The Tuesday JFI Seminar - Mohammad Hafezi, Joint Quantum Institute, University of Maryland

Topological Photonics: From Classical to Quantum

There are tremendous efforts underway to better understand systems with topological features --- global properties that are not discernible locally. The best-known examples are quantum Hall effects in electronic systems, where insensitivity to local properties manifests itself as conductance through edge states that are insensitive to defects and disorder. In this talk, I demonstrate how similar physics can be observed for photons; specifically, how various quantum Hall Hamiltonians can be simulated in an optical platform. I review the observation of topological photonic edge states using silicon-on-insulator technology, measurement of the associated topological invariants and our recent advances in studying the quantum transport of such structures. Furthermore, the addition of optical nonlinearity to this system provides a platform to implement fractional quantum Hall states of photons and anyonic states that have not yet been observed. More generally, the application of these ideas can lead to the development of optical devices with topological protection for classical and quantum information processing.

The Tuesday JFI Seminar

May 23, 2017
GCIS W301 | Tuesday, 4:00 pm

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Stephen J. Lippard: Massachusetts Institute of Technology

Understanding and Improving Platinum Anticancer Drugs


Chemistry

May 22, 2017
Kent 120 | Monday, 4:00 pm

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Dmitri Feldman, Brown University

Particle-hole symmetry without particle-hole symmetry in the quantum Hall effect at ν = 5/2

Numerical results suggest that the quantum Hall effect at the filling factor 5/2 is described by the Pfaffian or anti-Pfaffian state in the absence of disorder and Landau level mixing. Those states are incompatible with the observed transport properties of GaAs heterostructures, where disorder and Landau level mixing are strong. We show that the recent proposal of a PH-Pfaffian topological order by D. T. Son is consistent with all experiments. The absence of the particle-hole symmetry at the filling factor 5/2 is not an obstacle to the existence of the PH-Pfaffian order since the order is robust to symmetry breaking
Kadanoff Seminar

May 22, 2017
ACC 211 | Monday, 1:30 pm

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Anthony Hyman, PhD, MPI Molecular Cell Biology and Genetics, Dresden

Biomolecular condensates: Organizers of cellular biochemistry


Biophysical Dynamics

May 22, 2017
GCIS W301 | Monday, 12:00 pm

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Danna Freedman:Northwestern University

Applying Inorganic Chemistry to Challenges in Physics


Chemistry

May 19, 2017
Kent 120 | Friday, 1:15 pm

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the faster you run, the less you remember

Eat 12:00 noon
discuss, 12:15.
MRSEC Baglunch

May 19, 2017
GCIS E123 | Friday, 12:00 pm

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Joe Incandela, University of California,Santa Barbara/CERN

Zachariasen Lecture: "From the Higgs to dark matter: the search for the underlying code of our universe"


Physics Colloquium

May 18, 2017
KPTC 106 | Thursday, 4:00 pm

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Lee Lecture: Professor Matthew Rosseinsky, University of Liverpool

Beyond the unit cell: control of function by local structure and dynamics from fuel cell electrodes to metal-organic frameworks


Chemistry

May 17, 2017
SCL 240 | Wednesday, 4:00 pm

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Luca Delacretaz, Stanford University

Transport with translational order and bad metals

I will present a hydrodynamic theory of weakly disordered electronic systems with fluctuating or static translational order, such as charge/spin density waves or Wigner crystals. This hydrodynamic approach leads to universal expressions for low frequency ac conductivities and viscosities. I will argue that similar ac conductivities are observed experimentally in a variety of bad metals, and conjecture that such materials have short range fluctuating charge order.
Kadanoff Seminar

May 17, 2017
ACC 211 | Wednesday, 1:30 pm

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Jeremy England, MIT

Emergent Fine-tuning to Environment in a Complex Chemical reaction

The equilibrium steady state of an undriven mixture of reacting chemical species is uniquely determined by the free energy. Once external environmental drives are introduced, however, steady-state concentrations may deviate from these equilibrium values via sustained absorption and dissipation of work. From a physical standpoint, the living cell is a particularly intriguing example of such a nonequilibrium system, because the environmental work sources that power it are relatively difficult to access – only the proper orchestration of many distinct catalytic actors leads to a collective behavior that is competent to harvest and exploit available metabolites. Here, we study the dynamics of an in silico chemical network with random connectivity in a driven environment that only makes strong chemical forcing available to rare combinations of concentrations of different molecular species. We find that the long-time dynamics of such systems biased towards the spontaneous extremization of forcing, so that the molecular composition converges on states that exhibit exquisite fine-tuning to available work sources.

Computations in Science

May 17, 2017
KPTC 206 | Wednesday, 12:15 pm

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Lee Lecture: Prof. Matthew Rosseinsky, University of Liverpool

Design of Advanced Materials?


Chemistry

May 15, 2017
Kent 120 | Monday, 4:00 pm

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Lukasz Fidkowski, Stony Brook University

Chiral phases in Floquet quantum systems


Kadanoff Seminar

May 15, 2017
ACC 211 | Monday, 1:30 pm

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Alex Miller: University of North Carolina at Chapel Hill

Cation-Responsive Pincer-Crown Ether Complexes for Tunable Catalysis


Chemistry

May 12, 2017
Kent 120 | Friday, 4:00 pm

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1st Annual UChicago MRSEC Symposium

Learn about ongoing work in the Materials Research Center!
Explore new collaborations & research directions!

GCIS 3rd Floor Atrium
11:30am -1:30pm: Lunch and Poster Session

GCIS W301
1:30pm - 3:00pm: IRG 1 – Dynamics of Soft Interfaces
& IRG 2 – Active Materials

3:00pm - 3:15pm: Coffee Break

3:15pm-4:45pm: IRG 3 – Engineering Quantum Materials & Seed Research – “Multifunctional Interfaces of Different Dimensionality” & “Multifunctional Porous Materials”

4:45pm: Wine and Cheese
MRSEC Symposium

May 12, 2017
GCIS W301 | Friday, 11:30 am

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Lisa Manning, Syracuse University

Jamming in biological tissues

Host: Sid Nagel
Physics Colloquium

May 11, 2017
KPTC 106 | Thursday, 4:00 pm

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Philip Nelson, University of Pennsylvania

Old and new news about single-photon sensitivity in human vision

One often hears that human vision is “sensitive to single photons,” when in fact the faintest flash of light that can reliably be reported by human subjects is closer to 100 photons. Nevertheless, there is a sense in which the familiar claim is true. Experiments conducted long after the seminal work of Hecht, Shlaer, and Pirenne now allow a more precise, and in some ways even more remarkable, conclusion to be drawn about our visual apparatus. A simple model that incorporates both old news (response of single rod cells) and newer news (loss at the first synapse) can account in detail for both old and new psychophysical data.
Computations in Science

May 10, 2017
KPTC 206 | Wednesday, 12:15 pm

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The 2nd Tuesday JFI Colloquium - Eric Borguet - Department of Chemistry, Temple University

Interfacial water structure, which can be probed by vibrational sum-frequency generation (vSFG) spectroscopy, is key to many processes. Time-resolved vSFG shows that in the absence of surface charge (pH 2), water at silica surfaces exhibits significantly slower OH stretch vibrational relaxation (~600 fs) compared to bulk water. However, at charged silica surfaces (e.g., pH 6), bulk-like fast dynamics (~200 fs) are observed at low ionic strength. This decelerates to ~600 fs, with the addition of NaCl. In parallel, vSFG results demonstrated that silica interfacial water structure is most sensitive to cations at pH=6-8. Consequently, it is unclear whether the observed slowing of the vibrational dynamics is due to the reduction in Debye length, or because of changes in the local hydrogen bonding environment caused by the electrolyte and how this might depend on the identity of the ions. Additional spectroscopic and time-resolved vSFG experiments on aqueous Al2O3 interfaces shed light on the ongoing debate on the role of ions in interfacial water structure and whether the observed behavior is specific to silica/water interfaces or can be generalized to other systems. Philippe Guyot-Sionnest, 2-7461 or via email at pgs@uchicago.edu. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at bthomas@uchicago.edu.
The 2nd Tuesday JFI Colloquium

May 9, 2017
GCIS W301 | Tuesday, 4:00 pm

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Snir Gazit, University of California at Berkeley

Charged fermions coupled to Ising gauge fields: Symmetry breaking, confinement, and emergent Dirac fermions.

Lattice gauge theories are ubiquitous in physics, describing a wide range of phenomena from quark confinement to quantum materials. At finite fermion density, gauge theories are notoriously hard to analyze due to the fermion sign problem. Here, we investigate the Ising gauge theory in 2+1 dimensions, a problem of great interest in condensed matter, and show that it is free of the sign problem at arbitrary fermion density. At generic filling, we find that gauge fluctuations mediate pairing leading to a transition between a deconfined BCS state to a confined BEC. At half-filling, a π-flux phase is generated spontaneously with emergent Dirac fermions. The deconfined Dirac phase, with a vanishing Fermi surface volume, is a non-trivial example of violation of Luttinger's theorem due to fractionalization. At strong coupling, we find a single continuous transition between the deconfined Dirac phase and the confined BEC, in contrast to the expected split transition.
Kadanoff Seminar

May 8, 2017
ACC 211 | Monday, 1:30 pm

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Kharasch Memorial Lecture - Sir Shankar Balasubramanian, University of Cambridge

How large is the natural DNA alphabet?


Chemistry

May 5, 2017
Kent 120 | Friday, 1:15 pm

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Peter Littlewood, University of Chicago

Physics of Sustainability

Host: Mel Shochet
Physics Colloquium

May 4, 2017
KPTC 106 | Thursday, 4:00 pm

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Daniel Scolnic, University of Chicago

Measuring the size of the Universe with Standard Candle

Astrophysicists use standard candles, objects which have roughly the same luminosity, to infer distances to far-away parts of the universe. Standard candles of variable stars called ‘cepheids’ were used to discover the expanding universe, and standard candles of exploding stars called ‘supernovae’ were used to discover the accelerating universe. Together, these two standard candles can be used to measure the size of the universe. Interestingly, this measurement of the size of the universe recovered conflicts with measurements of the size of the universe from extrapolations of data from the Cosmic Microwave Background. I will go over how we make our measurement, from soup to nuts, and discuss how we can be confident in the accuracy of our values. I will then discuss different ways too explain the tension we see in the different sets of measurements, and possible new physics that may be on the horizon.
Computations in Science

May 3, 2017
KPTC 206 | Wednesday, 12:00 pm

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The 1st Tuesday JFI Colloquium - Benjamin Lev, Department of Physics and Applied Physics - Stanford University

New Tools for Exploring Nonequilibrium Quantum Many-Body Physics

ABSTRACT: The simulation of quantum systems using ultracold atomic gases—quantum simulation—may be viewed as the creation of novel quantum systems in their own right rather than the simulation of well-known models. Often these systems possess collective properties impossible to observe in the solid state. In particular, these gaseous systems provide unique testbeds for emergent physics, especially that out of equilibrium. We present two novel avenues of inquiry into quantum nonequilibrium physics: the creation of dissipative quantum spin glasses and quantum neural networks using atoms coupled to the photonic modes of a confocal optical resonator and the study of nonequilibrium quench dynamics in highly magnetic and strongly interacting gases. Besides investigating long-unresolved issues in statistical mechanics (i.e., the order of spin glasses and thermalization in closed quantum systems), the experimental directions discussed point to novel neuromorphic computational architectures relying on driven-dissipative quantum dynamics.Host: Jonathan Simon, 2-9661 or via email at simonjon@uchicago.edu. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at bthomas@uchicago.edu.
The 1st Tuesday JFI Colloquium

May 2, 2017
GCIS W301 | Tuesday, 4:00 pm

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Kharasch Memorial Lecture - Sir Shankar Balasubramanian, University of Cambridge

Decoding human genomes on a population scale


Chemistry

May 1, 2017
Kent 120 | Monday, 4:00 pm

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Dominic Else, University of California, Santa Barbara

Floquet Time Crystals: How time-translation symmetry protects phases of matter

A "Floquet time crystal" is a phase of matter in a periodically driven (Floquet) system which spontaneously breaks discrete time-translation symmetry. They are an entirely new "non-thermal" phase of matter which cannot exist in undriven systems. In this talk, I will discuss the recent theoretical prediction and experimental observation of Floquet time crystals. Time-translation symmetry occupies a special role in physics, since its generator is the Hamiltonian itself. Nevertheless, the theoretical formulation of time crystals turns out to be *almost* the same as for other symmetry-breaking phases of matter. I will also consider phases of matter in which the discrete time-translation symmetry is not spontaneously broken but nevertheless protects non-trivial phases, which are the analogs of "symmetry-protected topological" and "symmetry-enriched topological" phases for other symmetries.
Kadanoff Seminar

May 1, 2017
ACC 211 | Monday, 1:30 pm

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Jingyuan Chen, Stanford University

Exact Bose-Fermi Duality on 3D Euclidean Lattice

Recently a conjectured Bose-Fermi duality in 3 spacetime dimensions has drawn much interest from both high energy and condensed matter communities. We prove this duality by constructing an exact duality on lattice and showing our exact duality reduces to the conjectured duality in the continuum limit. All steps are analytic, exact, and simple.
Kadanoff Seminar

April 28, 2017
ACC 211 | Friday, 1:30 pm

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Qiu Wang, Duke University

Leveraging Chemistry for Biology and Therapy: – New amination strategies to access biologically important molecules


Chemistry

April 28, 2017
Kent 120 | Friday, 1:15 pm

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Cameron Reed, Alma College

The Manhattan Project: A Look at the Physics"

Host: Henry Frisch
Physics Colloquium

April 27, 2017
KPTC 106 | Thursday, 4:00 pm

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Andrew Kruse, PhD, Harvard Medical School

New approaches to investigate G protein-coupled receptor function


Biophysical Dynamics

April 27, 2017
GCIS W301 | Thursday, 12:00 pm

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Lenka Zdeborova, CNRS & CEA, Saclay, France

Statistical physics approach to compressed sensing and generalized linear regression

Bayesian inference and statistical physics are formally closely related. Therefore methodology and concepts developed in statistical physics to understand disordered materials such as glasses and spin glasses can be elevated to analyze models of in statistical inference. We will present this approach in a rather general setting that covers analysis of compressed sensing, generalized linear regression, and the perceptron - a kind of a single layer neural network. At the one hand, this approach leads to the approximate message passing algorithm that is gaining its place among other widely used regression and classification algorithms. At the other hand, the related analyses leads to identification of phase transitions in the performance of Bayes-optimal estimators. We will discuss relation between these phase transitions and algorithmic hardness, and in the case of compressed sensing we will show how this understanding leads to a design of optimal measurement protocols.
Based partly on "Statistical-physics-based reconstruction in compressed sensing" PRX 2012 and reviewed in "Statistical physics of inference: Thresholds and algorithms" Advances of Physics 2016.
Computations in Science

April 26, 2017
KPTC 206 | Wednesday, 12:15 pm

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Andy Borovik:University of California, Irvine

Synthetic Chemistry as a Window into Biology


Chemistry

April 24, 2017
Kent 120 | Monday, 4:00 pm

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JFI Seminar - Prof. David Cobden, Department of Physics, Washington University

"Electronic Phases and Phase Transitions in Van der Waals Monolayers"

ABSTRACT: Atomically thin materials can host many kinds of electronic phases, some unique to the 2D limit. Our observations indicate the realization of a quantum spin Hall state, an excitonic insulator, superconductivity, and ferro- and antiferromagnetism in van der Waals monolayers. Unlike 3D solids, monolayers are amenable to surface probes and can be doped by electrostatic gating. We are thus investigating ways to induce transitions between these phases electrostatically. In WTe2 monolayers at low temperatures we observe a transition between a two-dimensional topological insulator and a bulk conducting phase as a function of gate voltage, representing a gate-controlled quantum phase transition.Host: Jiwoong Park, 4-3179 or via email to jwpark@uchicago.edu. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at bthomas@uchicago.edu.
Special JFI Seminar

April 24, 2017
ERC 161 | Monday, 2:00 pm

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Cenke Xu, University of California, Santa Barbar

self-dual quantum critical points in 2+1 dimensions


Kadanoff Seminar

April 24, 2017
ACC 211 | Monday, 1:30 pm

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Jennifer M. Heemstra: University of Utah

Harnessing Nucleic Acid Molecular Recognition and Self-Assembly for Biosensing and Biomolecular Imaging


Chemistry

April 21, 2017
Kent 120 | Friday, 1:15 pm

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Two dynamical interfaces walk into an IRG…

a recap of tuesday's idea session

12:00 Eat real food
12:15 digest bloblets
MRSEC Baglunch

April 21, 2017
GCIS E123 | Friday, 12:00 pm

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Zoran Hadzibabic, University of Cambridge

Quantum gas in a box

Host: Cheng Chin
Physics Colloquium

April 20, 2017
KPTC 106 | Thursday, 4:00 pm

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Anette Hosoi, MIT

Hydrodynamics of Hairy Surfaces

Flexible slender structures in flow are everywhere. While a great deal is known about individual flexible fibers interacting with fluids, considerably less work has been done on fiber ensembles, such as fur or hair, in flow. These hairy surfaces are abundant in nature and perform multiple functions from thermal regulation to water harvesting to sensing. Motivated by these biological systems, we consider two examples of hairy surfaces interacting with flow: (1) air entrainment in the fur of diving mammals and (2) symmetry breaking in hairy micro-channels.
In the first example, we take inspiration from semi-aquatic mammals (such as fur seals, otters, and beavers) which have specially adapted fur that serves as an effective insulator both above and below water. Many of these animals have evolved pelts that naturally entrap air when they dive. This air: (1) provides additional insulation under water, (2) provides added buoyancy, and (3) facilitates water shedding when the animals resurface. In this study we investigate diving conditions and fur properties which amplify air entrainment in fur. In the second example, we consider a fundamental component in hydraulic systems, the flow rectifier. One of the simplest ways to generate asymmetry in these devices is with a ball valve in which flow is completely obstructed in one direction and free to flow in the other. In this work we seek a variation that: (1) allows the designer to modulate the relative resistances in the rectifier and (2) can be achieved with solid state components (i.e. no moving parts).
Computations in Science

April 19, 2017
KPTC 206 | Wednesday, 12:15 pm

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The Tuesday JFI Seminar - Monika Schleier-Smith, Department of Physics, Stanford University

"Echoes of Entanglement: from Quantum Metrology to Scrambling"

ABSTRACT: In the quest to approach the fundamental Heisenberg Limit in precision measurements, central challenges are the generation and detection of highly entangled states. I will describe how both of these challenges can be mitigated by “echo spectroscopy,” a technique inspired by the Loschmidt echo, a paradigmatic probe of chaos. A key ingredient is to effectively reverse the flow of time in an interacting many-body system by switching the sign of the Hamiltonian. I will describe progress towards engineering spin models with non-local, switchable-sign interactions using cold atoms strongly coupled to light an optical cavity. Intriguingly, similar non-local interactions feature in models for understanding fundamental bounds on chaos and information scrambling derived from the study of black holes, opening prospects for investigating these bounds in the laboratory.Host: Jonathan Simon, 2-9661 or via email at simonjon@uchicago.edu. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at bthomas@uchicago.edu.
The Tuesday JFI Seminar

April 18, 2017
GCIS W301 | Tuesday, 4:00 pm

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Viviana Gradinaru, PhD, CALTECH

Optogenetic, tissue clearing, and viral vector approaches to understand and influence whole-animal physiology and behavior

We develop & employ optogenetics, tissue clearing and viral vectors to gain new insights on circuits underlying locomotion, reward & sleep. I will discuss how bidirectional manipulation of mesopontine cholinergic cell bodies exerted opposing effects on locomotor behavior & reinforcement learning & how these effects were separable via limiting photostimulation to PPN cholinergic terminals in the ventral substantia nigra pars compacta or to the ventral tegmental area, respectively (Xiao et al, Neuron, '16). Genetically encoded tools that can be used to visualize, monitor, and modulate mammalian neurons are revolutionizing neuroscience. However, use of genetic tools in non-transgenic animals is often hindered by the lack of vectors capable of safe, efficient & specific delivery to the desired cellular targets. To begin to address these challenges, we have developed an in vivo Cre-based selection platform (CREATE) for identifying adeno-associated viruses (AAVs) that more efficiently transduce genetically defined cell populations (Deverman et al, Nature Biotechnology, '16). As a first test of the CREATE platform, we selected for viruses that transduced the brain after intravascular delivery and found a novel vector, AAV-PHP.B, that transduces most neuronal types and glia across the brain. We also demonstrate how whole-body tissue clearing can facilitate transduction maps of systemically delivered genes (Yang et al, Cell, '14; Treweek et al, Nature Protocols, '16) and how non-invasive delivery vectors can be used to achieve dense to sparse labeling to enable morphology tracing (unpublished). Since CNS disorders are notoriously challenging due to the restrictive nature of the blood brain barrier, the recombinant vectors engineered to overcome this barrier can enable potential future use of exciting advances in gene editing via the CRISPR-Cas, RNA interference and gene replacement strategies to restore diseased CNS circuits. In addition to control of neuronal activity we need feedback on how exactly the tissue is responding to modulation. We have worked on two related topics: optical voltage sensors and imaging of single molecule RNA in cleared tissue. We used directed evolution of opsins to make them better at reporting action potentials (Flytzanis et al, Nature Communications, '14). Changes in RNA transcripts can also report on activity history of brain circuits. Preserving spatial relationships while accessing the transcriptome of selected cells is a crucial feature for advancing many biological areas, from dev bio to neuroscience. We recently reported on methods for multi-color, multi-RNA, imaging in deep tissues. By using single-molecule hybridization chain reaction (smHCR), PACT tissue hydrogel embedding and clearing and light-sheet microscopy we detected single-molecule mRNAs in ~mm-thick brain tissue samples (Shah et al, Development, '16) and by rRNA labeling we mapped the identity & growth rate of pathogens in clinical samples (DePas et al,'16).
Biophysical Dynamics

April 18, 2017
GCIS W301 | Tuesday, 12:00 pm

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Closs Lecture-Professor Mostafa El-Sayed, Georgia Institute of Technology

Photothermal Therapy of Cancer in Cells and in Different Animals Using Gold Nano-Rods: A Progress Report


Chemistry

April 17, 2017
Kent 120 | Monday, 4:00 pm

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Roger Melko, Perimeter Institute

Machine Learning the Many-Body Problem

Condensed matter physics is the study of the collective behavior of infinitely complex assemblies of electrons, nuclei, magnetic moments, atoms or qubits. This complexity is reminiscent of the “curse of dimensionality” commonly encountered in machine learning. Despite this curse, the machine learning community has developed techniques with remarkable abilities to classify, characterize and interpret complex sets of data, such as images and natural language recordings. Here, we show that modern architectures for supervised learning, such as fully-connected and convolutional neural networks, can identify phases and phase transitions in a variety of condensed matter Hamiltonians. Readily programmable through open-source software libraries, neural networks can be trained to detect multiple types of order parameter, as well as highly non-trivial states with no conventional order, directly from raw state configurations sampled with standard Monte Carlo. Further, Monte Carlo configurations can be used to train a stochastic variant of a neural network, called a Restricted Boltzmann Machine (RBM), for use in unsupervised learning applications. We show how RBMs, once trained, can be sampled much like a physical Hamiltonian to produce configurations useful for estimating physical observables. Finally, we explore the representational power of quantum and classical RBMs, their role in deep learning, and its possible relationship to the renormalization group.
Kadanoff Seminar

April 17, 2017
ACC 211 | Monday, 1:30 pm

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John Jewett: University of Arizona

Viral muses to inspire chemistry


Chemistry

April 14, 2017
Kent 120 | Friday, 1:15 pm

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Bloblets in your cells: what is their mission?

12:00 Eat real food
12:15 digest bloblets
MRSEC Baglunch

April 14, 2017
GCIS E123 | Friday, 12:00 pm

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Steve Kivelson, Stanford University

Intertwined Order in Highly Correlated Electron Fluids

Host: Paul Wiegmann
Physics Colloquium

April 13, 2017
KPTC 106 | Thursday, 4:00 pm

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Minjung Ryu, PhD, Purdue

Language, Culture, and Learning: Implications for Interdisciplinary Research


Biophysical Dynamics

April 13, 2017
GCIS W105 | Thursday, 10:00 am

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Jonathan Simon, University of Chicago

Exploring Landau Levels in Curved Space

I will present recent work realizing topological phases of photons, both in curved space, and in lattices. The talk will focus on our recent exploration of Landau levels on a conical surface, generated using a non-planar (twisted) optical resonator to induce a synthetic magnetic field for optical photons, and employed to validate the famous Wen-Zee action. I will then discuss recent results demonstrating strong photon-photon interactions mediated by resonator Rydberg-electromagnetically induced transparency (EIT), and techniques we are developing to assemble topological few-body states both photon-by-photon, and through microscopic devices engineered for photon thermalization. I will conclude with our recent observation of time-resolved helical edge dynamics in Z_2 topological circuit lattices, and a T-broken extension in the microwave domain using arrays of 3D cavities and circuit quantum electrodynamics techniques. This work showcases the unique possibilities for Hamiltonian engineering and control in the photonic sector, a provides a taste of upcoming breakthroughs in engineering quantum materials from photons.
Computations in Science

April 12, 2017
KPTC 206 | Wednesday, 12:15 pm

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The Tuesday JFI Seminar - Elisabeth Guazzelli, Aix Marseille Univ, CNRS, IUSTI, Marseille, France

Rheology of Dense Suspensions of Non-Colloidal Particles

ABSTRACT: Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. These systems thus belong to an intermediate regime between pure suspensions and granular flows. We show that we can unify suspension and granular rheology under a common framework by transferring the frictional approach of dry granular media to wet suspensions of spherical particles. We also discuss non-Newtonian behavior such as normal-stress differences and shear-induced migration. Beyond the classical problem of dense suspension of hard spheres which is far from being completely resolved, there are also entirely novel avenues of study concerning more complex mixtures of particles and fluids such as those involving other types of particles (e.g. fibers) or non-Newtonian fluids (e.g. yield-stress fluids) that we will also address. Host: Heinrich Jaeger, 2-6074 or via email at h-jaeger@uchicago.edu. Persons with a disability who may need assistance contact Brenda Thomas at 2-7156 or by email at bthomas@uchicago.edu.
The Tuesday JFI Seminar

April 11, 2017
GCIS W301 | Tuesday, 4:00 pm

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Matthew Lapa, UIUC

Electromagnetic response and anomalies in bosonic symmetry-protected topological phases

Symmetry-protected topological (SPT) phases, gapped phases of matter protected by the symmetry of a group G and possessing interesting boundary states, have been the focus of intense investigation for the past several years. While much is known about the classification and properties of these phases, especially in low dimensions, it is still a challenge to understand the physical properties which characterize a given (interacting) SPT phase in a general dimension. In this talk I will explain how a field-theoretic description of bosonic SPT phases in terms of nonlinear sigma models (NLSMs) can be combined with the theory of gauged Wess-Zumino actions to study the electromagnetic response and anomalies of some bosonic SPT phases with U(1) symmetry in all dimensions. In particular, I will present a calculation of the topological part of the electromagnetic response of bosonic integer quantum Hall (BIQH) states in odd spacetime dimensions and bosonic topological insulator (BTI) states in even spacetime dimensions. In addition, I will argue that the boundary of the BTI state exhibits a global anomaly similar to the parity anomaly of Dirac fermions in odd spacetime dimensions. This argument can be made precise for the boundary theory of the BTI state in two spacetime dimensions. If time allows, I will explain how the connection between gauged Wess-Zumino actions and equivariant cohomology can be used to prove that these results are robust against smooth, symmetry-preserving deformations of the target space of the NLSM used to describe these states.
Kadanoff Seminar

April 11, 2017
ACC 211 | Tuesday, 2:00 pm

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Gregory T. Tietjen, PhD, Yale

A biophysical approach to engineering vascular targeted nanomedicine


Biophysical Dynamics

April 11, 2017
GCIS W301 | Tuesday, 12:00 pm

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Ribhu Kaul, University of Kentucky

Quantum phase transitions in square lattice SU(N) and SO(N) magnets

I will discuss the phases and phase transitions in some simple SU(N) and SO(N) quantum spin models, studied both using ideas from quantum field theory and with large scale numerical simulations.
Kadanoff Seminar

April 10, 2017
ACC 211 | Monday, 1:30 pm

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James Morken, Boston College

New Strategies in Organic Synthesis Enabled by Catalytic Reactions of Organoboron Reagents


Chemistry

April 7, 2017
Kent 120 | Friday, 1:15 pm

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The 1st Tuesday JFI Colloquium - Mark G. Raizen - Department of Physics, University of Texas at Austin

From Maxwell’s Demon to Einstein’s Speed Demon

ABSTRACT: In this talk, I will describe two historical thought experiments in statistical mechanics and their experimental realization. Maxwell’s Demon was proposed by James Clerk Maxwell in 1871 as a way to reduce the entropy of gas-phase particles by means of an “intelligent creature with deft hands.” We have realized this thought experiment with a self-acting one-way wall for atoms, as originally suggested by Maxwell. This construction has been used to cool atoms, and for efficient isotope separation which will have important medical applications. In 1907, Albert Einstein predicted that Brownian motion should be ballistic on very short time scales, rather than diffusive. Einstein concluded that this instantaneous velocity would be impossible to measure in practice, a prediction that held for over 100 years. We have realized such a ‘speed demon’ by measuring the motion of micrometer beads held in optical tweezers, and have resolved the instantaneous velocity of a Brownian particle in air and in liquid. This system can be used to study the onset of irreversibility, the “arrow of time.”Host(s):Cheng Chin, 2-7192 or via email to cchin@jfi.uchicago.edu. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at bthomas@uchicago.edu.
The 1st Tuesday JFI Colloquium

April 4, 2017
GCIS W301 | Tuesday, 4:00 pm

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Wolfgang Ketterle, MIT

New forms of matter with ultracold atoms: synthetic gauge fields and supersolidity

Hosts: Cheng Chin
Physics Colloquium

March 31, 2017
KPTC 106 | Friday, 4:00 pm

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Yimon Aye, Cornell

Stay On Target: Deconvoluting Mixed Redox Messages through Precision Redox Targeting


Chemistry

March 31, 2017
Kent 120 | Friday, 1:15 pm

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The Tuesday JFI Seminar - James F. Cahoon, Department of Chemistry, University of North Carolina - Chapel Hill

From Nanowires to Nanoplatelets: Designing Semiconductor Morphology so Form Follows Function

Semiconductors are used in a vast array of modern technologies, including solar cells that convert sunlight into electricity and microprocessors that drive computers. They can be used to direct the flow of energy in devices or to convert energy from one form to another. These functions are enabled by the specific choice of material and composition. Shape, however, is another fundamental characteristic that can be used to encode functionality. Here, I will describe my group’s efforts to usenanometer-scale morphology as a strategy to encode novel photovoltaic, electronic, and optical properties in materials created by bottom-up methods. We chemically synthesize nanostructures, such as metal oxide particles and group IV nanowires, with precise morphology and composition, and we evaluate their physical properties using nanofabrication, spectroscopic, electrochemical, and computational methods. For instance, I will describe a strategy to create silicon nanowires with lithographic-like patterns, enabling applications ranging from photonic crystals to non-volatile memory. In addition, I will outline our efforts to design wide-bandgap photocathode materials for integration in solar fuels devices. The results yield insights into the synthesis, structure-function relationships, and technological applications of designed, bottom-up semiconductor nanomaterials. Host: Bozhi Tian; Contact him at 2-8749 or via email at btian@uchicago.edu. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at bthomas@uchicago.edu.
The Tuesday JFI Seminar

March 28, 2017
GCIS W301 | Tuesday, 4:00 pm

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Wheland Lecture - John P. Maier: University of Basel

Electronic Spectroscopy of C60+ and its Identification in Interstellar Space


Chemistry

March 27, 2017
Kent 120 | Monday, 4:00 pm

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The 2nd Tuesday JFI Colloquium - Hui Zhai, Tsinghua University, Institute for Advanced Study


The 2nd Tuesday JFI Colloquium

March 14, 2017
GCIS W301 | Tuesday, 4:00 pm

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Closs Lecture - Christopher Chang, University of California, Berkeley

Transition Metal Signaling in the Brain and Beyond


Chemistry

March 8, 2017
Kent 120 | Wednesday, 1:15 pm

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Moh El-Naggar, PhD, Depts of Physics and Astronomy, of Biological Sciences, and of Chemistry, University of Southern California

Far, Fast, & Surprising: Extracellular Electron Transport in Microbial Redox Chains

The stepwise movement of electrons within and between molecules dictates all biological energy conversion strategies, including respiration and photosynthesis. With such a universal role across all domains of life, the fundamentals of ET and its precise impact on bioenergetics have received considerable attention, and the broad mechanisms allowing ET over small length scales in biomolecules are now well appreciated.

In what has become an established pattern, however, our planet’s oldest and most versatile organisms are now challenging our current state of knowledge. With the discovery of bacterial nanowires and multicellular bacterial cables, the length scales of microbial ET observations have jumped by 7 orders of magnitude, from nanometers to centimeters, during the last decade alone! This talk will take stock of where we are and where we are heading as we come to grips with the basic mechanisms and immense implications of microbial long-distance electron transport. We will focus on the biophysical and structural basis of long-distance, fast, extracellular electron transport by metal-reducing bacteria. These remarkable organisms have evolved direct charge transfer mechanisms to solid surfaces outside the cells, allowing them to use abundant minerals as electron acceptors for respiration, instead of oxygen or other soluble oxidants that would normally diffuse inside cells. From an environmental perspective, these microbes are major players in global elemental cycles. From a technological perspective, microbial extracellular electron transport is heavily pursued for interfacing redox reactions to electrodes in multiple renewable energy technologies.

But how can an organism transfer electrons to a surface many cell lengths away? What molecules mediate this transport? And, from a physics standpoint, what are the relevant length, time, and energy scales? We will describe new experimental and computational approaches that revealed how bacteria organize heme networks on outer cell membranes, and along the quasi-one-dimensional filaments known as bacterial nanowires, to facilitate long-range charge transport. Using correlated electron cryo-tomography and in vivo fluorescent microscopy, we are gaining new insight into the localization patterns of multiheme cytochromes along nanowires as well as the morphology and the formation mechanism of these structures. In addition, we will examine the fundamental limits of extracellular electron transport, down to microbial energy acquisition by single cells. These findings are shedding light on one of the earliest forms of respiration on Earth while unraveling surprising biotic-abiotic interactions.
Biophysical Dynamics

March 7, 2017
GCIS W301 | Tuesday, 12:00 pm

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2017 Hillhouse Memorial Lecture - Professor Martin Karplus of Harvard University

Motion: Hallmark of Life. From Marsupials to Molecules

This lecture will present an intellectual path from the role of motion in animals to the molecules that make the motion possible. Motion is usually a way of distinguishing live animals from those that are not, but not always. Just as for the whole animal, motion is an essential part of the function of the cellular components. What about the molecules themsleves? Does motion distinguish molecules designed by people from those developed by evolution? For animals to move, they require energy, which is obtained primarily by using oxygen. So how are whales and dolphins able to use their muscles to dive to great depths, where oxygen is not available? The immediate energy source for muscle function is the molecule ATP. For the generation of this molecule, Nature has developed a marvelous rotary nanomotor. Experiments and simulations, particularly those with supercomputers, are now revealing the mechanism of this nanomotor and other cellular machines.
Chemistry

March 6, 2017
Kent 120 | Monday, 4:00 pm

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Closs Lecture-Eric Jacobsen, Harvard University

Anion-Binding Catalysis


Chemistry

March 3, 2017
Kent 120 | Friday, 1:15 pm

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Frank Wise, Department of Physics, Cornell University

Optoelectronic Properties of Semiconductor Nanocrystal Solids

There is currently great interest in electron transport in nanocrystal solids, driven by potential applications to electronic and optoelectronic devices. A major goal of the field is to achieve bandtype transport of electrons, and despite much progress in this direction, claims of band transport remain controversial. Recently, the fabrication of quasi-two-dimensional superlattices of oriented and epitaxially connected nanocrystals was reported. The structures exhibit both short- and long-range order. Calculations of the electronic states of such “atomically-coherent” assemblies reveal bandwidths that imply promising transport properties. We will report on the synthesis of atomically-coherent superlattices of PbSe nanocrystals, along with structural characterization by x-ray diffraction and high-resolution electron microscopy. Studies of charge transport show that disorder plays a major role in the properties of existing nanocrystal solids. Prospects for achieving true band transport in these structures will be discussed. The talk will begin with a tutorial introduction to semiconductor nanocrystals and devices based on them such as solar cells and light emitters. Host: Philippe Guyot-Sionnest, contact via email at pgs@uchicago.edu or by phone at 2-7461.
The Tuesday JFI Seminar

February 28, 2017
GCIS W301 | Tuesday, 4:00 pm

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Nandini Ananth: Cornell University


Chemistry

February 27, 2017
Kent 120 | Monday, 4:00 pm

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Uttam Tambar: UT Southwestern

Stereoselective Functionalization of Unactivated Hydrocarbons


Chemistry

February 24, 2017
Kent 120 | Friday, 1:15 pm

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Rainer Weiss, MIT


Physics Colloquium

February 23, 2017
KPTC 106 | Thursday, 4:00 pm

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Meghan Thielges, Indiana University

Conformations and Dynamics of Protein Molecular Recognition


Chemistry

February 23, 2017
GCIS W301 | Thursday, 1:15 pm

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Pedro M Reis, Department of civil Engineering, MIT


Computations in Science

February 22, 2017
KPTC 206 | Wednesday, 12:00 pm

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Michael Filler, Department of Chemical and Biomolecular Engineering, Georgia Tech


The Tuesday JFI Seminar

February 21, 2017
GCIS W301 | Tuesday, 2:00 pm

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Xiaogang Peng, Zhejiang University


Chemistry

February 20, 2017
Kent 120 | Monday, 4:00 pm

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Cheng Chin, University of Chicago


Physics Colloquium

February 16, 2017
KPTC 106 | Thursday, 4:00 pm

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Arvind Murugan - Department of Physics, University of Chicago


The 2nd Tuesday JFI Colloquium

February 14, 2017
GCIS W301 | Tuesday, 4:00 pm

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Sean Garrett-Roe, University of Pittsburgh

Ultrafast vibrational spectroscopy of ionic liquids: Insight into carbon capture, chemical reactions, and energy storage


Chemistry

February 13, 2017
Kent 120 | Monday, 4:00 pm

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Jessie Shelton, University of Illinois (Urbana-Champaign)


Physics Colloquium

February 9, 2017
KPTC 106 | Thursday, 4:00 pm

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Sungyon Lee, Texas A&M University

Particle-induced viscous fingering


Computations in Science

February 8, 2017
KPTC 206 | Wednesday, 12:00 pm

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Edward Sargent, University of Toronto

Materials and Devices for Flexible Optoelectronics and Renewable Fuels

Vast advances in materials and physical chemistry have led us to the point that, today, we can create a wide range of tunable, solution-processed materials whose spectral properties span the visible and infrared [1]. These are enabling flexible solar cells [2], top-surface photodetectors, and ubiquitous light sources [3]. I will discuss recent advances that leverage innovations from inorganic synthetic chemists and physical chemists and apply them in the engineering of high-performance optoelectronic devices. I will then discuss a further implication of rapid progress in the cost-effective conversion of solar energy into electrical power. These advances bring about a new challenge, namely, the need for massive (seasonal-scale) storage of energy [4]. I will describe how the use of computational materials science, spectroscopies including ultrafast and synchrotron, and advances in materials chemistry, are accelerating the creation of new catalysts for CO2 reduction and oxygen evolution. I will discuss recent advances including a new high-activity OER catalyst [5] and a low-overpotential CO2 reduction catalyst based on field-induced reagent concentration [6]. Host: Philippe Guyot-Sionnest; contact via email at pgs@uchicago.edu or by phone at 2-7461. Persons with a disability who may need assistance please contact Brenda Thomas by email at bthomas@uchicago.edu or phone at 2-7156.
The 1st Tuesday JFI Colloquium

February 7, 2017
GCIS W301 | Tuesday, 4:00 pm

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Bloch Lecture - Dr. Jay Bradner, Dana-Farber Cancer Institute

Inhibition and Degradation of Bromodomain Proteins


Chemistry

February 6, 2017
Kent 120 | Monday, 4:00 pm

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Closs Lecture - Sarah Tolbert, UCLA

Solution Processed Nanomaterials: From Basic Science to Solutions to Practical Energy Problems


Chemistry

February 3, 2017
Kent 120 | Friday, 1:15 pm

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Shinsei Ryu, University of Chicago

Topological insulators and superconductors--from band theory to interacting systems


Physics Colloquium

February 2, 2017
KPTC 106 | Thursday, 4:00 pm

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Joshua A Frieman, Fermilab, University of Chicago

The Dark Energy Survey

I will overview the Dark Energy Survey (DES) project, highlight its early science results, and discuss its on-going activities and plans. The DES collaboration built the 570-megapixel Dark Energy Camera for the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory in Chile to carry out a 5-year, deep, multi-band, optical survey over one eighth of the sky and a time-domain survey that will discover several thousand supernovae. The survey started in Aug. 2013 and is now nearing completion of its fourth observing season. DES was designed to address the questions: why is the expansion of the Universe speeding up? Is cosmic acceleration due to dark energy or does it require a modification of General Relativity? If dark energy, is it the energy density of the vacuum (Einstein's cosmological constant) or something else? DES is addressing these questions by measuring the history of cosmic expansion and the growth of structure through four complementary techniques: galaxy clusters, the large-scale galaxy distribution, gravitational lensing, and supernovae, as well as through cross-correlation with other data sets. I will also discuss how the data are being used to make a variety of other astronomical discoveries, from our Solar System to the most distant quasars.
Computations in Science

February 1, 2017
KPTC 206 | Wednesday, 12:00 pm

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Steven Boxer, Stanford University

Electric Fields and Enzyme Catalysis


Chemistry

January 30, 2017
Kent 120 | Monday, 4:00 pm

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Dr. Daniel Greif, Harvard University

Quantum Antiferromagnets with Single-Site Resolution

Strongly correlated electron systems such as high-temperature superconductors and pseudo-gap states are a cornerstone of modern condensed matter research. A complementary approach to studying solid-state systems is to build an experimentally tunable quantum system governed by the Hubbard model, which is thought to qualitatively describe these systems but is difficult to understand theoretically. Ultracold fermionic quantum gases in optical lattices provide a clean and tunable implementation of the Hubbard model. At the same time, optical microscopy in these systems gives access to single-site observables and correlation functions, and provides dynamic control of the potential landscape at the single-site level. So far, ultracold atom experiments have not been able to reach the low-temperature regime of the Hubbard model, which becomes particularly interesting when doped. Here we report on the observation of antiferromagnetic long-range order in a repulsively interacting Fermi gas of Li-6 atoms on a 2D square lattice containing about 80 sites. The ordered state is directly detected from a peak in the spin structure factor and a diverging correlation length of the spin correlation function. When doping away from half-filling into a numerically intractable regime, we find that long-range order extends to doping concentrations of about 15%. Our results open the path for a controlled study of the low-temperature phase diagram of the Hubbard model.
The Tuesday JFI Seminar

January 27, 2017
GCIS W301 | Friday, 4:00 pm

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Dr. Scott W. Schmucker, Zyvex Labs, Richardson, Texas

Atomically-Precise Engineering of Low-Dimensional Systems

As ultra-precise manufacturing technology scales to its atomic limits, we transition into the realm of digital matter and novel composite materials while enabling a burgeoning array of quantum, electronic, and photonic devices. In this talk, we explore several fabrication technologies which enable atomic- precision while elucidating the fundamental science and the engineering applications motivated and enabled thereby. We first compare several related two-dimensional material systems: graphenic materials and hyperdoped delta layers in silicon, each of which can be chemically and lithographically engineered or combined to form van der Waals and covalent delta-doped heterostructures. We explore the influences of interlayer coupling, interfaces, and defects in layered systems. We will then expand our discussion beyond layered systems and extend atomic precision into three dimensions. Discussion will focus on scanned probe lithography for the fabrication of donor atom quantum devices in silicon and recent efforts to expand these devices to include acceptor dopants and to enable three-dimensional architectures. We discuss the physics and fabrication of donor atom qubits in silicon, and through a combination of scanning tunneling microscope-driven lithography and Zyvex engineering, we demonstrate the scaling of manufacturing precision to the atomic scale
JFI Special Seminar

December 16, 2016
GCIS E223 | Friday, 2:00 pm

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Daniel Diermeier, University of Chicago

Modeling Electrons

The talk will discuss models of elections from game-theory to statistical mechanics. I will discuss their relative strengths and weaknesses and their ability or inability to explain voting behavior in mass elections.
Physics Colloquium

December 10, 2016
KPTC 106 | Saturday, 4:00 pm

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