Author Correction: Analog errors in quantum annealing: doom and hope

Pearson, Adam; Mishra, Anurag; Hen, Itay; Lidar, Daniel A.

doi:10.1038/s41534-020-00297-8

Cited by 1 publication

(1 citation statement)

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“…In [61,62] an algorithm called quantum annealing correction (QAC) is proposed, which provides a substantial improvement in performance compared to linear chains with no QAC; substantial analysis and improved variants have subsequently been implemented [43,52,70,71]. QAC works by encoding a problem using a repetition code in conjunction with a bit-flip penalizing Hamiltonian.…”

Section: Literature Reviewmentioning

confidence: 99%

Noise dynamics of quantum annealers: estimating the effective noise using idle qubits

Pelofske

Hahn

Djidjev

2023

Quantum Sci. Technol.

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Quantum annealing is a type of analog computation that aims to use quantum mechanical fluctuations to search for optimal solutions of QUBO (quadratic unconstrained binary optimization) or, equivalently, Ising problems. Since NP-hard problems can in general be mapped to Ising and QUBO formulations, the quantum annealing paradigm has the potential to help solve various NP-hard problems. Current quantum annealers, such as those manufactured by D-Wave Systems, Inc., have various practical limitations including the size (number of qubits) of the problem that can be solved, the qubit connectivity, and sources of error from the environment or system calibration which can reduce the quality of the solutions. Typically, for an arbitrary problem instance, the corresponding QUBO (or Ising) structure will not natively embed onto the available qubit architecture on the quantum chip. Thus, in these cases, a minor embedding of the problem structure onto the device is necessary. However, minor embeddings on these devices do not always make use of the full sparse chip hardware graph, and a large portion of the available qubits stay unused during quantum annealing. In this work, we embed a disjoint random QUBO on the unused parts of the chip alongside the QUBO to be solved, which acts as an indicator of the solution quality of the device over time. Using experiments on three different D-Wave quantum annealers, we demonstrate that (i) long term trends in solution quality exist on the D-Wave device, and (ii) the unused qubits can be used to measure the current level of noise of the quantum system.

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