As scientists build smaller and smaller machines, they need to understand
the invisible forces that make those machines work.
Thanks to research and the initiative of then-UC Merced graduate student
Jake Pate, some of those forces can now be measured and manipulated.
Pate, who graduated in May with a Ph.D. in Physics and is now a postdoctoral
researcher at the National Institute of Standards and Technology in Boulder,
Colorado, worked under physics Professor Jay Sharping in the School of
Natural Sciences. While in his lab, Jake reached out to scientists in
Australia with a project focused on the Casimir effect — the force that
exists between two metallic objects when they are extremely close together,
but not touching.
“This force wants to push these two objects together,” Pate explained. “The
Casimir force is strong enough to change the intrinsic behavior of the
objects.”
He designed and made a pinning device — a small cone — that, when placed
near a vibrating drum at nanoscale distances can stop the vibration. With
enough pinpoints, called “clamps,” scientists can create new shapes and new
behaviors.
“This work is extremely important for micro-electromechanical systems
(MEMS), tiny machines with moving parts,” Sharping said. Some common
commercial applications of MEMS include inkjet printers; accelerometers in
cars that deploy airbags; accelerometers in game controllers, cell phones,
digital cameras and personal computers; silicon pressure sensors such as
those that sense car tire pressure sensors; biomedical devices such as
stents; ultrasound transducers; and tiny speakers, such as the ones in
earbuds and hearing aids.
“During the past 10 years we have learned to make machines small enough that
we need to understand quantum mechanics to understand how they work,”
Sharping said. “If you bring two pieces of material together, they
experience forces that would be irrelevant if they were farther apart. Up
close, they might not behave the way you want them to, so objects built with
them will not work the way you want them to.”
Pate’s device changes that, though technology has not quite caught up with
him yet.
“You can do all kinds of things with it,” Pate said. “You can enhance the
drum, making it vibrate longer, change the shape of vibrations, or even stop
it from oscillating at all — it’s a way of controlling the object without
ever actually touching it.”
The next steps will be to use the clamping device to see if it can enhance
the Casimir force’s sensitivity.
Until recently, researchers believed the Casimir effect only occurred at
very low temperatures such as absolute zero, but Pate and his team
demonstrate that the force can be used and have far-reaching implications at
room temperature, too.
“This work represents a major advance in precision measurement and control
with a variety of applications,” Department of Physics Chair Professor Ajay
Gopinathan said. “We are very proud of our physics students and faculty who
are making fundamental discoveries with a broad impact.”
The results of their study were recently published in Nature Physics, with
Pate as the lead author.
“If you can measure and manipulate the Casimir force on objects, then we
gain the ability to improve force sensitivity and reduce mechanical losses,
with the potential to strongly impact science and technology,” said
Professor Michael Tobar with the University of Western Australia, who
collaborated with Pate’s group on the project. “To understand this, we need
to delve into the weirdness of quantum physics. In reality, a perfect vacuum
does not exist — even in empty space at zero temperature, virtual particles,
like photons, flicker in and out of existence.”
Pate became curious about invisible forces when he was making microwave
cavities in the UC Merced machine shop and noticed some “strange results.”
He reached out to Tobar and drove the collaboration, which allowed him to
live in Australia for three months.
“Jake really created this opportunity for himself and for our team, and it
was great for him, for us and for both universities,” Sharping said. “He’s a
perfect example of how our students are unafraid to do things other people
might not try, like reaching out to another university for help. Science
works best when more scientists to talk to each other.”
Reference:
“Casimir spring and dilution in macroscopic cavity optomechanics” by J. M. Pate, M. Goryachev, R. Y. Chiao, J. E. Sharping and M. E. Tobar, 3 August 2020, Nature Physics. DOI: 10.1038/s41567-020-0975-9
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Physics