidence level. T2K data and the combined data analysis excluded standard oscillation at $1\, \sigma$. All three cases do not have any...

Many of the quantum algorithms that make theoretical guarantees on computational speedups are well beyond the capabilities of currently existing noisy intermediate-scale quantum (NISQ) hardware. The requisite resources (qubits, quantum gates) demands of these algorithms make their implementation impractical on such hardware. For some algorithms, various approaches exist to reduce these...

We present a quantum control scheme which allows for the control of a quantum system by other quantum systems, also called coherent feedback.[1] An assembly of control quantum controllers are coupled sequentially to the to-be-controlled quantum system, driving the system into a target state. We determine a broad class of coherent feedback control channels by identifying the necessary and...

Relativistic heavy-ion collisions at high energies such as those at the Relativistic Heavy Ion Collider (RHIC), Brookhaven National Laboratory, Long Island, New York and at the Large Hadron Collider (LHC), CERN, Switzerland, Geneva produce new state of matter leading up to many new particles. One approach to understanding the properties of the produced hot and dense matter in these collisions...

In this paper, GGA method and PBE pseudopotential method based on first principle density functional theory was used. The band structure and optical properties were calculated. It was noticed that doping SnO2 doped with N,Sb and Mo atoms reduces the bandgap of SnO2. The density of state was also calculated, and it was noticed that new states formed by new state of the dopants was introduced...

Abstract: Iron-cobalt alloys are considered a good candidate for high-temperature applications due to their high saturation magnetization and Curie temperature. These alloys are applicable in the automotive industry as actuators, however, they suffer brittleness at room temperature. In this study, ternary alloying was used to investigate the strength of the alloys. Titanium was chosen as the...

The scenario of warm inflationary scenario is reconsidered where the tachyon field plays the role of inflaton which drives inflation and interacts with the radiation during inflation. The interaction term includes a dissipative coefficient, and the model is considered for two different and common choices of it. The main perturbation parameters are obtained for the strong dissipative regime,...