Fundamental discovery in quantum and classical information processing

In collaboration with theorists from the Pritzker School of Molecular Engineering at the University of Chicago, researchers from the Argonne National Laboratory of the United States Department of Energy (DOE) carried out a scientific control which is the first of its kind. They demonstrated a new approach that allows real-time monitoring of interactions between microwave photons and magnons, which could lead to advances in electronic devices and quantum signal processing.

Microwave photons are elementary particles that form the electromagnetic waves that we use for wireless communications. On the flip side, magnons are the elementary particles that form what scientists call “spin waves” – wave-like disturbances in an ordered network of microscopic aligned spins that can occur in some magnetic materials.

Microwave photon-magnon interaction has emerged in recent years as a promising platform for both classical and quantum information processing. Yet this interaction had proved impossible to manipulate in real time, until now.

“Before our discovery, controlling the photon-magnon interaction was like shooting an arrow through the air,” said Xufeng Zhang, scientific assistant at the Center for Nanoscale Materials, a DOE user facility in Argonne, and corresponding author of this work. “We have no control over this arrow once in flight.”

The team’s discovery changed that. “Now it’s more like flying a drone, where we can guide and control its flight electronically,” Zhang said.

Through intelligent engineering, the team uses an electrical signal to periodically change the vibrational frequency of the magnon and thereby induce an efficient magnon-photon interaction. The result is a first-ever magneto-microwave device with on-demand tunability.

The team’s device can monitor the strength of the photon-magnon interaction at any time as information is transferred between photons and magnons. It can even turn the interaction on and off completely. With this tuning capability, scientists can process and manipulate information in a way that far surpasses current hybrid magnonic devices.

“Researchers have been looking for a way to control this interaction for a few years,” Zhang noted. The team’s discovery opens a new direction for magnon-based signal processing and should lead to electronic devices with new capabilities. It may also allow important applications for quantum signal processing, where microwave-magnon interactions are explored as a promising candidate for information transfer between different quantum systems.

The DOE’s Office of Basic Energy Sciences supported this research, which was published in Physical examination letters.