Consistency Tests of Classical and Quantum Models for a Quantum Annealer

Abstract

Recently the question of whether the D-Wave processors exhibit large-scale quantum behavior or can be described by a classical model has attracted significant interest. In this work we address this question by studying a 503 qubit D-Wave Two device in the "black box" model, i.e., by studying its input-output behavior. Our work generalizes an approach introduced in Boixo et al. [Nat. Commun. 4, 2067 (2013)], and uses groups of up to 20 qubits to realize a transverse Ising model evolution with a ground state degeneracy whose distribution acts as a sensitive probe that distinguishes classical and quantum models for the D-Wave device. Our findings rule out all classical models proposed to date for the device and provide evidence that an open system quantum dynamical description of the device that starts from a quantized energy level structure is well justified, even in the presence of relevant thermal excitations and a small value of the ratio of the single-qubit decoherence time to the annealing time.

36 pages, 36 figures. v2: Addresses the issues raised in arXiv:1404.6499. v3. Paper reorganized for clarity of presentation, but results have not change since v2. v4: Updated title, author order, abstract, and manuscript to match published version

References in corpus (3)

• Quantum Phase Transitions and Bipartite Entanglement
• Mathematical Foundation of Quantum Annealing
• Minor-embedding in adiabatic quantum computation: II. Minor-universal graph design

Cited by in corpus (14)

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• Reexamining classical and quantum models for the D-Wave One processor
• Experimental demonstration of perturbative anticrossing mitigation using non-uniform driver Hamiltonians
• Algorithm engineering for a quantum annealing platform
• Simulated quantum annealing as a simulator of non-equilibrium quantum dynamics
• Optimally Stopped Optimization
• Experimental and Theoretical Study of Thermodynamic Effects in a Quantum Annealer
• Comment on "Distinguishing Classical and Quantum Models for the D-Wave Device"
• Fair sampling of ground-state configurations of binary optimization problems
• Achieving fair sampling in quantum annealing
• PyQUBO: Python Library for Mapping Combinatorial Optimization Problems to QUBO Form
• Discriminating Non-Isomorphic Graphs with an Experimental Quantum Annealer
• Quantum Searches in a Hard 2SAT Ensemble
• Classical Control of Large-Scale Quantum Computers