The movement of electrons is the foundation of modern technology. From everyday appliances such as air fryers to the countless screens we use for professional tasks and entertainment, today’s electronic devices operate through the controlled movement of electrons.
The Strange Quantum Behavior of Electrons
However, electrons follow the unusual laws of quantum mechanics, exhibiting behaviors that do not appear in the macroscopic world. One example is superposition, which enables particles to occupy multiple possible states until scientists measure them, similar to Schrödinger’s famous thought experiment of a cat that remains both alive and dead until someone observes it.
Despite their strange quantum nature, some electron behaviors have practical similarities that help scientists better understand processes that are otherwise impossible to see directly.
Researchers at the University of Michigan have made a significant breakthrough by creating an “electron lighthouse” that reveals new aspects of electron behavior. The device generates a focused electron stream and lets scientists control its direction using different light wavelengths, without requiring an external electrical power source.
Steven Cundiff, an experimental physicist at the University of Michigan and senior author of the study, explains that this process differs from how electrons typically behave. Normally, electrons move through a material when an electric field is applied, causing them to collide with atoms and gradually drift through the substance.
Using light, the researchers were able to push electrons in a chosen direction without the need for an applied electric field.
Using Infrared Light to Control Electron Flow in Semiconductors
With funding from the US National Science Foundation, the team developed a device that uses two laser beams with different wavelengths — or “colors” — in the invisible infrared part of the electromagnetic spectrum to manipulate electron movement through a semiconductor.
Cundiff noted that one of the most unexpected findings was that the currents generated by this method were strong enough to be detected by the device they built.
Unlike typical electrical currents, which are usually diffusive because electrons repeatedly scatter off imperfections and impurities in a material, the current created in this experiment is ballistic. This means the electrons move along paths determined by their initial launch speed and direction, allowing them to travel more directly through the material.
The researchers constructed their device at the University of Michigan’s Lurie Nanofabrication Facility (LNF), exploring various approaches to create an experimental system free from external electric fields that could interfere with or distort their measurements.
Yiming Gong, a machine learning scientist at Grainger and the study’s lead author, explained that the main challenge was finding a reliable method to achieve this, since no established technique existed for the process.
Developing a New Fabrication Process for the Electron Device
“I worked together with the LNF team to test different fabrication approaches, adjusting materials, recipes, and temperatures until we developed a suitable manufacturing method,” Gong said.
Earlier theoretical and experimental studies had already suggested that light alone could provide enough energy to drive electron movement.
Cundiff noted that the project grew from earlier research he began years ago, originally aimed at creating a phase-sensitive detector for stabilizing frequency combs. These advanced tools are essential for precisely controlling electromagnetic waves and have important applications in areas such as highly accurate clocks, computing technologies, and communication systems.
This study expands on earlier research by showing that light can be used not only to generate electron movement but also to guide electrons into a focused, beam-like stream — a behavior the researchers compare to the function of a lighthouse.
“Light is no longer just turning the current on; it is also directing where it goes,” Cundiff explained.
However, controlling the direction of the electron beam is not as simple as rotating a light source. Instead, the researchers achieve this by changing the polarization of the light, meaning they adjust the orientation of the light waves’ oscillations to control the path of the electrons.
Confirming a Theoretical Prediction in Quantum Physics
The findings also confirm a theoretical prediction proposed earlier by John Sipe, a theoretical physicist at the University of Toronto, who collaborated on the research.
Sipe and his team had previously predicted that this experimental arrangement could create the “electron lighthouse” phenomenon, producing a directed beam of electrons without the need for an externally applied voltage.
The process behind this effect is called quantum interference, a fundamental feature of quantum mechanics.
Unlike classical objects that follow predictable trajectories, particles at the subatomic scale behave more like waves with uncertain paths. Quantum interference occurs when these wave-like states overlap, causing them to either reinforce each other or cancel each other out depending on how they combine.
In the future, this research could provide deeper insights into the quantum geometry of materials, which determines many of their essential properties. These findings may contribute to the development of advanced technologies, including quantum sensing systems designed to measure physical quantities with increasingly higher levels of accuracy.
Quantum Interference in Future Technologies
Advances in quantum interference could also lead to improvements in imaging and telecommunications, enabling more efficient signal transmission between devices and allowing greater amounts of information to be transferred.
Quantum interference may also contribute to faster computing by increasing the likelihood of obtaining useful solutions while reducing the chances of unwanted outcomes.
As quantum technologies continue to advance, this “lighthouse” could serve as a guide for exploring the complex and still poorly understood world of subatomic particles and fields that shape the physical universe.
Read the original article on: sciencealert
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