Quantum Computing Gets One Step Closer to Reality After Futuristic Computers Hit 99% Accuracy


KENSINGTON, Australia — Quantum computing could soon become a reality that will forever change digital technology after a landmark achievement by Australian researchers. The team proved that virtually error-free computing operations are possible using a silicon-based quantum device. Additionally, scientists have discovered that it is possible to build these ultra-fast computers using current semiconductor manufacturing technology available today.

“Today’s release shows that our operations were 99% error-free,” Professor Andrea Morello of the University of New South Wales-Sydney said in a statement.

“When 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 computations.

Morello, who leads a team of researchers from the United States, Japan, Egypt and Australia, is building what they call a “universal quantum computer” capable of performing more than one application.

“This research is an important step in the journey that will lead us there,” adds Professor Morello.

Why are quantum computers so special?

In a nutshell, quantum computers find better and faster ways to solve problems. Scientists believe that quantum technology could solve extremely complex problems in seconds, while the traditional supercomputers you see today could take months or even years to crack certain codes.

What sets these next-gen supercomputers apart from your everyday smartphone and laptop is how they handle data. Quantum computers exploit the properties of quantum physics to store data and perform their functions. While traditional computers use “bits” to encode information on your devices, quantum technology uses “qubits”.

The main difference between these two is that bits process information in a binary fashion – meaning something is either a “0” or “1” or a yes/no answer. They represent this two-choice system by the absence or presence of an electrical signal in the computer.

Qubits, on the other hand, use quantum objects that act as information processors, such as spin (controlling the spin of charged particles in a semiconductor), trapped atoms or ions, photons (particles of light) or semiconductor circuits.

As a bit, qubits also have two distinct states representing “0” and “1”, but they are also capable of operating in “superposition” states. A qubit can take into account incompatible measurements (beyond 0 and 1) and even become entangled with other qubits. All of this makes them incredibly more powerful than the average computer bit.

Crossing the 99% threshold

The new study actually includes three separate reports that detail the researchers’ breakthrough in ultra-precise quantum computing.

Professor Morello’s team achieved a qubit operating fidelity of 99.95%, which means the ability of a qubit to pass a test. They also achieved a two-qubit fidelity of 99.37%. The team conducted this test using a three-qubit system consisting of one electron and two phosphorus atoms inside silicon.

Artist’s impression of the quantum entanglement between three qubits in silicon: the two nuclear spins (red spheres) and an electronic spin (bright ellipse) that wraps around the two nuclei. (Image: UNSW/Tony Melov)

Another team in the Netherlands has reached the 99% accuracy threshold using qubits made up of electron spins in a stack of silicon and silicon-germanium alloy (Si/SiGe).

Finally, a third team in Japan broke the 99% barrier with a two-electron system using Si/SiGe quantum dots.

Scientists are focused on using qubits in silicon because of their stability and ability to retain quantum information for long periods of time. Professor Morello’s previous studies have shown that he can hold quantum data in silicon for 35 seconds. That might not seem like a lot to the average person, but it’s almost a lifetime for quantum computers.

“In the quantum world, 35 seconds is an eternity,” says Professor Morello. “To give a comparison, in the famous superconducting quantum computers from Google and IBM, the lifetime is about a hundred microseconds, or nearly a million times shorter.”

Scientists discover how to make qubits interact with each other

According to the researchers, the biggest breakthrough of the study is overcoming the need to isolate individual qubits in the computing process. Until now, it was apparently impossible for qubits to interact with each other. The team used an electron encompassing two nuclei of phosphorus atoms to overcome this problem.

“If you have two nuclei connected to the same electron, you can make them perform a quantum operation,” says study author Mateusz Mądzik.

“As long as you don’t operate the electron, these nuclei securely store their quantum information. But now you have the ability to make them talk to each other via the electron, to perform universal quantum operations that can be adapted to any computational problem.

silicon nanoelectronic device
Scientists built the silicon nanoelectronic device containing the quantum processor using methods compatible with industry standards for existing computer chips. (Photo: Tony Melov/UNSW)

“It really is unlocking technology,” adds Dr. Serwan Asaad. “Nuclear spins are the heart of the quantum processor. If you entangle them with the electron, then the electron can then be moved to another location and entangle with other qubit nuclei further away, paving the way for the creation of large qubit arrays capable of robust computations and useful.

With this breakthrough, the study authors say semiconductor spin qubits in silicon could soon become the platform of choice as scientists build the next wave of reliable quantum computers.

“Until now, however, the challenge has been to perform quantum logic operations with sufficiently high precision,” concludes Professor Morello. “Each of the three papers published today demonstrates how this challenge can be overcome to such a degree that errors can be corrected faster than they appear.”

The results are published in the journal Nature.