Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session S70: Quantum Annealers and Quantum Analog ComputingFocus
|
Hide Abstracts |
Sponsoring Units: DQI Chair: Xinyuan You, Fermilab Room: Room 409 |
Thursday, March 9, 2023 8:00AM - 8:12AM |
S70.00001: Portfolio Optimization via Quantum Zeno Dynamics on a Quantum Processor Yue Sun, Dylan Herman, Ruslan Shaydulin, Shouvanik Chakrabarti, Shaohan Hu, Pierre Minssen, Arthur Rattew, Romina Yalovetzky, Marco Pistoia Portfolio optimization is an important problem in mathematical finance, and a promising target for quantum optimization algorithms. The use cases solved daily in financial institutions are subject to many constraints that arise from business objectives and regulatory requirements, which make these problems challenging to solve on quantum computers. We introduce a technique that uses quantum Zeno dynamics to solve optimization problems with multiple arbitrary constraints, including inequalities. We show that the dynamics of the quantum optimization can be efficiently restricted to the in-constraint subspace via repeated projective measurements, requiring only a small number of auxiliary qubits and no post-selection. Our technique has broad applicability, which we demonstrate by incorporating it into the quantum approximate optimization algorithm (QAOA) and variational quantum circuits for optimization. We analytically show that achieving a constant minimum success probability in QAOA requires a number of measurements that is independent of the problem size for a specific choice of mixer operator. We evaluate our method numerically on the problem of portfolio optimization with multiple realistic constraints, and observe better solution quality and higher in-constraint probability than the state-of-the-art technique of enforcing constraints by introducing a penalty into the objective. We demonstrate the proposed method on the Quantinuum H1-2 trapped-ion quantum processor, observing performance improvements from circuits with two-qubit gate depths of up to 148. |
Thursday, March 9, 2023 8:12AM - 8:24AM |
S70.00002: Constrained quantum optimization for extractive summarization on a trapped-ion quantum computer Romina Yalovetzky, Pradeep Niroula, Ruslan Shaydulin, Pierre Minssen, Dylan Herman, Shaohan Hu, Marco Pistoia Realizing the potential of near-term quantum computers to solve industry-relevant constrained optimization problems is a promising path to quantum advantage. In this work, we consider the extractive summarization constrained-optimization problem and demonstrate the largest-to-date execution of a quantum optimization algorithm that natively preserves constraints on quantum hardware. We report results with the Quantum Alternating Operator Ansatz algorithm with a Hamming-weight-preserving XY mixer (XY-QAOA) on trapped-ion quantum computer. We successfully execute XY-QAOA circuits that restrict the quantum evolution to the in-constraint subspace, using up to 20 qubits and a two-qubit gate depth of up to 159. We demonstrate the necessity of directly encoding the constraints into the quantum circuit by showing the trade-off between the in-constraint probability and the quality of the solution that is implicit if unconstrained quantum optimization methods are used. We show that this trade-off makes choosing good parameters difficult in general. We compare XY-QAOA to the Layer Variational Quantum Eigensolver algorithm, which has a highly expressive constant-depth circuit, and the Quantum Approximate Optimization Algorithm. We discuss the respective trade-offs of the algorithms and implications for their execution on near-term quantum hardware. |
Thursday, March 9, 2023 8:24AM - 8:36AM |
S70.00003: Adaptive variational open quantum system dynamics Huo Chen, Niladri Gomes, Wibe A de Jong The theory of open quantum systems studies the properties of a small quantum system in contact with a large environment. Because perfect isolation of a quantum system is unrealistic, in practice, any quantum system should be treated as an open system. Thus, developing quantum algorithms that can efficiently simulate open quantum systems is of vital importance in searching for potential applications of quantum computers. Here we present an adaptive variational quantum algorithm to simulate the open quantum system dynamics. The method is based on variationally solving either the vectorized Lindblad master equation or the stochastic Schrodinger equation unraveled from the Lindblad master equation. The ansatz is adaptively built at every time step by minimizing McLachlan's distance, which is a measure of the simulation accuracy. We demonstrate the efficacy of the algorithm by benchmarking it against the exact solver for solving the quantum annealing dynamics. |
Thursday, March 9, 2023 8:36AM - 8:48AM |
S70.00004: Hybrid Gate-Based and Annealing Quantum Computing for Large-Size Ising Problems Chen-Yu Liu, Hsi-Sheng Goan One of the major problems of quantum computing applications is that the required number of qubits to solve a practical problem is much larger than that of today's quantum hardware. |
Thursday, March 9, 2023 8:48AM - 9:00AM |
S70.00005: Quantum Alternating Operator Ansatz (QAOA) performance regimes for continuous schedules Vladimir Kremenetski, Anuj Apte, Tad Hogg, Stuart Hadfield, Norm M Tubman The Quantum Approximate Optimization Algorithm and its generalization to Quantum Alternating Operator Ansatze (QAOA) are promising approaches for using quantum computers to tackle challenging problems in combinatorial optimization and beyond. For the setting of easier-to-optimize parameter sequences derived from continuous schedules such as linear ramps, QAOA performance diagrams capture the algorithm's varying performance over starkly different parameter regimes, and yet display qualitatively similar behavior across different target performance metrics and different application domains. In our work, we characterize and explain this observed universal behavior by elucidating the underlying mechanisms, which include the discrete adiabatic theorem, the magnitude of p controlling diabatic transitions at avoided crossings, small-parameter approximations, and holonomies due to changing eigenvector connections. Our results complement and generalize the insights obtained from the usual (continuous) adiabatic perspective. In contrast, we highlight that comparable performance to that of high-depth circuits can be achieved with smaller depth for suitably chosen (somewhat larger) parameters. Furthermore, we outline how our analysis could inform the design of protocols requiring fewer resources and constraints on the mixer than the standard approach to obtain comparable performance. |
Thursday, March 9, 2023 9:00AM - 9:12AM |
S70.00006: Trends in Classical Angle Optimization of ma-QAOA Anthony Wilkie, Rebekah Herrman, James Ostrowski Quantum approximation optimization algorithm (QAOA) is a variational quantum algorithm that has been well studied due to its application of solving combinatorial optimization problems. One such problem of interest is the MaxCut problem, where given a graph $G$, what is the best way to partition the vertices of $G$ such that the number of edges of $G$ that have a vertex in each partition is maximized. However, due to the large qubit and circuit depth requirements, implementing QAOA is not practical on NISQ devices. Multi-angle QAOA (ma-QAOA) is a variant of QAOA in which all clauses receive angles. It has been observed that 1-ma-QAOA outperforms 3-QAOA on small graphs. We explore whether $p$-ma-QAOA performs better than $(p+2)$-QAOA for larger $p$. We will also discuss how ma-QAOA circuits are, in general, shallower than QAOA circuits and how choice of initial classical optimizer seed for angle optimization affects algorithm output. |
Thursday, March 9, 2023 9:12AM - 9:24AM |
S70.00007: Exponential State Distributions in Quantum Approximate Optimization Phillip C Lotshaw, James Ostrowski, George Siopsis The quantum approximate optimization algorithm (QAOA) is a quantum algorithm for solving combinatorial optimization problems with near-term quantum computers. However, little is known about structure in the states that are produced by QAOA. Here, we analyze systematic structure in QAOA for optimized MaxCut instances on graph ensembles with 14-23 qubits and depth parameters p≤12. We decompose the total probability to measure any solution with a given cost into an average probability per basis state × the density of solutions. The average probability per basis state scales exponentially with costs in the Maxcut objective, and we devise an empirical relation that accounts for the scaling. Approximate QAOA states are then generated using the predicted scaling and the density of solutions. These approximate states predict approximation ratios with median errors of <1% and worst-case error of <3%, relative to exact results, across the 7,200 instances we consider. They also predict the probability for the optimal solution and cumulative distribution functions, but with larger errors. The simple patterns identified here are expected to lead to new investigations into QAOA behavior and performance. |
Thursday, March 9, 2023 9:24AM - 9:36AM |
S70.00008: Multi-angle QAOA is universal for computation Rebekah Herrman In this talk, we show that ma-QAOA is equivalent to a restriction of continuous-time quantum walks on dynamic graphs. We then show it is universal for computation by finding the appropriate B and C operators and angles that implement the universal gate set consisting of the Hadamard, pi/8 and Controlled-Not gates in the ma-QAOA framework. This result begins to bridge the gap between the continuous-time quantum walk model and gate model of quantum computation. |
Thursday, March 9, 2023 9:36AM - 9:48AM |
S70.00009: Effective-Temperature Reduction of Ising Spin-Glass Problems with Quantum Annealing Correction Humberto Munoz-Bauza, Evgeny Mozgunov, Daniel A Lidar Quantum annealers can sample increasingly larger and highly connected problems. However, the quality of collected samples can be affected by decoherence and analog control errors. We implement and benchmark quantum annealing correction (QAC) on the topology of the D-Wave Advantage quantum annealer, which yields up to 1,300 error-corrected qubits. We demonstrate that QAC outperforms unprotected quantum annealing in finding ground state solutions to random Ising spin glass problems by effectively reducing the temperature of the annealed samples. For the largest sizes available, QAC is also capable of sampling low energy states more efficiently than unprotected quantum annealing, particularly when the disorder of the spin glass problems is susceptible to analog errors. |
Thursday, March 9, 2023 9:48AM - 10:00AM |
S70.00010: How to experimentally evaluate the adiabatic condition for quantum annealing Yuichiro Mori, Shiro Kawabata, Yuichiro Matsuzaki We have proposed an experimental method for evaluating the adiabatic condition during quantum annealing (QA). Ordinarily, the adiabatic condition is given by an equation involving the transition matrix element and the energy gap, and our method simultaneously provides these components without diagonalizing the Hamiltonian. The key idea is to measure the power spectrum of a time domain signal by adding an oscillating field during QA, and we evaluate these values of the transition matrix element and energy gap from the measurement output. Our results will provide a powerful experimental basis for analyzing the performance of QA. |
Thursday, March 9, 2023 10:00AM - 10:12AM |
S70.00011: Coherent flux qubits for quantum annealing (Theory) David López-Núñez, Elia Bertoldo, Fabian Zwiehoff, Luca Cozzolino, Alba Torras Coloma, Boris Nedyalkov, Barkay Guttel, Paul G Baity, Martin P Weides, Manel Martinez, Pol Forn-Díaz Quantum annealing aims at solving combinatorial optimization problems faster than classical computing with less sensitivity to errors compared to gate-based quantum computing with no error correction. Here, we present the first generation of coherent qubit devices, consisting of both uncoupled and coupled four-Josephson junction flux qubits. We aim at low persistent currents for increased coherence and a large shunting capacitance both for charge noise reduction and higher parameter reproducibility. The inductive qubit-qubit coupling is achieved with rf-squids and the readout is performed with dispersive interaction with coplanar resonators. These processors serve as testbeds for quantum annealing experiments. Future designs in the context of the European FET Open project AVaQus will be discussed. |
Thursday, March 9, 2023 10:12AM - 10:24AM |
S70.00012: Coherent flux qubits for quantum annealing (Experiment) Elia Bertoldo, David López-Núñez, Fabian Zwiehoff, Luca Cozzolino, Alba Torras Coloma, Boris Nedyalkov, Paul G Baity, Martin P Weides, Manel Martinez, Pol Forn-Díaz The Annealing-Based Variational Quantum Processors (AVaQus) project is an European consortium aiming to produce a coherent quantum annealing prototype with capability to operate annealing-based operations as well as variational-type quantum algorithms. The final prototype will consist of five coupled coherent flux qubits. This talk presents the experimental implementation of the theoretical description from the previous talk. |
Thursday, March 9, 2023 10:24AM - 11:00AM |
S70.00013: Landau-Zener tunneling: from weak to strong environment coupling Invited Speaker: Adrian Lupascu Landau-Zener tunneling, which describes the transitions in a two-level system during the passage through an anti-crossing, is a model applicable to a wide range of physical phenomena. Dissipation due to coupling between the system and environment is an important factor in determining the transition rates. Using a superconducting tunable capacitively shunted flux qubit, we observe the crossover from weak to strong coupling to the environment. The weak coupling limit corresponds to small system-environment coupling and leads to environment-induced thermalization. In the strong coupling limit, environmental excitations dress the system and transitions occur between the dressed states. Our results confirm previous theoretical studies of dissipative Landau-Zener tunneling in the weak and strong coupling limits, and motivate further work on understanding the intermediate regime. This work is relevant for understanding the role of open system effects in quantum annealing, where Landau-Zener transitions at small gaps, occurring in large scale systems, are important for the success probability. |
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