Quantum Computing In Silicon Reaches 99 Percent Accuracy In Major Breakthrough

New work shows that we don’t have to abandon our trusty silicon, which underpins current semiconductor technology. In three papers, published in the journal Nature, researchers have shown that it is possible to create a silicon-based quantum device that has incredibly high accuracy.

The fundamental computational unit in a quantum computer is the qubit or quantum bit. While a bit can be either zero or one, a qubit can exist in a superposition of states allowing more power and versatility.

In the paper from the team at the University of New South Wales (UNSW), they achieved 99.95 percent accuracy for a 1-qubit setup and 99.37 percent for a 2-qubit. The work by the team at Delft University of Technology in the Netherlands achieved, respectively, 99.87 percent and 99.65 percent, while the RIKEN team in Japan had 99.84 percent and 99.51 percent. Truly extraordinary values from these three independent teams.

"Today's publication shows our operations were 99 percent error-free," lead author of the UNSW paper, Professor Andrea Morello, said in a statement.

"When the errors are so rare, it becomes possible to detect them and correct them when they occur. This shows that it is possible to build quantum computers that have enough scale, and enough power, to handle meaningful computation. This piece of research is an important milestone on the journey that will get us there."

The three teams had different approaches to qubits. Morello’s team used a pair of ion-implanted phosphorous nuclei in silicon and used their nuclear spin – a quantum mechanic property akin to angular momentum – as a qubit. The RIKEN and TU Delft team employed electron spin qubits in quantum dots. So silicon with different qubits is set as a serious contender for the base architecture of future quantum computers.

“The presented result makes spin qubits, for the first time, competitive against superconducting circuits and ion traps in terms of universal quantum control performance. This study demonstrates that silicon quantum computers are promising candidates, along with superconductivity and ion traps, for research and development toward the realization of large-scale quantum computers,” Seigo Tarucha, leader of the RIKEN research group, said in a statement.

In quantum computers, accuracy has to be higher than 99 percent to apply correction without disrupting the system. Now that this has been shown to be achievable, the teams aim to scale up the processors, adding more qubits, and testing more complex calculations.