A group of physicists at UNSW Sydney have built a super-fast version of the central building block of a quantum computer. The research is the milestone result of a vision first outlined by scientists 20 years ago.
A group of scientists led by 2018 Australian of the Year Professor Michelle Simmons have achieved the first two-qubit gate between atom qubits in silicon – a major milestone on the team’s quest to build an atom-scale quantum computer. The pivotal piece of research was published today in world-renowned journal Nature.
A two-qubit gate is the central building block of any quantum computer – and the UNSW team’s version of it is the fastest that’s ever been demonstrated in silicon, completing an operation in 0.8 nanoseconds, which is ~200 times faster than other existing spin-based two-qubit gates.
In the Simmons’ group approach, a two-qubit gate is an operation between two electron spins – comparable to the role that classical logic gates play in conventional electronics. For the first time, the team was able to build a two-qubit gate by placing two atom qubits closer together than ever before, and then – in real-time – controllably observing and measuring their spin states.
The team’s unique approach to quantum computing requires not only the placement of individual atom qubits in silicon but all the associated circuitry to initialise, control and read-out the qubits at the nanoscale – a concept that requires such exquisite precision it was long thought to be impossible. But with this major milestone, the team is now positioned to translate their technology into scalable processors.
Professor Simmons, Director of the Centre of Excellence for Quantum Computation and Communication Technology (CQC2T) and founder of Silicon Quantum Computing Pty Ltd., says the past decade of previous results perfectly set the team up to shift the boundaries of what’s thought to be “humanly possible”.
“Atom qubits hold the world record for the longest coherence times of a qubit in silicon with the highest fidelities,” she says. “Using our unique fabrication technologies, we have already demonstrated the ability to read and initialise single electron spins on atom qubits in silicon with very high accuracy. We’ve also demonstrated that our atomic-scale circuitry has the lowest electrical noise of any system yet devised to connect to a semiconductor qubit.
“Optimising every aspect of the device design with atomic precision has now allowed us to build a really fast, highly accurate two-qubit gate, which is the fundamental building block of a scalable, silicon-based quantum computer.
“We’ve really shown that it is possible to control the world at the atomic scale – and that the benefits of the approach are transformational, including the remarkable speed at which our system operates.”
UNSW Science Dean, Professor Emma Johnston AO, says this key paper further shows just how ground-breaking Professor Simmons’ research is.
“This was one of Michelle’s team’s final milestones to demonstrate that they can actually make a quantum computer using atom qubits. Their next major goal is building a 10-qubit quantum integrated circuit – and we hope they reach that within 3-4 years.”
Getting up and close with qubits – engineering with a precision of just thousand-millionths of a metre
Using a scanning tunnelling microscope to precision-place and encapsulate phosphorus atoms in silicon, the team first had to work out the optimal distance between two qubits to enable the crucial operation.
“Our fabrication technique allows us to place the qubits exactly where we want them. This allows us to engineer our two-qubit gate to be as fast as possible,” says study lead co-author Sam Gorman from CQC2T.
“Not only have we brought the qubits closer together since our last breakthrough, but we have learnt to control every aspect of the device design with sub-nanometer precision to maintain the high fidelities.”
Observing and controlling qubit interactions in real-time
The team was then able to measure how the qubits states evolved in real-time. And, most excitingly, the researchers showed how to control the interaction strength between two electrons on the nano-second timescale.
“Importantly, we were able to bring the qubit’s electrons closer or further apart, effectively turning on and off the interaction between them, a prerequisite for a quantum gate,” says other lead co-author Yu He.
“The tight confinement of the qubit’s electrons, unique to our approach, and the inherently low noise in our system enabled us to demonstrate the fastest two qubit gate in silicon to date.
“The quantum gate we demonstrated, the so-called SWAP gate, is also ideally suited to shuttle quantum information between qubits – and, when combined with a single qubit gate, allows you to run any quantum algorithm.”
A thing of physical impossibility? Not anymore
Professor Simmons says that this is the culmination of two decades’ worth of work.
“This is a massive advance: to be able to control nature at its very smallest level so that we can create interactions between two atoms but also individually talk to each one without disturbing the other is incredible. A lot of people thought this would not be possible,” she says.
“The promise has always been that if we could control the qubit world at this scale, they would be fast, and they sure are!”
The Latest on: Quantum computer
via Google News
The Latest on: Quantum computer
- Scientists Discover A Brand-New State Of Matter That Could Improve Quantum Computerson August 16, 2019 at 9:30 am
Matter can take many forms, from the familiar solid, liquid, and gas to the more complex states found only by tugging at the limits of physics. Researchers have now discovered a new peculiar state of ...
- Thales helps organizations combat the future security threats of quantum computingon August 16, 2019 at 7:40 am
Login or register now to gain instant access to the rest of this premium content! Thales has announced its collaboration with ISARA Corp. and ID Quantique (IDQ), leading providers of complementary ...
- New Report Forecasts $780 Million Quantum Computing Market in 2025 and Profiles 42 Leading Quantum Computing Organizationson August 15, 2019 at 11:28 am
CROZET, Va., Aug 15, 2019 (GLOBE NEWSWIRE via COMTEX) -- According to Quantum Computing Strategies: 2019 https://www.insidequantumtechnology.com/product/quantum-computing-strategies-2019/, a new ...
- Newfound superconductor material could be the 'silicon of quantum computers'on August 15, 2019 at 11:04 am
A potentially useful material for building quantum computers has been unearthed at the National Institute of Standards and Technology (NIST), whose scientists have found a superconductor that ...
- Investing in quantum computingon August 15, 2019 at 7:57 am
Quantum computing has promised much, and absorbed enormous resources, without delivering a great deal in practical terms yet. However, the rationale for investing in research remains impeccable. In ...
- Quantum system virtually cooled to half of its actual temperatureon August 15, 2019 at 7:03 am
Due to their quantum properties, quantum simulators can perform certain tasks like this that are out of the reach of classical computers, which cannot leverage quantum entanglement and superposition.
- IBM Q Wants You To Try Out Its Online Quantum Computer (Radio)on August 14, 2019 at 10:03 am
Bob Sutor, Vice President, IBM Q Strategy & Ecosystem, on building public and commercial quantum computing systems for business and science applications. Hosted by Lisa Abramowicz and Paul Sweeney.
- Airbus Looks For A Quantum LEAP In Computing Poweron August 13, 2019 at 11:23 pm
Once thought of as impossible due to its complexity, quantum computing could be a game-changing technology across industries—from science to medicine. In the aerospace industry, quantum computing is ...
- The Basics of Quantum Computing—A Tutorialon August 13, 2019 at 1:11 pm
In classic computing, uncertainty is unacceptable. With quantum computers, however, it’s an asset. Quantum computers have an innate ability to learn about the world, dealing in probability, as they ...
- The Quantum Computing Party Hasn’t Even Started Yeton August 12, 2019 at 3:40 pm
If you pay even a little attention to technology news, you've undoubtedly heard about the amazing potential of quantum computers, which exploit the unusual physics of the smallest particles in the ...
via Bing News