First-ever gated flow of chargeless quantum data carriers achieved with nano-switch
- Ritambhara K
- Sep 15
- 2 min read
Guiding excitons with light and nano-ridges could unite optics and electronics, unlocking faster and more efficient communication technologies.
Engineers at the University of Michigan have created a nanostructure that functions like both a wire and a switch, enabling—for the first time—the controlled flow of quantum quasiparticles known as excitons at room temperature.
The breakthrough device, resembling a transistor, could revolutionize how information is processed by allowing circuits to run on excitons instead of electrical currents. Such a shift could dramatically reduce the heat and energy losses that plague today’s electronic devices.
“Electronics are reaching their limits with AI and other heavy computations demanding enormous power and generating excessive heat,” said Mack Kira, co-corresponding author of the study published in ACS Nano and professor of electrical and computer engineering. “Excitonic circuits could eliminate much of this energy consumption.”
Excitons, while less familiar than electrons, are already part of everyday technology. They play central roles in energy conversion processes—powering solar cells, organic LEDs in smartphone screens, and even photosynthesis in plants. An exciton forms when an electron absorbs energy and leaps to a higher state, leaving behind a positively charged “hole.” The electron and hole remain bound together, creating a neutral particle that can transport quantum energy efficiently.
This neutrality, however, makes excitons difficult to steer. Unlike electrons, they cannot be guided by electrodes using electric charge alone. To address this, the U-M team engineered an “energy ridge” within a semiconductor that acts as a dedicated path—essentially, a wire for excitons. They then added electrodes alongside the ridge, functioning as a gate. By switching the voltage on or off, the team could block or allow exciton movement, mimicking the behavior of a transistor.
“When the electrodes are activated, they form an energy barrier that stops excitons from flowing. Turn them off, and the excitons move freely again,” explained Zhaohan Jiang, lead author and doctoral student in electrical and computer engineering. “This type of excitonic switching has never been demonstrated before.”
Tests revealed that the switch achieved an on/off ratio greater than 19 decibels—sufficient for high-performance optoelectronic applications such as ultrafast on-chip data transfer, supercomputing, data centers, AI-driven devices, wearables, and autonomous systems.
The device also incorporates a unique light-based mechanism, earning it the name optoexcitonic switch. Beyond generating excitons, light interacts with them to push them along the ridge in a preferred direction. This combination allowed the researchers to transport excitons one-way across distances of up to four micrometers in under half a nanosecond at room temperature.
The next step for the team is to scale the technology by linking hundreds of such switches together, potentially forming full-fledged excitonic circuits.
“Before we get to fully excitonic processors, this technology could first enhance how photonics and electronics interface, boosting the speed of data processing and communication,” said Parag Deotare, co-corresponding author and associate professor of electrical and computer engineering.
The advance comes at a time when global demand for faster, more energy-efficient data transmission is surging, particularly in fields like AI, machine learning, and cloud computing. The work was supported in part by the U.S. Army Research Office and the U.S. Air Force Office of Scientific Research, and the team has applied for patent protection with the help of U-M Innovation Partnerships.
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