Research Bits: May 3

Fingerprinting quantum noise
Scientists from the University of Chicago and Purdue University propose a different method of understanding the effect of noise in quantum computers. Instead of trying to measure it directly, they created a ‘fingerprint’ of how the noise impacts a program run on the computer.

“We wondered if there was a way to work with the noise, instead of against it,” said David Mazziotti, professor in the Department of Chemistry, University of Chicago and the Chicago Quantum Exchange.

Instead of directly measuring the actual noise of a qubit, they tried to understand the impact of the overall noise a system would experience. “Quite often in physics, it is actually easier to understand the overall behavior of a system than to know what each part is doing,” said Zixuan Hu, a postdoctoral researcher at Purdue. “For example, it is hard to simulate what each molecule in a glass of water is doing, but it is much easier to predict the behavior of the whole.”

They picked a particular computation of a molecule displaying quantum behavior and ran it as a simulation on a quantum computer. Then they tweaked the settings on the problem in several different directions and kept track of how the noise responded. “By putting this all together, we build a ‘fingerprint’ of the noise as perceived by the simulation that we’re running,” said Mazziotti.

Running a computation of a molecule that is already well known helped the team determine the specific effects of the noise, Hu explained. “We know very little about quantum computers and noise, but we know really well how this molecule behaves when excited. So we use quantum computers, which we don’t know much about, to mimic a molecule which we are familiar with, and we see how it behaves. With those familiar patterns we can draw some understanding.”

Along with potentially pointing to ways to design for noise correction, the researchers think the noise itself could be useful, if understood.

Mazziotti gave the example of simulating a quantum system such as a molecule, which would experience noise in the real world. Typically, that noise must be added as part of the simulation. “But instead of building noise in as additional operation on a quantum computer, maybe we could actually use the noise intrinsic to a quantum computer to mimic the noise in a quantum problem that is difficult to solve on a conventional computer,” Mazziotti said.

“We’re still not even sure what kinds of problems for which quantum computers will be most useful,” Mazziotti said. “We hope this will provide a different way to think about noise that will open up new avenues for simulating molecules with quantum devices.”

Healing tissue with a chip
Researchers from Indiana University School of Medicine and University of Chicago developed a silicon chip that could help heal blood vessel and nerve problems.

“This small silicon chip enables nanotechnology that can change the function of living body parts,” said Chandan Sen, director of the Indiana Center for Regenerative Medicine and Engineering, associate vice president for research and Distinguished Professor at the IU School of Medicine. “For example, if someone’s blood vessels were damaged because of a traffic accident and they need blood supply, we can’t rely on the pre-existing blood vessel anymore because that is crushed, but we can convert the skin tissue into blood vessels and rescue the limb at risk.”

The technology is called tissue nanotransfection. It reprograms tissue function by applying a harmless electric spark to deliver specific genes in a fraction of a second. In laboratory studies, the device successfully converted skin tissue into blood vessels to repair a badly injured leg. The technology is currently being used to reprogram tissue for different kinds of therapies, such as repairing brain damage caused by stroke or preventing and reversing nerve damage caused by diabetes.

In their paper, the team details the fabrication of the microchip used in tissue nanotransfection.

“This is about the engineering and manufacturing of the chip,” said Sen. “The chip’s nanofabrication process typically takes five to six days and, with the help of this report, can be achieved by anyone skilled in the art.”

They hope to seek FDA approval for the chip within a year, which would allow it to be used in clinical research in people.