Breaking: Engineers Designed a New Qubit for Quantum Computing

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Breaking: Engineers Designed a New Qubit for Quantum Computing
Gabriel Andrés Trujillo Escobedo | Flikcr.com

A group of Australian researchers just made another breakthrough by designing a new qubit for quantum computing.

The new qubit, dubbed the ‘flip-flop’ qubit, was invented by engineers from Australia’s University of New South Wales. Reports claimed that the invention would give quantum computing a radically new architecture that can potentially make large-scale manufacturing of quantum chips dramatically cheaper and easier.

The new qubit design was created by a team led by Andrea Morello, Program Manager in UNSW-based ARC Centre of Excellence for Quantum Computation and Communication Technology (CQC2T).

Lead author Guilherme Tosi, a Research Fellow at CQC2T, developed the pioneering concept along with Morello and co-authors Fahd Mohiyaddin, Vivien Schmitt and Stefanie Tenberg of CQC2T, with collaborators Rajib Rahman and Gerhard Klimeck of Purdue University in the USA, wrote a paper published in the journal Nature Communications.

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Referring to their latest achievement, Morello was quoted as saying:

“It’s a brilliant design, and like many such conceptual leaps, it’s amazing no-one had thought of it before.”

“What Guilherme and the team have invented is a new way to define a ‘spin qubit’ that uses both the electron and the nucleus of the atom. Crucially, this new qubit can be controlled using electric signals, instead of magnetic ones. Electric signals are significantly easier to distribute and localize within an electronic chip,” Morello went on to say.

Inventor of the new qubit - Professor Andrea Morello and Dr Guilherme Tosi at the UNSW quantum computing labs.
Inventor of the new qubit – Professor Andrea Morello and Dr Guilherme Tosi at the UNSW quantum computing labs. Photo: Quentin Jones/UNSW

The Problem With Qubits

A quantum bit or qubit is the counterpart of the traditional computing’s binary digit or bit in quantum computing. It is the basic unit of information in a quantum computer. One might say that qubit resembles bit in some ways, but they are far different from each other.

Without qubits, it would be impossible to make a quantum computer.

In essence, there are plenty of ways to create a quantum computer. However, the most common way is to capture a qubit by using a standard atom-taming technology such as ion straps and optical tweezers. These technologies can hold up particles long enough for researchers to analyze them.

Another method is by using circuits made of superconducting materials that will enable the detection of superpositions within slippery currents of electricity. These systems use exiting equipment which makes them affordable and easy to put together.

However, the problem with these existing technologies is that they are only applicable to a relatively small number of qubits and not feasible for harnessing hundreds or thousands of qubits. Most of them use a magnetic field to control the atoms’ electron or nucleus property of spin.

Spin qubits, as what researchers called them, have issues keeping hold of entanglement. Apparently, to create chips needed to make a quantum computer, the qubits need to be spaced at a distance of only 10-20 nanometres, or 50 atoms apart, and this does not work on a computer chip.

“If they’re too close, or too far apart, the ‘entanglement’ between quantum bits – which is what makes quantum computers so special – doesn’t occur,” Guilherme Tosi said.

The New Qubit ‘Flipflop’ to Revolutionize Quantum Computing

Now, thanks to the invention of the new qubit, the problem may have been resolved.

The new silicon qubit ‘flipflop’ has coding information in both the nucleus and electron of an atom which makes them electrically-controlled, unlike the magnetic ones. Meaning, distance would not be a problem since the qubits would be able to sustain quantum entanglement across a larger distance.

“Our new silicon-based approach sits right at the sweet spot,” Morello stated. “It’s easier to fabricate than atomic-scale devices, but still allows us to place a million qubits on a square millimetre.”

The ‘flipflop’ qubit was created by using a silicon chip covered with a layer of insulating silicon oxide, “on top of which rests a pattern of metallic electrodes that operate at temperatures near absolute zero and in the presence of a very strong magnetic field.”

‘Flipflop’ qubit is considered to be a new qubit that uses both the nucleus and the electron. In this approach, a qubit ‘0’ state is defined when the spin of the electron is down, and the nucleus spin is up, while the ‘1’ state is when the electron spin is up, and the nuclear spin is down.

“We call it the ‘flip-flop’ qubit,” Tosi explained. “To operate this qubit, you need to pull the electron a little bit away from the nucleus, using the electrodes at the top. By doing so, you also create an electric dipole.”

“This is the crucial point. These electric dipoles interact with each other over fairly large distances, a good fraction of a micron, or 1,000 nanometres. This means we can now place the single-atom qubits much further apart than previously thought possible. So there is plenty of space to intersperse the key classical components such as interconnects, control electrodes and readout devices, while retaining the precise atom-like nature of the quantum bit,” Morello added.

To set the record straight, the quantum chip or any device based on Morello and Tosi’s concept has not been built yet. What they have right now is a blueprint of the device. Morello likened their discovery to the seminal 1998 paper in Nature by Bruce Kane, which kicked off the silicon quantum computing movement.

Morello believes that the new architecture “could make a silicon-based quantum computer a reality – triggering Australia’s race to build a quantum computer.”

“Like Kane’s paper, this is a theory, a proposal – the qubit has yet to be built,” said Morello. “We have some preliminary experimental data that suggests it’s entirely feasible, so we’re working to fully demonstrate this. But I think this is as visionary as Kane’s original paper.”

Right now, this new qubit means a balance that would make the manufacturing of future quantum computers more affordable and smaller.

“It’s a brilliant design, and like many such conceptual leaps, it’s amazing no-one had thought of it before,” says Morello.

Do you believe that the invention of this new qubit would help bring quantum computers to every household in the future? Let us know your thoughts in the comment section below!

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