May 27 2019
Researchers at the University of Bath have patented a novel method for stabilizing the density of alkali metal vapor through gold nanoparticles.
This innovative technique will make it possible to access electrons for various applications like precision measurements, atom cooling, and quantum computing. Alkali metal vapors, such as cesium, rubidium, lithium, potassium, and sodium enable researchers to access separate electrons, because of the presence of an electron in the exterior “shell” of alkali metals.
This has immense potential for many different applications, such as storage and sensing in quantum computing, logic operations, and also in medical diagnostics including encephalograms and cardiograms, or in ultra-accurate time measurements with atomic clocks.
Conversely, one major technical barrier was to consistently regulate the vapor pressure inside an enclosed space, for example, an optical fiber’s tube. It is important to prevent the vapor from adhering to the sides of the tube so as to retain its quantum characteristics; however, prevalent techniques that are available to do this, including the direct heating of vapor containers, are expensive, slow, and not viable at scale.
Now, in association with a colleague at the Bulgarian Academy of Sciences, researchers at the University of Bath have come up with a novel technique to control the vapor pressure—that is, coating the containers’ interior with nanoscopic gold particles that measure 300,000 times smaller than a pinhead.
When the nanoparticles are illuminated with a green laser light, they quickly absorb and change this light into heat, heating up the vapor and allowing it to disperse within the container over 1,000 times faster when compared to other techniques. This is a highly reproducible process and the novel nanoparticle coating can also retain the quantum states of the alkali metal atoms bouncing from it. The results of the study have been reported in Nature Communications.
We are very excited by this discovery because it has so many applications in current and future technologies! It would be useful in atomic cooling, in atomic clocks, in magnetometry and in ultra-high-resolution spectroscopy. Our coating allows fast and reproducible external control of the vapour density and related optical depth, crucial for quantum optics in these confined geometries.
Ventsislav Valev, Professor, Department of Physics, University of Bath
The study was headed by Professor Valev.
In this proof of principle, it was demonstrated that illuminating our coating significantly outperforms conventional methods and is compatible with standard polymer coatings used to preserve quantum states of single atoms and coherent ensembles.
Dimitar Slavov, Associate Professor, Institute of Electronics, Bulgarian Academy of Sciences
Further improvements of our coating are possible by tuning particle size, material composition and polymer environment. The coating can find applications in various containers, including optical cells, magneto-optical traps, micro cells, capillaries and hollow-core optical fibres.
Dr Kristina Rusimova, Prize Fellow, Department of Physics, University of Bath
The study was funded by the Royal Society and the Engineering and Physical Sciences Research Council (EPSRC) UK Quantum Technology Hub “Networked Quantum Information Technologies.”