Simultaneous detection of quantum errors achieved for first time.
IBM is getting closer to the realisation of a practical quantum computer after two critical advances.
The company has displayed the ability to detect and measure both kinds of quantum errors simultaneously, as well as demonstrating a square quantum bit circuit design.
Being able to detect and measure bit-flip and phase-flip is a big step forward, as previously it was only possible to address one type or the other but never both at the same time. Quantum error correction is a critical requirement for building a large-scale quantum computer.
Arvind Krishna, SVP of IBM Research, said: "Quantum computing could be potentially transformative, enabling us to solve problems that are impossible or impractical to solve today."
"While quantum computers have traditionally been explored for cryptography, one area we find very compelling is the potential for practical quantum systems to solve problems in physics and quantum chemistry that are unsolvable today. This could have enormous potential in materials or drug design, opening up a new realm of applications."
The quantum bit circuit is based on a square lattice of four superconducting qubits, on a chip roughly one-quarter-inch square.
One of the big challenges for scientists is controlling or removing quantum decoherence, which is the creation of errors in calculations caused by interference from factors such as heat, electromagnetic radiation, and material defects.
Jay Gambetta, Manager, IBM Quantum Computing Group, said: "Up until now, researchers have been able to detect bit-flip or phase-flip quantum errors, but never the two together. Previous work in this area, using linear arrangements, only looked at bit-flip errors offering incomplete information on the quantum state of a system and making them inadequate for a quantum computer."
"Our four qubit results take us past this hurdle by detecting both types of quantum errors and can be scalable to larger systems, as the qubits are arranged in a square lattice as opposed to a linear array."