Events Archive

In principle, quantum computers that exploit the nature of quantum physics can solve some problems much more efficiently than classical computers can..

Interfaces between two distinct complex oxide materials can display ground states which diverge greatly from the parent compounds, making them a..

How do fluids become turbulent as their flow velocity is increased? In recent years, careful experiments in pipes and Taylor-Couette systems have revealed that the lifetime of transient turbulent regions in a fluid appears to diverge with flow velocity just before the onset of turbulence, faster than any power law or exponential function. I show how this superexponential scaling of the turbulent lifetime in pipe flow is related to extreme value statistics, which I show is a manifestation of a mapping between transitional turbulence and the statistical mechanics model of directed percolation. This mapping itself arises from a further surprising and remarkable connection: laminar and turbulent regions in a fluid behave as a predator-prey ecosystem. Such ecosystems are governed by individual fluctuations in the population and being naturally quantized, are solvable by path integral techniques from field theory. I explain the evidence for this mapping, and propose how a unified picture of the transition to turbulence emerges in systems ranging from turbulent convection to magnetohydrodynamics.

The Aharonov-Bohm effect (AB) concerns the role in quantum physics of the vector potential of an impenetrable line of magnetic flux. Its partial..

Band-limited functions can oscillate arbitrarily faster than their fastest Fourier component over arbitrarily long intervals: they can ‘..

Majorana fermions are non-trivial quantum excitations that have remarkable topological properties and can be used to protect quantum information against decoherence. Tunneling spectroscopy measurements on one-dimensional superconducting hybrid materials have revealed signatures of Majorana fermions which are the edge states of a bulk topological superconducting phase. We couple strong spin-orbit semiconductor InSb nanowires to conventional superconductors (NbTiN, Al) to obtain additional signatures of Majorana fermions and to explore the topological phase transition. A potent alternative explanation for many of the recent experimental Majorana reports is that a non-topological Andreev state localizes near the end of a nanowire. We compare Andreev and Majorana modes and investigate ways to clearly distinguish the two phenomena. We are also exploring how Andreev states can be chained together along the nanowire to realize the one-dimensional Kitaev model, a discrete way of generating Majorana modes.

Artificial neural networks are performing tasks, image recognition and natural language processing, for artificial intelligence. However, these algorithms run on traditional computers and consume orders of magnitude more energy more than the brain does at the same task. One promising path to reduce the energy consumption is to build dedicated hardware to perform artificial intelligence. Nanodevices are particularly interesting because they allow for complex functionality with low energy consumption and small size. I discuss two nanodevices. First, I focus on stochastic magnetic tunnel junctions, which can emulate the spike trains emitted by neurons with a switching rate that can be controlled by an input. junctions can be combined with CMOS circuitry to implement population coding to build low power computing systems capable of controlling output behavior. Second, I turn to different nanodevices, memristors, to implement a different type of computation occurring in nature: swarm intelligence. A broad class of algorithms inspired by the behavior of swarms have been proven successful at solving optimization problems (for example an ant colony can solve a maze). Networks of memristors can perform swarm intelligence and find the shortest paths in mazes, without any supervision or training. These results are striking illustrations of how matching the functionalities of nanodevices with relevant properties of natural systems open the way to low power hardware implementations of difficult computing problems.

We calculate the effect of impurities on the superconducting phase diagram of transition metal dichalcogenide monolayers in the presence of an in-..

When atomically thin two-dimensional (2D) materials are layered, they often form incommensurable noncrystalline structures that exhibit long-period moiré patterns when examined by scanning probes. In this presentation we will use graphene and hexagonal boron nitride as examples of gapless and gapped Dirac materials to illustrate how the moire superlattices due to interlayer coupling can alter the materials' intrinsic electronic properties. The derivation of the effective models for these van der Waals materials heterojunctions for arbitrary twist angles can benefit from input obtained from ab initio calculations carried out for commensurate short period crystalline structures. We will discuss how the moire pattern modified electronic structures give rise to a variety of experimentally measurable features including enhanced density of states through van Hove singularities, and flat bands, or to their suppression due to formation of band gaps.

We investigate the energetic relaxation and spatial localization of photoexcited states in conformationally disordered p-conjugated models, choosing poly(para-phenylene vinylene) as a model system. Assuming vertical excitations, the initial photoexcited eigenstates are obtained via the disordered Frenkel model. The subsequent relaxation and localization of the excited statesis determined via the disordered Frenkel-Holstein model coupled to a dissipative environment. In particular, we solve the Lindblad master equation via the time-evolving block decimation (TEBD) and quantum jump trajectory methods. The values of the model parameters physically relevant to polymer systems naturally lead to a separation of time scales, with the ultra-fast dynamics corresponding to energy transfer from the exciton to the internal phonon modes (i.e., the C-C bond oscillations), while the longer time dynamics correspond to damping of these phonon modes by the external dissipation. Associated with these time scales, we investigate the following processes that are indicative of the system relaxing onto the emissive chromophores of the polymer: 1) Exciton-polaron formation occurs on an ultra-fast time scale, with the associated exciton-phonon correlations present within half a vibrational time period of the C-C bond oscillations. 2) Exciton decoherence is driven by the decay in the vibrational overlaps associated with exciton-polaron formation, occurring on the same time scale. 3) Exciton density localization is driven by the external dissipation, arising from ‘wavefunction collapse’ occurring as a result of the system-environment interactions. Finally, we show how fluorescence anisotropy measurements can be used to investigate the exciton decoherence process during the relaxation dynamics.

Two dimensional (2D) quantum materials provide a versatile experimental platform to probe spin-dependent novel quantum phenomena emerging at the nanoscale. The possibility of on-demand tuning of spin properties of 2D materials by external knobs such as electric field, substrate engineered proximity, etc., can have far-reaching implications for spintronics. I will discuss our experiments demonstrating a strong modulation of spin currents in bilayer graphene using static and fluctuating proximity exchange fields of a ferromagnetic insulator (FMI). We achieve complete spin modulation in graphene layers by controlling the direction of the exchange field of a nearby magnetic material in graphene/FMI heterostructures. A strong magnetic exchange coupling across the interface in graphene/FMI heterostructures leads to the experimental observation of full spin modulation at low externally applied magnetic fields in mesoscopic graphene spin channels. In graphene/FMI heterostructures, we also discover a novel spin dephasing mechanism due to randomly fluctuating magnetic exchange fields. This is manifested as an unusually strong temperature dependence of the non-local spin signals in graphene, which is due to spin relaxation by thermally-induced transverse fluctuations of the FMI magnetization. In the second half of my talk, I will discuss spin-charge interconversion driven by the Rashba effect in van der Waal bonded platinum/graphene (Pt/Gr) heterostructures. The interfacial spin-orbit interaction driven Rashba effect in low-dimensional systems can enable efficient and tunable spin-charge interconversion for spintronics applications. I will show that an applied electric field at the Pt/Gr Rashba interface results in a net spin accumulation in graphene, with spin polarization quantized along a direction transverse to the applied electric field. This current induced non-zero spin accumulation at the Pt/Gr interface is a direct consequence of uncompensated spin-textured Femi surfaces of the graphene Dirac states due to a symmetry-breaking electric field normal to the Pt/Gr heterostructure. Employing the Pt/Gr Rashba interface, we also realize the first experimental demonstration of the Onsager reciprocity between charge and spin via Rashba Edelstein effect (REE) and inverse-REE. This work is a significant advancement in graphene spintronics and provides an alternative experimental approach to generating and detecting spins using extrinsically tunable interfacial spin-orbit phenomena in two-dimensional materials.

This colloquium aims to explain why classical thermodynamics is insufficient for solids. After a review of classical equilibrium and non-equilibrium thermodynamics, two examples will be considered, grain growth and crystal plasticity, the latter one in more details. The major complication for development of thermodynamic theory for these cases was the lack of understanding of phase flow geometry. Recently, this geometry was described for dynamics of edge dislocations. Based on this finding, thermodynamics of crystal plasticity can be constructed. It includes two new thermodynamic parameters, entropy and temperature of microstructure.They have simple physical meaning: the rate of microstructure entropy coincides with the rate of slip avalanches while microstructure temperature is average energy drop in a slip avalanche. Perhaps, the phase flow geometry and the corresponding thermodynamic are common for many avalanche-type phenomena.

The annual PQI signature event will cover a wide range of topics in quantum science and engineering by featuring prominent invited keynote lecturers and highlighting the current research of PQI members. All talks are colloquium-style and accessible to a broad audience.

Considering a career path outside academia? It can be confusing to figure out what else is out there, how to look for jobs, and how to decide what's right for you. Edward Dunlea, Special Assistant to the Dean of MCS, has been down this road and will offer some insights gleaned from his experiences in program management within the government, science policy both at a non-profit and within the private sector, and research administration in academia. His talk will focus on the field of science policy - what it is and how to find jobs - and he will also offer some general advice with an emphasis on careers outside of academia.

We set out to combine a mechanical system in which classical mechanics breaks down and quantum mechanics must be used with a seemingly unlikely application, measurement of the strength and effects of gravity. Our optomechanical system consists of a silica microsphere levitated in ultra-high vacuum in a magneto-gravitational trap. The microsphere is trapped in a magnetic field gradient created by permanent magnets and ferromagnetic pole pieces using the weak diamagnetism of the particle. With optical position measurements and feedback, the mechanical motion can be cooled by several orders of magnitude, ideally reaching the quantum ground state. The extreme sensitivity of this optomechanical system to external forces makes it a promising approach to a new measurement of the Newtonian gravitational constant. Furthermore, by measuring the decoherence rate of non-classical motional states of the trapped particle, it may be possible to place limits on theories of gravitational decoherence. This material is based upon work supported by the National Science Foundation under Grant No. 1757005

Quantum mechanics is a strange theory, and it has been used to justify all manner of religious claims such as extra-sensory perception. This year we bring together five experts on the physics of quantum mechanics to discuss what we know and what we don’t know. We will work both to make the basic laws of quantum mechanics accessible to the non-expert, while at the same time addressing cutting-edge debates in the philosophy and application of quantum physics. Reegister here!

There is considerable excitement about in realizing non-Abelian Anyons, particles whose phase upon exchange depends on the path taken. Their..

Artificial neural networks play a prominent role in the rapidly growing field of machine learning and are recently introduced to quantum many-body..

Introduction: In the halls of Congress there is widespread agreement about the role of R&D in the success of the America’s most innovative corporations. However, too often lawmakers view government models of discovery, from NASA to public university research labs, as obsolete and costly superstructures in today’s .com marketplace. What happened to the case for public exploration and discovery and why shouldn’t the private sector be trusted to find the cure for Grandma’s dementia or Johnny’s brain tumor? Long-time Washington political insider, former lobbyist, Administration appointee, and AIMBE’s Executive Director, Milan Yager, will reveal the hidden truth about why Congress doesn’t fund needed biomedical research. Results and Discussion : This presentation will highlight innovations and achievements made possible from past federal investments in basic research; such as the internet, wireless communications, even mapping the human genome. Today, Congress seems less interested in past accomplishments as they assume new priorities to balance the budget, reduce government, and free the private sector to assume long-standing government responsibilities for innovation and discovery. How did Congress make spending decisions to permit federal R&D spending to be flat for over a decade? Learn about why Congress is no long accountable for reduce investments in basic research. Discover three secrets to making a winning case for federal funding for medical and biological research. Learn practical steps to successfully getting your point across to a Member of Congress. Find out how to brand your research as the Sputnik in the race to cure cancer, manage chronic disease, or Type I diabetes. Conclusions: Arming yourself with the strategies for the political warfare in the case for innovation is more than just changing public policy; it can provide the key to changing the future landscape of new biomedical materials, products or procedures. Attendees will get insight into America’s next biomedical “moonshot” initiative.

The concept of “courses ” has not changed much over centuries. However, online learning technology is quickly starting to challenge our understanding of what it means by a “course”. The abundance of online learning resources challenges the role of courses being the disseminators of knowledge, while the high registration numbers and low finishing numbers of Massive Open Online Courses (MOOCs) challenges not only the necessity to “pass” a course, but also the optimum length and scope of a course. Given the fact that more than 70% of today’s undergraduate students are non-traditional in one way or another, it might be a good time to think about how online learning technology might help to evolve the structure of courses to accommodate an increasingly diverse student population. In this workshop, I will initiate the discussion of “what might a future STEM course look like”, by introducing three relatively old ideas: mastery-based learning, flipped or blended classroom , and modularized instructional design. I will talk about how those ideas, when combined with the latest online learning technologies, might re-shape how students take a course, how teachers teach a course, and how instructors create a course , especially for STEM disciplines. We will also brainstorm about what STEM instructors can do to embrace the possible changes ahead.

Surface plasmons (SPs) are evanescent waves generated through the collective oscillations of electrons at a metal/dielectric interface under optical..

PQI is holding a coffee hour for our student and postdoc members. Our veteran poster award winners will talk about tricks and ways to prepare an..

Advances in atomic force microscopy (AFM) have made it possible to achieve unprecedented images of covalent bonds, in some cases even to resolve the..

In recent decades, a large scientific effort has focused on harnessing spin transport for providing insights into novel materials and low-dissipation..

Quantum optics has had a profound impact on precision measurements, and recently enabled probing various physical quantities, such as magnetic fields..

The basic laws of evolution have been known for more than a century and there is overwhelming evidence for the facts of evolution. Yet little is..

The chiral spin textures are a consequence of the anti-symmetric exchange interaction, which presents in the material systems with broken inversion..

An introductory session to Pivot led by Ryan Champagne from the Office of Research and Robin Kear from the University Library System. The hands-on..

Trapped atomic ions are an ideal system for quantum computation, with optically-accessible qubit states with long coherence times and fidelities..

Atomically thin semiconducting crystals derived from new classes of layered materials have rapidly emerged to enable two-dimensional (2D)..

The plethora of fascinating properties observed in oxide heterostructures has attracted a lot of interest. Most noticeably, the confined electron gas..

The ability to engineer and manipulate different types of quantum mechanical objects allows us to take advantage of their unique properties and..

Pedram Roushan was born and raised in Iran. In 2001, he moved to the US as a religious refugee and attended Pitt, where he graduated summa cum laude in 2005. During his years at Pitt, he worked at the laboratories of X. L. Wu and W. Goldberg, focusing on the dynamics in 2D fluids. He received his PhD in 2011 from Princeton University, performing the first scanning tunneling microscopy on the surface of topological insulators in the lab of A. Yazdani. After three years of post-doctoral studies in the J. Martinis lab at the University of California, Santa Barbara, in 2014 he joined the Google quantum hardware lab aiming on making a quantum computer. The current focus of his research is on simulating condensed matter systems with engineered quantum platforms.

The Defense Advanced Research Projects Agency (DARPA) Defense Sciences Office (DSO) is sponsoring a Proposers Day webcast to provide information to..

How does a microscopic system like an atom or a small molecule get rid of the excess electronic energy it has acquired, for instance, by absorbing a..

The symposium will focus on in-situ electron microscopy and applications of advanced microscopy. It will include invited speakers and contributed..

Dramatic advances in tabletop generation of THz pulses with high field levels have enabled nonlinear THz spectroscopy and THz control over molecules..

The laws of thermodynamics are fundamental laws of nature that classify energy changes for macroscopic systems as work performed by external driving..

Quantum materials research aims to uncover exotic physics and identify avenues towards next generation technologies. In particular, van der Waals..

Come help unify and promote Quantum Science and Engineering in Pittsburgh at Science2017: Wednesday through Friday, October 18-20, 2017 Alumni Hall & Wyndham Pittsburgh University Center

Geometrical effects influencing the measured spin coherence and quantum phase coherence in mesoscopic structures were characterized by low-..

Pennsylvania Chapter of American Vacuum Society will be hosting two days-long “Vacuum Fundamentals, Techniques, and Deposition Technology” workshop at the University Club of the University of Pittsburgh Pittsburgh, PA on October 16-17, 2017.

Entangled states are a key resource in fundamental quantum physics, quantum cryptography and quantum computation. Unfortunately, these states are..

Can a scientific realist epistemology be maintained in the context of quantum field theory? I have suggested, following similar proposals by David..

NIST will be hosting a day-long “Building the Foundations for Quantum Industry” discussion at THEIR main campus in Gaithersburg, MD on October 5th.

I will describe a method "DMT" for approximating density operators of 1D systems as low bond dimension matrix product operators that, when combined..

Graphene, a single layer of carbon atoms arranged in a hexagonal lattice, is probably the best known, and most extensively characterized two-..

The presentation will give an overview of the Innovation Institute, with an emphasis on how the Institute supports faculty and students with their entrepreneurial pursuits.

The Weyl semimetal is a new topological state of matter discovered recently. It exhibits not only topologically protected surface states (similar to..

Plenary Lecture: Karl-Heinz Ernst (University of Zurich) Helical molecules in flatland: chiral recognition, spin-filtering and molecular machines

Topological superconductors are one of the most exotic states predicted for electronic matter. Recently a new family of superconductors, which appear..

In this talk, I am going to present some of the work that I have done during my PhD. In the first part I will mostly focus on building a low-..

The Asher Symposium on Adventures in Enhanced Spectroscopies: Resonance Raman, Surface Enhanced Raman, and Twisted Chiro-Optical Spectroscopies will be held May 11, 2017-9:00am to 6:00pm. For more information, contact Sharon Mansfield, Assistant to Distinguished Professor Sanford A. Asher, Department of Chemistry at (412) 624-6295 or sharone@pitt.edu

The two-dimensional diffusive metal stabilized at the interface of SrTiO3 and the Mott Insulator perovskite LaTiO3[1-2] has challenged many notions..

The PQI Women in Quantum Science and Engineering Lecture Series is held in the framework of the Year of Diversity at Pitt to celebrate women scientists. All talks are colloquium-style and open to the public.

Magnetic skyrmions [1] are particle-like twists of the magnetization taking the form of nanoscale vortices or bubbles that are topologically..

The PQI Women in Quantum Science and Engineering Lecture Series is held in the framework of the Year of Diversity at Pitt to celebrate women scientists. All talks are colloquium-style and open to the public.

Two-dimensional (2D) atomic crystals have emerged as a very attractive class of optoelectronic material due to the unprecedented strength in its..

The PQI Women in Quantum Science and Engineering Lecture Series is held in the framework of the Year of Diversity at Pitt to celebrate women scientists. All talks are colloquium-style and open to the public.

In this talk, I will describe my background and my approach to the fabrication of nanostructures through three different interdisciplinary projects..

Discovering exotic quantum effects of plasmons and their coupling with other quasiparticles in solids may help to understand such collective..

Under gamma-ray or charged-particle excitation, scintillation light yield is a complicated function of carrier diffusion and cooling in the track..

The understanding of the catalytic properties of nanoparticle catalysts and the design of optimal composition and structures demands fast methods for..

Many groups are severely under-represented in STEM professions. This workshop will explore strategies to help women thrive in STEM professions. We..

Nature becomes amazingly different from what we perceive with our eyes when zoomed in to the nanometer scale, where atomic spins interact and form..

The PQI Women in Quantum Science and Engineering Lecture Series is held in the framework of the Year of Diversity at Pitt to celebrate women scientists. All talks are colloquium-style and open to the public.

The recently discovered Dzyaloshinskii-Moriya Interaction (DMI) in thin films has spawned a new direction for magnetism in spintronic application..

Recent developments in the study of quantum gravity have revealed a surprising and beautiful connection between quantum entanglement and the geometry..

The PQI Women in Quantum Science and Engineering Lecture Series is held in the framework of the Year of Diversity at Pitt to celebrate women scientists. All talks are colloquium-style and open to the public.

Nanotechnology is an interdisciplinary field focused on studying and manipulating ultraminiaturized structures, ones with at least one dimension 10,..

Much of condensed matter physics is concerned with understanding how different kinds of order emerge from interactions between a large number of..

Spin-transfer torque magnetic random access memory (STT-MRAM) is a scalable, low-power, non-volatile memory structure based on the magnetic tunnel..

We demonstrate that spatially separated populations of one-dimensional electrons and holes may form a true condensate of dipolar excitons..

Molecular crystals have applications in nonlinear optics, organic electronics, and particularly in pharmaceuticals, as most drugs are marketed in the..

The S-matrix is among the most basic -- and most physically relevant -- observables in any quantum field theory. At tree-level, it is well-defined..

We provide a perspective on the recent emergence of “topological spintronics,” which relies on the existence of helical Dirac electrons in condensed..

Prof. Ryan Steele of the University of Utah will be leading a workshop on the efficient calculation of vibrational anharmonicities. The workshop is..

Individual spins in semiconductors can retain their quantum phase coherence for times exceeding one second. Such long coherence times makes spins a..

First-principles computational approaches are making steady progress to quantitatively predict, for specific materials, the conceptual phenomena that..

Strong repulsive interactions and potential in homogeneities both tend to localize Fermions on a lattice and lead to loss of superconductivity. The..

Adiabatic quantum computation (AQC) is one of the paradigms of quantum computation that has recently gained great attention by advancements in..

Throughout the history of mankind, scientists and engineers have relied on the slow and serendipitous trial-and-error approach for materials..

Metal and semiconductor quantum dots (QDs) exhibit unique size and composition dependent optical properties. The key elements that determine their..

Attend the PQI spotlight and poster sessions & drop by the PQI booth! Come help unify and promote Quantum Science and Engineering in Pittsburgh at Science2016-Gamechangers. Wednesday through Friday, October 19-21 Alumni Hall & Wyndham Pittsburgh University Center

Superconducting qubits are created by connecting Josephson junctions, which are non-linear, non-dissipative elements,to simple electrical circuits..

Single-layer of molybdenum disulfide (MoS2) and other transition metal dichalcogenides (TMDC) appear to be promising materials for next generation..

Common magnets, such as refrigerator magnets and recorded bits in your hard disk, have aligned magnetic moments as compelled by the exchange..

Over the past four years the Pavanello Research Group has developed an array of density embedding methods for the description of periodic and..

Probability density function (PDF) methods have been useful in describing many physical aspects of turbulent mixing. In applications of these methods..

Reaction Pathway Searches for Unexpected Chemical Events

Active liquid crystals are aqueous in vitro suspensions of cytoskeletal proteins that self-assemble into elongated fibers and develop sustained flows..

Topological superconductors, which host Majorana zero modes, are a most attractive research topic in condensed matter physics. Due to the Kramers..

Colloidal chemistry is used to control the size, shape and composition of metal nanoparticles usually in the 1-10 nm range. In-situ methods are used..

The PPG Symposium: Innovations in Materials Chemistry will run from Thursday, May 5 to Saturday, May 7 in the Chevron Science Center. Contributing..

Computational materials design offers tremendous potential for discovery and innovation. This powerful concept relies on computational exploration of..

The grain microstructure is well-known to have a profound influence on the properties of materials so there is great interest in the properties of..

Title & abstract: TBA

Our signature PQI event will cover a broad range of research being performed in quantum science and engineering, and will feature prominent invited keynote lecturers, as well as highlighting current research in the PQI. All of the talks will be colloquium-style, and accessible to a broad range of people in quantum-related fields.

The Manhattan Project was the United States Army’s effort to develop the first generation of nuclear weapons, which were used against Japan in August..

Emil Sanielevici Lecture: This award is given annually in the Department of Physics and Astronomy in memory of our student Emil Sanielevici (1979-..

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The 2015 Majorana Conference will take place here at the University of Pittsburgh in November, and you are invited to attend! Speakers from all over..

PQI2015: Quantum Coherence 15-17 April 2015 Our third annual PQI event will be held from Wednesday April 15th to Friday April 17th, 2015 at the..