The “world's purest silicon” promises to revolutionize quantum computing

The promise of quantum computing

Quantum computing represents a revolutionary advance in computing, offering the potential to solve complex problems at a speed and scale never before achieved.

Unlike classical computers that use bits to store and process information as a 0 or a 1, quantum computers primarily use qubits, which can be in a state of superposition, allowing them to be 0 and 1 simultaneously.

This ability opens the door to massive parallel calculations and unparalleled computing power for several reasons.

First, this quantum superposition allows qubits to store and process a significantly larger amount of information than classical bits. In fact, while a classical bit can only represent one state at a time (0 or 1), a qubit can represent a linear combination of both states (0 and 1 simultaneously). Therefore, a quantum computer consisting of several qubits can perform a large number of different calculations simultaneously, significantly speeding up the time needed to solve complex problems.

In addition, the ability of qubits to be in a state of superposition allows them to explore many potential solutions in parallel when solving optimization or research problems. Unlike classical computers that must test each solution individually, quantum computers can explore all possibilities simultaneously, greatly speeding up the process of finding the optimal solution.

Technology that is still vulnerable

However, a major challenge in quantum computing lies in the volatile nature of qubits, which are vulnerable to external interference, such as temperature changes, mechanical vibrations, electromagnetic fields and radiation. These disturbances essentially weaken the quantum state of qubits, leading to errors in calculations and damaging the reliability of the results obtained.

To overcome these problems, qubits must be cooled to extremely low temperatures, generally close to absolute zero (-273.15 degrees Celsius). At these temperatures, the thermal motions of atoms and molecules are reduced to a minimum, reducing interference and extending the coherence time of qubits.

However, cooling qubits to these temperatures requires expensive and complex infrastructure, which poses an additional challenge for the development of large-scale quantum computing, which brings us back to this recent work.

As part of the study, the researchers propose a promising solution to this problem by developing an ultra-pure form of silicon. Unlike traditional superconducting metal qubits (usually niobium or tantalum), which are susceptible to interference, these silicon qubits could be less prone to failure and easier to manufacture.

Purification and isotope separation

In detail, researchers have developed an innovative method to produce silicon-28 of exceptional purity by removing impurities found in natural silicon.

First, scientists isolated natural silicon, which consists of three main isotopes: Si-28, Si-29, and Si-30. Among these elements, Si-28 is the one that offers the most interesting properties for building qubits due to its quantum stability.

Next, the researchers developed purification processes that make it possible to selectively eliminate unwanted isotopes, especially Si-29. This purification step is crucial because unwanted isotopes can disrupt the quantum coherence of silicon bits.

To do this, scientists used advanced techniques such as mass spectroscopy and laser isotope separation. These methods separate isotopes based on their atomic masses, exploiting subtle differences in their physical properties.

Once the unwanted isotopes are removed, the researchers obtain silicon-28 of exceptional purity, free of impurities that could disrupt the operation of quantum qubits. This ultra-pure silicon forms the ideal basis for manufacturing highly reliable and consistent silicon qubits.

Lead author Ravi Acharya prepares a silicon chip for enrichment at the P-NAME Focused Ion Beam Laboratory at the University of Manchester. Credits: University of Manchester

What are the effects?

One of the most notable features of this advance is the ability to create qubits on a very small scale, about the size of a pinhead. This size reduction is critical for the design of complex chips that require large numbers of qubits to operate efficiently.

Imagine a typical electronic chip: it could contain billions of transistors, each occupying a small fraction of the available space. Likewise, by reducing the size of qubits, it becomes possible to integrate an amazing amount of these quantum units onto a single chip.

This miniaturization paves the way for more efficient and scalable quantum computers capable of processing massive amounts of information and performing complex calculations at amazing speed, far exceeding the capabilities of classical supercomputers.

This opens up a whole new field of possibilities. Quantum computers could revolutionize many fields, from science to finance to medicine. For example, they could make it possible to simulate complex natural phenomena, design new materials with revolutionary properties, new medicines, improve industrial processes, or even solve advanced cryptographic problems.

In short, the miniaturization of silicon qubits heralds an exciting new era of quantum computing, where computational capabilities are limited only by the imagination.

source : Nature Communications Materials