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A new approach to quantum memory

by Cynthia Macdonald Dec 17 / 18

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Banner image courtesy of Daniele Levis Pelusi on Unsplash.

When working quantum computers are finally developed, they’ll be much faster and more powerful for some purposes than the classical machines we now use.

Their ability to model chemical processes alone could revolutionize drug and materials design, leading to an exciting new era in fields such as engineering and medicine.  

One of the many problems that remain to be solved, however, is how to give a quantum computer a quantum memory. Recently, physicists at the University of Alberta devised a simplified and energy-efficient way of doing this, using ultracold rubidium atoms.

Lindsay LeBlanc is a fellow in the Quantum Materials program at CIFAR. In her lab she routinely cools atoms to temperatures that are a million times colder than interstellar space. At that point, they lose the randomness associated with thermal motion, and exhibit interesting new properties.

LeBlanc’s post-doctoral fellow, Erhan Saglamyurek, suggested that clouds of such atoms might be able to store single pulses of light – photons – which could later be retrieved through the shining of a control pulse. The pair developed a method to do that, and the results of their successful experiment were published in Nature Photonics on November 5.

“Quantum memory’s not a new idea,” says LeBlanc. “But our method is less technically demanding, doesn’t use as much laser power and doesn’t require you to prepare a difficult sample. It’s also good for broadband signals, which have a large frequency range.” This could make it a helpful tool in quantum communication, which is already in limited use and, once perfected, promises to usher in a new era of hack-proof security.

Our method is less technically demanding, doesn’t use as much laser power and doesn’t require you to prepare a difficult sample. It’s also good for broadband signals, which have a large frequency range.

LeBlanc is working on extending the capability of her discovery. “The storage time isn’t very long, so that’s definitely something we’d like to improve,” she says. Her technique is currently more flash drive than hard drive, but the theory supporting it allows for longer storage over time. “Right now it’s about a microsecond, and we want to push that to a millisecond. I think we can do that using colder atoms.”

LeBlanc’s research is applicable not only to quantum computing, but to quantum materials as well: two key areas of discovery supported by CIFAR. “In all that we do,” she has written, “we are keen to better understand, from the ground up, what makes these quantum particles behave as they do.”