This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Quantum technologies promise secure communication networks, powerful forms of computing and new sensing tools. One of the major challenges, however, is that different quantum systems often operate at different wavelengths of light.
Quantum memories, trapped ions and other quantum devices may work best in the ultraviolet or visible range, while long-distance communication over optical fibers works most efficiently at telecommunications wavelengths. Building practical quantum networks will require reliable ways to translate quantum information between these different optical bands without losing the information carried by the light. A new study published in Advanced Photonics Nexus explores a promising route to achieving that goal through a process known as four-wave mixing (FWM).
The research team—from UCLA, SLAC National Accelerator Laboratory, the University of Rochester and the University of Ottawa—investigated whether FWM can preserve one of the most important properties of a quantum light signal: its phase. Phase describes part of a light wave's structure and plays a central role in encoding and transmitting quantum information. If a wavelength-conversion process alters this phase unpredictably, information can be degraded or lost.
Demonstrating phase-preserving conversion is therefore a key step toward creating interfaces that allow different quantum technologies to work together. To study this problem, the team modeled frequency conversion in a gas-filled hollow-core capillary fiber, a hollow optical waveguide filled with xenon gas. In their scheme, an input light signal interacts with a strong intermediary laser pulse inside the fiber, generating a new output wavelength through four-wave mixing.
The researchers examined three conversion scenarios chosen for their relevance to future quantum technologies: converting infrared light at 1,030 nm to ultraviolet light at 343 nm, converting telecommunications-band light at 1,550 nm to ultraviolet light at 308 nm and converting telecommunications-band light at 1,550 nm to visible light at 516 nm. These wavelength combinations could help link fiber-based communication networks with systems such as optical clocks, trapped-ion quantum devices, Rydberg-atom platforms and rare-earth quantum memories. Rather than focusing only on conversion efficiency, the team analyzed how faithfully phase information was transferred from the input signal to the newly generated output light.
They simulated different types of phase structures, including linear phase patterns and two forms of quadratic phase modulation that change how a pulse evolves in time. By comparing the phases of the input and output signals, they calculated correlation values that indicate how accurately phase information is preserved during conversion. The simulations revealed strong phase preservation across a wide range of operating conditions.
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