Electron states in a semiconductor, set and changed with pulses of light, could be the 0 and 1 of future “lightwave” electronics or room-temperature quantum computers.| Medium Read

Enlarge IMAGE: An artist's rendering of a pulse of circularly polarized light hitting a 2-D semiconductor, putting the electrons into a pseudospin state that could store information as part of a new, faster computing technology. Credit: Stephen Alvey/Michigan Engineering

A technique to manipulate electrons with light could bring quantum computing up to room temperature. A team of researchers in Germany and at the University of Michigan have demonstrated how infrared laser pulses can shift electrons between two different states, the classic 1 and 0, in a thin sheet of semiconductor. “Ordinary electronics are in the range of gigahertz, one billion operations per second. This method is a million times faster,” said Mackillo Kira, a professor of electrical engineering and computer science at U-M. He led the theoretical part of the study, to be published in the journal Nature, collaborating with physicists at the University of Marburg in Germany. The experiment was done at the University of Regensburg in Germany.

Quantum computing could solve problems that take too long on conventional computers, advancing areas such as artificial intelligence, weather forecasting and drug design. Quantum computers get their power from the way that their quantum-mechanical bits, or qubits, aren’t merely 1s or 0s, but they can be mixtures— known as superpositions—of these states. “In a classical computer, each bit configuration must be stored and processed one by one while a set of qubits can ideally store and process all configurations with one run,” said Kira. This means that when you want to look at a bunch of possible solutions to a problem and find the best fit, quantum computing can get you there a lot faster.

But qubits are hard to make because quantum states are extremely fragile. The main commercial route, pursued by companies such as Intel, IBM, Microsoft and D-Wave, uses superconducting circuits—loops of wire cooled to extremely cold temperatures (-321°F or less), at which the electrons stop colliding with each other and instead form shared quantum states through a phenomenon known as coherence. Rather than finding a way to hang onto a quantum state for a long time, the new study demonstrates a way to do the processing before the states fall apart. “In the long run, we see a realistic chance of introducing quantum information devices that perform operations faster than a single oscillation of a lightwave,” said Rupert Huber, a professor of physics at the University of Regensburg, who led the experiment. “The material is relatively easy to make, it works in room temperature air, and at just a few atoms thick, it is maximally compact.”

“Ordinary electronics are in the range of gigahertz, one billion operations per second. This method is a million times faster.” Mackillo Kira, EECS Tweet