Researchers funded by the US Army and Air Force have taken a step towards building a fault-tolerant quantum computer. It will provide advanced data processing capabilities.
Quantum computing is the gateway to new computing power. It can also contribute to the discovery of materials, artificial intelligence, biochemical engineering and many other disciplines necessary for the future military; however, because qubits, the fundamental building blocks of quantum computers, are inherently fragile, an efficient implementation of quantum error correction has been a long-standing obstacle to quantum computing. In addition, the military plans to “fight and win” in so-called multi-domain operations using quantum computing, according to the US Army Research Laboratory.
Researchers at the University of Massachusetts Amherst have identified a way to protect quantum information from a common source of error in superconducting systems, one of the leading platforms for implementing large-scale quantum computers. In a study published in the journal Nature, scientists have implemented a new way to spontaneously correct quantum errors.
Today’s computers are built with transistors representing the classical bits, either 1 or 0. In turn, quantum computing is a new paradigm for computing using quantum bits or qubits, where quantum superposition and entanglement can be used to exponentially increase computing power.
Existing demonstrations of quantum error correction are active. This means that they need to be checked periodically for errors and corrected immediately. In turn, this requires hardware resources and thus inhibits the scaling of quantum computers.
In contrast, the researchers’ experiment achieves passive quantum error correction by correcting the friction, or dissipation, experienced by the qubit. Since friction is generally considered an important impediment to quantum coherence, this result may seem surprising. The trick is that the dissipation has to be specially designed in a quantum way.
This general strategy has been known in theory for about two decades, but a practical way to obtain such dissipation and use it for quantum error correction has been challenging.
“Demonstrating these unconventional approaches will hopefully spur smarter ideas to overcome some of the most challenging problems in quantum science,” explains Grace Metcalfe, female program manager for Quantum Informatics at AFOSR.
The researchers said it is implied that there may be more ways to protect qubits from errors and to do so at a lower cost.
“While our experiment is still a fairly rudimentary demonstration, we have finally realized this conflicting theoretical possibility of dissipative QECs,” said Dr. Chen Wang, a physicist at the University of Massachusetts Amherst. “This experiment raises the prospect of creating a useful fault-tolerant quantum computer in the medium to long term.”