Virtual Seminar Series
Virtual Seminar Series
Starting in June 2020, we are hosting a series of online talks about topics related to Quantum Information Sciences in its various forms, including (but not limiting to):
- Quantum computers
- Measuring the elusive Majorana fermion
Talks will be given by senior researchers as well as students and postdocs.
Click here to view the schedule for upcoming seminars.
Tuesday, July 28 | 11:00 a.m. CST
Eric Chitambar Quantum resource theories
A quantum resource theory is a broad framework for studying some particular features of quantum mechanics under a restricted class of physical operations. A paradigm example is the resource theory of quantum entanglement, which characterizes the behavior of multi-party entanglement under the restriction of local dynamics and classical communication. When viewed through the lens of a quantum resource theory, seemingly different quantum phenomena often emerge as having many formal similarities.
In this seminar, Eric provides a survey of quantum resource theories and some of its applications in quantum information science. We first motivate the topic by considering some well-known results in thermodynamics and statistical decision problems. We then discuss some of the basic elements and common structural properties found in most resource theories. To see this formalism in action, we will consider in some detail the resource theories of coherence, incompatibility, and nonlocality. Elements of this talk will be taken from [Rev. Mod. Phys 91, 25001 (2019)]; [Phys. Rev. Lett. 124, 120401 (2020)]; [Phys. Rev. Res. 2, 23298 (2020)].
Tuesday, July 21 | 11:00 a.m. CST
Elizabeth Goldschmidt Quantum light-matter interfaces
Elizabeth gives an overview of recent, ongoing, and future work using coherent atomic and atom-like optical emitters to build quantum light-matter interfaces. Optical fields play an important role in virtually all schemes for interconnected quantum information systems since only optical photons are well-suited for carrying quantum information at room temperature. I will discuss different physical platforms that can form the basis for quantum light-matter interfaces, different modalities of light-matter entanglement for various applications in quantum information science, and the tradeoffs related to these different systems. She includes recent experimental results efficiently generating high-fidelity single photons, investigating the role of inhomogeneity in ensemble-based quantum memory, and developing a new integrated photonic platform with highly coherent emitters.
Tuesday, July 7 | 11:00 a.m. CST
Edgar Solomonik Tensor software and algorithms for quantum simulation
Tensor computations are central numerical primitives for computational modeling of quantum systems. These include standard linear algebra operations on multidimensional data (tensors) as well as specialized methods for decomposition of tensors and for optimization of tensor networks. I will discuss challenges and opportunities in this area and present our work on algorithms and software in this domain. Specifically, I will introduce new methods for (1) handling symmetries in tensors, (2) numerical optimization for tensor decomposition, and (3) contraction of 2D tensor networks. On the software side, I will also describe three efforts: (1) Cyclops, a library for distributed-memory tensor computations, (2) AutoHOOT, tensor-algebra-centric library for automatic differentiation, and (3) Koala, a library for simulation of 2D quantum systems. Special focus will be given to the Koala library, which provides efficient parallel algorithms for approximate simulation of 2D quantum circuits (https://arxiv.org/abs/2006.15234).
Tuesday, June 23 | 11:00 a.m. CST
Vidya Madhavan Creating and measuring the elusive Majorana fermion
In 1937, Ettore Majorana predicted the existence of a special class of fermions where the particle and the anti-particle are identical. However, with the possible exception of neutrinos, there are no known fundamental particles that belong to this class. The potential realization of Majorana fermions as quasiparticle excitations in solids has rekindled interest in these particles, especially since Majorana states in solids may be useful as fault tolerant qubits for quantum information processing. While most studies have focused on Majorana bound states which can serve as topological qubits, more generally, akin to elementary particles, Majorana fermions can propagate and display linear dispersion. This talk is focused on recent work in realizing Majorana modes in condensed matter systems. I will first describe in detail the conditions under which such states can be realized and what their signatures are. I will then show scanning tunneling microscopy data on 1D domain walls and step edges in two different superconductors, which might potentially be the first realizations of dispersing Majorana states in 1D.
Tuesday, June 16 | 10:00 a.m. CST
Benjamin Villalonga A Look Into the Strong Quantum Advantage Experiment
The quantum supremacy experiment announced last year aimed at providing the first practical demonstration of a quantum computer performing a task that is out of reach for classical computers at that date. Behind this demonstration is the problem of random circuit sampling, i.e., a task that (1) shows a separation in the amount of computing resources needed to be carried out by the quantum computer and its classical counterpart and (2) whose output can be verified. Classical simulations of the quantum computer have a dual role: on the one hand they serve as a competitor for the quantum computer to beat, while on the other hand they are an essential tool to verify that the quantum hardware is operating as expected. In this talk I will first give a broad overview of the experiment and the task of random circuit sampling; I will then focus on my fractional contribution to the simulation side of this large effort. Finally, I will briefly talk about how this demonstration might be a stepping stone towards useful applications in the near term, as well as convey the idea that the quantum supremacy frontier is not a fixed target but rather one that moves with classical hardware and algorithmic improvements.
Tuesday, June 2 | 10:00 a.m. CST
Taylor Hughes Melting a Topological Quantum Computer
After an elementary introduction to some unique properties of topological phases of matter, I will discuss the possibility of realizing bound topological qubits on semiclassical defects in topological phases coexisting with a conventional ordered phase. These defects take the form of vortices, dislocations, or disclinations, and there is a rich interplay between topology and symmetry which will be outlined