Abstract

A recent experiment [T. Lanting et al., Phys. Rev. X 4, 021041 (2014)10.1103/PhysRevX.4.021041] claimed to provide evidence of up to eight-qubit entanglement in a D-Wave quantum annealing device. However, entanglement was measured using qubit tunneling spectroscopy, a technique that provides indirect access to the state of the system at intermediate times during the anneal by performing measurements at the end of the anneal with a probe qubit. In addition, an underlying assumption was that the quantum transverse-field Ising Hamiltonian, whose ground states are already highly entangled, is an appropriate model of the device and not some other (possibly classical) model. This begs the question of whether alternative classical or semiclassical models would be equally effective at predicting the observed spectrum and thermal state populations. To check this, we consider a recently proposed classical …

Date

January 1, 1970

Authors

Tameem Albash, Itay Hen, Federico M Spedalieri, Daniel A Lidar

Journal

Physical Review A

Volume

92

Issue

6

Pages

062328

Publisher

American Physical Society