Error Terror: How Quantum Computers may soontackle problems Desite Errors

Thursday - June 29 2023, 01:55 UTC - 1 year ago

A new collaboration between IBM and UC Berkeley has shown that quantum computers may soon tackle problems that today’s powerful supercomputers couldn't, even with errors. The study suggests that corrections can be achieved by post-processing the results of quantum calculations. The team pitted IBM’s 127-qubit Eagle chip against supercomputers at Lawrence Berkeley National Lab and Purdue University for increasingly complex tasks and with easier calculations, the chip matched the supercomputers' results.

Quantum computers may soon tackle problems that stump today’s powerful supercomputers—even when riddled with errors. Computation and accuracy go hand in hand. But a new collaboration between IBM and UC Berkeley showed that perfection isn’t necessarily required for solving challenging problems, from understanding the behavior of magnetic materials to modeling how neural networks behave or how information spreads across social networks .

The teams pitted IBM’s 127-qubit Eagle chip against supercomputers at Lawrence Berkeley National Lab and Purdue University for increasingly complex tasks. With easier calculations, Eagle matched the supercomputers’ results every time—suggesting that even with noise, the quantum computer could generate accurate responses. But where it shone was in its ability to tolerate scale, returning results that are—in theory—far more accurate than what’s possible today with state-of-the-art silicon computer chips .

At the heart is a post-processing technique that decreases noise. Similar to looking at a large painting, the method ignores each brush stroke. Rather, it focuses on small portions of the painting and captures the general "gist" of the artwork. The study, published in Nature, isn’t chasing quantum advantage, the theory that quantum computers can solve problems faster than conventional computers. Rather, it shows that today’s quantum computers, even when imperfect, may become part of scientific research—and perhaps our lives—sooner than expected .

In other words, we’ve now entered the realm of quantum utility. "The crux of the work is that we can now use all 127 of Eagle’s qubits to run a pretty sizable and deep circuit—and the numbers come out correct," said Dr. Kristan Temme, principle research staff member and manager for the Theory of Quantum Algorithms group at IBM Quantum. The Error Terror The Achilles heel of quantum computers is their errors .

Similar to classic silicon-based computer chips—those running in your phone or laptop—quantum computers use packets of data called bits as the basic method of calculation. What’s different is that in classical computers, bits represent 1 or 0. But thanks to quantum quirks, the quantum equivalent of bits, qubits, exist in a state of flux, with a chance of landing in either position. This weirdness, along with other attributes, makes it possible for quantum computers to simultaneously compute multiple complex calculations—essentially, everything, everywhere, all at once (wink)—making them, in theory, far more efficient than today’s silicon chips .

Proving the idea is harder. "The race to show that these processors can outperform their classical counterparts is a difficult one," said Drs. Göran Wendin and Jonas Bylander at the Chalmers University of Technology in Sweden, who were not involved in the study. The main trip-up? Errors. Qubits are finicky things, as are the ways in which they interact with each other. Even minor changes in their state or environment can throw a calculation off track .

"Developing the full potential of quantum computers requires devices that can correct their own errors," said Wendin and Bylander. The Berkeley-IBM collaboration goes a step further: it suggests that corrections can be achieved by post-processing the results of quantum calculations, said Alexey Gorshkov, physicist at the University of Maryland and research trustees of the Kavli Foundation.