The inclusion of pure silicon may serve as a concealed component in the construction of dependable quantum computers

Silicone plays a fundamental role in the world of computing. The properties and abundance of it have contributed to its significance. You are currently reading this on a device that utilizes silicon chips. Quantum computers represent a significant advancement in computing, enabling calculations that surpass the capabilities of our most powerful supercomputers. And they could still rely on silicon, but with a unique requirement: it may need to reach an unprecedented level of purity. Humans have achieved the ability to create silicon.

There is an issue regarding the different forms of silicon found in nature: silicon-28, silicon-29, and silicon-30. These are referred to as isotopes. Silicon-28 is composed of 14 protons and 14 neutrons in its nucleus, making it the predominant form of silicon found in nature, accounting for more than 92.2 percent of all silicon. The other two have one and two additional neutrons and make up 4.7 percent and 3.1 percent of natural silicon, respectively.

The inclusion of silicon 29 and 30 in computer chips is of little significance. However, quantum computing presents a unique set of challenges. Everything ultimately depends on the coherence of quantum bits, or qubits. That’s the remarkable capability of quantum computers to maintain error-free operations. Operating qubits near absolute zero is necessary due to their high susceptibility to the environment.

Just when you thought everything was going smoothly, the presence of an additional neutron in silicon-29 throws coherence out of whack, leading to pesky errors in the quantum chip. Using a beam of silicon-28 atoms, a team of researchers successfully decreased the amount of silicon-29 from 4.5 percent to just two parts per million (0.0002 percent).

Everyday computer chips are made up of billions of transistors, which can also be utilized to produce qubits for silicon-based quantum devices. Until now, the purity of the silicon starting material has been a limiting factor in the creation of high-quality silicon qubits. The purity breakthrough demonstrated here effectively addresses this issue,” stated Ravi Acharya, the lead author and a Cookson Scholar from the joint University of Manchester/University of Melbourne program.

According to Professor David Jamieson from the University of Melbourne, silicon is considered the top contender for quantum computer chips due to its ability to maintain enduring coherence, which is essential for accurate quantum calculations. While others are exploring different options, silicon remains the leading candidate.

Certain quantum computers have operated with 1,000 qubits, yet the preservation of quantum coherence has been limited to mere milliseconds, thus constraining their potential. Previously, lower-quality silicon was utilized to maintain coherence for a duration of 30 seconds for a single qubit, which remains an unbeaten record.

Now that we have achieved a high level of purity in silicon-28, our next goal is to show that we can maintain quantum coherence for multiple qubits at the same time. According to Jamieson, a mere 30 qubits in a quantum computer would surpass the capabilities of today’s supercomputers in certain applications.