Two Brandeis Professors Receive 2017 Simons Fellowships, part II

Spectral Flow

Spectral Flow (full caption below)

Two Brandeis professors have been awarded highly prestigious and competitive Simons Fellowships for 2017. Daniel Ruberman received a 2017 Simons Fellowship in Mathematics. Matthew Headrick was awarded a 2017 Simons Fellowship in Theoretical Physics. This is the second of two articles where each recipient describes their award-winning research.

Daniel Ruberman’s research asks “What is the large-scale structure of our world?” Einstein’s unification of physical space and time tells us that the universe is fundamentally 4-dimensional. Paradoxically, the large-scale structure, or topology, of 4-dimensional spaces, is much less understood than the topology in other dimensions. Surfaces (2-dimensional spaces) are completely classified, and the study of 3-dimensional spaces is largely dominated by geometry. In contrast, problems about spaces of dimension greater than 4 are translated, using the technique called surgery theory, into the abstract questions of algebra.

Ruberman will work on several projects studying the large-scale topology of 4-dimensional spaces. His work combines geometric techniques with the study of partial differential equations arising in physics. One major project, with Nikolai Saveliev (Miami) is to test a prediction of the high-dimensional surgery theory, that there should be `exotic’ manifolds that resemble a product of a circle and a 3-dimensional sphere. The proposed method, which would show that this prediction is incorrect, is to compare numerical invariants derived from the solutions to the Yang-Mills and Seiberg-Witten equations, by embedding both in a more complicated master equation. The study of the Seiberg-Witten invariants is complicated by their instability with respect to varying geometric parameters in the theory. A key step in their analysis is the introduction of the notion of end-periodic spectral flow, which compensates for that instability, as illustrated below.

Other projects for the year will apply techniques from 4-dimensional topology to classical problems of combinatorics and geometry about configurations of lines in projective space. In recent years, combinatorial methods have been used to decide if a specified incidence relation between certain objects (“lines”) and other objects (“points”) can be realized by actual points and lines in a projective plane. For the real and complex fields, one can weaken the condition to look for topologically embedded lines (circles in the real case, spheres in the complex case) that meet according to a specified incidence relation. Ruberman’s work with Laura Starkston (Stanford) gives new topological restrictions on the realization of configurations of spheres in the complex projective plane.

Caption: Solutions to the Seiberg-Witten equations of quantum field theory provide topological information about 4-dimensional spaces. However, the set of solutions, or moduli space, can undergo a phase transition as a parameter T is varied, making those solutions hard to count. This figure illustrates a key calculation: the phase transition is equal to the end-periodic spectral flow, a new concept introduced in work of Mrowka-Ruberman-Saveliev. In the figure, the spectral set, illustrated by the red curves, evolves with the parameter T. Every time the spectral set crosses the cylinder, the moduli space changes, gaining or losing points according to the direction of the crossing.

Physics Graduate Student Receives Kavli Fellowship

Cesar Agon at Kavli Institute Cesar Agon, a graduate student in the High-Energy and Gravitational Theory group, was awarded a prestigious Graduate Fellowship at the Kavli Institute for Theoretical Physics (KITP) at the University of California, Santa Barbara. KITP is one of the world’s leading centers for research in all areas of theoretical physics. In addition to having its own faculty and postdocs, it hosts visiting faculty from around the world and holds conferences and semester-long programs on topics of current interest. The Graduate Fellowship program allows exceptional students to benefit from this activity and the scientific ambience of KITP by spending a semester there. This is a very competitive program, with only about half a dozen students coming from around the world each semester. Agon, who is advised by Profs. Matthew Headrick, Albion Lawrence, and Howard Schnitzer, is currently spending the spring term at KITP, before heading off to Stony Brook University as a postdoc in the fall.

Back in the summer of 2015, Agon had the opportunity to visit KITP during two important programs on the physics frontiers, both of special interest to him, namely ”Entanglement in Strongly-Correlated Quantum Matter” and ”Quantum Gravity Foundations: UV to IR”. That was a great opportunity to meet in person the leaders of the field from around the world in the relaxed and friendly atmosphere of the KITP. Discussions among the researchers and students were tremendously common all around the institute and there were many activities that facilitated such discussions such as daily coffees, lunches, and dinners.

[Read more…]

Two Brandeis Professors Receive 2017 Simons Fellowships

Bit threads in a holographic spacetime

Bit threads in a holographic spacetime

Two Brandeis professors have been awarded highly prestigious and competitive Simons Fellowships for 2017. Daniel Ruberman received a 2017 Simons Fellowship in Mathematics. Matthew Headrick was awarded a 2017 Simons Fellowship in Theoretical Physics. This is the first of two articles where each recipient’s award-winning research is described.

Matthew Headrick’s research studies the phenomenon of entanglement in certain quantum systems and its connection to the geometry of spacetime in general relativity. This very active area of research is the culmination of three developments in theoretical physics over the past 20 years.

First, in 1997, string theorists discovered that certain quantum systems involving a large number of very strongly interacting constituents — whose analysis would normally be intractable — are secretly equivalent to general relativity — a classical theory describing gravity in terms of curved spacetime — in a space with an extra dimension. For example, if the quantum system has two dimensions of space, then the general relativity has three; the phenomenon is thus naturally dubbed “holography”.

This equivalence between two very different-looking theories is incredibly powerful, and has led to much progress in understanding both strongly-interacting quantum systems and general relativity. However, it is still not fully understood how or precisely under what conditions such an equivalence holds.

[Read more…]

“Exceptionally Helpful” Matthew Headrick Receives Award

Associate Professor of Physics Matthew Headrick was named by the American Physical Society as an Outstanding Referee for 2017. The award recognizes “scientists who have been exceptionally helpful in assessing manuscripts for publication in the APS journals”. Headrick, who works in string theory and related areas of theoretical physics, is one of 150 Outstanding Referees named this year, out of about 60,000 active referees for the APS journals. Headrick is not the only Brandeis physicist to have received this honor; Robert Meyer, now Emeritus Professor, was named an Outstanding Referee in 2011.

Headrick’s research is primarily focused on the intersection of quantum gravity, quantum field theory, and quantum information theory. He is specifically interested in information-theoretic aspects of holographic field theories (field theories that are dual to higher-dimensional gravitational theories), such as entanglement entropies and related quantities.

Simons Foundation funds Brandeis Math, Physics collaborations

In 2014, the Simons Foundation, one of the world’s largest and most prominent basic science philanthropies, launched an unprecedented program to fund multi-year, international research collaborations in mathematics and theoretical physics. These are $10M grants over four years, renewable, that aim to drive progress on fundamental scientific questions of major importance in mathematics, theoretical physics, and theoretical computer science. There were 82 proposals in this first round. In September 2015, two were funded. Both involve Brandeis.

Matthew Headrick (Physics) is deputy director of the Simons Collaboration It from Qubit, which involves 16 faculty members at 15 institutions in six countries. This project is trying from multiple angles to bring together physics and quantum information theory, and show how some fundamental physical phenomena (spacetime, black holes etc.) emerge from the very nature of quantum information. Fundamental physics and quantum information theory remain distinct disciplines and communities, separated by significant barriers to communication and collaboration. “It from Qubit” is a large-scale effort by some of the leading researchers in both communities to foster communication, education and collaboration between them, thereby advancing both fields and ultimately solving some of the deepest problems in physics. The overarching scientific questions motivating the Collaboration include:

  • Does spacetime emerge from entanglement?
  • Do black holes have interiors?
  • Does the universe exist outside our horizon?
  • What is the information-theoretic structure of quantum field theories?
  • Can quantum computers simulate all physical phenomena?
  • How does quantum information flow in time?

Bong Lian (Mathematics) is a member of the Simons Collaboration on Homological Mirror Symmetry, which involves nine investigators from eight different institutions in three countries. Mirror Symmetry, first discovered by theoretical physicists in late ‘80s, is a relationship between two very different-looking physical models of Nature, a remarkable equivalence or “duality” between different versions of a particular species of multidimensional space or shape (Calabi-Yau manifolds) that seemed to give rise to the same physics. People have been trying to give a precise and general mathematical description of this mirroring ever since, and in the process have generated a long list of very surprising and far-reaching mathematical predictions and conjectures. The so-called “Homological Mirror Symmetry Conjecture” (HMS) may be thought of as a culmination of these efforts, and Lian was a member of the group (including S.-T. Yau) that gave a proof of a precursor to HMS in a series of papers in the late ‘90s.

Lian and his Simons collaborators are determined to prove HMS in full generality and explore its applications. One consequence of HMS says that if one starts from a “complex manifold” (a type of even-dimensioned space that geometers have been studying since Riemann described the first examples in 1845), then all its internal geometric structures can in fact be described using a certain partner space, called a “symplectic manifold”. The latter type of space was a mathematical edifice invented to understand classical physics in the mid-1900s. This connection goes both ways: any internal geometric structure of the symplectic partner also has an equally compelling description using the original complex partner. No one had even remotely expected such a connection, especially given that the discoveries of the two types of spaces — complex and symplectic — were separated by more than 100 years and were invented for very different reasons. If proven true, HMS will give us ways to answer questions about the internal geometric structure of a complex manifold by studying its symplectic partner, and vice versa.

Proving HMS will also help resolve many very difficult problems in enumerative geometry that for more than a century were thought to be intractable. Enumerative geometry is an ancient (and until recently moribund) branch of geometry in which people count the number of geometric objects of a particular type that can be contained inside a space. Mirror symmetry and HMS have turned enumerative geometry into a new way to characterize and relate shapes and spaces.

7 Division of Science Faculty Recently Promoted

Congratulations to the following 7 Division of Science faculty members were recently promoted:

katz_dbDonald B. Katz (Psychology) has been promoted to Professor of Psychology. Don came to Brandeis as an Assistant Professor with a joint appointment in the Volen Center for Complex Systems in 2002 and was promoted to Associate Professor and awarded tenure in 2008. Don’s teaching and research serve central roles in both Psychology and the Neuroscience program. His systems approach to investigating gustation blends behavioral testing of awake rodents with multi-neuronal recording and pharmacological, optogenetic, and modelling techniques. Broad themes of the neural dynamics of perceptual coding, learning, social learning, decision making, and insight run through his work on gustation. For his research, Don has won the 2007 Polak Award and the 2004 Ajinomoto Young Investigator in Gustation Award, both from the Association for Chemoreception Sciences. Don has taught “Introduction to Behavioral Neuroscience” (NPSY11b), “Advanced Topics in Behavioral Neuroscience” (NPSY197a), “Neuroscience Proseminar” (NBIO250a), “Proseminar in Brain, Body, and Behavior II” (PSYC302a), “How Do We Know What We Know?” (SYS1c). For his excellence in teaching, Don has been recognized with the 2013 Jeanette Lerman-Neubauer ’69 and Joseph Neubauer Prize for Excellence in Teaching and Mentoring, the 2006 Brandeis Student Union Teaching Award, and the 2006 Michael L. Walzer Award for Teaching and Scholarship.

Nicolas RohlederNicolas Rohleder (Psychology) has been promoted to Associate Professor in Psychology. Nic is a member of the Volen Center for Complex Systems and on the faculty of the Neuroscience and Health, Science, Society and Policy programs. His course offerings include “Health Psychology” (PSYC38a), “Stress, Physiology and Health” (NPSY141a), and” Research Methods and Laboratory in Psychology” (PSYC52a). Nic’s research investigates how acute and chronic or repeated stress experiences affect human health across individuals and age groups. His laboratory performs studies with human participants using methods than span behavioral to molecular to understand how the hypothalamus-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS) regulate peripheral immunological responses and how these processes mediate cardiovascular disease, type 2 diabetes, and cancer, and aging. His research and teaching fill unique niches for all his Brandeis departmental and program affiliations. Nic’s research excellence has been recognized outside Brandeis with awards including the 2013 Herbert Weiner Early Career Award of the American Psychosomatic Society and the 2011 Curt P. Richter Award of the International Society of Psychoneuroendocrinology.

Matthew HeadrickMatthew Headrick (Physics) has been promoted to Associate Professor of Physics. He works at the intersection of three areas of modern theoretical physics: quantum field theory, general relativity, and quantum information theory. In particular, he uses information-theoretic techniques to study the structure of entanglement — a fundamental and ubiquitous property of quantum systems — in various kinds of field theories. Much of his work is devoted to the study of so-called “holographic” field theories, which are equivalent, in a subtle and still mysterious way, to theories of gravity in higher-dimensional spacetimes. Holographic theories have revealed a deep connection between entanglement and spacetime geometry, and Headrick has made significant contributions to the elucidation of this connection. Understanding the role of entanglement in holographic theories, and in quantum gravity more generally, may eventually lead to an understanding of the microscopic origin of space and time themselves.

Isaac Krauss

Isaac Krauss (Chemistry) has been promoted to Associate Professor of Chemistry. He is an organic chemist and chemical biologist whose research is at the interface of carbohydrate chemistry and biology. His lab has devised tools for directed evolution of modified DNA and peptides as an approach to designing carbohydrate vaccines against HIV. Krauss is also a very popular teacher and the recipient of the 2015 Walzer prize in teaching for tenure-track faculty.

Xiaodong Liu (Psychology) has been promoted to Associate Professor in Psychology. Xiaodong provides statistical training for graduate students in Psychology, Heller School, IBS, Neuroscience, Biology, and Computer Science, he serves as a statistical consultant for Xiaodong LiuPsychology faculty and student projects, and he performs research on general & generalized linear modeling and longitudinal data analysis, which he applies to child development, including psychological adjustment and school performance. He teaches “Advanced Psychological Statistics I and II” (PSYC210a,b), “SAS Applications” (PSYC140a), “Multivariate Statistics I: Applied Structural Equation Modeling” (PSYC215a), and “Multivariate Statistics II: Applied Hierarchical Linear Models” (PSYC216a). He is developing a new course on “The R Statistical Package and Applied Bayes Analysis”, and he recently won a Provost’s Innovations in Teaching Grant for “Incorporating Project-based modules in Learning and Teaching of Applied Statistics”.

Gabriella SciollaGabriella Sciolla (Physics) has been promoted to Professor of Physics. She is a particle physicist working on the ATLAS experiment at CERN in Geneva, Switzerland. Sciolla and her group study the properties of the newly discovered Higgs Boson and search for Dark Matter particles produced in high-energy proton-proton collisions at the Large Hadron Collider. Sciolla is also responsible for the reconstruction and calibration of the muons produced in ATLAS. These particles are key to both Higgs studies and searches for New Physics.

Nianwen Xue (Computer Science) has been promoted to Associate Professor of Computer Science.  The Computer Science Department is pleased to annNianwen Xueounce the promotion of Nianwen (Bert) Xue to Associate Professor with tenure. Since joining Computer Science he has made significant contributions to the research and teaching efforts in Computational Linguistics, including growing a masters program from zero up to 18 students this year. His publications are very well regarded, and focus on the development and use of large corpora for natural language processing, especially in Chinese. He has built a sizable lab with diverse funding that students from around the world are vying to enter.

Thank you to the following department chairs for their contributions to this post:

  • Paul DiZio, Psychology
  • Jane Kondev, Physics
  • Jordan Pollack, Computer Science
  • Barry Snider, Chemistry

Protected by Akismet
Blog with WordPress

Welcome Guest | Login (Brandeis Members Only)