An analysis of the relative effects of connectivity and coupling interactions on spin networks emulating the D-Wave 2000Q quantum annealer

TL;DR

This paper investigates how connectivity and coupling interactions influence the correlations and dynamics in spin networks emulating the D-Wave 2000Q quantum annealer, revealing complex effects of architecture on system behavior.

Contribution

It provides an analysis of spatial correlations and the impact of network connectivity and coupling scaling on spin network dynamics, highlighting architectural influences.

Findings

Strong positive spatial correlations in qubits across unit cells.

Connectivity and coupling strength significantly affect node correlations.

Architectural features can divert quantum system performance from ideal models.

Abstract

From available data, we show strong positive spatial correlations in the qubits of a D-Wave 2000Q quantum annealing chip that are connected to qubits outside their own unit cell. Then, by simulating the dynamics of three different spin networks and two different initial conditions, we then show that correlation between nodes is affected by a number of factors. The different connectivity of qubits within the network means that information transfer is not straightforward even when all the qubit-qubit couplings have equal weighting. Connected nodes behave even more dissimilarly when the couplings' strength is scaled according to the physical length of the connections (here to simulate dipole-dipole interactions). This highlights the importance of understanding the architectural features and potentially unprogrammed interactions/connections that can divert the performance of a quantum system away from the idealised model of identical qubits and couplings across the chip.