Hollow-Core Fiber Could Bridge Quantum
Modeling shows gas-filled hollow-core fibers can translate quantum light between wavelengths while preserving crucial phase information, a key step for
A new modeling study published on August 30, 2026, in Advanced Photonics Nexus proposes a hollow-core fiber platform to translate quantum information between different wavelengths of light. The research, led by Hao Zhang and involving teams from UCLA, SLAC, Rochester, and Ottawa, demonstrates that a process called four-wave mixing in these fibers can preserve the phase of light signals with high fidelity.
Quantum technologies like memories, trapped ions, and communication networks often operate at incompatible wavelengths. Building a functional quantum network requires interfaces that can convert light from one band to another without corrupting the quantum information it carries. This study investigates whether four-wave mixing in a xenon-gas-filled hollow-core capillary fiber can serve as such an interface while maintaining phase coherence.
Testing Phase Transfer Across Wavelengths
The team modeled three specific wavelength conversions relevant to potential quantum links. They simulated converting infrared light at 1,030 nanometers to ultraviolet at 343 nm, telecommunications-band light at 1,550 nm to ultraviolet at 308 nm, and telecom light at 1,550 nm to visible light at 516 nm. These pathways could connect fiber networks to devices like optical clocks or rare-earth quantum memories.
The analysis focused not on raw efficiency but on phase preservation. Phase is a critical property for encoding quantum information. The researchers simulated different phase structures on the input light and calculated correlation values to see how accurately that phase was copied to the new output wavelength.
Where Coherence Held Up Best
The simulations revealed strong phase preservation, with correlations often exceeding 0.95 and reaching above 0.99 under optimal conditions. Performance was best when the powerful intermediary laser pulse used in the process had low energy and narrow bandwidth. The results also showed that some conversion paths were more robust than others.
The telecommunications-to-visible conversion (1,550 nm to 516 nm) proved especially resilient, maintaining high phase correlations across a broad range of parameters. In contrast, the telecommunications-to-ultraviolet conversion was more sensitive, with fidelity dropping as pulse energies increased.
The team identified a fundamental trade-off. Conditions that boost conversion efficiency, like higher pulse energies, also introduce nonlinear effects that distort the phase. This means a practical quantum transducer must balance these two competing metrics.
The modeled conversion efficiencies for the three tested pathways are shown in the table below.
| Conversion Pathway | Maximum Efficiency |
|---|---|
| Infrared (1,030 nm) to Ultraviolet (343 nm) | 28% |
| Telecom (1,550 nm) to Ultraviolet (308 nm) | 8.4% |
| Telecom (1,550 nm) to Visible (516 nm) | 10.8% |
A Fiber Route Toward Quantum Links
While based on modeling and not direct quantum-state measurement, the work suggests a practical path forward. Corresponding author Hao Zhang states the findings "lay the groundwork for integrating heterogeneous quantum platforms across widely separated optical bands." Future experiments must confirm the phase-preserving behavior extends to fragile quantum states and entanglement. If successful, this hollow-core fiber approach could help bridge the spectral gaps isolating today's quantum technologies.
