Why Electrical Qubit Control Will Revolutionize Quantum Computing

One of the major obstacles facing the quantum computing ecosystem was a lack of an excellent method for manipulating qubits states. Yes, manipulation could be achieved using magnetic fields, but that approach wasn't fast enough to make quantum computing practical on a large scale.

We're happy to say that that has now changed, thanks to the pioneering work of researchers at Diraq and UNSW Sydney. With help from the Quantum Machines’ OPX+, they discovered a means of manipulating qubit states using electrical fields, which is a huge deal.

Here's why we're so excited about the news – and why you should be, too.

What happened? Electrical qubit control

In a January 2023 paper in Nature Nanotechnology [1], the researchers, led by Dr. Will Gilbert, describe a means of controlling qubits using electrical fields. Compared to other known methods of changing qubit state – which include electron spin resonance and electric dipole spin resonance – the new approach is both faster and provides tighter control over individual electrons without disturbing those nearby.

This is a big deal for several reasons. For one, it makes it possible to achieve high-fidelity measurements of the qubit state. Although the researchers acknowledge in their paper that they have not yet calculated an error rate for their methodology, they are confident that the approach will prove reliable.

"Magnetically driven spin qubits in similar devices have led to significant improvements in control fidelity, achieving error rates below 0.05%."

[Gilbert, Will, et al. "On-demand electrical control of spin qubits." Nature Nanotechnology (2023): 1-6.]

A second advantage is that this new approach makes it possible to manipulate individual electrons with minimal impact on those nearby. This is essential if you want to be able to build quantum computers using silicon. Using this technique, it's now conceivable that the quantum computers of the future will be constructed with the same comparatively inexpensive, easily manufactured core material – silicon – that we rely on for classical computers.

"(This) builds on our work to make quantum computing in silicon a reality, based on essentially the same semiconductor component technology as existing computer chips, rather than relying on exotic materials."

- Andrew Dzurak of UNSW said in a statement published by the university's communications office.

And it's not just about being able to build computers more cheaply and with abundantly available material that makes silicon attractive. It also means that billions of qubits could potentially be integrated into a single computer. Since it’s based on the same CMOS technology as today’s computer industry, the approach will make it easier and faster to scale up for commercial production and achieve a long-held goal of fabricating billions of qubits without disturbance on a single chip.

Brightening the future for quantum computing

This discovery has the potential to be pathbreaking as it could usher in the era of silicon-based quantum computing. That could mean that inexpensive, large-scale quantum computers could become feasible.

If that happens – and assuming we have the quantum control technologies necessary to control those computers effectively – it won't be a stretch to say we've achieved the age of quantum computing practicality. Quantum computers will then be capable of transforming all types of industries and domains – from cybersecurity (where quantum will require both attackers and defenders to rethink their fundamental approaches) to financial services (which could benefit from much better prediction and analytics models, among other quantum-driven advancements).

A humble brag: How the OPX+ helped improve qubit control

Of course, it goes without saying that the researchers involved deserve all the credit for discovering this new qubit control method – but we're pleased that our devices played a role in the work. As the paper explains with regard to the measurement setup:

The SET current of devices A, B, & C are amplified using a room temperature I/V converter (Basel SP983c)and sampled by a digitiser (Gage Octopus CS8389 for devices A & B, QM OPX for device C). The SET of deviceD is connected to a tank circuit and measured via reflec-tometry, where the source tone is generated from the QM OPX, and the return signal amplified with a Cosmic Mi-crowave Technology CITFL1 LNA at the 4K stage, and a Mini-circuits ZX60-P33ULN+ and Mini-circuits ZFL-1000LN+ at room temperature, before being digitised and demodulated with the QM OPX.

The Quantum Machines team has been working for a long time to provide the quantum control hardware and software necessary to make quantum an everyday reality. We're delighted that our products contribute to the works of researchers and engineers ' that bring the world as a whole significantly closer to that goal.

Conclusion

In closing, let us congratulate the researchers on their outstanding work and breakthrough discovery. We're looking forward to seeing the innovations that will grow out of this important work, and we're excited to be a part of the community that strives to make quantum computing systems usable and helps it come closer every day to transforming computing as we know it.

You can read the full research paper here.

[1] Gilbert, Will, et al. "On-demand electrical control of spin qubits." Nature Nanotechnology (2023): 1-6.