Virtual Seminar Series

Virtual Seminar Series

Click here to view the schedule for upcoming seminars.

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
  • Quantum simulation
  • Measuring the elusive Majorana fermion
  • Photons

Talks will be given by senior researchers as well as students and postdocs. 

Click here for all previous seminar videos

Seminars are organized in collaboration with Mikael Backlund, Jacob Covey, and Dakshita Khurana. Please feel free to reach out to them by e-mail with any comments and suggestions.

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Past Talks -- Fall 2021

Tuesday, September 14 | 11:00 a.m. CST

John Teufel Listening to the Sound of Entanglement

Quantum mechanics is traditionally considered when measuring at the extreme microscopic scale, i.e. single photons, electrons or atoms.  However, even the early pioneers of the quantum theory postulated gedanken experiments in which quantum effects would manifest on an everyday scale. I will present recent experiments in which we engineer and measure microelectromechanical (MEMs) circuits to observe and to exploit quantum behavior at an increasingly macroscopic scale.  By embedding mechanical resonators in superconducting microwave circuits, we achieve strong radiation-pressure coupling between fields and motion that allows us to perform quantum experiments of massive objects.  I will present our recent experimental demonstration of deterministic macroscopic entanglement, as well as ongoing efforts toward arbitrary quantum control of mechanical systems.  The ability to prepare and to “listen” to quantum sound has implications for fundamental science as well as many powerful applications including the processing, storage and networking of quantum information.

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Tuesday, September 7 | 11:00 a.m. CST

Michael Foss-Feig Simulating many-body physics using quantum tensor networks

Tensor network techniques exploit the structure of entanglement to dramatically reduce the difficulty of simulating quantum systems on classical computers. But these techniques have limitations, and many problems in many-body quantum physics, for example simulating dynamics, remain intractable despite decades of effort to solve them.  Quantum computers offer an alternative route to simulating quantum systems that is in principle efficient, but their small size and limited fidelities have so far prevented solution of problems of real practical interest that cannot be solved classically.  Here we discuss prospects for combining these two techniques by directly representing tensor-network states as quantum circuits, and show that recent developments in quantum hardware make it possible to carry out quantitatively accurate simulations of quantum dynamics directly in the thermodynamic (infinite system size) limit using a small number of qubits.

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Tuesday, August 31 | 11:00 a.m. CST

Andrei Faraon Towards optical quantum networks based on rare-earth ions and nano-photonics

Optical quantum networks for distributing entanglement between quantum machines will enable distributed quantum computing, secure communications and new sensing methods. These networks will contain quantum transducers for connecting computing qubits to travelling optical photon qubits, and quantum repeater links for distributing entanglement at long distances. In this talk I discuss implementations of quantum hardware for repeaters and transducers using rare-earth ions, like ytterbium and erbium, exhibiting highly coherent optical and spin transitions in a solid-state environment.  We show that single ytterbium ions in nano-photonic resonators are well suited for optically addressable quantum bits with long spin coherence, single shot readout and good optical stability [1]. These single qubits will form the backbone of future quantum repeater networks and will be augmented by optical storage and linear processing capabilities, also implemented using rare-earth ions. Towards this end we demonstrated optical quantum storage using erbium ensembles coupled to silicon photonics, where the frequency and release time of the stored photon can be controlled using on-chip electronics [2,3]. Finally, to connect the optical network to superconducting quantum computers, we develop optical to microwave quantum transducers based on rare-earth ensembles simultaneously coupled to on-chip optical and microwave superconducting resonators [4]. I conclude by addressing the remaining challenges for interconnecting these components into future quantum networks.

[1] Jonathan M. Kindem, Andrei Ruskuc, John G. Bartholomew, Jake Rochman, Yan Qi Huan, Andrei Faraon, Control and single-shot readout of an ion embedded in a nanophotonic cavity, Nature, 580, 201–204 (2020)

[2] Craiciu et al, Nanophotonic quantum storage at telecommunications wavelength, Physical Review Applied, 12, 024062, 2019

[3] Zhong et al, Nanophotonic rare-earth quantum memory with optically controlled retrieval, Science, Vol. 357, Issue 6358, pp. 1392-1395 (2017)

[4] John G. Bartholomew, Jake Rochman, Tian Xie, Jonathan M. Kindem, Andrei Ruskuc, Ioana Craiciu, Mi Lei, Andrei Faraon, On-chip coherent microwave-to-optical transduction mediated by ytterbium in YVO4, Nature Communications, 11, Article 3266 (2020)

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