Emerging magnetic monopolies isolated using quantum annealing computer – Los Alamos Reporter


The researchers used a D-Wave quantum annealing computer as a test bed to examine the behavior of emerging magnetic monopoles. Shown here, emerging magnetic monopoles traverse a qubit lattice in superconducting quantum annealing. A non-zero flow programmed around the border creates a monopole trapped in the degenerated ground state. Courtesy of LANL


Using a D-Wave quantum annealing computer as a test bed, scientists at Los Alamos National Laboratory have shown that it is possible to isolate so-called emerging magnetic monopoles, a class of quasiparticles, creating a new approach to develop “materials by design”.

“We wanted to study emerging magnetic monopoles by harnessing the collective dynamics of qubits,” said Cristiano Nisoli, one of the study’s lead authors at Los Alamos. “Magnetic monopoles, as elementary particles with a single magnetic pole, have been hypothesized by many, and famously by Dirac, but have so far proved elusive.”

They made an artificial spin ice using the superconducting qubits of the quantum machine as a magnetic building block. The generation of magnetic materials with exotic properties in this way is revolutionary in many ways. Their process used Gauss’s law to trap monopoles, allowing scientists to observe their activated quantum dynamics and mutual interaction. This work unambiguously demonstrates that magnetic monopoles can not only emerge from an underlying spin structure, but can be controlled, isolated and studied with precision.

“It has been demonstrated over the past decade or so that monopoles can emerge as quasi-particles to describe excitation spin ices of various geometries. Previously, the pulsed field facility at the National High Magnetic Field Laboratory in Los Alamos was able to “listen” to the noise of monopolies in artificial spin ice. And now, using a D-Wave quantum annealing system, we have enough control to actually trap one or more of these particles and study them individually. We’ve seen them walk around, get stuck, and be created and annihilated in pairs of opposing magnetic charges. And so we were able to confirm our quantitative theoretical predictions, that they interact and in fact filter out, ”said Nisoli.

“D-Wave processors are designed to excel at optimization, but can also be used as quantum simulators. By programming the desired interactions of our magnetic material into the qubits of D-Wave, we can perform experiments that are otherwise extremely difficult, ”said Andrew King, director of performance research at D-Wave and author of The article. “This collaborative proof-of-principle work demonstrates new experimental capabilities, improving the power and versatility of artificial spin ice studies. The ability to programmatically manipulate emerging quasiparticles may become a key aspect of materials engineering and even topological quantum computing; we hope that it will be fundamental for future research.

Nisoli added: “We have only scratched the surface of this approach. Previous artificial spin ice systems were made with nanomagnets and obeyed classical physics. This realization, on the contrary, is entirely quantum. To avoid skipping any steps, we have focused so far on a near-classical study, but in the future we can really increase these quantum fluctuations and study very current issues of decoherence, memory, quantum information. and topological order, with important technological implications. “

“These results also have particularly relevant technological consequences for the DOE and Los Alamos, particularly in the idea of ​​materials by design, to produce future nanomagnets that could show advanced and desirable functionality for detection and computation. Monopolies, as carriers of binary information, may be relevant for spintronics. They also contribute significantly to Los Alamos D-Wave investments, ”noted Los Alamos’ Alejandro Lopez-Bezanilla, who works on the D-Wave processor and has formed the team.
Nisoli suggests moreover that besides fruitful applications, these results could perhaps also feed the reflection of fundamental physics.

“Our fundamental particle theories are parameterized models. We ask ourselves: what is a particle? We show here experimentally that not only the particles but also their Long rangeinteractions can be a top-level description of a very simple underlying structure, only one coupled to closest neighbors. Could even “real” particles and interactions that we consider fundamental, such as leptons and quarks, instead be interpreted as an emerging upper-level description of a more complex lower-level binary substrate, a kind of like our monopoles emerging from a pile of qubits? “

The paper: Qubit Spin Ice, Science First version (online), July 15, 2021. Andrew King, Cristiano Nisoli, Edward D. Dahl, Gabriel Poulin-Lamarre, Alejandro Lopez-Bezanilla. DOI 10.1126 / science.abe2824 Funding: This project was funded through a research grant led by the Los Alamos National Laboratory.

About D-Wave Systems Inc.D-Wave is the leader in the development and delivery of quantum computing systems, software and services and is the world’s leading commercial supplier of quantum computers. Our mission is to unleash the power of quantum computing for the world. We do this by delivering customer value with practical quantum applications for issues as diverse as logistics, artificial intelligence, materials science, drug discovery, planning, cybersecurity, fault detection and financial modeling. D-Wave systems are used by some of the most advanced organizations in the world, including NEC, Volkswagen, DENSO, Lockheed Martin, USRA, USC, and Los Alamos National Laboratory. Headquartered near Vancouver, Canada, D-Wave’s US operations are based in Palo Alto, California. D-Wave has a base of blue chip investors including PSP Investments, Goldman Sachs, BDC Capital, NEC Corp. and In-Q-Tel. For more information visit: www.dwavesys.com.

About Los Alamos National LaboratoryThe Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science in the name of national security, is managed by Triad, a public service-oriented national security scientific organization owned equally by its three founding members: Battelle Memorial Institute (Battelle), the Texas A&M University System (TAMUS) and the University of California (UC) regents for the National Nuclear Security Administration of the Department of Energy. Los Alamos strengthens national security by ensuring the safety and reliability of the US nuclear stockpile, by developing technologies to reduce threats from weapons of mass destruction and by solving problems related to energy, environment, infrastructure, to global health and security. LA-UR-21-26585

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