Researchers at Stanford University have demonstrated a nanoscale optical device that entangles the spin of photons and electrons at room temperature, overcoming a major practical limitation in quantum signaling systems. The work, published in Nature Communications, shows how “twisted light,” in which photons carry angular momentum, can be used to stabilize quantum states in a solid-state platform without the need for cryogenic cooling.

Many experimental quantum technologies rely on temperatures close to absolute zero to prevent decoherence, the loss of fragile quantum information. This requirement makes such systems large, costly, and difficult to deploy outside specialized laboratory environments. By contrast, the Stanford device operates at room temperature, raising the prospect of smaller and more energy-efficient quantum components.

The system uses a nanoscale silicon structure to shape how light behaves as it passes through the device, giving the researchers greater control over how optical signals interact with electronic states in a semiconductor layer. By engineering this light-matter interface at the chip level, the team was able to strengthen and stabilize the coupling between photons and electrons, which is essential for reliable quantum signaling at room temperature.

Feng Pan, a postdoctoral researcher at Stanford and first author of the study, explained that the researchers designed the silicon nanostructure to generate what they call twisted light. Photons spin in a corkscrew fashion, enabling them to impart spin on electrons in the semiconductor layer.

“The core idea is to leverage symmetries in the nanostructure,” Pan said. He added that by breaking mirror and inversion symmetry, the team can confine and control twisted light in a way that improves performance at room temperature.

A key performance metric for the system is the degree of circular polarization, which measures how effectively the device entangles photon and electron spin. Pan said the team achieved a degree of circular polarization of 0.5, establishing a new room-temperature record for this class of devices.

“Notably, our device operates independently of the system’s initialization, paving the way for electro-optic spin transduction in integrated optoelectronic platforms, including spin-polarized light emission and detection without the need for external optics,” Pan added. 

The researchers built the prototype using complementary metal-oxide-semiconductor-compatible silicon photonics alongside atomically thin semiconductors, a combination intended to ease integration with existing semiconductor manufacturing processes.

“The silicon nanostructure is readily compatible with existing semiconductor manufacturing workflows; for example, modulators can be integrated on the same chip, which is one direction we are actively pursuing,” Pan said. “In addition, our device enables efficient photon extraction and can be seamlessly interfaced with existing fiber-based systems for information transmission.” 

While the work remains a laboratory demonstration, the researchers say it could serve as a building block for future quantum communication systems and compact quantum light sources. Pan said the next phase of the research will focus on three areas: improving the integration of atomically thin semiconductors with silicon nanostructures, developing new photonic designs to strengthen photon–electron coupling, and scaling the technology beyond individual devices.

The team now plans to collaborate with semiconductor foundries on wafer-scale fabrication and system-level integration, an essential step if the approach is to be manufactured and incorporated into larger quantum photonic platforms.