Intel is testing silicon "spin qubits" to realize quantum computing

Intel is one of the first companies exploring ways to realize the potential of spin-based qubits in silicon in quantum computing. The company claims that spin qubits in silicon, which utilize the spin (rotation) of a single electron in a silicon device to perform quantum calculations, offer several advantages over their more familiar counterparts, superconducting qubits.

Quantum computing is the next news thanks to its inherent potential to deal with problems that today's conventional computers are unable to solve. Scientists and industries hope that quantum computing will accelerate progress in fields such as chemistry or drug development, financial modeling and even climate forecasting.

In order to realize the potential of quantum computing, in 2015 Intel initiated a joint research program designed to develop a quantum computing system that can be commercially produced.

Despite the great progress that has been made, research on quantum computing is still in its infancy. It can be said that the industry is at the beginning of the quantum computing marathon. In order to realize the new computing paradigm, many problems must be solved and many architectural decisions must be made. For example, it is not yet clear what the structure of the quantum processors will be. This is why Intel operates in two meaningful research directions with identical investments in both.

One of the possible forms is of qubits based on super-conducting qubits. Intel is making rapid progress in the development of this type of chip at the same time as other bodies in industry and academia are examining this direction. In addition, Intel is investigating an alternative structure based on the company's renowned expertise in the production of silicon transistors. This alternative architecture is called spin qubits and it may help solve some of the scientific hurdles hindering the transformation of quantum computing from research to reality.

What is the spin qubit?

Spin qubits are very similar to the electronic components and semiconductor transistors as we know them today. They provide their quantum capability by exploiting the spin of a single electron in a silicon device and controlling the movement by tiny microwave pulses.

Electrons are able to contain spin in different directions. When an electron spins up, the data indicates a binary value of 1. When the electron spins down, the data indicates a binary value of 0. However, similar to how superconducting qubits work, these electrons may also exist in superposition. That is, probability of spin up and down at the same time. In such a rotation, the spin qubits can theoretically process huge data sets at the same time, much faster than a classical computer.

Why study the spin qubits?

One of the challenges researchers must overcome to make quantum computing a commercial reality is the extremely fragile nature of qubits. Any noise and even unintended observation can cause data loss. This fragility requires that they operate at extremely low temperatures, which poses challenges in designing the materials of the chips themselves and the control electronics needed to enable them to work. Superconducting qubits are quite large and operate in systems the size of a 209 liter barrel. These dimensions make it difficult to scale quantum systems to the millions of qubits needed to create a truly useful commercial system.

Unlike superconducting qubits, spin qubits offer several advantages to address these challenges:

They are small and powerful: the physical dimensions of spin qubits are much smaller and their coherence time is expected to be longer (the time in which they are able to keep the information intact), a characteristic that is an advantage for researchers who aim to expand the system to the millions of qubits that will be required for a commercial system.

They are able to operate at higher temperatures: Silicon spin qubits are able to operate at higher temperatures than superconducting qubits (1 Kelvin versus 20 thousand Kelvin). This ability will drastically reduce the complexity of the system required to operate the chips and allow the integration of electronic control components much closer to the processor. Intel and its academic research partner, QuTech, are looking at activating spin qubits at a higher temperature and have so far achieved interesting results of up to 1 Kelvin (ie 50 times hotter) than superconducting qubits. The research team will present the results at the American Physical Society (APS) meeting in March.

Intel's know-how in manufacturing: the design of spin qubit processors is very similar to the traditional technologies for manufacturing silicon transistors. Despite the scientific and engineering challenges involved in expanding the technology, Intel has the equipment and infrastructure from decades of mass-producing transistors.

What is the state of research in spin qubits?

This week, at the annual conference of the American Association for the Advancement of Science (AAAS), QuTech presented its success in creating a two-spin qubit quantum computer that can be programmed to execute two simple quantum algorithms. This development paves the way for larger spin qubit-based processors capable of more complex applications. To read another article on this topic, go to the Nature article.

And in addition, Intel has developed a manufacturing process for spin qubits in 300 mm technology in which it uses silicon wafers free of isotopes that were produced specifically for the production of spin qubit chips for testing purposes. The production is carried out in the same facility where other advanced transistor technologies of Intel are used and the company has begun testing the first silicon wafers. Intel It is expected that within a few months you will be able to produce a large number of silicon wafers every week, which every One of them contains thousands of small qubit arrays.

At the same time, Intel and QuTech will continue their research in spin-based and conductive qubits on the entire quantum system or "stack" - from qubit devices to the hardware and software architectures needed to control the devices as well as quantum applications. All these elements are essential for advancing quantum computing from the research stage to reality.

Thanks to Chan Tardonski for helping with editing the article