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.

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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.

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“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

Brandeis in Aspen I: String theory and quantum information

The Aspen Center for Physics is a physics retreat in which groups of researchers in a given field gather for a few weeks during the summer to discuss the latest developments and create the next ones. This May, a record four Brandeis physicists — almost a quarter of the department — visited the Center at the same time, attending two different workshops. This posting is about a workshop attended by string theorists Matthew Headrick and Albion Lawrence (and co-organized by Headrick);  another posting will describe a workshop attended by condensed-matter theorists Aparna Baskaran and Bulbul Chakraborty (a member of the Center’s advisory board).  Entry into Aspen workshops is competitive, so this strong Brandeis representation is remarkable; as always, we punch above our weight.

Headrick and Lawrence attended the workshop Quantum information in quantum gravity and condensed matter physics.  This was a highly interdisciplinary workshop, which brought together specialists in quantum gravity, including Headrick and Lawrence; experts in quantum information theory; and experts in “hard” condensed matter physics (who study material properties for which quantum phenomena play a central role).

Quantum information theorists study how the counterintuitive features of quantum mechanics — such as superpositions of states, entanglement between separated systems, and the collapse of the wave function brought on by measurement — could be exploited to produce remarkable (but so far mostly hypothetical) technologies like teleportation of quantum states, unbreakable encryption, and superfast computation. What does this have to do with gravity? When we try to formulate a consistent quantum-mechanical theory of gravity — which would subsume Einstein’s classical general theory of relativity — the concept of information crops up in numerous and often puzzling ways. For example, Stephen Hawking showed in the 1970s that, on account of quantum effects, black holes emit thermal radiation. Unlike the radiation emitted by conventional hot objects, which is only approximately thermal, pure thermal radiation of the kind that Hawking’s calculation predicted cannot carry information. Many physicists (including Hawking) therefore originally interpreted his result as implying that black holes fundamentally destroy information, challenging a sacred principle of physics. Today, based on advances in string theory, physicists (including Hawking) generally believe that in fact black holes do not destroy the information they contain.  Rather, black holes hide information in very subtle ways, by scrambling, encryption, and perhaps quantum teleportation — in other words, the same kinds of tricks that the quantum information people have been inventing and studying independently at the same time.

Another connection between gravity and information is provided by the so-called “holographic principle”, which also arose in the study of black holes and which has been given a precise realization in the context of string theory. This principle posits that, due to a combination of gravitational and quantum effects, there is a fundamental limit to the amount of information (i.e. the number of bits) that can be stored in a region of space, and furthermore that limit is related to its surface area, not its volume. String theorists, beginning with the seminal work of Juan Maldacena, have uncovered a number of precise implementations of this principle, in which certain quantum theories without gravity are holograms of theories of quantum gravity.  This should provide an avenue for uncovering the “tricks” gravity uses to hide information, a subject Lawrence is active in.  An additional benefit of these implementations is that calculations in the nongravitational theories which seemed prohibitively difficult become fairly simple in the gravitational side; these include  the computation of interesting quantities in quantum information theory, an area in which Headrick has done influential work.

All of these issues and many others were discussed in Aspen. This rather unique workshop was a very fruitful exchange of ideas, with physicists from three fields learning from each other and forging new interdisciplinary collaborations, in a setting where the scenery matched the grandeur of the subject.

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