# Many Electron Collaboration: Collaboration Scientists

### Bismayan Chakrabarti

Bismayan Chakrabarti is a member of the Real Materials Group and a graduate student at Rutgers, The State University of New Jersey, where he works with Professors Kristjan Haule and Gabriel Kotliar. Chakrabarti’s research interests lie in the field of strongly correlated systems, in particular using dynamical mean field theory to obtain a realistic description of their properties. Some of the systems he is currently working on include the investigation of the magnetic form factors and dynamical magnetic excitations of alpha and gamma Cerium and delta Plutonium.

### Chia-Min Chung, Ph.D.

Chia-Min Chung, a member of the Tensor Networks Group, works with Steven White at the University of California, Irvine. He obtained his B.Sc. in physics in 2007 at National Cheng Kung University in Taiwan, and he earned his Ph.D. in physics in 2014 at National Tsing Hua University, also in Taiwan. His early research focused on bosonic many-body systems, which he studied using the path-integral quantum Monte Carlo (QMC) algorithm. He also worked on developing new methods based on QMC to calculate entanglement quantities. His current research focuses on developing new numerical methods to simulate challenging many-body systems, such as the 2D Hubbard model, by using matrix product states as well as QMC.

### Glen Evenbly, Ph.D.

Glen Evenbly is a member of the Tensor Networks Group, working with Steven White at the University of California, Irvine. He was born in New Zealand and obtained his B.Sc. in Physics at the University of Auckland, New Zealand in 2004. He performed physics research for his Ph.D. at the University of Queensland with Professor Guifre Vidal, and received his Ph.D. in Physics in 2010. Afterwards, he was awarded the Sherman-Fairchild Prize Postdoctoral Scholarship in Theoretical Physics at California Institute of Technology (2011–2014) working in Professor John Preskill’s group.

Evenbly’s research is focused on the development and implementation of tensor network approaches for the efficient simulation of quantum many-body systems. In particular, he has made significant contributions to the development of the multi-scale entanglement renormalization ansatz (MERA) and its application to the study of many-body systems at criticality.

### Alexander Gaenko, Ph.D.

Alexander Gaenko is a member of the Monte Carlo Group and a staff member of the Advanced Research Computing at University of Michigan, working with Emanuel Gull’s Computational Condensed Matter Physics Group. Gaenko received his Ph.D. in Physical and Organic Chemistry in 2008 from St. Petersburg State Institute of Technology, Russia. Before coming to the University of Michigan, he was an assistant scientist at the Ames Laboratory of the U.S. Department of Energy, run by Iowa State University. Gaenko’s specialization is computational science, particularly electronic structure theory and computational chemistry areas. His research focus is on analyzing and improving the performance of scientific software, on taking advantage of current and emerging HPC systems (including accelerators) for scientific codes, and on scientific software interoperability across packages and languages.

### Martin Ganahl

Martin Ganahl is a member of the Tensor Networks Group, working with Guifre Vidal at the Perimeter Institute. He currently studies physics at the Graz University of Technology, where he is finishing his Ph.D. with Hans Gerd Evertz. His present research relates to non-equilibrium dynamics of quantum system in one dimension, where he uses matrix product state (MPS) methods to numerically solve the many electron Schrödinger equation. He is also interested in hybrid approaches where MPS are combined with other techniques like dynamical mean‑field theory.

### James P.F. LeBlanc, Ph.D.

James LeBlanc is a member of the Monte Carlo Group and he is a member of the Computational Condensed Matter Physics Group at the University of Michigan working with Emanuel Gull. He received his Ph.D. in 2012 from the University of Guelph, an affiliate of the Guelph-Waterloo Physics Institute in Ontario, Canada. Afterward, he was awarded a postdoctoral fellowship at the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany.

His early research focused on the phenomenology of the pseudogap state in the underdoped cuprates. More recently he has studied the effects of correlations and collective excitations on properties of graphene and topological surface states. He currently works on creating benchmark solutions to the 2D Hubbard model using large scale dynamical cluster approximation simulations and is developing cluster algorithms using two-particle correlation functions.

LeBlanc has been the recipient of significant funding from the Natural Sciences and Engineering Research Council of Canada (NSERC), including a Canadian Graduate Scholarship and a Postdoctoral Fellowship.

### Zhendong Li, Ph.D.

Zhendong Li works with Professor Garnet Chan at Princeton University. He obtained his B.Sc. in Chemistry and Mathematics at the Peking University, China, in 2009. He received his Ph.D. at the Peking University in quantum chemistry in 2014 under the supervision of Professor Wenjian Liu.

His research has focused on the developments of theoretical methods for excited states of open-shell molecules, relativistic Hamiltonians for spin-dependent properties and symbolic algebra for tensor expressions. His current interests lie in the development of new numerical methods for the many electron problem in quantum chemistry.

### Sergey Nikolaev, Ph.D.

Sergey Nikolaev is a member of the Real Materials Group, working with Evgeny Kozik at King’s College London. He received his Ph.D. in 2015 from Ural Federal University and is now a postdoctoral fellow in the Theory and Simulation of Condensed Matter Group in the Physics Department at King’s College London. His scientific interests are in the field of first-principles calculations and model Hamiltonians, as well as non-equilibrium phenomena and many-body methods. He is currently working on the problem of extending the GW method by incorporating vertex corrections using diagrammatic Monte Carlo and its implementation for systems out of equilibrium.

### Dimitar Pashov, Ph.D.

Dimitar Pashov is a member of the Real Materials Group, working with Mark van Schilfgaarde at King’s College London. He obtained his Ph.D. at the Atomistic Simulations Centre, Queen’s University Belfast, under the supervision of Professor Paxton.

His interests presently are in treating spin fluctuations in an *ab initio* framework with the quasiparticle self-consistent GW theory. He is also involved with various algorithmic improvements in the LM suite, containing a spectrum of electronic structure codes from a full-potential linear muffin-tin all-electron method, polarizable ion tight binding theory and others. His earlier work includes Green functions, linear scaling, bond-order potential parameterization and parallel implementation, and multilevel parallel tight binding implementation, utilizing GPUs on suitable parts of the solution.

### Julian Rincon, Ph.D.

Julian Rincon is a member of the Tensor Networks Group, working with Guifre Vidal at the Perimeter Institute. He is currently a postdoctoral fellow at the Center for Nanophase Materials Science at Oak Ridge National Laboratory and received his Ph.D. at the Balseiro Institute in 2010. His present research concerns the study of transport properties through low-dimensional strongly correlated electron systems, using analytical and numerical tools such as the density matrix renormalization group.

His earlier work was focused on the effect of correlations and quantum interference on the transport and real-time properties of nanoscopic devices, like quantum dots, molecules and nanowires. He then turned to the study of order in models for multi-orbital systems, such as iron-based superconductors and Hund’s metals, and their associated orbital-related quantum phase transitions. He is very interested in the improvement, development and implementation of efficient algorithms in the tensor network language.

### Lorenzo Sponza, Ph.D.

Lorenzo Sponza is a member of the Real Materials Group at King’s College London, where he works as a research associate with Professor Mark van Schilfgaarde, in collaboration with Professor Gabriel Kotliar of Rutgers University. He obtained his Ph.D. in the Theoretical Spectroscopy Group of the Laboratoire des Solides Irradiés (LSI), École Polytechnique (Palaiseau, France), under the supervision of Lucia Reining and Christine Giorgetti. He continued his scientific career as a research and teaching assistant at the Institut des NanoSciences de Paris (INSP) in the Oxides in Low Dimensions Group directed by Claudine Noguera and Jacek Goniakowski.

Sponza’s interests are principally in the *ab initio* description of the electronic structure of real materials, with particular interest in the spectra of two-particle excitations (e.g., absorption or electron energy loss). His current research focuses on the theoretical and technical development of methods merging the dynamical mean-field theory and the quasiparticle self-consistent GW (QSGW) approaches, with the aim of overcoming the limitations of both. In his earlier works, he focused mainly in many-body perturbation theory, either applying state-of-the-art methods to the prediction of optical spectra of systems interesting for technological applications or developing novel theoretical approaches to include dynamical effects in the description of light absorption.

### Igor Tupitsyn, Ph.D.

Igor Tupitsyn is a member of the Monte Carlo Group, working with Nikolay Prokof’ev and Boris Svistunov at the University of Massachusetts, Amherst. He obtained his Ph.D. in theoretical condensed matter physics from Kurchatov Institute (Moscow). After a two-year postdoc at the Spinoza Institute of Theoretical Physics (Utrecht University, the Netherlands), he worked as a research scientist at the Pacific Institute of Theoretical Physics (University of British Columbia, Vancouver).

Tupitsyn’s research interests are in the fields of quantum information, critical phenomena, novel computational techniques, topological order and excitations, and Bose-Einstein condensation of quasiparticles. He is a co-inventor of the worm algorithm used in quantum Monte Carlo simulations and co-author of the theory of environmental quantum decoherence for electronic spin insulators and semiconductors. The latter has recently lead to the first absolute comparison of theoretical and experimental decoherence times for complex condensed matter systems and opened a new way for a design of quantum information processing devices.

### Wei Wu, Ph.D.

Wei Wu is a member of the Cluster Embeddings Group, working with Michel Ferrero and Antoine Georges at École Polytechnique and with Evgeny Kozik (King’s College). He received his Ph.D. in 2012 from the Institute of Physics, Chinese Academy of Sciences (Beijing). He currently works as a postdoctoral fellow at the Université de Sherbrooke in Québec, Canada. His research is mainly focused on applying dynamical mean-field theory and large-scale quantum Monte Carlo methods to study various quantum many body systems. Recently, he has studied correlation effects in graphene and topological insulators, as well as unconventional superconductivity in heavy fermion systems.