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Seminars

Due to the Covid-19 pandemic all Fall 2020 and Spring 2021 Seminars will be Virtual.

Zoom Links will be provided on the calendar and through email.

Center for Soft Matter and Biological Physics Seminars

Spring 2021

Organizer: Vinh Nguyen

These meetings occur on Mondays from 4:00pm to 5:00pm
Virtual Zoom Seminars (unless otherwise indicated)

January 2021
January 18

Monday 4:00pm
Virtual Zoom

(poster)

Martin Luther King Jr. Day

No Seminar

Host:

January 25

Monday 4:00pm
Zoom Link
(poster)

Joint CDM & CSB Seminar

Dr. Sascha Wald (Dresden, Germany)

NON-EQUILIBRIUM DYNAMICS IN MANY-BODY QUANTUM SYSTEMS

We study dynamical transition phenomena in analytically solvable many-body quantum systems. Here, we focus on the quantum spherical model and other closely related models that have proven to be a valuable tool for the study of universal properties where one would usually strictly employ numerical methods. We show how the external constraints that define these models can induce surprisingly rich dynamical behavior, such as chaotic phases and freezing-by-heating transitions, on relatively simple single-body systems. We then discuss a naive Lindblad approach to the many-body dynamics and we pinpoint the shortcomings of such an approach. To overcome these problems, we present a physical motivation of how to formulate sensible many-body quantum dynamics using quantum Langevin equations and we apply this type of dynamics to quench problems in the quantum spherical model

Host: Uwe Tauber

February 2021
February 1

Monday 4:00pm
Zoom Link
(poster)

No Seminar

Host:

February 8

Monday 4:00pm
Zoom Link
(poster)

Condensed Matter Seminar

Prof. David Pekker (University of Pittsburgh)

"Simulating the dynamics of braiding of Majorana zero modes on the IBM quantum computer"

Topological quantum computing relies on braiding of non-abelian anyons like Majorana zero modes. While there has been considerable work on Majorana zero modes in engineered superconducting-semiconducting systems, thus far all attempts at observing branding experimentally have failed. Being interested in quantum simulation and braiding, it was natural to attempt to simulate the dynamics of braiding on an IBM quantum computer. Our first attempt failed as we found that the native quantum gates introduce too much noise. In order to overcome this problem, we used Qiskit Pulse to develop scaled two-qubit quantum gates that better match the unitary time evolution operator and enable us to observe braiding. This work demonstrates that quantum computers can indeed be used for simulating non-trivial quantum dynamics and highlights the use of pulse-level control for programming quantum computers. Finally, we remark that as far as we know our work is the first demonstration of braiding in a quantum system.

Host: Ed Barnes

February 15

Monday 4:00pm
Zoom Link

(poster)

No Seminar

Host:

February 22

Monday 4:00pm
Zoom Link

(poster)

Condensed Matter Seminar

Prof. Yi-Ting Hsu (University of Notre Dame)

"Inversion-protected Majorana corner modes: A case study of superconducting mono-layer WTe2"

Mono-layer WTe2, an inversion-symmetric transition metal dichalcogenide, has recently been established as a quantum spin Hall insulator and found superconducting upon gating. It is therefore natural to wonder whether this discovered superconductivity is topological. In this talk I will first show that gated mono-layer WTe2 in fact satisfies a general recipe we find for an inversion-protected ``higher-order" topological superconductor. Such a class of 2D superconductors feature Majorana corner modes. Then I will present numerical results demonstrating that corner Majoranas indeed appear throughout the WTe2 superconducting phase diagram self-consistently. Finally, I will discuss the bulk-boundary correspondence and present topological in variants that can diagnose the type of Majorana boundary modes from ab initiation band structures. Our topological in variants could guide future material search for more candidate superconductors hosting corner Majoranas without utilizing proximity effect.

Host: Kyungwha Park

March 2021
March 1

Monday, 4:00pm
Zoom Link
(poster)

No Seminar

Host:

March 8

Monday 4:00pm
Zoom Link
(poster)

No Seminar

Host:

March 15

Monday 4:00pm
Zoom Link

(poster)

March Meeting-No Seminar


Host:

March 22

Monday 4:00pm
Zoom Link

(poster)

Joint CDM & CSMB Seminar

Prof. Reza Mirzaeifar (Mechanical Engineering, Virginia Tech)

"Metal-Graphene Composites"

For years, in classic engineering, tremendous amount of work was dedicated to improve the metals properties by utilizing various therm-mechanical post-processing techniques. But at some point, almost everyone was accepting those methods have reached a saturation and modifying these techniques can only make insignificant improvements in mechanical properties. In recent years the idea of using some nano materials (such stenographer) changed the whole story and promised a chance to drastically improve the metals performance. However, in the process of reinforcing metals materialization many challenges evolved when the initial theoretical concepts-were tried to be implemented in practical applications. Although nano materials exhibit ultra-high strength and large recoverable strains (due to the absence of crystalline defects in their structure), when a nano-filler, e.g. graphene,is added to conventional metal matrices to create composites, their exceptional intrinsic mechanical properties cannot be fully harvested. This failure in achieving the intrinsic large elastic strain and high strengths of nano materials, once they are in composite, is commonly dubbed the “valley of death”, pointing to the loss of mechanical performance over two different length scales. In this talk, we review our recent investigations nonmetal-geographer composites and a new concept of matching the large recoverable strain in the transforming metal matrix with the large elastic strain of the graphene. Using the large recoverable strains in the metallic matrix, and the exceptional strength of reinforced composite particles in the composite, this system can make a significant advancement in transferring the exceptional mechanical properties of nano-fillers across larger scales, and can make a substantial progression in overcoming the longstanding strength-ductility trade-off challenge.

Host: Prof. Uwe Tauber

March 29

Friday 4:00pm
Zoom Link
(poster)

Condensed Matter Seminar

Prof. Shruti Puri (Yale University)

"Quantum Error Correction with Bosonic Qubits"

With fault-tolerant quantum error correction (FTQEC) it is possible to reliably simulate an arbitrarily long quantum circuit using faulty quantum operations as long as the error rate is below a threshold. Unfortunately, this tolerance to errors comes at the cost of dauntingly large overheads in the number of qubits and gates. Therefore, it is essential to develop natively robust qubits and gates to reduce the overheads for FTQEC. Recently, an alternate paradigm of quantum information processing has gained momentum which is based on encoding a qubit in an oscillator. Such qubits are referred to as bosonic qubits and can have some in-built protection against common errors from the environment. In this talk, I will discuss a particularly appealing bosonic qubit called the Kerr-cat qubit. This qubit is engineered to have inherent protection against certain errors which leads to a highly asymmetric or biased noise channel. I will show how the inherent bias in these qubits can be exploited to achieve hardware-efficient FTQEC.

Host: Prof. Ed Barnes

April 2021
April 5

Monday 4:00pm
Zoom Link

(poster)

Condensed Matter Seminar

Prof. Vincent Sokalski (Carnegie Mellon University)

"A New Kind of Magnetism- The Dzyaloshinskii-Moriya Interaction"

Magnetism has had a profound effect on our everyday lives from compass needles in ancient times to the modern hard disc drive in today’s computers. The existence of magnetic materials is rooted in the Heisenberg exchange interaction energy, , which favors parallel (or anti-parallel) alignment of neighboring spin vectors and their associated magnetic dipole moments as found, for example, in Fe, Ni, and Co. In the past decade a different type of magnetic exchange came to the forefront of modern physics called the Dzyaloshinskii-Moriya Interaction (DMI) given by , which instead favors an orthogonal alignment. The combination of these two effects leads to unusual magnetic configurations characterized by a chiral winding texture of the internal magnetization; a type of order very different than that found in a conventional ferromagnet. In this presentation, I will introduce the most important concepts in chiral magnetism including topologically protected magnetic features like skyrmions and domain walls, which can be manipulated by electric current with unprecedented efficiency. I will present the magnetic imaging techniques (Kerr microscopy and Lorentz TEM) we use to characterize this interaction and discuss how ultra thin magnetic films can be engineered to enhance it with inter-facial effects. I hope to convince you that the Dzyaloshinskii-Moriya Interaction presents rich new physics in magnetism and also opens the door to the design of future, energy-efficient magnetic memory. Bio Professor Sokalski is an Associate Professor in the department of Materials Science &Engineering at Carnegie Mellon University. He obtained his B.S. in Materials Science & Engineering from the University of Pittsburgh in 2007 followed by M.S. and Ph.D degrees from Carnegie Mellon University in 2009 and 2011 also in Materials Science &Engineering. He spent two years as a postdoctoral fellow in the Electrical and Computer Engineering department at CMU working on spin devices for low-power memory and electronics. He joined the faculty at Carnegie Mellon University in September of 2013 where his research is focused on emerging phenomena in nano-scale magnetic and spintronic materials. He is currently chair of the Pittsburgh chapter of the IEEE magnetic society.

Host: Prof Satoru Emori

April 12

Monday 4:00pm
Zoom Link

(poster)

Joint CDM & CSMB Seminar

Dr. Michael Salemo (U.S. Army Research Laboratory)

"TBD"

Host:Prof. Shengfeng Cheng

April 19

Monday 4:00pm
Zoom Link

(poster)

Condensed Matter Seminar

(Argonne National Lab)

"Classical symmetries and QAOA"

We study the relationship between the Quantum Approximate Optimization Algorithm (QAOA) and the underlying symmetries of the objective function to be optimized. Our approach formalizes the connection between quantum symmetry properties of the QAOA dynamics and the group of classical symmetries of the objective function. The connection is general and includes but is not limited to problems defined on graphs. We show a series of results exploring the connection and highlight examples of hard problem classes where a nontrivial symmetry subgroup can be obtained efficiently. In particular we show how classical objective function symmetries lead to invariant measurement outcome probabilities across states connected by such symmetries, independent of the choice of algorithm parameters or number of layers. We illustrate the power of the developed connection in two ways. First, we apply machine learning techniques towards predicting QAOA performance based on symmetry considerations. We provide numerical evidence that a small set of graph symmetry properties suffices to predict the minimum QAOA depth required to achieve a target approximation ratio on the Max Cut problem, in a practically important setting where QAOA parameter schedules are constrained to be linear and hence easier to optimize. Second, we show a connection between classical symmetries of the objective function and the symmetries of the terms of the cost Hamiltonian with respect to the QAOA energy. We show how by considering only the terms that are not connected by symmetry, we can significantly reduce the cost of evaluating the QAOA energy. <

Host: Prof. Sophia Economou

April 26

Monday 4:00pm
Zoom Link

(poster)

Condensed Matter Seminar

Dr. Nicholas Frattini (Yale University)

" The Kerr-cat qubit: stabilization, readout and operations "

Schrödinger cat states, super positions of coherent states in an oscillator, encode a noise-biased qubit that is naturally protected against phase-flip errors. To be practical for quantum information processing, these highly excited states must be stabilized to maintain the protection in a way that is simultaneously compatible with fast gates and readout of the encoded information. We experimentally demonstrate a method for the generation and stabilization of Schrödinger cat states--the Kerr-cat qubit--that is based on the interplay between Kerr non-linearity and single-mode squeezing in a superconducting microwave resonator. The realized Kerr-cat qubit exhibits over an order of magnitude increase in the transverse relaxation time over the single-photon Fock-state encoding, and all single-qubit gates were performed sixty times faster than the shortest coherence time. Unlike traditional two-level systems, the Kerr-cat qubit also admits a CNOT gate that preserves its noise-bias. All together, the Kerr-cat qubit is a potentially powerful tool for quantum information processing and even promises significant overhead reduction for quantum error correction in surface-code-style architectures.


Host: Prof. Sophia Economou

May 2021

May 3
Monday 4:00pm
Zoom Link
(poster)

Condensed Matter Seminar

Dr. Hanhee Paik (IBM Quantum)

Host: Prof. Sophia Economou

Center for Soft Matter and Biological Physics Seminars

Fall 2020

Organizer: Vinh Nguyen

These meetings occur on Mondays from 4:00pm to 5:00pm
Virtual Zoom Seminars (unless otherwise indicated)

August 2020
August 24

Monday 4:00pm
Virtual
(poster)

Classes Begin (No Seminar)

Host:

August 31

Monday 4:00pm
Zoom Link
(poster)

Ruslan Mukhamadiarov (Physics, Virginia Tech)

"Temperature interfaces in the Katz-Lebowitz-Spohn model"

We have explored a novel variant of the Katz-Lebowitz-Spohn (KLS) driven lattice gas, where the lattice is split into two regions that are coupled to heat baths with distinct temperatures. The hopping rates in two regions are governed by different temperatures T > Tc and Tc, respectively, where Tc indicates the critical temperature for phase ordering. The geometry of the two temperature regions can be arranged such that the temperature boundaries are oriented either perpendicular or parallel to the external particle drive and resulting net current. In the case when the temperature boundaries are oriented perpendicular to the drive, in the hotter region, the system behaves like the (totally) asymmetric exclusion processes (TASEP), and experiences particle blockage in front of the interface to the critical region. In analogy with (TASEP) systems containing“slow” bonds, we argue that transport in the high-temperature subsystem is impeded by the lower current in the cooler region, and that results in the particle density accumulation near the interface to the critical region. We observe the density profiles in both high- and low-temperature subsystems to be similar to the well-characterized coexistence and maximal-current phases in(TASEP) models with open boundary conditions, which are respectively governed by hyperbolic and trigonometric tangent functions. For our other work we arranged the geometry such that the temperature boundaries are oriented parallel to the external particle drive and resulting net current. We have explored the changes in the dynamical behavior that are induced by our choice of the hopping rates across the temperature boundaries.If these hopping rates at the interfaces satisfy particle-hole symmetry, the current difference across them generates a vector flow diagram akin to an infinite flat vortex sheet. We have studied the finite-size scaling of the density fluctuations in both temperature regions, and observed that it is controlled by the respective temperature values.

Host: Uwe Tauber

September 2020
September 7

Monday, 4:00pm
Zoom Link
(poster)

"Labor Day" (No Classes)

Host:

September 14

Monday 4:00pm
Zoom Link
(poster)

No Seminar

Host:

September 21

Monday 4:00pm
Zoom Link
(poster)

No Seminar

.

Host:

September 28

Monday 4:00pm
Zoom Link
(poster)

Prof. Navid Ghaffarzadegan (Industrial & Systems Engineering, Virginia Tech)

"Systems sciences, behavioral complexities, and the challenge of dynamic modeling of the spread of covid-19"

Mathematical modeling is essential for understanding the spread of an infectious disease and developing proper policies to contain it. In the case of covid-19, however, we are dealing with a unique complex situation that requires revisiting conventional models and including several dynamic and behavioral mechanisms that are specific to this novel virus. To mention a few characteristics: 1) A large fraction of covid-19 patients are asymptomatic and undiagnosed, 2) the virus is novel thus it seems that almost all human population are susceptible, 3) there is a considerable delay between exposure to the virus and the symptom onset, 4) risks are high; the infected fatality rate is considerable, 5) test capacities and their accuracy are limited, and 6) public risk perception has been changing and it influences people's behavior. Therefore, from a systems science perspective, we are dealing with a complex system that is only partially observable with considerable delays and inaccuracy, and our observations are influencing the (human-side of the) system. To elaborate this point, I will offer three examples of my recent modeling efforts, in collaboration with several colleagues. First, I will offer an example of how the number of unknown cases of covid-19 can be estimated using a dynamic simulation model; second, I will report on a project to estimate the impact of weather on the transmission of the disease; and third, I will offer a model of estimating the spread of covid-19 in universities and optimal university-level policies to contain the disease. Finally I will reflect on these experiences from a systems science point of view and complexity theories.

Host: Uwe Tauber

October 2020
October 5

Monday 4:00pm
Zoom Link
(poster)

Dr. Tatiana Rostovtseva (National Institutes of Health)

"A mitochondrial throttle: lipid-mediated protein complexes at the mitochondrial surface"

Mitochondria are organelles found in virtually all eukaryotic cells. Mitochondria are not only “the powerhouse of the cell” but are also involved in multiple crucial cellular functions. Mitochondrial dysfunction plays a central role in a wide range of age-related disorders, neurodegenerations, and cancer. Mitochondria are composed of two membranes. The inner membrane plays a prominent role in power production via oxidative phosphorylation, while the mitochondrial outer membrane (MOM) acts as a “throttle”, controlling the access of metabolites to the inner membrane and thus the rate of energy production. A significant portion of the control functions is carried on by the voltage-dependent anion channel (VDAC), a passive transport channel which allows water soluble metabolites and ions to cross MOM. Recent findings uncover an efficient regulatory mechanism of this channel through its interactions with cytosolic proteins. One such regulator is α-synuclein (αSyn), the intrinsically disordered neuronal protein highly expressed in nervous system and associated with Parkinson’s Disease pathology. αSyn is directly involved in mitochondrial dysfunction in neurodegeneration. Probing the interactions of αSyn with VDAC nanopore by single-channel recordings we showed that αSyn induces transient blockages of the ionic current through the channel; identified as the insertion and escape of the unstructured charged C-terminal tail of αSyn into the channel in response to a transmembrane potential. The discovery of this novel regulatory mechanism of mitochondrial respiration has raised several fundamental biophysical questions, including a mechanism of αSyn transient blockage of the VDAC nanopore and translocation through it, and what role mitochondrial lipids assume in mediating the αSyn-VDAC interaction. In this talk, I will discuss of how we answer these questions by using a combination of single-molecule electrophysiology, theoretical modeling, and macroscopic biophysical studies of αSyn binding to planar and liposome membranes. The VDAC nanopore thus proves to be extremely sensitive single-molecule probe for peripheral membrane protein interaction with integral membrane proteins of mitochondria. This study could be important for the structure-inspired design of mitochondria-targeting agents.

Host: Rana Ashkar

October 12

Monday, 4:00pm
Zoom Link
(poster)

Prof. Carla Finkielstein (Fralin Biomedical Research Institute at Virginia Tech Carilion)

Emerging opportunities in cancer chrono-therapy

Previously, cancer treatment modalities relied primarily on chemotherapeutic agents; nowadays, advances in rationally-designed drugs and targeted therapies have enabled the manipulation of cancer-specific molecules and cancer regulators that are frequently mutated and globally identified in various cancers. Regardless of the approach, the objective of controlling cancer progression has always been to attenuate, eliminate, or control then eomorphic activity of target driver mutations in tumors by maintaining steady levels of therapeutic agents. As precision medicine gains momentum, so does the possibility of customizing individual patients’ treatments to the “time-of-day” when tumor cells exhibit the highest susceptibility to therapeutics (1). However, a gap exists in our knowledge regarding the times at which therapeutically-targeted molecules are likely to be most susceptible to drugs and yield the greatest cellular effect. As a result, there is a need to unveil “when” and “where” druggable targets are in the cell and “to what extent” the tumor’s time-keeping system differs from normal tissue. Defining priorities that address those needs across the hierarchical system of organization will allow researchers to find the best time-windows where delivery of treatment modalities can be most effective.

Host: Uwe Tauber

October 19

Special Time
Monday 9:00 am
Zoom Link
(poster)

Prof. Jiajia Zhou (Beihang University, Beijing,China)

"Onsager variational principle and its applications in soft matter systems"

Onsager principle is the variational principle proposed by Onsager in his celebrated paper on the reciprocal relation. The principle is useful not only in deriving many evolution equations in soft matter systems, it is also useful in solving such equations approximately. Three examples are discussed: the capillary filling and rising, the stratification in binary colloidal solutions, and the viscoelasticity of polymer solutions. These examples show that the method can give new perspectives of the essential dynamics in soft matter systems.

Host: Shengfeng Cheng

November 2020
November 2

Monday 4:00pm
Zoom Link
(poster)

No CSB Seminar

Host:

November 9

Monday 4:00pm
Zoom Link
(poster)

Prof. Michael Bartlett (Mechanical Engineering, Virginia Tech)

“Multi-functional Soft Materials for Electronics and Adhesives”

Multi-functional soft materials and interfaces create intriguing new opportunities to enhance performance through programmable and adaptable properties. I will discuss two examples of this approach: 1) Novel material architectures of solid-liquid soft composites for soft machines and deformable, self-healing electronics, and 2) Switchable adhesives through programmable interfacial structures and stiffness. For soft composites, I will present an all-soft matter approach that combines soft elastomers with dispersions of liquid-phase eutectic Ga-In (EGaIn) metal alloy microdroplets. Experimental and theoretical investigations show that liquid metal droplets incorporated into elastomers enables exceptional combinations of soft elasticity and electrical and thermal properties with extreme toughness, autonomously self-healing circuits, and damage detection. I will then show how rigidity can be controlled through droplet architecture and composition. For switchable adhesives, I will present a framework for designing adhesives through kirigami, the Japanese art of paper cutting, and pneumatically controlled soft membranes. By incorporating kirigami-inspired structures at interfaces, we can enhance adhesive force by ∼100x across a spatially patterned sheet while tuning adhesion in different directions for high capacity yet easy release interfaces. We will also show how pneumatically controlled shape and rigidity tuning can be coupled to rapidly switch adhesion (≈0.1 s) across a wide range of programmable adhesion forces with measured switching ratios as high as 1300x. These approaches provide model systems to study fundamental material properties while enabling electronic skins, soft robots, and ‘smart’ adhesives for a variety of soft matter systems.

Host: Uwe Tauber

November 16

Monday 4:00pm
Zoom Link
(poster)

Dr. James McClure (Research Computing, Virginia Tech)

"Modeling multi-phase flow and anomalous diffusion with mesoscopic methods" 

Lattice Boltzmann methods provide a practical bridge between molecular- and continuum-scale models, relying on quasi-molecular interaction rules to simulate physics at significantly larger length and time scales compared to what is accessible from molecular dynamics. This talk will review approaches to develop mesoscopic models using the lattice Boltzmann method, with applications to wetting and spreading on heterogenous surfaces, fluid flow in porous media, and diffusion in electrochemical cells. Using simulation data, we consider how time-and-space averaging can be applied to understand scale effects in heterogeneous systems, particularly for long-wavelength fluctuations in non-equilibrium systems. Consequences for symmetry-breaking are explored within this context.

Host: Uwe Tauber

November 23

Monday 4:00pm
Zoom Link
(poster)

Thanksgiving Break (No Seminar)

Host:

December 2020
December 7

Monday 4:00pm
Zoom Link
(poster)

Prof. Jonathon Boreyko (Mechanical Engineering, Virginia Tech)

Host: Uwe Tauber

December 14

Monday, 4:00pm
Zoom Link
(poster)

Final Exams (No Seminar)

Host:

Center for Soft Matter and Biological Physics Seminars

Spring 2020



"We regret that Center seminars, meetings, and all other in-person events needed to be cancelled as a consequence of the Covid-19 pandemic."

Organizer: Vinh Nguyen

These meetings occur on Mondays from 4:00pm to 5:00pm in Robeson 304.
Refreshments are served before the seminars (unless otherwise indicated)

January 2020
January 20

Monday 4:00pm
304 Robeson Hall
(poster)

"No Seminar Martin Luther King Holiday"

Host:

January 27

Monday 4:00pm
304 Robeson Hall
(poster)

"TBD"

Host:

January 29

Wednesday, 2:00pm
221 Kelly Hall
"Special Time and Date" (poster)

Dr. Mahdi Ghadiri (University of Alberta, Canada)

"Physical System Evolving on Time-Dependent Domains"

Despite the ubiquity of physical systems evolving on time-dependent spatial domains ranging from transport-reaction processes—crystal growth, metal casting, gas-liquid, and gas-solid reaction systems—to quantum particles in an expanding potential and formation of galaxies agglomeration in the expanding Universe, to name a few—understanding of their dynamical properties is still in a quite rudimentary state. In this talk, I will present a summary of my research focused on physical systems evolving on time-dependent domains. Using the synergy of our experimental and theoretical studies, the key differences in the dynamics between extended systems on time-fixed and time-dependent spatial domains will be explored. As a paradigm we have chosen to study Faraday patterns—standing waves formed when a fluid layer is vibrated vertically—on time-varying domain leading to a number of intriguing results. First, the observation of a transverse instabil-ity—namely, when a two-dimensional pattern experiences an instability in the direction orthogonal to the direction of the domain deformation—provides a new facet to the stability picture compared to the one-dimensional systems. Second, the domain deformation is not only able to transform the chaotic state of two competing modes into a regular (periodic) one, but also to isolate one of the competing modes in the regime. The latter navigated us to the discovery of controlling chaos using the spatial domain size.

Host: Prof. Nadir Kaplan

February 2020
February 3

Monday, 4:00pm
304 Robeson Hall
(poster)

"Special Seminar for Faculty Candidate"

Host:

February 10

Monday 4:00pm
304 Robeson Hall
(poster)

"Special Seminar for Faculty Candidate"

Host:

February 17, 2020

Monday 4:00pm
304 Robeson Hall
(poster)

"Special Seminar for Faculty Candidate"

Host:

February 24,

Monday 4:00pm
304 Robeson Hall

(poster)

"Tenure Track Physics Meeting" (No Seminar)

Host:

March 2020
March 2

Monday 4:00pm
304 Robeson Hall
Joint Seminar with Condensed Matter
(poster)

Prof. Irep Gözen (University of Oslo, Norway)

“Lipid Nanotubes: a possible route to primitive cell formation and growth”

Membrane-enclosed cellular compartments create spatially distinct microenvironments which confine and protect biochemical reactions in the cell. On the early Earth, the autonomous formation of compartments is presumed to have enabled encapsulation of nucleotides, satisfying a starting condition for the emergence of life. Recently, surfaces have become into focus as potential platforms for the self-assembly of prebiotic compartments, as notably enhanced vesicle formation was reported in the presence of solid interfaces. The detailed mechanism of such formation at the mesoscale however is still under discussion. I will describe the spontaneous transformation of lipid reservoirs on solid substrates to unilamellar membrane compartments through a sequence of topological changes, proceeding via a network of interconnected lipid nanotubes. We show that this transformation is entirely driven by surface-free energy minimization and does not require hydrolysis of organic molecules, or external stimuli such as electrical currents or mechanical agitation. The compartments grow by taking up the external fluid environment and can subsequently separate and migrate upon exposure to hydrodynamic flow. This may explain, for the first time, the details of self-directed transition from weakly organized bio amphiphile assemblies on solid surfaces to protocells with secluded internal contents.

Host: Prof. Nadir Kaplan

March 9

Monday, 4:00pm
304 Robeson Hall

(poster)

"Spring Break" (No Seminar)

Host:

March 16

Monday 4:00pm
304 Robeson Hall

(poster)

No Seminar (Due to COVID-19)

"TBD"

Host:

March 23

Monday 4:00pm
304 Robeson Hall

(poster)

No Seminar (Due to COVID-19)

"TBD"

Host:

March 30

Monday 4:00pm
304 Robeson Hall

(poster)

No Seminar (Due to COVID-19)

"TBD"

Host:

April 2020
April 6

Monday 4:00pm
304 Robeson Hall

(poster)

No Seminar (Due to COVID-19)

"TBD"

Host:

April 13

Monday 4:00pm
304 Robeson Hall
Condensed Matter Seminar

(poster)

No Seminar (Due to COVID-19)

"TBD"

Host:

April 20

Monday 4:00pm
304 Robeson Hall

(poster)

No Seminar (Due to COVID-19)

"TBD"

Host:

April 27

Monday 4:00pm
304 Robeson Hall
Condensed Matter Seminar

(poster)

No Seminar (Due to COVID-19)

"TBD"

Host:

May 2020
May 4

Monday 4:00pm

Virtual Link

Joint Seminar

(poster)

Riya Nandi (Virginia Tech, Physics)

“Critical Aging Scaling Dynamics of Heisenberg Antiferromagnets”

Host: Uwe Tauber

May 7

Thursday
304 Robeson Hall
(poster)

"Reading Day"

Host:

May 15

Friday
Virtual Ceremony
(poster)

"University Commencemenet" (Virtual Ceremony)

Host: University

May 18

Monday, 4:00pm
304 Robeson Hall
(poster)

"No Seminar Semester has Ended"

Host:
Center for Soft Matter and Biological Physics Seminars

Fall 2019

Organizer: Vinh Nguyen

These meetings occur on Mondays from 4:00pm to 5:00pm in Robeson 304.
Refreshments are served before the seminars (unless otherwise indicated)

August 2019
August 26

Monday 4:00pm
304 Robeson Hall
(poster)

"Fall Semester Classes Begin"

Host:

September 2019
September 2

Monday, 4:00pm
304 Robeson Hall
(poster)

"Labor Day" (No Classes)

Host:

September 9

Monday 4:00pm
304 Robeson Hall
(poster)

Dr. Carolina Tallon (Materials Science and Engineering, Virginia Tech)

“Rocket Science meets Colloidal Surface Science: Near-Net-Shaping of Dense and Porous Ultra High Temperature Ceramics for Extreme Applications”

Ultra High Temperature Ceramics and other non-oxide ceramics represent the best candidate materials for use in extreme applications, including components for hypersonic vehicles, personal armor devices and cathodes for aluminum smelting and lithium air batteries. However, most of these applications require either a very complex geometry or very high and intricate porosity which cannot be achieved or designed using the current state-of-the-art for these types of compounds. The colloidal powder processing approach seems the natural answer to this problem, since it allows the preparation of high and uniform green density bodies facilitating densification, to control the porosity and the preparation of near-net-shaped dense and porous components, while minimizing defects and flaws through the preparation of ceramic powder suspensions. In this presentation, two cases studies related to hypersonic applications are discussed: The first one comprises the preparation of dense ultra-high temperature ceramics for leading edges in hypersonic vehicles by using the combination of colloidal processing and pressure less sintering. The second case study focused on the preparation of multi-scale porous materials for ultra-high temperature insulation. Highly porous UHTC materials have been produced by four different processing routes. The exhaustive control of the forces between particles and understanding the interaction between additives and powder surfaces have been key in developing highly porous ZrB2 and TiB2. The relationship between microstructure and properties of these materials was elucidated by the 3D image reconstruction and predictive modelling via a combination of x-ray tomography and simulations, which are validated against experimental values at room temperature. These models can be used to simulate and predict the thermal and mechanical properties of the materials under relevant extreme environment conditions.

Host: Vinh Nguyen

September 16

Monday 4:00pm
304 Robeson Hall
(poster)

.

Host:

September 23

Monday 4:00pm
304 Robeson Hall

(poster)

Vinh Ho (Physics, Virginia Tech)

“Fast and High Responsivity Graphene-based Photodetectors at Room-temperature by Engineering Dielectric Films”

The realization of low-cost photodetectors with high quantum efficiency, high sensitivity, and fast photo-response in the visible and infrared remains one of the challenges in optoelectronics. Ideally, these photodetectors should be based on Complementary Metal-Oxide-Semiconductor (CMOS) compatible platform for monolithic integration with read-out electronics to provide for high-density, high-throughput and low-cost manufacturing. Graphene is ideally suitable for optoelectronic photodetectors sensitive from visible to infrared frequencies, and have proved to fulfil those requirements. Here, we have engineered the interface between graphene and dielectric Ta2O5 and Ti2O3 thin-films by e-beam evaporation method to introduce quantum dots as absorption centers from visible to infrared region. Our graphene-based photodetectors have showed a high responsivity up to 2×105 A/W as well as a fast response time in the nano-second time scale at room temperature. These results address key challenges for broadband photodetectors from visible to infrared region, and are promising for the development of graphene-based optoelectronic applications.

Host: Vinh Nguyen

September 30

Monday, 4:00pm
304 Robeson Hall
(poster)

Prof. Rui Qiao (Mechanical Engineering, Virginia Tech)

"Modeling of Inter-facial and Transport Phenomena: Ionic Self-assembly, Active Colloids, and Beyond "

Interfacial and transport processes are at the core of many engineering and biological technologies. Experimental studies of these phenomena often have difficulties in fully resolving their underlying phenomena and pinpointing their physical mechanisms. These difficulties can often be addressed using numerical modeling. Our group specializes in molecular, mesoscopic and continuum simulations of interfacial and transport phenomena, especially those involving ions and non-equilibrium effects. In this talk, I will first introduce our molecular modeling of ionic liquids near electrified interfaces and in nanoscale confinement, with a focus on the self-assembly of ions, the transport of ions under far-from equilibrium conditions, and the effects of impurities. Next, I will introduce our continuum modeling of active colloids, with a focus on their hydrodynamic behavior in multiphase systems and in confinements. Ample time will be left for the discussion of possible collaborative work with the audience.

Host: Vinh Nguyen

October 2019
October 7

Monday 4:00pm
304 Robeson Hall

(poster)

Dr. Patrick Dennis (Air Force Research Lab, Wright-Patterson Air Force Base, Ohio)

"Protein Hydrogels from Marine Invertebrates: A Platform for Tunable Functionality”

Sclerotized, proteinaceous structures in marine invertebrates are used for predation by facilitating grappling, piercing and tearing of prey. These structures must have robust mechanical properties that are tailored to the size, shape and function of the specific predatory tool. Two such structures are the squid sucker ring teeth (SRT) assembly and jaws from the North Atlantic sandworm, Nereis virens. Both structures are not mineralized and are primarily comprised of proteins. Intriguingly, these sclerotized acellular structures are formed in a constitutive marine environment without the benefit of evaporation to aid in removal of bulk water. We have studied this phenomenon in hydrogels created from two proteins, suckerin and Nvjp-1, derived from the squid SRT assembly and sandworm jaw, respectively. Upon exposure of the protein-based hydrogels to aqueous salt solutions, a significant decrease in hydrogel size occurs where bulk water is driven out and a condensation of the protein hydrogel occurs. Interestingly, the contraction rate as well as the mechanical properties of the condensed hydrogels are greatly dependent on the type of cation and anion present in the salt, and the trends differ among the two proteins. The final size and mechanical properties of the condensed structures is dependent on both the initial concentration of the hydrogels as well as the ions used for condensation. Together, the results suggest that spatially controlled casting densities coupled with a selective exposure to ions can create features in the final condensed structure with tunable mechanical properties, similar to what is observed in the marine organisms.

Host: Vinh Nguyen

October 14

Monday, 4:00pm
304 Robeson Hall

(poster)

No Seminar Holiday (Columbus Day)

Host:

October 21

Monday 4:00pm
304 Robeson Hall

(poster)

Prof. Qi-Huo Wei (Kent State University)

“Printing Molecular Orientations as You Wish”

Liquid crystals consisting of rod-shaped molecules are a remarkable soft matter with extraordinary responsivity to external stimuli. Techniques to control molecular orientations are essential in both making and operating liquid crystal devices that have changed our daily lives completely. Traditional display devices are based on uniform alignments of molecules at substrate surfaces. In this talk, I will present a new photopatterning approach for aligning molecules into complex 2D and 3D orientations with sub-micron resolutions. This approach relies on so-called plasmonic metamasks to generate designer polarization direction patterns and photoalignments. I will present the basic principles behind this approach and a number of intriguing applications enabled by it, including micro-optical devices for laser beam shaping, commanding chaotic motions of bacteria, and creating topological defects with designer structures.

Host: Shengfeng Cheng

October 28

Monday 4:00pm
304 Robeson Hall

(poster)

Dr. Greg Quiroz (Johns Hopkins Applied Physics Lab)

“Deep Reinforcement Learning for Quantum Control: Learning to Optimally Navigate in Complex Noisy Environments”

Quantum control seeks to establish control over a quantum system in such a way so that logical operations are implemented while simultaneously mitigating unwanted interactions between the system and its environment. From the point of view of quantum computation, quantum control can potentially provide significant improvements in computational accuracy when quantum logic operations are tailored for the particular noise plaguing the hardware. Specifically tailoring each controlled operation can be quite demanding if one wishes to perform this task for every instantiation of a quantum algorithm. Here, we examine how one can leverage reinforcement learning to learn and predict quantum gates in the presence of noise; thus, providing a streamlined method for gate design for generic quantum algorithms.

Host: Sophia Economou

November 2019
November 4

Monday 4:00pm
304 Robeson Hall

(poster)

Host:

November 11

Monday 4:00pm
304 Robeson Hall


(poster)

Dr. Kin Chung Fong (Raytheon, BBN)

Host: Ed Barnes

November 18

Monday 4:00pm
304 Robeson Hall

(poster)

Dr. Vivek Amin (NIST)

Host: Satoru Emori

November 25

Monday 4:00pm
304 Robeson Hall

(poster)

Host:

December 2019
December 2

Monday 4:00pm
304 Robeson Hall
(poster)

Host:

December 9

Monday, 4:00pm
304 Robeson Hall
(poster)

Prof. Kwon Park (Korea Institute for Advanced Study)

Host: Vito Scarola

December 16

Monday, 4:00pm
304 Robeson Hall
(poster)


Host:
December 23

Monday, 4:00pm
304 Robeson Hall
(poster)


Host:
December 30

Monday, 4:00pm
304 Robeson Hall
(poster)


Host:
Center for Soft Matter and Biological Physics Seminars

Spring 2019

Organizer: Vinh Nguyen

These meetings occur on Mondays from 4:00pm to 5:00pm in Robeson 304.
Refreshments are served before the semnars (unless otherwise indicated)

January 2019
January 21

Monday 4:00pm
304 Robeson Hall
Joint CM Seminar
(poster)

"Martin Luther King holiday (No Classes-University Offices Closed)

Host:

January 28

Monday 4:00pm
304 Robeson Hall
(poster)

Host:

February 2019
February 4

Monday 4:00pm
304 Robeson Hall
(poster)

Host:

February 11

Monday 4:00pm
304 Robeson Hall
(poster)

Host:

February 18

Monday 4:00pm
304 Robeson Hall

(poster)

Host:

February 25

Monday 4:00pm
304 Robeson Hall

(poster)

Host:

March 2019
March 1

Friday 2:30pm

Special Seminar

210 Robeson Hall
(poster)

Prof. Maikel Rheinstadter (McMaster University)

Host: Rana Ashkar

March 4

Monday 4:00pm
304 Robeson Hall
(poster)

Host:

March 11

Monday 4:00pm
304 Robeson Hall

(poster)


Host:

March 18

Monday 4:00pm
304 Robeson Hall

(poster)

Host:

March 22

Friday 2:30pm

Special Seminar

210 Robeson Hall
(poster)

Prof. Matt Helgeson (UC Santa Barbara)

Host: Rana Ashkar

March 25

Monday 4:00pm
304 Robeson Hall

(poster)

Host:

April 2019
April 1

Monday 4:00pm
304 Robeson Hall

(poster)

Host:

April 8

Monday 4:00pm
304 Robeson Hall

(poster)

Host:

April 15

Monday 4:00pm
304 Robeson Hall

(poster)

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April 22

Monday 4:00pm
304 Robeson Hall

(poster)


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April 29

Monday 4:00pm
304 Robeson Hall

(poster)


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May 2019

May 6
Monday 4:00pm
304 Robeson Hall
(poster)

Host:

May 13

Monday 4:00pm
304 Robeson Hall
(poster)

Exam Week No Seminar

Host: