Quantum computers today are notoriously difficult and expensive to operate. Most require temperatures near absolute zero, about -459 degrees Fahrenheit, to maintain the fragile quantum states needed for computation and communication.
Now, researchers at Stanford University have developed a nanoscale optical device that functions at room temperature while linking the quantum properties of light and electrons. The advance could help pave the way for smaller, lower-cost quantum technologies capable of transmitting information across long distances.
The new device enables entanglement between photons, the particles that make up light, and electrons. This quantum connection is considered a fundamental requirement for future quantum communication systems.
“The material in question is not really new, but the way we use it is,” says Jennifer Dionne, a professor of materials science and engineering at Stanford and senior author of the study published in Nature Communications. “It provides a very versatile, stable spin connection between electrons and photons that is the theoretical basis of quantum communication. Typically, however, the electrons lose their spin too quickly to be useful.”
Twisted Light and Quantum Spin
The device combines a thin patterned layer of molybdenum diselenide (MoSe2) with a nanopatterned silicon substrate. Molybdenum diselenide belongs to a family of materials known as transition metal dichalcogenides (TMDCs), which are valued for their unique optical and quantum properties.
According to the researchers, the silicon nanostructures play a critical role by generating what they call “twisted light.”
“The Silicon nanostructures enable what we call ‘twisted light,'” explains Feng Pan, a postdoctoral scholar in Dionne’s lab and the paper’s first author. “The photons spin in a corkscrew fashion, but more importantly, we can use these spinning photons to impart spin on electrons that are the heart of quantum computing.”
Dionne notes that the patterned structures are incredibly small, roughly comparable in size to visible light wavelengths and impossible to see with the naked eye.
“The patterned nanostructures are imperceptible to the human eye, about the size of the wavelength of visible light,” Dionne adds. “But they help us manipulate photons very precisely to make them spin — to twist them- in a specific direction, for example, up or down.”
A Simpler Path to Quantum Communication
Researchers can use this twisted light to become entangled with electron spins, creating qubits, the basic building blocks of quantum information systems.
In conventional computing, information is represented by zeros and ones. In quantum technologies, qubits serve a similar purpose but can take advantage of quantum mechanical effects to process and transmit information in entirely new ways.
One of the biggest challenges facing quantum technologies is maintaining stable quantum states. In many existing systems, extreme cooling is necessary to prevent a process known as decoherence, in which delicate quantum information is lost.
Because the new device operates at room temperature, it avoids one of the major obstacles that has limited the widespread use of quantum technologies. The researchers say the compact design is also relatively inexpensive and practical compared with many current quantum systems.
If further developed, the technology could contribute to advances in secure communications, advanced sensing, high-performance computing, artificial intelligence, and other emerging applications.
Why the Material Matters
The team selected TMDC materials because of their unusual quantum characteristics and collaborated with Stanford researchers Fang Liu and Tony Heinz, who specialize in these materials.
“It all comes down to this material and our Silicon chip,” Pan says. “Together, they efficiently confine and enhance the twisting of light to create a strong coupling of spin between photons and electrons. This stabilizes the quantum state that makes quantum communication possible.”
The combination allows light and matter to interact more strongly, helping preserve the quantum properties needed for communication and computing tasks.
Toward Future Quantum Networks
The researchers are continuing to improve the device and are exploring additional TMDC materials and material combinations that could deliver even better performance. They are also investigating whether these systems might reveal new quantum capabilities that are not currently possible at room temperature.
A longer-term goal is integrating devices like this into larger quantum networks. Achieving that vision will require improvements in supporting technologies such as light sources, modulators, detectors, and interconnects.
Ultimately, researchers hope quantum components can be miniaturized enough to be incorporated into everyday electronics. While that future remains many years away, the work represents a step toward making quantum technology more accessible and practical.
“If we can do that, maybe someday we could do quantum computing in a cell phone,” Pan says with a smile. “But that’s a 10-plus-year plan.”