Events

Wisconsin Quantum Institute

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Events During the Week of February 27th through March 6th, 2022

Monday, February 28th, 2022

No events scheduled

Tuesday, March 1st, 2022

Unraveling the Bulk and Surface Theories of Helical Higher-Order Topological Insulators
Time: 10:00 am - 11:00 am
Place: 5310 Chamberlin Hall
Speaker: Ben Wieder, MIT
Abstract: Solid-state materials including bismuth, MoTe2, and BiBr have been predicted to be higher-order topological insulators (HOTIs). In theoretical HOTI models, the 3D bulk and 2D surfaces are gapped, and odd numbers of 1D gapless topological modes appear bound to the hinges of finite-sized 3D samples, providing an indicator of the bulk HOTI phase in the presence of global crystal symmetries. However, the boundaries of real material samples lack the global symmetries of HOTI models, and there exist topologically trivial models with extrinsic hinge states. In HOTIs with chiral hinge states, the bulk topology has been shown to be characterized by a nontrivial axion angle, and hence chiral HOTIs can in principle be characterized experimentally through the framework of axion electrodynamics, rather than higher-order topology. For helical HOTIs, however, the bulk axion angle is trivial, and the only experimental signatures proposed to date rely on global symmetry arguments and hinge-state measurements. It is hence desirable to identify unambiguous bulk and surface signatures of helical HOTI phases analogous to - but distinct from - the axionic magnetoelectric effects present in 3D topological insulators (TIs) and chiral HOTIs. In this talk, I will present numerical and theoretical analysis of helical HOTIs demonstrating the existence of quantized bulk topological signatures beyond the axion angle, placing helical HOTIs on the same physical footing as well-understood 3D TIs and magnetic axion insulators.​
Host: Robert McDermott
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Wednesday, March 2nd, 2022

No events scheduled

Thursday, March 3rd, 2022

How to create and leverage many-body entanglement for near-term quantum networks and simulation
Time: 10:00 am - 11:00 am
Place: 5310 Chamberlin Hall
Speaker: Sophia Economou, Virginia Tech
Abstract: Quantum information science and related technologies include quantum computers, which will be able to solve important problems beyond the reach of classical computers, as well as the ‘quantum internet’, an inherently secure network for communication and for accessing remote quantum computers. I will discuss these technologies, focusing on the question of how to enable them by creating and leveraging multipartite entangled states using near-term quantum systems. In the case of quantum networks, I will describe our protocols for the generation of logically encoded photonic graph states from quantum emitters. For quantum simulation, I will present our recent work on efficient variational quantum algorithms. Bio: Sophia Economou is a Professor of Physics and the Hassinger Senior Fellow of Physics at Virginia Tech. She focuses on theoretical research in quantum information science, including quantum computing with solid-state and photonic qubits, quantum communications, and quantum simulation algorithms.
Host: Mark Saffman
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Quantum computing with semiconductor spins
Time: 4:00 pm - 5:00 pm
Place: 5310 Chamberlin Hall
Speaker: Edwin Barnes, Virginia Tech
Abstract: Recent years have witnessed enormous progress toward the development of quantum computers---novel devices that exploit quantum mechanics to perform tasks far beyond the reach of the world’s best supercomputers. Qubits based on semiconductor spins are particularly promising because of their long coherence times and prospects for scaling up to large processors by leveraging the existing semiconductor electronics infrastructure. However, many fundamental challenges related to decoherence, controllability, and device architecture remain. I will describe our efforts to address these challenges on multiple fronts using smart control schemes, dynamical stabilization with Floquet physics, and entanglement generation between remote spins.
Host: Mark Saffman
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Friday, March 4th, 2022

No events scheduled