Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session B51: Quantum Annealing: Architecture and HardwareFocus
|
Hide Abstracts |
Sponsoring Units: GQI Chair: Eleanor Rieffel, NASA Ames Room: 398 |
Monday, March 13, 2017 11:15AM - 11:51AM |
B51.00001: Quantum annealing with parametrically driven nonlinear oscillators Invited Speaker: Shruti Puri While progress has been made towards building Ising machines to solve hard combinatorial optimization problems, quantum speedups have so far been elusive. Furthermore, protecting annealers against decoherence and achieving long-range connectivity remain important outstanding challenges. With the hope of overcoming these challenges, I introduce a new paradigm for quantum annealing that relies on continuous variable states. Unlike the more conventional approach based on two-level systems, in this approach, quantum information is encoded in two coherent states that are stabilized by parametrically driving a nonlinear resonator. I will show that a fully connected Ising problem can be mapped onto a network of such resonators, and outline an annealing protocol based on adiabatic quantum computing. During the protocol, the resonators in the network evolve from vacuum to coherent states representing the ground state configuration of the encoded problem. In short, the system evolves between two classical states following non-classical dynamics. As will be supported by numerical results, this new annealing paradigm leads to superior noise resilience. Finally, I will discuss a realistic circuit QED realization of an all-to-all connected network of parametrically driven nonlinear resonators. The continuous variable nature of the states in the large Hilbert space of the resonator provides new opportunities for exploring quantum phase transitions and non-stoquastic dynamics during the annealing schedule. [Preview Abstract] |
Monday, March 13, 2017 11:51AM - 12:03PM |
B51.00002: Coupled Qubits for Next Generation Quantum Annealing: Novel Interactions Gabriel Samach, Steven Weber, David Hover, Danna Rosenberg, Jonilyn Yoder, David Kim, William D. Oliver, Andrew J. Kerman While the first generation of quantum annealers based on Josephson junction technology have been successfully engineered to represent arrays of spins in the quantum transverse-field Ising model, no circuit architecture to date has succeeded in emulating the more complicated non-stoquastic Hamiltonians of interest for next generation quantum annealing. Here, we present our recent results for tunable ZZ- and XX-coupling between high coherence superconducting flux qubits. We discuss the larger architectures these coupled two-qubit building blocks will enable, as well as comment on the limitations of such architectures. This research was funded by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA) and by the Assistant Secretary of Defense for Research {\&} Engineering under Air Force Contract No. FA8721-05-C-0002. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of ODNI, IARPA, or the US Government. [Preview Abstract] |
Monday, March 13, 2017 12:03PM - 12:15PM |
B51.00003: Coupled Qubits for Next Generation Quantum Annealing: Improving Coherence Steven Weber, Gabriel Samach, David Hover, Danna Rosenberg, Jonilyn Yoder, David K. Kim, Andrew Kerman, William D. Oliver Quantum annealing is an optimization technique which potentially leverages quantum tunneling to enhance computational performance. Existing quantum annealers use superconducting flux qubits with short coherence times, limited primarily by the use of large persistent currents. Here, we examine an alternative approach, using flux qubits with smaller persistent currents and longer coherence times. We demonstrate tunable coupling, a basic building-block for quantum annealing, between two such qubits. Furthermore, we characterize qubit coherence as a function of coupler setting and investigate the effect of flux noise in the coupler loop on qubit coherence. Our results provide insight into the available design space for next-generation quantum annealers with improved coherence. This research was funded by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA) and by the Assistant Secretary of Defense for Research {\&} Engineering under Air Force Contract No. FA8721-05-C-0002. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of ODNI, IARPA, or the US Government. [Preview Abstract] |
Monday, March 13, 2017 12:15PM - 12:27PM |
B51.00004: Progress towards a small-scale quantum annealer I: Architecture Yu Chen, Chris Quintana, Dvir Kafri, Alireza Shabani, Ben Chiaro, Brooks Foxen, Zijun Chen, Andrew Dunsworth, Charles Neill, James Wenner, Hartmut Neven, John Martinis A quantum annealer holds promise for improving solutions to hard optimization problems using quantum enhancement. Constructing a quantum annealer, however, stands as an outstanding challenge. It requires an architecture delicately balanced between connectivity, coherence and controls. Here, we report our recent progress on building a small-scale quantum annealer and we discuss the key features of our proposed architecture. Composed of “fluxmon” qubits and tunable couplers, our architecture allows for ultra-strong qubit-qubit coupling with reduced control crosstalks. This opens up the possibility of constructing complex graphs with high connectivity degrees. We conclude by discussing how 3-D circuit integration can be used to further improve device performance. [Preview Abstract] |
Monday, March 13, 2017 12:27PM - 12:39PM |
B51.00005: Progress towards a small-scale quantum annealer II: Device characterization and ultra-strong tunable coupling Chris Quintana, Yu Chen, Dvir Kafri, Z. Chen, B. Chiaro, A. Dunsworth, B. Foxen, C. Neill, J. Wenner, A. Shabani, H. Neven, J. M. Martinis We discuss experimental progress with fluxmon qubits and tunable couplers for quantum annealing. We summarize measurements of ultra-strong tunable coupling, crosstalk, and coherence in the first few iterations of two-qubit coupled fluxmon devices, including both planar and 3D circuit architectures compatible with high connectivity. We explore the range of validity of the Born-Oppenheimer and two-level approximations, and also discuss techniques for automated device calibration and accurate, scalable device modeling. [Preview Abstract] |
Monday, March 13, 2017 12:39PM - 12:51PM |
B51.00006: Progress towards a small-scale quantum annealer III: Device theory and modeling Dvir Kafri, Chris Quintana, Yu Chen, Alireza Shabani, Vasil Denchev, John Martinis, Hartmut Neven Future superconducting quantum annealers will require precise calibration and control. This is especially difficult for systems with strong couplings and large Josephson nonlinearities, which are challenging to accurately model. In these regimes, linear (harmonic) approximations to circuit physics break down and phenomenological modeling is not practical because of the large number of control fields. Furthermore, such systems tend to have multiple interacting degrees of freedom, making numerical diagonalization of exact Hamiltonians exponentially inefficient. To overcome these difficulties, we develop an approximate, low dimensional theory equivalent to the Born-Oppenheimer Approximation in molecular physics. By effectively integrating out `fast' degrees of freedom, this allows for efficient modeling of individual circuit components while including corrections due to interactions. Importantly, out theory is non-perturbative with respect to circuit interactions, making it applicable in the ultra-strong coupling regime. We apply these techniques to the precise calibration and control of coupled superconducting flux qubits. [Preview Abstract] |
Monday, March 13, 2017 12:51PM - 1:03PM |
B51.00007: Performance of Quantum Annealers on Hard Scheduling Problems Bibek Pokharel, Davide Venturelli, Eleanor Rieffel Quantum annealers have been employed to attack a variety of optimization problems. We compared the performance of the current D-Wave 2X quantum annealer to that of the previous generation D-Wave Two quantum annealer on scheduling-type planning problems. Further, we compared the effect of different anneal times, embeddings of the logical problem, and different settings of the ferromagnetic coupling $J_F$ across the logical vertex-model on the performance of the D-Wave 2X quantum annealer. Our results show that at the best settings, the scaling of expected anneal time to solution for D-WAVE 2X is better than that of the DWave Two, but still inferior to that of state of the art classical solvers on these problems. We discuss the implication of our results for the design and programming of future quantum annealers. [Preview Abstract] |
Monday, March 13, 2017 1:03PM - 1:15PM |
B51.00008: Non-stoquastic XX couplers for superconducting flux qubits David Ferguson, Ryan Epstein, Kenneth Zick The design of non-stoquastic qubit coupling systems enable small-scale adiabatic optimizers to exhibit uniquely quantum effects that are believed to be beyond any practical classical simulation techniques at the 50-100 qubit level. This talk will describe an innovative XX coupler design, developed by Northrop Grumman Corporation, that may allow the experimental exploration of this important regime. [Preview Abstract] |
Monday, March 13, 2017 1:15PM - 1:27PM |
B51.00009: ZZZ coupler for native embedding of MAX-3SAT problem instances in quantum annealing hardware Joel Strand, Anthony Przybysz, David Ferguson, Ken Zick Most particle interactions found in nature are two body in character. When three body terms exist, they tend to be weak in comparison to two body interactions. Northrop Grumman Corporation has developed an innovative coupling design that generates a strong, tunable, three body ZZZ interaction, as well as independently tunable two body ZZ interactions. The coupler allows MAX-3SAT instances to be embedded natively into device hardware. [Preview Abstract] |
Monday, March 13, 2017 1:27PM - 1:39PM |
B51.00010: Geometric Non-Stoquasticity in Quantum Annealing Walter Vinci, Daniel Lidar We argue that a correct description of quantum annealing implemented with flux-qubits must take into account geometric interactions that arise when the flux-qubit Hamiltonian changes during the anneal. In the effective quantum Ising Hamiltonian that describes a system of coupled flux-qubits, such interactions are represented by additional non-stoquastic terms. The realization of non-stoquastic Hamiltonians has important implications from a computational complexity perspective, since it is believed that in many cases quantum annealing with stoquastic Hamiltonians can be efficiently simulated with classical algorithms such as Quantum Monte Carlo. It is well-known that the direct implementation of non-stoquastic interactions with flux-qubits is particularly challenging. Our results may lead to an alternative approach to engineer controllable non-stoquastic interactions via geometric phases that can be exploited for computational purposes. [Preview Abstract] |
Monday, March 13, 2017 1:39PM - 1:51PM |
B51.00011: Optimal Annealing Times on the D-Wave Processors Tameem Albash, Daniel Lidar Benchmarking studies on the D-Wave quantum annealing processors have been inconclusive to date. The optimal annealing time, defined as the run-time at which the time-to-solution is minimized, has been outside the range of allowed annealing times on the devices. We construct a toy gadget that exhibits a non-monotonic behavior in its ground state probability as we increase the annealing time, and we use it to construct instances that exhibit an optimal annealing time in the available range of the device. [Preview Abstract] |
Monday, March 13, 2017 1:51PM - 2:03PM |
B51.00012: Universal Adiabatic Quantum Computing using Double Quantum Dot Charge Qubits Ciaran Ryan-Anderson, N. Tobias Jacobson, Andrew Landahl Adiabatic quantum computation (AQC) provides one path to achieving universal quantum computing in experiment. Computation in the AQC model occurs by starting with an easy to prepare groundstate of some simple Hamiltonian and then adiabatically evolving the Hamiltonian to obtain the groundstate of a final, more complex Hamiltonian. It has been shown that the circuit model can be mapped to AQC Hamiltonians and, thus, AQC can be made universal. Further, these Hamiltonians can be made planar and two-local. We propose using double quantum dot charge qubits (DQDs) to implement such universal AQC Hamiltonians. However, the geometry and restricted set of interactions of DQDs make the application of even these 2-local planar Hamiltonians non-trivial. We present a construction tailored to DQDs to overcome the geometric and interaction contraints and allow for universal AQC. These constraints are dealt with in this construction by making use of perturbation gadgets, which introduce ancillary qubits to mediate interactions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. [Preview Abstract] |
Monday, March 13, 2017 2:03PM - 2:15PM |
B51.00013: A fully programmable 100-spin coherent Ising machine with all-to-all connections Peter McMahon, Alireza Marandi, Yoshitaka Haribara, Ryan Hamerly, Carsten Langrock, Shuhei Tamate, Takahiro Inagaki, Hiroki Takesue, Shoko Utsunomiya, Kazuyuki Aihara, Robert Byer, Martin Fejer, Hideo Mabuchi, Yoshihisa Yamamoto We present a scalable optical processor with electronic feedback, based on networks of optical parametric oscillators. The design of our machine is inspired by adiabatic quantum computers, although it is not an AQC itself. Our prototype machine is able to find exact solutions of, or sample good approximate solutions to, a variety of hard instances of Ising problems with up to 100 spins and 10,000 spin-spin connections. Reference: P.L. McMahon, A. Marandi, et al. Science 354, No. 6312, pp. 614-617 (2016). [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700