Manufacturing Bits: Aug. 17

Scaling qubits
Australia is a hotbed of R&D activity, especially in the field of quantum computing.

For example, the University of New South Wales (UNSW) in Australia has demonstrated a possible way to control millions of qubits in a silicon quantum chip.

Researchers from UNSW Sydney have devised a new three-dimensional dielectric resonator, a technology that could deliver controlled signals to millions of qubits simultaneously. This in turn could pave the way towards the realization of a true, universal quantum computer.

In today’s computing, the information is stored in bits, which can be either a “0” or “1”. In quantum computing, the information is stored in quantum bits, or qubits, which can exist as a “0” or “1” or a combination of both. The superposition state enables a quantum computer to perform multiple calculations at once, enabling it to outperform a traditional system. But the technology faces a number of challenges, and many industry experts believe these systems are still a decade away from being practical.

What prevents quantum computing from realizing its full potential are several major issues. First, qubits lose their properties, typically within 100 microseconds, due to noise, according to IBM. That’s why qubits must operate in extremely cold environments.

In addition, noise causes errors in the qubits. So quantum computers require error correction. On top of that, the industry needs to scale up quantum computers with thousands of qubits. It’s nowhere close to that figure. Researchers from China have devised a 66-qubit processor. That represents the most number of qubits in a processor to date.

There are several ways to make qubits. Silicon spin qubits are promising. The idea is to develop a transistor that has one electron in the channel. “That single electron can either have spin up or spin down,” said James Clarke, director of quantum hardware at Intel, in a recent interview. “That spin up or spin down represents the ‘0’ and the ‘1’.”

Making a few qubits is doable. But to make a multitude of them, there are several challenges. “Up until this point, controlling electron spin qubits relied on us delivering microwave magnetic fields by putting a current through a wire right beside the qubit,” said Jarryd Pla, a faculty member in UNSW’s School of Electrical Engineering and Telecommunications.

There is a solution. “One approach for spin qubit control successfully deployed in current few-qubit devices is based on a direct magnetic drive using an on-chip transmission line,” Pla said in Science Advances, a technology journal. “A strong microwave current is passed through a wire placed close to the QD (quantum dot) to generate an alternating magnetic field.”

This solution, however, would require multiple transmission lines, which would take up too much chip space. Heat dissipation is also an issue.

So, researchers looked at the feasibility of generating a magnetic field from above the chip. This in turn could manipulate all of the qubits simultaneously.

Researchers introduced a new component directly above the silicon chip – a dielectric resonator. When microwaves are directed into the resonator, it focuses the wavelength of the microwaves down to a much smaller size.

“The dielectric resonator shrinks the wavelength down below one millimeter, so we now have a very efficient conversion of microwave power into the magnetic field that controls the spins of all the qubits,” Pla said. “There are two key innovations here. The first is that we don’t have to put in a lot of power to get a strong driving field for the qubits, which crucially means we don’t generate much heat. The second is that the field is very uniform across the chip, so that millions of qubits all experience the same level of control.”

Next, the team plans to use this new technology to simplify the design of near-term silicon quantum processors.

Diamond quantum computers
Quantum Brilliance is developing the world’s first room-temperature quantum computer.

The Australian National University (ANU) has invented the technology used in the new computer—a room-temperature diamond quantum accelerator. The system is set to be installed at the Pawsey Supercomputing Center in Perth and activated later this year.

ANU is the driving force behind Quantum Brilliance. Quantum Brilliance will collaborate with Australia’s industry to develop cutting-edge quantum applications in machine learning, logistics, defense and aerospace.

Quantum Brilliance’s goal is to develop an affordable room-temperature, lunchbox-sized quantum computer, said Brian Schmidt, vice chancellor and professor of ANU. “Because of our unique diamond-based technology, customers can run our quantum computers themselves, and we provide them a full set of tools to explore how quantum can help create new capabilities,” Schmidt said.

Quantum scopes
University of Queensland researchers recently created a quantum microscope that can see the structures of biological samples.

The first microscope powered by quantum entanglement, the so-called quantum microscope can be used for a range of applications, such as biotechnology, medical imaging, and more.

Quantum entanglement describes the phenomenon in which two particles can become “entangled” and mirror each other’s properties, according to Cosmos Magazine. “What happens to one instantly happens to the other, even if they’re light years apart,” they added.

In quantum microscopes, this entanglement phenomenon allows the quantum sensor to perform better than all existing light-based microscopes. “The best light microscopes use bright lasers that are billions of times brighter than the sun”, according to Warwick Bowen, professor at the University of Queensland. “Fragile biological systems like a human cell can only survive a short time in them, and this is a major roadblock. The quantum entanglement in our microscope provides 35% improved clarity without destroying the cell, allowing us to see minute biological structures that would otherwise be invisible.”

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