Probing phases of matter with advanced control of a quantum annealing processor

Mark W. Johnson

Siyuan Han

This chapter focuses on the application of Nb Josephson junctions (JJs) in quantum annealing (QA). It begins with a brief introduction to diffident strategies for implementing quantum computation (QC) with an emphasis on quantum annealing. The chapter presents the basic physics of the simplest superconducting flux qubit: radio frequency superconducting quantum interference devices (RF-SQUID). It gives a brief description on the design and realization of couplers, and control and measurement circuitry using Nb Josephson junctions. The chapter describes a scalable architecture upon which quantum annealing processors consisting up to 1024 superconducting flux qubits made of more than 104 Nb Josephson junctions. It discusses evidence on whether D-Wave 2X, which is the latest quantum annealing processor available, works as expected. The chapter also focuses on the physics and application of RF-SQUID flux qubits because the fundamental building blocks of the most advanced quantum annealers demonstrated so far are variations of superconducting flux qubits with one Josephson junction, a.k.a. the RF-SQUID.

Wade DeGottardi, David Ferguson, С. А. Новиков +2 more

Elijah Pelofske, Pratik Sathe, Cristiano Nisoli +1 more

Using programmable analog quantum annealing processors, we implement a sampling-based magnetic hysteresis protocol to probe the counterintuitive notion of magnetic memory in antiferromagnetic models. A key component of this protocol responsible for the hysteresis is a transverse field, which enables state transitions, while the longitudinal magnetic field sweep is done via a longitudinal control field. We observe intriguing non-monotonic magnetization, alongside full saturation and reversal of the hysteresis curve, Barkhausen-like noise, as well as emergent magnetic domains mediated by quantum fluctuations that give rise to the magnetic memory effect in antiferromagnets.

Saud Owyed, Abdel‐Haleem Abdel‐Aty, Mohamed A. Mabrok +1 more

In this paper, a new model of 3-qubits quantum annealing processor is designed. The spin-chain model is used to simulate the quantum annealing processor. The Hamiltonian which describes the system is introduced and analytically solved using the unitary operator method taking into account, processor in, ground state. The generated entanglement between processor parts is quantified using, concurrence method. The effect of quantum processor parameters on the dynamics of entanglement is investigated. The results show that enough quantum correlation is generated between quantum annealing processor nodes (qubits). However, it has shown that we can control the dynamics of entanglement over the system by controlling the system parameters.

Sheir Yarkoni, Elena Raponi, Thomas Bäck +1 more

Quantum annealing (QA) is a heuristic quantum optimization algorithm that can be used to solve combinatorial optimization problems. In recent years, advances in quantum technologies have enabled the development of small- and intermediate-scale quantum processors that implement the QA algorithm for programmable use. Specifically, QA processors produced by D-Wave systems have been studied and tested extensively in both research and industrial settings across different disciplines. In this paper we provide a literature review of the theoretical motivations for QA as a heuristic quantum optimization algorithm, the software and hardware that is required to use such quantum processors, and the state-of-the-art applications and proofs-of-concepts that have been demonstrated using them. The goal of our review is to provide a centralized and condensed source regarding applications of QA technology. We identify the advantages, limitations, and potential of QA for both researchers and practitioners from various fields.