How Can a Quantum Computer Catch its Own Errors in Calculations?

Read about how Lukas Postler and his team built a quantum computer that can catch its own errors in calculations.

A collection of 16 qubits has been organized in such a way that they may be able to operate any computation without error. It is an important step toward constructing quantum computers that outperform standard ones.

When completing any task, a quantum computer consisting of charged atoms can detect its own faults.  Because conventional computers constantly detect and rectify their own flaws, quantum computers will need to do the same in order to fully outperform them. Nevertheless, quantum effects can cause errors to propagate rapidly through the qubits, or quantum bits, that comprise these devices.

Lukas Postler and his team from the Austria's University of Innsbruck have created a quantum computer that can perform any calculation without error.

Any computation of a quantum computer can be decomposed into smaller computations known as quantum gates. These can be used to change the quantum state of a qubit by striking it with a laser. The experts developed a set of gates that serve as building blocks for more complex calculations and ensure that even the most complicated of them are error-free.

They employed electric fields to hold 14 calcium ions in place, generating two logical qubits, each of which had 7 entangled ions. Two more qubits functioned as "flags," indicating to the computer when an incorrect computation needed fixing.

"With this comprehensive set of gates, you can simulate every calculation that a quantum computer could possibly accomplish," Postler explains. The experts showed that each of the logic gates in their system functions properly, reducing errors.

While this configuration may be advantageous for certain types of quantum computers, it may not be suitable for more complex systems, according to Christopher Monroe of the Joint Quantum Institute in Maryland. The difficulty of implementing error correction into quantum computers differs greatly depending on the technology. Error correction needs devices far larger than 16 qubits for quantum computers that utilize superconducting qubits, like Google's Sycamore, he states.

Monroe and his team employed 13 trapped ions in 2021 to construct a single logical qubit that stored data with unexpected accuracy due to error correction.

According to him, the new quantum computer is not yet large or trustworthy enough to solve any realistic real-world challenge. "Various research groups are piecing together how to achieve that with trapped ion qubits," he explains. "This new research is another piece to the puzzle."