34 research outputs found
Approximate Approximation on a Quantum Annealer
Many problems of industrial interest are NP-complete, and quickly exhaust
resources of computational devices with increasing input sizes. Quantum
annealers (QA) are physical devices that aim at this class of problems by
exploiting quantum mechanical properties of nature. However, they compete with
efficient heuristics and probabilistic or randomised algorithms on classical
machines that allow for finding approximate solutions to large NP-complete
problems. While first implementations of QA have become commercially available,
their practical benefits are far from fully explored. To the best of our
knowledge, approximation techniques have not yet received substantial
attention. In this paper, we explore how problems' approximate versions of
varying degree can be systematically constructed for quantum annealer programs,
and how this influences result quality or the handling of larger problem
instances on given set of qubits. We illustrate various approximation
techniques on both, simulations and real QA hardware, on different seminal
problems, and interpret the results to contribute towards a better
understanding of the real-world power and limitations of current-state and
future quantum computing.Comment: Proceedings of the 17th ACM International Conference on Computing
Frontiers (CF 2020
Benchmarking Advantage and D-Wave 2000Q quantum annealers with exact cover problems
We benchmark the quantum processing units of the largest quantum annealers to
date, the 5000+ qubit quantum annealer Advantage and its 2000+ qubit
predecessor D-Wave 2000Q, using tail assignment and exact cover problems from
aircraft scheduling scenarios. The benchmark set contains small, intermediate,
and large problems with both sparsely connected and almost fully connected
instances. We find that Advantage outperforms D-Wave 2000Q for almost all
problems, with a notable increase in success rate and problem size. In
particular, Advantage is also able to solve the largest problems with 120
logical qubits that D-Wave 2000Q cannot solve anymore. Furthermore, problems
that can still be solved by D-Wave 2000Q are solved faster by Advantage. We
find, however, that D-Wave 2000Q can achieve better success rates for sparsely
connected problems that do not require the many new couplers present on
Advantage, so improving the connectivity of a quantum annealer does not per se
improve its performance.Comment: new experiments to test the conjecture about unused couplers
(appendix B