Research Activities


Publications  | Grants

Recent Publications

Generalised uncertainty relations from finite-accuracy measurements

Authors: M. J. Lake, M. Miller, R. Ganardi, T. Paterek

Journal: Front. Astron. Space Sci. 10, 1087724 (2023)

Motion of charged particles in spacetimes with magnetic fields of spherical and hyperbolic symmetry

Yen-Kheng Lim

Physical Review D 106  064023 (2022)

Structure of test magnetic fields and charged particle motion around the Hayward spacetime

Ziou Yang and Yen-Kheng Lim

Physical Review D 105  124045 (2022)

A single-atom library for guided monometallic and concentration-complex multimetallic designs

Lili Han, Hao Cheng, Wei Liu, Haoqiang Li, Pengfei Ou, Ruoqian Lin, Hsiao-Tsu Wang, Chih-Wen Pao, Ashley R. Head, Chia-Hsin Wang, Xiao Tong, Cheng-Jun Sun, Way-Faung Pong, Jun Luo, Jin-Cheng Zheng, and Huolin L. Xin

Nature Materials (2022)

Long range electromagnetic field nature of nerve signal propagation in myelinated axons

Qing-Wei Zhai, Kelvin J A Ooi, Sheng-Yong Xu, and C K Ong

Chinese Physics B 31 038701 (2022)

Solenoid Configurations and Gravitational Free Energy of the AdS–Melvin Spacetime

Yen-Kheng Lim

Entropy 23(11) 1477 (2021)

The zero-temperature limit of grand canonical ensembles via tropical geometry

Mounir Nisse and Yen-Kheng Lim

Analysis and Mathematical Physics 11 113 (2021)

Summary: summary_nisse_yklim_tropical_2021.pdf

Light-ring pairs from A-discriminantal varieties

Yen-Kheng Lim, Mounir Nisse

Physical Review D 104 104012 (2021)

Summary: summary_yklim_nisse_light_2021.pdf 

Motion of charged particles around a magnetic black hole/topological star with a compact extra dimension

Yen-Kheng Lim

Physical Review D 103 084044 (2021)

Null geodesics in the C-metric with a cosmological constant

Yen-Kheng Lim

Physical Review D 103 024007 (2021)

Enhancing High-Frequency Properties of Nanocrystalline Sputtered Fe Thin Films by Using MnIr Underlayer and Oblique Deposition

Kh. Gheisari and C. K. Ong

Journal of Superconductivity and Novel Magnetism 34 1 (2021)

Nonreciprocal multimode and indirect couplings in cavity magnonics

C. Zhang, C. Jia, Y. Shi, C. Jiang, D. Xue, C. K. Ong, and G. Chai

Phys. Rev. B 103 184427 (2021)

Facile synthesis of hierarchical porous Na3V2(PO4)3/C composites with high-performance Na storage properties

A.H. Salehi, S.M. Masoudpanah, M. Hasheminiasari, A. Yaghtin, D. Safanama,C. K. Ong, S. Adams, K. Zaghib, and M.V. Reddy

Journal of Power Sources 481 228828 (2021)

Influence of MoO3 additive on grain growth and magnetic properties of Mg0.3Cu0.2Zn0.5Fe2O4 ceramics sintered at low temperature

H. Bahiraei ,C. K. Ong

Journal of Materials Science: Materials in Electronics 32 26967 (2021)

Mirror symmetric nonreciprocity and circular transmission in cavity magnonics

Y. Shi, C. Zhang, C. Jiang, C. K. Ong, and G. Chai

Appl. Phys. Lett. 119 132403 (2021)

Dirac terahertz plasmonics in two and three dimensions

Kelvin J.A.Ooi, Y.S.Ang, Q.Zhai, X.Sun, P.Xing, C.K.On, L.K.Ang, and Dawn T.H.Tan

Optics Communications 462 125319 (2020)

Broadband strong optical dichroism in topological Dirac semimetals with Fermi velocity anisotropy

 J Lim, K J A Ooi, C Zhang, L K Ang, and Yee Sin Ang

Chinese Phys. B 29 077802 (2020)

Effect of Reducing Agent on Solution Synthesis of Li3V2(PO4)3 Cathode Material for Lithium Ion Batteries

Amirhossein Salehi, Dorsasadat Safanama , Chong Kim Ong , Stefan Adams  and Mogalahalli V. Reddy

Molecules 25 3746 (2020)

A solution synthesis of Na3V2(PO4)3 cathode for sodium storage by using CTAB additive

A.H. Salehi, S.M. Masoudpanah, M.Hasheminiasari, A. Yaghtin, D. Safanama,C. K. Ong, M.V. Reddy, and S. Adams

Solid State Ionics 347 115269 (2020)

Hypocycloid motion in the Melvin magnetic universe

Yen-Kheng Lim

Physical Review D 101 104031 (2020)

Magnetic properties and thermal stability of nanocrystalline Fe films prepared by oblique sputtering deposition method

Kh. Gheisari and C. K. Ong

Physica B: Condensed Matter 595 412365 (2020)

Research Grants/Projects
Mode coupling between magnons and other bosonic quasi-particles

C K Ong and GZ Chai,Lanzhou Uniersity

Magnons (the quanta of spin waves) are the dynamic eigen-excitations of a magnetically ordered magnet. It can carry information, and can be transported in insulators without charges, avoiding the energy loss caused by Joule heating. While individual magnon modes can be tuned by changing the parameters of the magnetic material, a new way to create new magnon is to achieve coupling by tuning the two modes into resonance, and the physical parameters of the coupled mode can be control in a larger range. This project intends to aim at experiments about the coupling between magnons or other quasiparticles, such as photons and phonons. In the point of view of physics, we would like to deepen the understanding of the intrinsic physical mechanism of the generation, regulation and manifestation of non-reciprocal behaviors of magnons. In terms of applications, we expect to provide references for designing microwave nonreciprocal devices using nonreciprocal properties of magnons.

Bio-electromagnetism of the Nervous System

C K Ong and Kelvin Ooi Jian Aun (funded by XMUMRF)

Electrical signal transmission in conductive channels would entail the phenomenon of electromagnetic wavepropagation. In nerve fibers, however, the established Hodgkin-Huxley model treats the saltatory conductionbetween nodes-of-Ranvier separated by Myelin sheaths as a purely electric-field capacitive charging-discharging effect . The celebrated model could accurately explain most of the experimental observations of simple nerve fibers found in squids, shrimps and earthworms, but may fail to explain some of the observations for complex mammalian nerve fibers. and analyze their advantages and disadvantages, while proposing that electromagnetic transmission models may be more suitable to explain nerve conduction in myelinated nerve fibers.                 


1. To understand the propagation of neural signals from an electromagnetic wave perspective.

2. To come up with new neuron models and their corresponding parameters                 

Algebraic and topological structure of spacetime geodesics

Y.-K. Lim (funded by XMUMRF)

In recent years, breakthroughs in gravitational physics such as gravitational wave detection and black-hole imaging has made many aspects of strong-field gravitational physics an observational reality, and hence a priority for theoretical understanding. For instance, the quasinormal merger of ringing and the radius of the black-hole shadow is related to photon orbits around a black hole spacetime. On the other hand, time-like particle orbits are related to the radii of the innermost stable circular orbits which can be observed by spectral line broadening of accretion disk emmissions. In this project, we wish to study the nature, properties, and existence of stable orbits (time-like and null) around black holes and other compact objects.

A first step in this project would be to carry over the methods of algebraic geometry to the formalism of geodesic analysis. Currently, the standard practice in literature is to derive the geodesic equations from which an effective potential is obtained. The properties of the effective potential is studied by analytical ornumerical methods. It turns out that the mathematical structure of the effective potential equations are equivalent to A-discriminantal varieties in algebraic geometry, for which there is a well-developed theory and formalism available. It is therefore worthwhile to translate this formalism to the problem of geodesics in general relativity. Once such a formalism is applicable to geodesics, it is hoped that we then have the tools to answer various questions. For instance, the existence of stable/unstable photon surfaces around a given compact object. Such tools may help in addressing whether observations such as gravitational waves or the M87/Sgr A* image are black holes or ultracompact objects, as well as constraining the parameters of alternative theories of gravity.

Quantitative bounds on non-classicality of mediator only from the gain of quantum entanglement it mediates

Paterek Tomasz (funded by XMURF)

Gravitation is the only fundamental interaction for which we have no direct evidence of quantum effects. One of the most promising routes towards direct verification of non-classical features of gravity relies on ideas from quantum information. Namely, if two masses get entangled via gravitational interaction the coupling field must admit non-classical features. This qualitative statement has been established in 2017 and since then has not been upgraded to a quantitative method. The main purpose of the present proposal is to fill this gap. To this aim we will study abstractly A three-body system composed of two particles over which we assume to have control (model of the masses) and a third object, that couples the particles, and is assumed to be unknown (model of the gravitational field).We shall derive lower bounds on various non-classicality quantifiers known in quantum information from the gain of entanglement between the particles.


A Glance at XMUMC