Today’s quantum computers are notoriously difficult and expensive to operate. In most cases, maintaining the fragile quantum states necessary for computation and communication requires temperatures close to absolute zero (about -459 degrees Fahrenheit).
Now, researchers at Stanford University have developed a nanoscale optical device that combines the quantum properties of light and electrons to function at room temperature. This advance could help pave the way for smaller, lower-cost quantum technologies that can transmit information over long distances.
This new device enables entanglement between photons and electrons, the particles that make up light. This quantum connectivity is considered a fundamental requirement for future quantum communication systems.
“The material in question isn’t really new, but the way we use it is,” says Jennifer Dion, a professor of materials science and engineering at Stanford University and lead author of the study published in 2006. nature communications. “This provides a very versatile and stable spin connection between electrons and photons, which is the theoretical basis for quantum communication. However, electrons typically lose their spin too quickly to be useful.”
Twisted light and quantum spin
The device combines a patterned thin layer of molybdenum diselenide (MoSe2) with a nanopatterned silicon substrate. Molybdenum diselenide belongs to a family of materials known as transition metal dichalcogenides (TMDCs) and is valued for its unique optical and quantum properties.
Researchers say the silicon nanostructures play a key role by generating something called “twisted light.”
“Silicon’s nanostructures enable so-called ‘twisted light,'” explains Feng Pan, a postdoctoral fellow in Dionne’s lab and lead author of the paper. “Photons rotate in a spiral, but more importantly, these rotating photons can be used to impart spin to electrons, which is the heart of quantum computing.”
Dionne points out that the patterned structures are incredibly small, roughly comparable in size to the wavelength of visible light, and cannot be seen with the naked eye.
“The patterned nanostructures are imperceptible to the human eye and are only about the wavelength of visible light,” Dionne added. “But they can help manipulate photons very precisely to rotate, or twist, photons in a particular direction, for example up or down.”
A simpler path to quantum communications
Researchers can use this twisted light to entangle with electron spins to create qubits, the basic building blocks of quantum information systems.
In traditional computing, information is represented by 0s and 1s. In quantum technology, qubits serve a similar purpose, but quantum mechanical effects can be used to process and transmit information in entirely new ways.
One of the biggest challenges facing quantum technology is maintaining stable quantum states. Many existing systems require extreme cooling to prevent a process known as decoherence, in which sensitive quantum information is lost.
The new device operates at room temperature, avoiding one of the major obstacles limiting the widespread adoption of quantum technology. The researchers say the compact design is also relatively cheap and practical compared to many current quantum systems.
Further development of this technology could help advance secure communications, advanced sensing, high-performance computing, artificial intelligence, and other new applications.
Why is material important?
The research team selected TMDC materials for their unusual quantum properties and collaborated with Stanford researchers Fang Liu and Tony Heinz, who specialize in these materials.
“It all comes down to this material and the silicone chip,” Pan says. “Together, these effectively confine and strengthen the twisting of light, creating a strong coupling of spins between photons and electrons. This stabilizes the quantum state that enables quantum communication.”
This combination allows for stronger interactions between light and matter, helping to maintain the quantum properties needed for communications and computing tasks.
Toward the quantum network of the future
Researchers continue to improve the device and are exploring additional TMDC materials and material combinations that can achieve even better performance. They are also investigating whether these systems have the potential to reveal new quantum functions not currently possible at room temperature.
The long-term goal is to integrate such devices into larger quantum networks. Achieving that vision will require improvements in supporting technologies such as light sources, modulators, detectors, and interconnects.
Researchers hope that eventually, quantum components can be made small enough to be incorporated into everyday electronic devices. Although that future is still years away, this research represents a step toward making quantum technology more accessible and practical.
“If we can do that, we might someday be able to do quantum computing on our mobile phones,” Pang says with a laugh. “But it’s a 10-year plan.”
