The Interdisciplinary Quantum Seminar is run by the Brown Quantum Initiative (BQI) with the support of several Departments at Brown University. The seminar is focused on inviting Brown and external speakers who work across the many fields that intersect in Quantum Science and Engineering. To get emails about upcoming seminars, events, and other news about Quantum Science and Engineering at Brown, you can request to join our mailing list/Google Group by following this link.
Proposing a talk
If you would like to give a talk, please reach out to the BQI via email! We welcome presentations from Faculty, Postdocs, and Senior Graduate Students. Some previous talks can also be found in our YouTube channel.
Summer and Fall 2024 Schedule
Time and Location
All talks are held from 2 to 3PM on Fridays in Barus & Holley 190 unless otherwise stated.
| Date | Speaker | Title | Abstract | Recording |
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| July 9 (Tue) | Jacob Barandes | Quantum Theory & Indivisible Stochastic Processes | The notion of an ‘indivisible’ stochastic process, which generalizes the textbook non-Markovian case, appeared only recently in the research literature. In this talk, I will explain how any quantum system can be understood as an indivisible stochastic process unfolding on an old-fashioned configuration space, without a fundamental role for Hilbert spaces or wave functions. On the one hand, this connection demystifies and deflates many of the exotic features of quantum systems, like interference, superposition, decoherence, entanglement, and noncommutative measurement outcomes. On the other hand, this stochastic-quantum correspondence opens up new possibilities for modeling non-Markovian stochastic processes efficiently on quantum hardware. I will also explain how this correspondence leads to a new microphysical definition of causal influences, which can be used to challenge the premises of various no-go theorems, including Bell’s theorem, with potentially significant consequences for locality and local causality. |
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| October 16 (Wed) | Yusong Bai | Designing and probing exciton quantum phase transitions in two-dimensional semiconductors | Designing and harnessing quantum phases of matter is a central goal in modern physical sciences and information technologies. These quantum phases are predominantly characterized as interacting many-body systems, where quantum phase transitions occur due to the competition between many-body Coulomb potentials and the particles’ kinetic energy. In this context, interlayer excitons in 2D transition metal dichalcogenides (TMDC) with type-II-aligned heterostructures offer a versatile bosonic system for realizing quantum phases of matter, given by their large out-of-plane dipole moments that enable long-range Coulomb interactions. By constructing a symmetric WSe2/MoSe2/WSe2 heterotrilayer, we have realized ordered phases of interlayer excitons. This ordered phase is characterized by sharp photoluminescence persisting at an exciton density of ~10¹² cm⁻², an electric-field-driven exciton Mott transition, and negligible exciton mobility. More recently, we have further regulated the competition between exciton many-body Coulomb potentials and kinetic energy by constructing a WS2/WS2/WSe2/WSe2 hetero-twisted double homobilayer. This system hosts emergent heavy excitons with distinct photoluminescence compared to that observed in regular heterobilayers, originating from the Coulomb binding of highly hybridized electrons and holes residing in each twisted homobilayer. Our experimental observations underscore that multilayer interlayer excitons can be explored as a capable model bosonic system for programming a range of quantum phases of matter. |
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| November 1 (Fri) | Jia Leo Li | Bilayer excitons as a new type of quantum particle | Quantum statistics underpins our understanding of various quantum phases of matter, a cornerstone of condensed matter research. Beyond the well-known fermions and bosons, an exotic class of particles called anyons emerges from the fractional quantum Hall effect, characterized by fractional quantum statistics. Decades of research have uncovered a profound connection between fractional braiding phases and Coulomb-driven charge fractionalization. In this talk, I will focus on a distinct quantum particle: the bilayer exciton, generally defined as a charge-neutral bound state of electrons and holes. Typically, excitons act as bosons, with their low-temperature ground state forming a Bose-Einstein condensate. I will discuss experimental observations of this condensate phase within quantum Hall bilayer systems and then delve into more exotic forms of bilayer excitons that exhibit anyonic properties. The discovery of anyonic excitons challenges two longstanding paradigms: (i) that excitons are inherently bosonic and (ii) that anyons must carry fractional electronic charge. These breakthroughs have profound implications for future quantum science research and open new avenues for potential applications in quantum computation. |
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| November 15 (Fri) | Dima Feldman | Beyond bosons and fermions: How to detect and use anyons | According to basic quantum mechanics, all particles are classified as either bosons or fermions. Yet, two-dimensional topological systems allow another type of quasiparticles called anyons. Non-Abelian anyons are particularly interesting since, if found in nature, they would allow building a topological quantum computer that needs no error correction. The talk will review recent experimental and theoretical developments in the search for anyons with the emphasis on the discovery and probes of non-Abelian particles. |
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| December 6 (Fri) | Victoria Manfredi | From Quantum Networks to Quantum Key Distribution | This talk will overview the basics of quantum networking, which relies on entanglement swapping to securely communicate quantum information (qubits) between quantum nodes. We will then focus on a key application of quantum networks: quantum key distribution (QKD), a method that enables two parties to generate and share a secret key while detecting the presence of any eavesdroppers. By leveraging a network, the range of QKD systems can be extended. Finally, we will discuss practical approaches to improving the overall key generation rate in QKD networks. |