MSE Department Seminar

In low-dimensional and nanostructured materials, the optical response is dominated by correlated electron-hole pairs---or excitons---bound together by the Coulomb interaction. By now, it is well-established that these large excitonic effects in low dimensions are a combined consequence of quantum confinement and inhomogeneous screening. However, many challenges remain in understanding nonlinear and dynamical processes, especially when it comes to correlating complex experimental signatures with underlying physical phenomena using quantitatively predictive theories.

An increasingly large number of van der Waals materials have been found to be direct-bandgap semiconductors that feature simultaneously strong optical responses, unusual material properties, and unprecedented flexibility to construct heterostructures and to integrate with diverse substrates. These features enable access to coherent light-matter interaction regimes that are challenging or even inaccessible in traditional materials.

Living tissues grow and organize through a continuous feedback loop between mechanics and biological decision-making. Here, I present a framework that treats each cell as a “computing unit,” making discrete decisions such as division, differentiation, or migration, based on local mechanical and chemical cues. Drawing inspiration from Hopfield networks, we model these decisions as threshold-based rules whose interactions produce emergent, tissue-scale mechanics. This perspective allows us to bridge the gap between the physics of soft matter and the logic of biological computation.

In the pursuit of a sustainable future, the last decade has seen a concerted effort in accelerating the discovery of materials for energy needs. In this talk I will focus on few 2D materials that provide the playground for understanding and manipulating their chemical and physical properties to harness novel functionalities. I will show how defects in single-layer hexagonal boron nitride (h-BN) transform the local electronic structure such that it captures and converts CO2 to value added products [1].

The possibilities of manipulating magnetization without applied magnetic fields have attracted growing attention over the last two decades. The low-power manipulation of magnetization, preferably at ultra-short time scales, has become a fundamental challenge with implications for future magnetic information storage and memory technologies. I will discuss recent experiments on the optical manipulation of the magnetization of engineered materials and devices using 50-5000 fs optical pulses.

Quantum materials provide responses and states of matter with no classical analogs. As such, they offer opportunities to create various platforms for future devices crucial to human health, energy efficiency, communications, and imaging. I will describe the physics challenges and sensing opportunities these materials offer, including our efforts to detect novel nonlinear responses and emergent quasi-particles using light. I will then focus on using the relativistic electrons in graphene for biosensing.

The phenomena in which a magnetic or electric polarization is induced via an external electric or magnetic field has attracted renewed research interest owing to the possibility of creating novel electronic and optoelectronic devices. In this direction, multifunctional materials such as multiferroics, with their enhanced coupling between electronic, vibrational, and spin degrees of freedom, are ushering in a new era of revolutionary advances in optoelectronics, spintronics, and quantum sensing.

A crucial yet unavailable component in high-performance photonic integrated circuits (ICs) and other chip-scale photonic systems is an on-chip light source that is efficient, functional, IC-compatible, and electronically addressable. In this talk, I will cover several types of on-chip sources, including perovskite microlasers and luminescent hyperbolic metamaterials, topologically protected microlasers on the III-V platform, as well as spintronic THz emitters on the III-N platform.

Quantum technologies have progressed greatly over the past 3 decades, with qubits coherence times approaching millisecond lifetimes. However, it is recognized that to scale quantum computing to the level required for tackling problems of practical importance, many challenges remain. Challenges including predictability & stability of qubit performance, circuit size shrinking, qubit control / read-out, and quantum signal transduction to telecom-optical wavelengths need to be urgently addressed.

We provide an overview of a NASA University Leadership Initiative project entitled “Development of an Ecosystem for Qualification of Additive Manufacturing Processes and Materials in Aviation”. This involved multiple universities and other collaborators working together to build a quantitative connection between AM processing, microstructure and properties in laser powder bed fusion of Ti-6Al-4V. Microstructure focused on defect structure and the key property was fatigue.