# QIS Workshop

from to (US/Central)
at Argonne - Bldg 240
9700 Cass Ave, Lemont, IL 60439
 Description The purpose of the workshop is to bring together researchers working in two general and overlapping QIS areas, quantum computing/algorithms/simulations and quantum materials/devices/sensing, respectively, with the aim of providing an interactive venue for substantive discussions and to possibly develop/explore collaborations with Argonne scientists. There will be a Workshop Dinner on Monday, September 23rd at Chuck's Southern Comfort Cafe. Chuck's is located at 8025 S. Cass Ave. Darien, IL 60561  Material: Support Email: stezak@anl.gov
Go to day
• Monday, September 23, 2019
• 08:30 - 09:00 Registration & Continential Breakfast 30'
• 09:00 - 10:45 Plenary Session  Location: 1416
• 09:00 Welcome 15'  Speaker: Dr. Salman Habib (Argonne National Laboratory) Material:
• 09:15 Argonne QIS Overview 45'  Speaker: Stephen Gray (Argonne National Laboratory) Material:
• 10:00 Coherent nonlinear photonics: from attojoule to quantum 45'
Looming technical challenges for both general- and special-purpose computation provide strong motivation to revisit device and architecture concepts for all-optical information processing.  Communication bottlenecks and power constraints in conventional multi-core processor design are driving increasing interest in on-chip and chip-to-chip optical interconnect, while unique features of all-optical approaches make them attractive for edge computing and distributed sensor networks as well.  One can already see, however, that demands for high speed and ultra-low power consumption are driving us to the picosecond-attojoule switching regime in which the quantum nature of optical fields becomes prominent.  In this talk I will discuss our group's recent work to develop modeling infrastructure and autonomous coherent feedback control methods for quantum nonlinear photonics.  I will illustrate the utility of these tools via circuit-design case studies for both quantum and ultra-low power classical all-optical information processing.  I will conclude by discussing emerging challenges in expanding the toolbox to incorporate systematic model reduction and to accommodate broadband signal formats, as motivated by ongoing experiments in quantum nonlinear optics with integrated nanostructures and ultra-fast pump fields.
 Speaker: Prof. Hideo Mabuchi (Stanford University) Material:
• 10:45 - 11:05 Break
• 11:05 - 12:15 Parallel Track A - Theory  Location: 1404/1405
• 11:05 Hybrid Quantum/Classical Algorithms for Photochemistry 20'
We present some recent developments in hybrid quantum/classical methodology for first-principles photochemistry simulations of large multichromophoric complexes. The first key tool utilized is an ab initio exciton model (AIEM) that uses on-the-fly ab initio computations on chromophore monomers to parametrize a Frenkel-Davydov-type exciton model that is mappable to a Pauli-sparse qubit Hamiltonian with one or more qubits per monomer. The second key tool involved is the "multistate, contracted variational quantum eigensolver" (MC-VQE), a new extension of VQE that enables the even-handed quantum circuit treatment of ground-, excited-, and transition-property observables. MC-VQE+AIEM shows promise for the accurate treatment of absorption spectra and other photochemical observables for systems with several thousand atoms using only a few dozen qubits and relatively short quantum circuits. We numerically demonstrate the potential accuracy of the method for the classically-simulated MC-VQE+AIEM computation of the absorption spectrum of the B850 ring of LHII, discuss the extension of the method to the efficient computation of the analytical nuclear gradient (needed for dynamics simulations), and the consider prospects for deployment of the method on near-term quantum circuit hardware.
 Speaker: Dr. Robert Parrish (QC Ware Corporation)
• 11:30 Robustness of persistent oscillations in kinematically constrained qubit systems 20'
Recent quantum simulators have found unexpected coherent and persistent oscillations in an ergodic system at infinite temperature. This behavior has been theoretically understood by studying kinematically constrained spin models that lead to special low-entangled states that are embedded in a thermalizing spectrum. We study the robustness of the dynamics generated by these special states against the presence of disorder and external drives. To do this, we evaluate diagnostic quantities such as the revival probability, the spatial entanglement, and the average spin dynamics. The goal of this study is to capture features that could be explored more generally in other types of quantum simulators such as coupled superconducting qubits.
 Speaker: Dr. Ian Mondragon (Argonne National Laboratory) Material:
• 11:55 Crystalline Cluster States for Topological Measurement-Based Quantum Computing 20'
Although there are promising near-term applications for NISQ algorithms, quantum computing’s most impactful algorithms will likely require a fully fault-tolerant quantum computer.  Given the fragility of quantum information, building this computer is a daunting task.  Most proposals for fault-tolerance are based on quantum error-correcting codes, in which the information is preserved in code qubits while ancilla are periodically measured to check for errors.

Recently, a more general framework for fault-tolerance in one-way quantum computers was proposed in which logical information is passed among all of the qubits, without any distinction between data and ancilla.  In this talk, we discuss an algebraic framework for building these generalized fault-tolerant one-way quantum computers based on combinatorial tiling theory.  This yields a variety of robust candidates, including some that require only degree-$3$ connectivity.
 Speaker: Dr. Michael Newman (Duke University) Material:
• 11:05 - 12:15 Parallel Track B - Experiment
• 11:05 QIS activities at IU Bloomington 20'
Indiana University in Bloomington has recently established a center for Quantum Science and Engineering, involving researchers from Physics, Computer Science, Intelligent Systems Engineering and Chemistry. I will provide an overview of some of the activities of the center over the last year.
 Speaker: Prof. Baxter David (Indiana University) Material:
• 11:30 Spins in InAs quantum dots: qubits, sensors, and photon sources 20'
InAs quantum dots (QDs) are known for their strong optical transitions that lead to a nearly ideal source of single photons. Additional functionality comes from charging the QD with a single electron or hole spin that acts as a stationary quantum bit. In this presentation, I will discuss how a spin in a QD or in a pair of coupled QDs can be used for sensing mechanical motion and for generating tunable single photons. To sense motion, QDs have been incorporated into mechanical resonators, which couple to the dots through strain. When mechanical resonators are driven, the optical transitions of QDs shift significantly, and the spin states shift as well [1]. In single QDs, the hole spin shows much stronger coupling to strain than electrons spins, due to the stronger spin-orbit interaction. In coupled QDs, a pair of interacting electron spins can be made highly sensitive to strain gradients that change the relative QD energies [2].  To generate photons, we make use of the Raman spin-flip process, often enhancing the process by integrating the QDs into photonic crystal cavities [3]. The Raman process has the advantage of generating photons with properties determined by the drive laser and the spin properties. In this way, we are able to demonstrate spectral and temporal control over single photon wavepackets [4], with very low two photon emission probability and high indistinguishability. Finally, I will briefly discuss efforts that combine these topics, in which highly localized strain is used to tune multiple QD photon emitters into resonance within nanophotonic waveguides [5].

This work is supported by the U.S. Office of Naval Research, the Defense Threat Reduction Agency (grant no. HDTRA1- 15-1-0011) and the OSD Quantum Sciences and Engineering Program.

[1] Carter, S. G. et al. Spin-mechanical coupling of an InAs quantum dot embedded in a mechanical resonator. Phys. Rev. Lett. **121**, 246801 (2018).

[2] Carter, S. G. et al. Tunable coupling of a double quantum dot spin system to a mechanical resonator. Nano Lett. **19**, 6166–6172 (2019).

[3] Sweeney, T. M. et al. Cavity-stimulated Raman emission from a single quantum dot spin. Nat. Photonics **8**, 442–447 (2014).

[4] Pursley, B. C., Carter, S. G., Yakes, M. K., Bracker, A. S. & Gammon, D. Picosecond pulse shaping of single photons using quantum dots. Nat. Commun. **9**, 115 (2018).

[5] Grim, J. Q. et al. Scalable in operando strain tuning in nanophotonic waveguides enabling three- quantum-dot superradiance. Nat. Mater. **18**, 963–969 (2019).
 Speaker: Dr. Samuel Carter (US Naval Research Laboratory) Material:
• 11:55 Quantum simulation and computing with atomic arrays 20'
The realization of large-scale controlled quantum systems is an exciting frontier in modern physical science. Such systems can provide insights into fundamental properties of quantum matter, enable the realization of exotic quantum phases, and ultimately offer a platform for quantum information processing that could surpass any classical approach.

Recently, reconfigurable arrays of neutral atoms with programmable Rydberg interactions have become promising systems to study such quantum many-body phenomena, due to their isolation from the environment, and high degree of control. I will show how these techniques can be used to study quantum phase transitions by realizing quantum spin models with system sizes up to 51 qubits.
Furthermore, I will discuss the prospect for quantum information processing with arrays of atoms and present our recent results on the creation of a 20 qubit GHZ entangled state.

Prospects for scaling this approach beyond hundreds of qubits and the implementation of quantum algorithms will be discussed.
 Speaker: Prof. Hannes Bernien (University of Chicago) Material:
• 12:15 - 12:30 Break to pick-up lunch
• 12:30 - 13:30 Working Lunch / Breakout Session 1h0' ( 1416 )
Quantum Transduction
Quantum Photonics
• 12:30 - 13:30 Working Lunch / Breakout Session 1h0' ( 1404-1405 )
Quantum Networks
NISQ/Quantum Computing Issues
• 13:30 - 15:00 Plenary Session  Location: 1416
• 13:30 “Quantum Supremacy” and the Complexity of Random Circuit Sampling 45'  Speaker: Bill Fefferman (University of Chicago) Material:
• 14:15 Controlling light with a single photon using semiconductor quantum dots 45'  Speaker: Edo Waks (University of Maryland)
• 15:00 - 15:20 Break
• 15:20 - 16:10 Parallel Track B - Experiment
• 15:20 TiO2 nanophotonic cavities for high-efficiency coupling to quantum states in diamond 20'
In this talk, we will discuss our development of nanophotonic resonators utilizing templated atomic layer deposition and ongoing efforts to interface these cavities with vacancy centers in diamond membranes. Vacancy centers in diamond, such as the nitrogen vacancy (NV) or silicon vacancy (SiV), exhibit outstanding quantum coherence combined with a straightforward optical interface. Advanced QIS applications with vacancy centers require integration with nanophotonics to achieve efficient photon/qubit interactions. State-of-the-art approaches utilize reactive-ion etching to etch photonic crystals directly into diamond, which creates charge traps, surface roughness, and dangling chemical bonds that degrade coherence. Here, we will show how we can utilize templated atomic layer deposition to grow titanium dioxide nanophotonics directly onto arbitrary surfaces, including oxides, 2D materials, and diamond. The process requires no destructive etching and should be fully passive to the underlying substrate, opening a new path to coherent interfaces with vacancy centers. We will also discuss our ongoing efforts to make diamond membranes.
 Speaker: Prof. Alex High (University of Chicago) Material:
• 15:45 Quantum metrology for detection of classical dark matter waves 20'
Various techniques will be presented to improve detection of the Glauber displacement of a photon mode due to the weak classical force exerted by oscillating background dark matter waves.
 Speaker: Aaron Chou (Fermilab) Material:
• 15:20 - 16:10 Parallel Track A - Theory
• 15:20 Hybrid Quantum-Classical Computing Architectures 20'
This talk explains how classical supercomputing can aid unreliable quantum processors of intermediate size to solve large problem instances reliably. I will describe the benefits of using a hybrid quantum-classical architecture where larger quantum circuits are broken into smaller sub-circuits that are evaluated separately, either using a quantum processor or a quantum simulator running on a classical supercomputer. Circuit compilation techniques that determine which qubits are simulated classically will greatly impact the system performance as well as provide a tradeoff between circuit reliability and runtime.
 Speaker: Martin Suchara (Argonne National Laboratory) Material:
• 15:45 Principal component analysis in static and dynamical quantum problems 20'
Principal component analysis (PCA) is a popular Machine Learning algorithm used for dimensional reduction. We show that PCA is naturally suited for the extraction (and subsequent utilization) of quantum information in problems involving state ensembles. We illustrate its representational power in the context of quantum manybody ground state manifolds, and discuss an application in predicting the quantum dynamics of driven systems.
 Speaker: Dr. Zhoushen Huang (Argonne)
• 16:10 - 16:30 Day 1 Wrap-Up 20'
• 16:45 - 18:30 Reception/Poster Session ( 1416 )
• 18:30 - 21:30 Dinner ( Chuck's Southern Comfort Cafe )
• Tuesday, September 24, 2019
• 08:30 - 09:00 Registration & Continental Breakfast 30'
• 09:00 - 10:35 Plenary Session
• 09:00 Welcome 5'  Speaker: Dr. Salman Habib (Argonne National Laboratory)
• 09:05 Emerging Semiconductor Single Photon Counters and Quantum Photonic Integrated Circuits 45'  Speaker: Seth Bank (University of Texas at Austin)
• 09:50 Progress in Quantum Computing with Trapped Ions 45'  Speaker: Jungsang Kim (Duke University) Material:
• 10:35 - 11:00 Break
• 11:00 - 12:10 Plenary Session
• 11:00 Learning Quantum Algorithms for NISQ Computers 20'  Speaker: Lukasz Cincio (Los Alamos National Laboratory)
• 11:25 Title TBD 20'  Speaker: Prof. David Schuster (U.Chicago)
• 11:50 Quantum Computing at Scale 20'  Speaker: Dr. Yuri Alexeev (Argonne National Laboratory) Material:
• 12:10 - 12:25 Break to pick-up lunch
• 12:25 - 13:30 Working Lunch / Breakout Session 1h5'
•	Quantum Chemistry
•	Metrology
• 12:25 - 13:30 Working Lunch / Breakout Session 1h5'
Quantum Defects
Quantum Algorithms
• 13:30 - 15:35 Plenary Session
• 13:30 Trapped-ion experiments at NIST 45'  Speaker: Dr. David Hume (NIST)
• 14:15 Variational Quantum-Classical Algorithms: New Applications and Noise Resilience 45'  Speaker: Patrick Coles (Los Alamos National Laboratory)
• 15:00 Day 2 Wrap-up 15'  Speaker: Dr. Salman Habib (Argonne National Laboratory)