3D printing helps ultra-cold quantum experiments get small
The Nottingham team’s experiment does not take an entire table – it has a volume of 0.15 cubic meters, making it slightly larger than a stack of 10 large pizza boxes. “It’s very, very small. We have reduced the size by about 70% compared to a conventional setup, ”says Somaya Madkhaly, a graduate student at Nottingham and the study’s first author. To build it, she and her colleagues embarked on something like a very customizable Lego set. Instead of buying parts, they assembled their setup from blocks that they 3D printed to be shaped exactly the way they wanted.
Instead of machining the vacuum chamber from sturdy but heavy metals, the team printed it from a lighter aluminum alloy. Instead of building a sprawling maze of lenses and mirrors, they inserted them into a holder that they printed from a polymer. This rectangular piece, only 5 inches long, 4 inches wide and very sturdy, replaced the delicate optical maze which is usually several feet long.
Importantly, the miniaturized setup worked. The team loaded 200 million rubidium atoms into their vacuum chamber and passed the laser light through all of the optical components, causing the light to collide with the atoms. The atoms formed a sample cooler than -450 degrees Fahrenheit, just as scientists have done with the most conventional type of device for the past 30 years.
“I think building a cold atom system like this is a huge step. Only the individual components have been 3D printed before, ”explains Aline Dinkelaker, a physicist at the Leibniz Institute for Astrophysics in Potsdam who was not involved in the study. If previous experiences were somehow like buying a special Lego kit that lets you build a pre-designed spaceship, the Nottingham team’s approach was more like designing the spaceship first and then 3D printing of the blocks that compose it.
A big advantage of using 3D printing is that you can customize each component, notes Dinkelaker. “Sometimes you just have a little odd-shaped component or an odd-shaped space. Here, 3D printing can be a great solution, ”she says.
Lucia Hackermuller, another co-author of the article, says making each part to their own specifications allowed them to optimize. “We want to have the best possible design, and the problem is that normally we have construction constraints,” she says. “But if you use 3D printing methods, you can pretty much print anything you can think of.” As part of this optimization process, the team used a computer algorithm they developed to find the best location for their magnets. They also worked on about ten iterations of their 3D printed components until they refined them completely.
The new study is a step forward in making this basic physics research tool more affordable and accessible. “I hope this will speed up – and also democratize to some extent – standard experiments on ultra-cold atoms by making them cheaper and much faster to set up,” Cooper said. He speculates that if he were stranded on a desert island with just a few lenses and mirrors, rubidium atoms, and a 3D printer, he could go from zero to a fully functional device in about a month, five or six times faster than usually. For Madkhaly, starting from scratch may not be just an imaginary scenario. After graduating, she says, she could return to her home country of Saudi Arabia and use 3D printing to initiate new research on ultra-cold atoms. “It’s a very new area there,” she adds.