2025 Annual Physics Poster Competition

Eundeok Mun

Transition Metal Dichalcogenide MX₂

Robert F. Frindt. 

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Sungeun Oh

Global Quantum Security Network

Quantum mechanics brought a revolutionary shift in technology of network, particularly by introducing the concept of a quantum security network. The persistence of hacking is largely due to the fact that conventional encryption keys are not truly random but rather predictable and susceptible to interception by third parties. The inherent quantum randomness exhibited by particles in nature makes them an ideal candidate for generating truly random keys, offering a promising solution to fortify network security. Currently, Canada is funding the Quantum Encryption and Science Satellite (QEYSSat) mission through the Canadian Space Agency (CSA) to advance long-distance quantum communication. In this work, we present an overview of this mission and its objectives.

George Lertzman-Lepofsky

Energy Landscape of Noncollinear Exchange Coupled Magnetic Multilayers

Spin-transfer and spin-orbit torque magnetic random-access memory (STT/SOT-MRAM) designs promise to combine the density and low-cost of dynamic RAM, the performance of static RAM, and the non-volatility of traditional magnetic hard drives, and yet the switching currents and write-error-rates of state-of-the-art devices remain unacceptably large. In this work, we conduct an exploration of the energy landscape of two coupled ferromagnetic layers with perpendicular-to-plane uniaxial anisotropy, Ku, using finite-element micromagnetic simulations. These multilayers can be used to produce noncollinearity in the reference layers of STT/SOT-MRAM cells, which has been shown to increase the performance of these classes of MRAM by ensuring a non-zero spin-torque at the beginning of switching processes. We show that there exists a range of values of the interlayer exchange coupling constants, J1 and J2, for which the magnetic state of these multilayers can relax into either one or two energy minima, depending on the initial conditions of the multilayer, parallel (PP) or antiparallel (AP). A noncollinear antiparallel state with one minimum is optimal for use in STT/SOT devices and we show that there is a wide range of experimentally achievable coupling constants that can produce such alignment. This range increases with the difference in the ferromagnetic layer anisotropies. We further investigate the thermal stability of the structures in the two minima regions, using string method simulations to determine the energy barriers. We show that the stabilities of the minima increase with increasing difference in the anisotropy of the ferromagnetic layers. Finally, we provide an analytical solution to the location of the minima in the energy landscape of coupled macrospins, which has good agreement with our micromagnetic results for a simplified case involving ferromagnetic layers with the same thickness and anisotropy.

Nicholas Pranjatno

In Search of New Excited States In ¹¹⁴Sn from the Positron Decay Of ¹¹⁴Sb

Nuclei with fully filled proton and neutron shells are considered “magic” and, analogous to noble gases, are traditionally known to be extra stable and have spherical shapes. However, recent experimental observations of rotational bands, located at high excitation energies, built on their lowest energy state suggested that nuclei with magic numbers of photons or neutrons can also have shapes that are different from the expected spherical shape. This phenomenon is called shape coexistence. The semi-magic 110-122Sn isotopes display signs of shape coexistence and this study aims to further explore these effects on 114Sn. This experiment was performed at the ISAC facility of TRIUMF. Excited states of 114Sn were populated through the β+/electron capture decay of 114Sb. The decay of these excited states was then observed using the GRIFFIN decay station. GRIFFIN is composed of 15 Clover-type Compton-suppressed High Purity Germanium (HPGe) detectors and is coupled to PACES and the ZDS ancillary detectors, used to detect conversion electrons and β-decay electrons, respectively. Data from these detectors were used to construct the level scheme of 114Sn. Preliminary results from the analysis will be presented and discussed.

Michael Yakovlev

Atypical Vortex Lattice and the Magnetic Penetration Depth in Superconducting Sr₂RuO₄ Deduced by μSR

This study investigates the in-plane magnetic penetration depth (λ_ab) in the vortex state of the unconventional superconductor Sr₂RuO₄ using the muon spin rotation (μSR) technique, with a focus on its implications for the superconducting order parameter. Recent μSR studies report a linear temperature dependence of λ_ab at low temperatures, contrasting with earlier results. However, our analysis reveals no significant difference between the datasets, instead showing compatibility with a limiting λ_ab ∝ T² dependence. Furthermore, we identify an unusual square vortex lattice, introducing a new constraint on possible superconducting order parameters for Sr₂RuO₄ and highlighting the need for a more reliable theoretical framework to determine absolute values of λ_ab from μSR.

Heinz Asch

Mirror Symmetry in the f7/2 Shell below 56Ni: Excited States and Electromagnetic Transition Rates in 55Ni and 55Co

Nuclear theories often assume that the strong nuclear force is independent of electric charge and therefore treats protons and neutrons interchangeably. This independence can be probed by comparing pairs of mirror nuclei, where each pair has the property that one partner's proton (neutron) count is the other's neutron (proton) count. By comparing mirror nuclei such as 55Ni and 55Co, one can demonstrate the electric dependence of the strong force. The data to do this comes from experiments which aimed to produce and measure 55Ni and 55Co by utilizing high intensity beams, volatile calcium targetry, high resolution gamma-ray spectroscopy, charged particle identification, and recoil-nucleus mass separation at TRIUMF. This presentation will focus upon the cutting-edge selectivity provided by this never-before-seen combination of beam, target, and detection apparatus to demonstrate how studies of this kind can be conducted and what state the ongoing analysis is in

Jordan Sawchuk

Hierarchy of Manifolds in Thermodynamic Geometry

Whether by our ignorance or for our advantage, many interesting physical systems can be modelled as continuous-time Markov chains: one imagines a system stochastically jumping between a set of N states, the randomness reflecting information tossed out during model construction. Even without perfect knowledge of a system's state in time, we might like to control it to accomplish some task. For a variety of experimental and theoretical applications, one is interested in minimum work protocols, i.e. driving schedules that minimize the expended work on average. The friction-tensor formalism is a near-equilibrium asymptotic approximation that renders the optimization more tractable. In doing so, it introduces an abstract thermodynamic geometry. I detail some of the insights and opportunities afforded by seriously engaging with this abstraction: the construction of a global manifold drastically reduces computational costs and unveils an intimate connection between the thermodynamic metric tensor and the equilibrium relaxation dynamics of the controlled system. What immediately follows is a new notion of extrinsic thermodynamic geometry which permits comparison of control parameter sets prior to computation of optimal protocols and which may have powerful implications in reaction coordinate identification.

W. Callum Wareham

Periodic Optimal Control in Stochastic Thermodynamics

Many of the cell's important functions are performed by molecular machines; tiny protein walkers, turbines, and factories, often tasked with converting one form of energy to another. Unlike macroscopic machines, these proteins must contend with random thermal fluctuations of a similar scale to their size and energy. A ubiquitous example is FOF1 ATP synthase, a rotary motor which is the final step in converting energy from food or sunlight to adenosine triphosphate (ATP), a common cellular energy currency. Efficient and fast operation of this machine in vivo should therefore be selectively favorable for the organism. Optimal control theory is a theoretical framework that can be used to understand efficient operation of stochastic systems like molecular machines. However, most work in this field has focused on processes that either do not repeat or that occur slowly (near equilibrium), and the key assumptions of these results do not apply to ATP synthase. In this poster presentation, I will discuss the unique characteristics of this periodic optimal control problem, and describe our preliminary progress towards a solution.

Nasim Nozarnejad

Lilianna Hariasz

Dilraj Ghuman
 

Calibration Instruments for the Pacific Ocean Neutrino Experiment

The Pacific Ocean Neutrino Experiment (P-ONE) is a cubic-kilometer scale neutrino telescope to be deployed in the northern Pacific Ocean off the West Coast of Canada. P-ONE will observe high-energy neutrinos using an array of kilometer tall mooring lines instrumented with P-ONE Optical Modules (P-OMs) which detect Cherenkov light from neutrino-induced secondary particles within the detector volume. To accurately understand the signals from incident neutrinos, the optical properties of seawater, detector geometry, and optical backgrounds must be precisely calibrated. However, the ocean is a dynamic environment where these parameters can vary over time. To achieve this goal, P-ONE includes a variety of calibration systems for both localized and ranged real time detector calibration measurements. These include integrated small, fast light flashers for optical inter-module measurements, acoustic receivers for spatial trilateration, and auxiliary sensors for tilt and orientation measurements. The acoustic positioning system is further complemented with autonomous and cabled acoustic pingers on the seafloor. In addition, some P-OMs in the detector are designed as hybrid calibration modules (P-CALs) which additionally contain long-range, isotropic nanosecond light flashers and cameras. This poster highlights the simulation, development, and field testing of all P-ONE calibration systems

Noor E Kainat

Exploring the Excited States of 114Sn with the GRIFFIN Spectrometer at TRIUMF

Tin (Sn), with its magic proton number Z = 50, stands out in the chart of nuclides for having the maximum number of stable isotopes, making it an ideal candidate for testing theoretical models aimed at describing the effective nuclear force. The semi-magic nucleus 114Sn, with N = 64, is situated in the neutron mid-shell between the N = 50 and N = 82 magic numbers. Sn isotopes that have an even number of protons and neutrons, such as 114Sn, typically have a spherical shape in their ground states. However, these isotopes exhibit excited states with characteristics of deformed shapes in a narrow energy range; a phenomenon called shape coexistence. The deformed shape arises from a 2-particle 2-hole (2p-2h) excitation across the Z = 50 proton shell gap, promoting two protons into higher unoccupied orbitals while leaving two holes in the original lower energy orbitals. This deformation presents as low-lying excited 0+ states. Though it has been observed in neighboring Sn nuclei, key information about these intruder bands in 114Sn remains missing. To investigate these intruder bands and thus shape coexistence in 114Sn, the competing betadecay and electron capture of 114Sb were used to populate excited states in 114Sn at TRIUMF’S ISAC facility. The GRIFFIN spectrometer, composed of up to 16 HPGe detectors, is a gammaray spectrometer coupled to a plastic scintillator detector for beta particle detection and 5 Si(Li) detectors for internal conversion electrons. These were used to detect events associated with 114Sn. The investigation will allow a more in-depth understanding of the intruder configurations and their band-heads in 114Sn. Current analysis and recent findings will be presented.

Siddharth S. Sane

How (not) to measure the distance to equilibrium

The Mpemba effect is the counterintuitive fact that certain systems can cool to room temperature more rapidly if their initial temperature is hotter. Critical to the analysis of such systems is a distance function with a set of well-defined properties that allows one to quantitatively describe how far a given system is from equilibrium. This is particularly important because the Mpemba effect, a nonequilibrium phenomenon, often deals with systems that do not have a well-defined temperature at intermediate times. Some recent research has used the average energy of the system instead of standard distance functions to characterise the Mpemba effect. However, using the average energy to describe the distance to equilibrium can lead to major unintended consequences. This poster will discuss some of those consequences.

Sepideh Mirabi

Angle-dependent magnetoresistance in the presence of magnetic breakdown and temperature dependence anisotropic scattering

Angle-dependent magnetoresistance oscillations (AMRO) are a powerful technique for exploring the Fermi surfaces of layered quantum materials. In an AMRO experiment, the resistivity perpendicular to conducting layers is measured as a function of an applied magnetic field. In a sufficiently strong magnetic field, the electron tunnels from one segment of the Fermi surface into another, creating new orbits known as magnetic breakdown. We use a Boltzmann equation framework to study AMRO for materials with anisotropic Fermi surfaces and anisotropic scattering in combination with magnetic breakdown.

Jonathan Barenboim

Sara Iranbakhsh

Zachary Podrebersek and Obinna Uzoh

Electronic Structure and Quantum Oscillations of LaTiGe3

High-quality single crystals of LaTiGe3 have been successfully grown from a high-temperature ternary melt. The physical properties are investigated by measurements of specific heat, electrical resistivity, thermoelectric power, and magnetization. In addition, the Fermi surface topology and band structure is modeled using Density-Functional-Theory (DFT) techniques. Quantum oscillations are clearly observed from all physical property measurements in magnetic fields as low as 10 kOe and at temperatures as high as 45 K. In earlier studies no quantum oscillations were observed from both single-crystal and polycrystalline samples. The large residual resistivity ratio (= 57) and quantum oscillations indicate relatively high quality of LaTiGe3 samples used in the present study. Several small electron effective masses (~ 0.03 me) are obtained from the analysis of the de Haas-van Alphen (dHvA) oscillations, which is consistent with both the small electronic specific heat coefficient 3.8 mJ/mole-K2 and the complex Fermi surface topology from DFT analysis.

Seyed Hamidreza Mirpoorian

Modified recombination and the Hubble tension

We investigate the extent to which modifying the ionization history at cosmological recombination can relieve the Hubble tension, taking into account all relevant datasets and considering the implications for the galaxy clustering parameter $S_8$ and the matter density fraction $\Omega_m$. We use the linear response approximation to systematically search for candidate ionization histories parameterized with a cubic-spline that provide good fits to the Planck CMB and DESI BAO data while relieving the $H_0$ tension, followed by MCMC fits of the most promising candidate models to the data. We also fit to the data a physically motivated phenomenological model of ionization history that has four parameters. Our main result is that models of modified recombination can reduce the Hubble tension to below 2$\sigma$ while improving the fit to the current CMB and BAO data and reducing the $S_8$ tension. The promising candidate ionization histories have simple shapes, with no need for an oscillatory dependence on redshift. Our study also demonstrates the importance of the high-resolution CMB temperature and polarization anisotropies for constraining modified recombination, with the candidate models in this study showing varying levels of agreement with the current ACT DR4 and SPT-3G data

Juliana Lisik

Noncollinear Magnetic Coupling Across IrFe Spacer Layers

Antiferromagnetic interlayer exchange coupling between two ferromagnetic layers across a nonmagnetic spacer layer is incorporated into almost all spintronic devices. However, the optimal design of spintronic devices almost always requires noncollinear alignment between ferromagnetic layers. Recently, we discovered that the coupling angle between two Co layers can be precisely controlled between 0° (ferromagnetic alignment) and 180° (antiferromagnetic alignment) by adding a magnetic material, Fe or Co, to a nonmagnetic Ru spacer layer [1,2]. In the current work [3], we studied IrFe spacer layers between two Co layers and found that the spacer layer composition and thickness range of Co|IrFe|Co is significantly larger than that of Co|RuFe|Co or Co|RuCo|Co. Notably, we achieved the largest antiferromagnetic coupling strength ever observed across spacer layers of 0.6 nm or thicker. After annealing our Co|IrFe|Co samples at 350°C for 1 hour, which is typical for device fabrication, we found that orthogonal (90°) coupling is favoured across the majority of the samples. Since the highest sensitivity of magnetic sensors is achieved through orthogonal alignment of neighbouring magnetic layers, IrFe could enable new designs for sensors. Measurements of the saturation magnetization of Co|IrFe|Co structures revealed that IrFe has a magnetic moment in the spacer layer composition range for which noncollinear coupling is observed. As described in the current work, this indicates that the origin of noncollinear coupling in Co|IrFe|Co could be attributed to the competition between the antiferromagnetic coupling of magnetic atoms across Ir atoms in the spacer layer and the ferromagnetic coupling of neighbouring magnetic atoms.

Prithviraj Basak

Forgetting information benefits work

Information engines represent a fascinating approach to powering engines and extracting work, with recent experiments and theoretical studies enhancing our understanding of these concepts. In the classical Szilard engine, a Maxwell demon is envisioned to make perfect measurements, allowing for complete work extraction from stored information. Yet, real systems often have structural limitations that render some observations ambiguous when extracting work. For instance, a crooked divider in a Szilard engine can obscure the precise location of a particle. Inspired by the recent work of Daimer and Still [1], we experimentally realize optimally encoded measurements on a Szilard engine, where the divider’s shape introduces an ambiguous region and observations made in this region are not useful for work extraction. Using feedback optical tweezers to manipulate a colloidal particle in water, we explore the implications.

Avijit Kundu

Heat flow can distinguish information engines from conventional ones

Information engines provide a compelling framework for explaining the second law of thermodynamics by converting thermal fluctuations into useful work. Molecular motors, such as kinesin, are thought to operate through fluctuating-ratchet mechanisms independent of the system's state. Using feedback optical tweezers, we experimentally emulate this motor dynamic and compare it to a conventional engine, where a trapped bead is dragged at constant velocity. We show that heat flow between the cargo and its environment reveals the type of driving mechanism in molecular transport systems and present an estimator for heat flow based solely on the cargo's mean-squared displacement, eliminating the need for direct motor observation. Our findings indicate that while conventional engines dissipate energy as heat, information engines draw heat from the bath, reversing the direction of heat flow. Although complete knowledge of bead and trap states is required to measure these flows, we demonstrate that the statistical properties of cargo motion alone suffice to classify engine mechanisms, providing new insights into molecular motor operations.

Katarina Preocanin

Developments in Collinear Fast Beam Laser Spectroscopy (CFBS) at TRIUMF

Collinear Fast Beam Laser Spectroscopy (CFBS) is an ultra-sensitive, Doppler-free spectroscopy method suited to perform laser spectroscopy on short-lived radioactive isotopes. TRIUMF, Canada’s particle accelerator centre, is located on the south UBC campus and operates the radioactive ion beam facility, ISAC. Here, radioactive isotopes with half-lives as short as a few milliseconds are extracted as fast ion beams, upon which CFBS can be performed. Ions extracted from the on-line ion source are velocity bunched in the beam direction to a Doppler width below the natural linewidth of the probed optical transitions. Consequently, Doppler-free laser spectroscopy can be performed on all atoms in the beam, yielding the highest sensitivity. We can resolve the optical isotope shift for optical transitions between isotopes of the same element, which corresponds with changes in nuclear mean-squared charge radii. We can also fully resolve the optical hyperfine structure and thus derive nuclear moments and nuclear spin. My experiment uses CFBS to measure optical isotope shifts and hyperfine structures in the 216 nm optical ground state transition in astatine – the rarest element on earth - to improve on previous in-source resonance ionization spectroscopy. The difficulty with CFBS on astatine is that it requires the neutralization of the incoming fast ion beam, production of CW ultraviolet laser light, and creation of an optical system suitable for astatine fluorescence detection. Not only is 216 nm difficult to detect, but the fluorescence detection also suffers from laser scatter background, since the wavelength of atomic fluorescent light is close to that of the exciting laser light. I designed an optical detection system to detect 216 nm astatine fluorescence and minimize the laser scatter background. We aim to conduct CFBS on astatine in the upcoming TRIUMF radioactive beam schedule 148 from May-December 2025

Afan Terko

David Lister

Growth of Cubic GaN on Patterned Si(100)

Cubic gallium nitride offers a performance advantage over hexagonal gallium nitride for optoelectronics due to its lack of intrinsic polarization along the growth axis. This significantly reduces the quantum-confined Stark effects, raising the speed and efficiency of carrier recombination. This study investigates the growth of c-GaN on patterned Si(100) substrates using organometallic vapor phase epitaxy via selective area epitaxy. By leveraging anisotropic KOH etching to expose Si(111) facets, we enable the controlled nucleation and coalescence of c-GaN. Initial results, confirmed via TEM diffraction and XRD, demonstrate successful c-GaN formation.

Tzu-Wei Kuo