Jin Ming Koh

California Institute of Technology | CIT

Graphene and transition metal dichalcogenide flat-band systems show similar phase diagrams, replete with magnetic and superconducting phases. An abiding question has been whether magnetic ordering competes with superconductivity or facilitates pairing. The advent of crystalline graphene superconductors enables a new generation of controlled experim...

One of the fundamental tenets of quantum mechanics is that non-orthogonal states cannot be distinguished perfectly. When distinguishing multiple copies of a mixed quantum state, a collective measurement, which generates entanglement between the different copies of the unknown state, can achieve a lower error probability than non-entangling measurem...

We explore Bernal bilayer graphene in the presence of long-range Coulomb interactions, short-range Hund's coupling, and proximity-induced Ising spin-orbit coupling using self-consistent Hartree-Fock simulations. We show that the interplay between these three ingredients produces an intricate phase diagram comprising a multitude of symmetry-broken m...

Programmable quantum simulators may one day outperform classical computers at certain tasks. But at present, the range of viable applications with noisy intermediate-scale quantum (NISQ) devices remains limited by gate errors and the number of high-quality qubits. Here, we develop an approach that places digital NISQ hardware as a versatile platfor...

Current-day quantum computing platforms are subject to readout errors, in which faulty measurement outcomes are reported by the device. On circuits with mid-circuit measurements and feedforward, readout noise can cause incorrect conditional quantum operations to be applied on a per-shot basis. Standard readout error mitigation methods for terminal...

The quantum computation of molecular response properties on near-term quantum hardware is a topic of substantial interest. Computing these properties directly in the frequency domain is desirable, but the circuits require large depth if the typical hardware gate set consisting of single- and two-qubit gates is used. While high-fidelity multipartite...

Recent experiments indicate that crystalline graphene multilayers exhibit much of the richness of their twisted counterparts, including cascades of symmetry-broken states and unconventional superconductivity. Interfacing Bernal bilayer graphene with a WSe2 monolayer was shown to dramatically enhance superconductivity—suggesting that proximity-induc...

The quantum computation of molecular response properties on near-term quantum hardware is a topic of substantial interest. Computing these properties directly in the frequency domain is desirable, but the circuits require large depth if the typical hardware gate set consisting of single- and two-qubit gates is used. While high-fidelity multipartite...

Programmable quantum simulators such as superconducting quantum processors and ultracold atomic lattices represent rapidly developing emergent technology that may one day qualitatively outperform existing classical computers. Yet, apart from a few breakthroughs, the range of viable computational applications with current-day noisy intermediate-scal...

Recent experiments indicate that crystalline graphene multilayers exhibit much of the richness of their twisted counterparts, including cascades of symmetry-broken states and unconventional superconductivity. Interfacing Bernal bilayer graphene with a WSe$_2$ monolayer was shown to dramatically enhance superconductivity -- suggesting that proximity...

Quantum many-body systems subjected to unitary evolution with the addition of interspersed measurements exhibit a variety of dynamical phases that do not occur under pure unitary evolution. However, these systems remain challenging to investigate on near-term quantum hardware owing to the need for numerous ancilla qubits or repeated high-fidelity m...

Programmable quantum simulators such as superconducting quantum processors and ultracold atomic lattices represent rapidly developing emergent technology that may one day qualitatively outperform existing classical computers. Yet, apart from a few breakthroughs, the range of viable computational applications with current-day noisy intermediate-scal...

The quantum computation of molecular response properties on near-term quantum hardware is a topic of significant interest. While computing time-domain response properties is in principle straightforward due to the natural ability of quantum computers to simulate unitary time evolution, circuit depth limitations restrict the maximum time that can be...

Chiral edge states are highly sought after as paradigmatic topological states relevant to both quantum information processing and dissipationless electron transport. Using superconducting transmon-based quantum computers, we demonstrate chiral topological propagation that is induced by suitably designed interactions, instead of flux or spin-orbit c...

Non-hermiticity presents a vast newly opened territory that harbors new physics and applications such as lasing and sensing. However, only non-Hermitian systems with real eigenenergies are stable, and great efforts have been devoted in designing them through enforcing parity-time (PT) symmetry. In this work, we exploit a lesser-known dynamical mech...

Chiral edge states are highly sought-after as paradigmatic topological states relevant to both quantum information processing and dissipationless electron transport. Using superconducting transmon-based quantum computers, we demonstrate chiral topological propagation that is induced by suitably designed interactions, instead of flux or spin-orbit c...

Resolution of the intrinsic conflict between the reproduction of single cells and the homeostasis of a multicellular organism is central to animal biology and has direct impact on aging and cancer. Intercellular competition is indispensable in multicellular organisms because it weeds out senescent cells, thereby increasing the organism's fitness an...

The growing application of Parrondo’s paradox as a model in various ecological settings reveals its extensive relevance in biology and nature. To accommodate the apparent ubiquity of periodicity and quasi-periodicity in natural environments, a recent study proposed a capital-dependent Parrondo model coupled with periodic variations. However, the ab...

Significance Bacteriophages, the most widespread reproducing biological entity on Earth, employ two strategies of virus–host interaction: lysis of the host cell and lysogeny whereby the virus genome integrates into the host genome and propagates vertically with it. We present a population model that reveals an effect known as Parrondo’s paradox in...

Ergodic quantum many-body systems undergoing unitary dynamics evolve towards increasingly entangled states characterized by an extensive scaling of entanglement entropy with system volume. At the other extreme, quantum systems repeatedly measured may be stabilized in a measurement eigenstate, a phenomenon known as the quantum Zeno effect. Recently,...

In classical and single-particle settings, non-trivial band topology always gives rise to robust boundary modes. For quantum many-body systems, however, multiple topological fermions are not always able to coexist, since Pauli exclusion prevents additional fermions from occupying the limited number of available topological modes. In this work, we s...

Non-hermiticity presents a vast newly opened territory that harbors new physics and applications such as lasing and sensing. However, only non-Hermitian systems with real eigenenergies are stable, and great efforts have been devoted in designing them through enforcing parity-time (PT) symmetry. In this work, we exploit a lesser-known dynamical mech...

Influence maximization in a social network refers to the selection of node sets that support the fastest and broadest propagation of information under a chosen transmission model. The efficient identification of such influence-maximizing groups is an active area of research with diverse practical relevance. Greedy-based methods can provide solution...

In classical and single-particle settings, non-trivial band topology always gives rise to robust boundary modes. For quantum many-body systems, however, multiple topological fermions are not always able to coexist, since Pauli exclusion prevents additional fermions from occupying the limited number of available topological modes. In this work, we s...

In game theory, Parrondo's paradox describes the possibility of achieving winning outcomes by alternating between losing strategies. The framework had been conceptualized from a physical phenomenon termed flashing Brownian ratchets, but has since been useful in understanding a broad range of phenomena in the physical and life sciences, including th...

In the design of functionally graded materials, bi-directional design offers greater design freedom than the typical single-direction approach. This paper studies the shape and size design of variable-thickness bi-directional functionally graded plates (2D-FGPs) with multi-objective optimization. A method integrating generalized iso-geometrical ana...

Recent studies suggest that the tetracycline antibiotic minocycline, or its cousins, hold therapeutic potential for affective and psychotic disorders. This is proposed on the basis of a direct effect on microglia‐mediated frontocortical synaptic pruning (FSP) during adolescence, perhaps in genetically susceptible individuals harboring risk alleles...

Recently, a population model has been analyzed using the framework of Parrondo’s paradox to explain how behavior-switching organisms can achieve long-term survival, despite each behavior individually resulting in extinction. By incorporating environmental noise, the model has been shown to be robust to natural variations. Apart from the role of noi...

In response to the transboundary haze problem in Southeast Asia, a physical model is adopted to simulate the spread and extinguishing of fire. This study is done in the context of Dumai, Indonesia, as it is one of the areas that significantly contribute to the haze problem. This model aims to provide perspectives on the persistence of forest fires...

Many predators produce dormant offspring to escape harsh environmental conditions, but the evolutionary stability of this adaptation has not been fully explored. Like seed banks in plants, dormancy provides a stable competitive advantage when seasonal variations occur, because the persistence of dormant forms under harsh conditions compensates for...

In this paper, a co-evolution method of game dynamics and network structure is adopted to demonstrate that neighboring niches of an individual or population may have great influence in determining lifestyle adoption. The model encompasses network structure evolution, denoted CaseA, and pure games participated in by individuals in the network with t...

The Parrondo's paradox is a counterintuitive phenomenon in which individually losing strategies, canonically termed game A and game B, are combined to produce winning outcomes. In this paper, a co-evolution of game dynamics and network structure is adopted to study adaptability and survivability in multi-agent dynamics. The model includes action A,...

Data centers are mission-critical infrastructures. There are strict service level requirements and standards imposed on operators and maintainers to ensure reliable run-the-clock operation. In the context of thermal management and data hall environmental control, the formation of hot and cold spots around server cabinets are especially undesirable,...

A minimalistic multi-agent Parrondo’s game structure with branching dependent on local capital spread was previously introduced, indicating that stochastically mixing two losing games can produce winning outcomes with bounded capital variance among players. Using a similar game structure, we unveil further intriguing behavior that a bias toward sel...

Air pollution has emerged as one of the world's largest environmental health threats, with various studies demonstrating associations between exposure to air pollution and respiratory and cardiovascular diseases. Regional air quality in Southeast Asia has been seasonally affected by the transboundary haze problem, which has often been the result of...

Thermal and visual comfort are important for the health and productivity of occupants in office buildings. In this paper, we present a simulation-aided approach in analyzing and optimizing lighting and thermal conditions in building interiors, encompassing the modelling of the interior space in virtual facilities, ray-tracing simulations for illumi...

Fluid-filled shells are near-ubiquitous in natural and engineered structures-a familiar example is that of glass harps comprising partially filled wineglasses or glass bowls, whose acoustic properties are readily noticeable. Existing theories modelling the mechanical properties of such systems under vibrational load either vastly simplify shell geo...

We present an efficient and scalable system to predict emergency department (ED) patient volume in hospitals using publicly available Google Trends search data. Search volume data is retrieved for a selected set of context-relevant query keywords with refinements, on which a series of correlation analyses is performed, and a multiple regression pre...

Classical refractors require at least two lenses, an objective and an eyepiece, to achieve image magnification and focusing. In this study, a minimalistic telescope design consisting of a single lens and a small aperture (the single-lens telescope) is examined. The design exploits the angular limiting properties of the aperture to achieve approxima...

Despite the major roles played by genetic recombination in ecoevolutionary processes, limited progress has been made in analyzing realistic recombination models to date, due largely to the complexity of the associated mechanisms and the strongly nonlinear nature of the dynamical differential systems. In this paper, we consider a many-loci genomic m...

Parrondo's paradox, in which losing strategies can be combined to produce winning outcomes, has received much attention in mathematics and the physical sciences; a plethora of exciting applications has also been found in biology at an astounding pace. In this review paper, the authors examine a large range of recent developments of Parrondo's parad...

Recent waves of controversies surrounding genetic engineering have spilled into popular science in Twitter battles between reputable scientists and their followers. Here, a cautionary perspective on the possible blind spots and risks of CRISPR and related biotechnologies is presented, focusing in particular on the stochastic nature of cellular cont...

Parrondo’s games to date have largely focused on the dynamics of capital mean, and not capital spread—the potential of the framework in modelling ecological and socioeconomic sustainability and inequality has thus been ignored. Based on behavioural heuristics of distinct individualistic and multipartite interactive strategies, we introduce a novel...

The dynamics of a spherical pendulum with a horizontally rotating support, exhibiting regimes of intriguing lagging behaviour in the presence of aerodynamic drag, is analysed in the present study. The dynamic equilibria of the pendulum are derived through both numerical and analytical means, with excellent experiment agreement across key system par...

Not all workable spectrometer systems can be represented by an exact analytical field; furthermore, while traditional design methods typically involve approximating known analytical fields with appropriate electrode/magnet configurations, modern simulation-based approaches do away with analytical representations altogether. Nonetheless, analytical...

The advent of social media and technologies augmenting social communication has dramatically amplified the role of rumour spreading in shaping society, via means of misinformation and fact distortion. Existing research commonly utilize contagion mechanisms, statistical mechanics frameworks, or complex-network opinion dynamics models. In this paper,...

Background Prior studies have demonstrated correlations between air pollution and cardiovascular deaths. This study specifically investigates the association between air pollution and acute myocardial infarction (AMI) incidence in Singapore, a Southeast Asian city exposed to seasonal transboundary haze. Methods A time-stratified case-crossover stu...

Advancements in computational tools have driven increasingly automated, simulation-centric approaches in the design and optimization of spectroscopic electron-optical systems. These augmented methodologies accelerate the optimization process, and can yield better-performing instruments. While classical gradient-based methods had been explored, mode...

We remark on Nelson and Masel’s (2017, 2018) papers [Intercellular competition and the inevitability of multicellular aging, Proc. Natl. Acad. Sci. USA114 (2017) 12982–12987; Reply to Cheong et al.: Unicellular survival precludes Parrondo’s paradox, Proc. Natl. Acad. Sci. USA115 (2018) E5260, doi:10.1073/pnas.1806709115], addressing the connection...

The subject of probability and statistics is easily dismissed by students as assemblages of formulae to be rote-memorized. We propose here an integration of simulation-based activities with certain mathematical paradoxes using patchwork assessment to first-year undergraduates, such that they can better appreciate the real-world context of probabili...

Video surveillance is gaining popularity in numerous applications, including facility management, traffic monitoring, crowd analysis, and urban security. Despite the increasing demand for closed-circuit television (CCTV) and related infrastructure in public spaces, there remains a notable lack of readily-deployable automated surveillance systems. I...

Abstract When imaging bright light sources, rays of light emanating from their centres are commonly observed; this ubiquitous phenomenon is known as the starburst effect. The prediction and characterization of starburst patterns formed by extended sources have been neglected to date. In the present study, we propose a novel trichromatic computation...

In the present study, we present a virtual learning laboratory environment for undergraduate mathematics education using an inquiry-based learning approach. The Visible Thinking pedagogical framework is also suggested to achieve a good complement to traditional lecture-tutorial systems. The virtual laboratory is implemented in an open-access Java i...

Previously, we developed a population model incorporating the Allee effect and periodic environmental fluctuations, in which organisms alternate between nomadic and colonial behaviours. This switching strategy is regulated by biological clocks and the abundance of environmental resources, and can lead to population persistence despite both behaviou...

The Crow-Kimura model is commonly used in the modeling of genetic evolution in the presence of mutations and associated selection pressures. We consider a modified version of the Crow-Kimura model, in which population sizes are not fixed and Allee saturation effects are present. We demonstrate the evolutionary dynamics in this system through an ana...

In the current study, we demonstrate an automated optimization method based on the Levenberg–Marquardt algorithm for electron-optical systems, incorporating an adaptive merit function switching process that enhances minimization convergence. The algorithm is successfully applied to three energy spectrometer designs—a radial mirror analyzer, a paral...

Recent years have witnessed the proliferation of worldwide efforts towards developing technologies for enabling smart cities, to improve the quality of life for citizens. These smart city solutions are typically deployed across large spatial regions over long time scales, generating massive volumes of data. An efficient way of data retrieval is thu...

We design and implement an Android application, Sensorem, for efficient retrieval and visualization of wireless sensor network (WSN) data. In light of data distribution and visualization being important developmental keystones of smart cities, we seek to enhance sensor data accessibility by developing a user-friendly mobile application (Sensorem) f...