One of the central engineering problems in quantum technology is heat. The qubits in today’s most advanced quantum computers must be cooled to within a few thousandths of a degree above absolute zero — requiring dilution refrigerators the size of a washing machine that cost millions of dollars and consume megawatts of power. A superconducting quantum processor at Google or IBM runs colder than deep space.
A study published in Nature Communications by researchers at Stanford University demonstrates a fundamentally different approach: using “twisted light” — photons carrying orbital angular momentum — coupled to an atomically thin semiconductor to generate quantum-coherent emission at room temperature.
The device
The core of the experiment is a heterostructure: a single layer of molybdenum diselenide (MoSe₂), a transition metal dichalcogenide that is just three atoms thick, placed on top of a nanopatterned silicon substrate. The silicon is etched with nanoscale structures that form a chiral resonant cavity — a high-quality-factor optical resonator (Q-factor up to 450 at visible wavelengths) that selectively amplifies one handedness of circulating light.
When the Stanford team — led by first author Feng Pan, a postdoctoral scholar, and senior author Jennifer A. Dionne, professor of materials science and engineering — shone laser light onto this structure, the cavity confined and twisted the photons, imprinting them with orbital angular momentum (OAM) : a corkscrew-like spatial rotation of the light wavefront.
Valley-spin locking
The critical insight involves a property of MoSe₂ called valley pseudospin. In the crystal’s electronic band structure, electrons in two distinct momentum valleys (labeled K and K’) carry opposite spins. This valley-spin locking is normally stable only at cryogenic temperatures; at room temperature, thermal vibrations (phonons) scatter electrons between valleys, destroying the polarization.
The Stanford device overcame this by engineering the chiral cavity to produce a 13-fold enhancement of the valley-specific radiative emission rate. By making the light-emission process faster than the decoherence process — analogous to a sprinter who finishes the race before the starting gun’s echo fades — the team achieved a record degree of circular polarization (DOP) of 0.5 at room temperature, independent of the excitation laser’s polarization.
“Effectively, the cavity is twisting light and making it interact preferentially with one valley of the MoSe₂,” Pan explained. “The process is so fast that it outcompetes the normal pathways that would destroy the valley polarization at room temperature.”
What this means
The result is a demonstration of valley-selective quantum emission at room temperature — a building block for several quantum technologies:
- Quantum light sources: The device can emit single photons with controlled spin properties at room temperature, which is necessary for quantum communication networks.
- Spin-photon interfaces: The natural coupling between valley spin (matter) and photon angular momentum (light) provides a direct interface for quantum information conversion — light-based qubits talking to matter-based qubits.
- Compact photonic integration: The entire structure is fabricated on silicon using existing semiconductor manufacturing techniques, making it potentially scalable.
The caveats
The Nature Communications paper demonstrates a valleytronic-photonic platform — the enabling hardware — not a quantum computer. It shows that spin-photon coupling can be maintained at room temperature and that chiral cavities can selectively amplify one quantum state. But translating this into a functional qubit, quantum gate, or logical operation requires additional layers of engineering.
The device emits polarized light — it does not yet demonstrate quantum entanglement, superposition control, or error correction. Those remain significant challenges.
“It’s a critical enabler,” Dionne said. “It means we can think about quantum photonic devices that don’t require the cryogenic infrastructure that currently limits scalability.”
The work is an experimental advance in valleytronics — a field that seeks to use the valley degree of freedom in 2D materials as an information carrier, analogous to electron spin in spintronics. Whether valley-based quantum information can be read, written, and manipulated with the fidelity required for fault-tolerant quantum computing remains an open question.
Source: Pan, F. et al. “Room-temperature valley-selective emission in Si-MoSe₂ heterostructures enabled by high-quality-factor chiroptical cavities.” Nature Communications 17, Article 20 (2026). DOI: 10.1038/s41467-025-66502-4
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Lead institution: Dionne Lab, Department of Materials Science and Engineering, Stanford University