Engineering on the cutting edge of quantum theory

Hundreds of years ago, as the use of ships increased for trade and exploration, British fleets established themselves as superior in navigation to those of almost all other countries. The main ingredient in their success, according to Scott Palo of Smead Aerospace Engineering, was accurate time-keeping devices.

While ships are now equipped with GPS devices that take the pressure off clocks, a similar problem faces new frontiers. To navigate through space, you need very precise clocks—the most precise of which come from quantum technologies.

“We don’t get GPS out in the solar system,” Palo said. “So now you’re back to the problem of the 1700s. You’re sailing through space. How do you figure out where you are and where you’re going in space?”

Baowen Li, a faculty member in mechanical engineering and a leader of the college’s new Quantum Integrated Sensor Systems interdisciplinary research effort, sees an opportunity for CU Boulder to distinguish itself in the application of quantum theory to create devices and gadgets that will bolster the way we explore the world, space and ourselves.

“Top schools are feeling the urgency for quantum engineering,” Li said. “We need to make use of this advantage we have with physics.”

We are trying to bring quantum systems to users who know nothing about quantum. 

The physics department at CU Boulder is home to four Nobel laureates recognized for their contributions to the understanding of atoms and their manipulation. Putting that knowledge to use is where engineering comes in.

“Engineering is about integrating different technologies into a cohesive system,” Li said. “Each individual quantum sensor is not useful. But for broad application you need to integrate it with something else. Take existing quantum technologies and put them together for industry application.”

Quantum mechanics is the study of a minuscule world, attempting to uncover the habits of atoms and subatomic particles. In this tiny reality, the rules of physics are different. Notably, where properties such as energy and momentum on a larger scale appear to come on a continuum, quantum mechanics indicates that physical properties at a subatomic level, such as the energy of a particle, come in discrete values.

Svenja Knappe of mechanical engineering is already working with quantum concepts, with brain imaging technology that tries to capture the magnetic fields coming off the brain as clusters of neurons fire.

The sensing of magnetic fields from the brain is called magnetoencephalography, or MEG. Where an MRI can sense the water and fat in the brain, and through that can assess its structure, an MEG can analyze the function of the brain.

“There are some circumstances where MRI cannot provide the answer,” Knappe said, giving the examples of epilepsy, autism and some forms of depression. “In those cases there’s nothing structurally wrong with the brain; the problem lies in how it functions.”

Current MEGs require the supercooling of materials to make them superconductors. This means in order to detect the minuscule magnetic fields of the brain, materials are placed in a machine containing liquid helium that cools them to negative 269 degrees Celsius, or 4 degrees Kelvin. This souped-up refrigerator costs several million dollars, a price barrier that Knappe’s research is working to mitigate. Her sensor operates at room temperature, negating the necessity for a large and expensive cooling mechanism. This could drastically increase availability, in both clinical and research settings, to accurate brain imaging systems.

The quantum sensor—which uses gas and a laser to orient the atoms all in the same direction to detect the slightest changes in the magnetic fields of the brain—could aid neuroscientists and medical researchers who would not have had access to the more expensive MEGs.

“We are trying to bring quantum systems to users who know nothing about quantum,” Knappe said.

Palo, meanwhile, is more interested in the use of quantum technologies than in developing them himself.

“I’m not a quantum physicist,” he said. “I’m not a quantum engineer. I’m a user of the technology for space applications.”

Palo’s research is concentrated on small satellites and their capabilities—he builds satellites the size of a loaf of bread. But he is also invested in the exploration of deep space, where quantum devices will likely prove paramount.

“Right now our approach to exploring deep space is to talk to the ground a lot,” Palo said, explaining that the difficulty with this is the time lag between satellite and ground crews, as well as the incredible use of resources this kind of communication requires. “If we can make our spacecraft more capable, that frees up resources for more exploration.”

Palo said he imagines that small autonomous spacecraft, outfitted with quantum devices, could be sent to various planets and moons to take measurements and return with data, like something out of Star Trek.

“I picture these new types of sensors that are smaller, use less power, and are more capable as enablers to better explore other worlds,” he said. “These types of technologies will allow us to explore our solar system as we never have before.”

Professor Dana Anderson of the Department of Physics, who helped Li draft the QISS research proposal, said that excitement for quantum could push CU further ahead in the field and draw in brilliant minds from outside Boulder to contribute to the development of quantum devices.

“We’ve always been strong in physics, and now that (quantum mechanics) is ready to be deployable, we should grow our strength and gain national visibility,” Anderson said. “We need to get the best faculty in fields that are needed to get interested in quantum problems. I don’t want them to be quantum engineers or scientists; I want them to apply their expertise to the barriers quantum is experiencing.”