Researchers use lasers to measure and manipulate magnetic ripple interactions

One vision for computing the future is to use ripples in magnetic fields as the fundamental mechanism. In this application, magnetic oscillators can be comparable to electricity and serve as the foundation of electronic products.

In traditional digital technology, this magnetic system is expected to be much faster than today's technology, from laptops and smartphones to telecommunications. In quantum computing, the advantages of magnetism include not only faster speeds, but also more stable devices.
A recent research report published in the journal Nature Physics reported an early discovery on the road to developing magnetic computers. Researchers generated two different types of ripples in the magnetic field of thin alloy plates, measured the results, and indicated that the magnetic oscillators interact in a nonlinear manner. "Nonlinear" refers to outputs that are not proportional to the input, which is a necessity for any type of computing application.

So far, most research in this field has focused on one type of magnetic oscillator, which is described as equilibrium under relatively stable conditions. As done in these studies, manipulating magnetic oscillators can cause the system to lose balance.

This is one of the many studies conducted through years of collaboration between theorists and experimenters from multiple scientific and engineering fields, including the second study recently published in the journal Nature Physics. This project has received support from both government and private funders, bringing together researchers from the University of California, Los Angeles, Massachusetts Institute of Technology, University of Texas at Austin, and University of Tokyo in Japan.

"Together with our colleagues, we have begun a movement that I call stimulating progress in non-equilibrium physics," said Prineha Narang, co-author of the study and professor of physics at the University of California, Los Angeles. The work we are doing here fundamentally advances the understanding of non-equilibrium and nonlinear phenomena. It may be a step towards computer memory, utilizing ultrafast phenomena that occur around one billionth of a second.

A key technology behind these findings is an advanced technique for adding energy to samples and evaluating them using lasers with frequencies in the terahertz range, located between microwave and infrared radiation wavelengths. This method comes from chemical and medical imaging and is rarely used to study magnetic fields.

Nalang, a member of the California Nanosystems Institute at the University of California, Los Angeles, said that the use of terahertz lasers indicates potential synergies with increasingly mature technologies.

"The terahertz technology itself has reached the point where we can talk about a second technology that relies on it," she said. It makes sense to perform this type of nonlinear control in the frequency band where we have lasers and detectors that can be placed on chips. Now is the time to truly move forward, because we have both technical and interesting theoretical frameworks, as well as theoretical frameworks for studying the interactions between magnetic oscillators.

Researchers applied laser pulses to a 2mm thick plate made of carefully selected alloys containing yttrium, a metal used in LED and radar technology. In some experiments, a second terahertz laser was used in a coordinated manner, which paradoxically increased energy but helped stabilize the sample.

The magnetic field is applied to yttrium in a specific way, allowing only two types of magnetic oscillators. Researchers can drive two types of magnetic oscillators individually or simultaneously by rotating the sample to a specific angle relative to the laser. They are able to measure the interaction between two types and find that they can cause nonlinear responses.

"Clearly demonstrating this nonlinear interaction is important for any signal processing based application," said co author and postdoctoral researcher Jonathan Curtis at the University of California, Los Angeles NarangLab. A mixed signal like this allows us to convert between different magnetic inputs and outputs, which is necessary for devices that rely on magnetic manipulation information.

Narang said that trainees are crucial for current research and larger projects.
"This is a very arduous multi-year effort, involving many parts," she said. What is the right system, how do we use it? How do we consider making predictions? How do we limit the system to run the way we want? Without talented students and postdoctoral fellows, we will not be able to do this.

This study includes Keith Nelson, a chemistry professor at the Massachusetts Institute of Technology, Eduardo Baldini, a physics professor at UT Austin, and a team led by Narang from the University of California, Los Angeles, with support from the Quantum Science Center, which is the National Quantum Information Science Research Center of the Department of Energy and is headquartered at the Oak Ridge National Laboratory. 

This study is primarily supported by the Ministry of Energy, as well as the Alexander von Humboldt Foundation, Gordon and Betty Moore Foundation, John Simon Guggenheim Memorial Foundation, and Japan Association for the Advancement of Science, all of which provide ongoing support for collaboration.

Source: Laser Net