Researchers at Fudan University have made a notable leap in quantum optics. They demonstrated the quantum Rabi model in atomically thin semiconductors built from tungsten diselenide (WSeâ‚‚).
Their experiments dig into how light interacts with excitons—those bound electron–hole pairs—in various WSe₂ configurations. Along the way, they uncovered key parameters that shape quantum coherence and performance in two-dimensional materials.
This work doesn’t just confirm a theoretical idea. It also nudges us closer to advances in quantum information processing and the next wave of optoelectronics.
Exploring Light–Matter Interaction in 2D Semiconductors
The team looked at how photons couple with excitons in monolayer, bilayer, and hexagonal boron nitride (hBN)-capped WSe₂ films. These materials are just a few atoms thick—perfect for exploring quantum optical effects.
They combined careful experiments with detailed theoretical modeling. This approach let them pull out critical quantum measurements and see how those numbers shift across different setups.
Techniques Used in the Study
They used reflectance and photoluminescence spectroscopy, two sharp tools for probing the electronic and excitonic structure of these films. Reflectance spectra highlighted resonances inside the system.
Photoluminescence let the team measure emission energies and intensities. With these methods, they could pinpoint:
- Decoherence times—how long quantum states keep their phase before fading out.
- Transition matrix elements—basically, the odds of quantum jumps between states.
- Rabi frequencies—the rate at which light and matter swap energy.
Key Findings on Quantum Coherence
The results showed clear differences between monolayer and bilayer WSeâ‚‚. Bilayers lost quantum coherence faster, with shorter decoherence times, but they also had larger matrix elements, so transitions happened more readily.
Meanwhile, monolayers capped with hBN hung onto coherence much longer. That hints at hBN’s knack for shielding excitonic states from environmental noise.
Impact of Temperature on Performance
As temperature climbed, all the measured parameters—coherence time, matrix elements, and Rabi frequencies—took a hit. The rate of this decline depended on the film’s thickness and whether hBN capping was in play.
This temperature effect really matters when designing quantum devices that need to work reliably in the real world.
Optical Signatures and Bandgap Characteristics
In the reflectance spectra, a strong A exciton resonance showed up around 1.75 eV. Monolayer WSeâ‚‚ samples had more pronounced excitonic oscillations than bilayers, pointing to clear layer-dependent optical effects.
Photoluminescence backed this up. Bilayer WSeâ‚‚ emitted at lower energy and with weaker intensity, which fits with its indirect bandgap nature.
Validation of the Quantum Rabi Model
The team used a refined quantum Rabi framework to make sense of these optical signatures. They solved Bloch equations and matched the observed spectra with striking accuracy.
This result puts the quantum Rabi model front and center as a solid tool for describing light–matter interactions in 2D semiconductor systems.
Implications for Future Technologies
All of this could matter a lot for both quantum physics and real-world tech. If we get a better grip on coherence in 2D materials, we might see faster progress in things like:
- Quantum information systems, where you really need long-lived coherence.
- Advanced optoelectronic devices—think low-power lasers and modulators.
- Hybrid systems that mesh 2D materials with photonic circuits for ultra-fast information processing.
Opening New Pathways
Researchers have shown that complex quantum optical models can actually describe real-world 2D materials. That’s a big deal—it means we can start designing devices that use quantum effects in smarter ways.
This work from Fudan University feels like a bridge between theory and hands-on tech. The quantum Rabi model isn’t just some abstract idea; it’s turning into a real tool for building the next wave of quantum systems.
As 2D semiconductor research keeps moving forward, controlling and preserving quantum coherence will shape how these materials fuel future innovations. It’s wild to think quantum optics isn’t just about mind-bending theory—it’s pushing real, transformative tech into our lives.
Here is the source article for this story: Quantum Optics Demonstration In Few-Layer WSe2 Semiconductors Validates Quantum Rabi Model Predictions