Back to Table of contents

Primeur weekly 2019-03-25

Special

Meeting the challenges of tomorrow - at scale ...

FocusCoE to support HPC Centres of Excellence for outreach to the broader European HPC community ...

Focus

University of Maribor and XENYA signed contract for an HPC system as part of the national research infrastructure project HPC - RIVR, readying Slovenia for EuroHPC participation ...

Exascale supercomputing

U.S. Department of Energy and Intel to deliver first exascale supercomputer ...

Argonne deepens the Department of Energy's footprint in high-impact computing ...

Crowd computing

NVIDIA announces Jetson Nano: $99 tiny, yet mighty NVIDIA CUDA-X AI computer that runs all AI models ...

Quantum computing

In a new quantum simulator, light behaves like a magnet ...

Long-distance quantum information exchange - success at the nanoscale ...

Middleware

NERSC and NVIDIA to partner on compiler development for Perlmutter system ...

Hardware

DDN to unveil transformative solutions for accelerating AI, analytics and Deep Learning at NVIDIA GTC 2019 ...

NVIDIA introduces new breed of high-performance workstations for millions of data scientists ...

Global computer companies announce NVIDIA-powered enterprise servers optimized for data science ...

Mellanox HDR 200G InfiniBand deep learning acceleration engines demonstrates two times higher performance for Artificial Intelligence (AI) platforms with NVIDIA ...

Altair OptiStruct runs up to 10x faster on NVIDIA GPUs ...

Pure Storage unveils NVIDIA-powered solutions for full spectrum of AI initiatives ...

Preferred Networks builds MN-2, a state-of-the-art supercomputer powered with NVIDIA GPUs ...

Supermicro offers end-to-end portfolio of NVIDIA GPU systems ...

Applications

H5 Data Centers completes a High-Performance Compute (HPC) suite in partnership with Forced Physics Data Center Technology ...

Supercomputers to help supercharge ceramic matrix composite manufacturing ...

A surprising, cascading earthquake ...

Brain-inspired AI inspires insights about the brain and vice versa ...

Supercomputer simulations shed light on how liquid drops combine ...

Novel MD simulation sheds light on mystery of hydrated electron's structure ...

Kicking neural network automation into high gear ...

DOE extends University PPPL contract ...

The Cloud

NVIDIA teams with Amazon Web Services to bring AI to millions of connected devices ...

Long-distance quantum information exchange - success at the nanoscale


Researchers at the Niels Bohr Institute cooled a chip containing a large array of spin qubits below -273 Celsius. To manipulate individual electrons within the quantum-dot array, they applied fast voltage pulses to metallic gate electrodes located on the surface of the gallium-arsenide crystal (see scanning electron micrograph). Because each electron also carries a quantum spin, this allows quantum information processing based on the array's spin states (the arrows on the graphic illustration). During the mediated spin exchange, which only took a billionth of a second, two correlated electron pairs were coherently superposed and entangled over five quantum dots, constituting a new world record within the community. Credit: Ferdinand Kuemmeth.
21 Mar 2019 Copenhagen - At the Niels Bohr Institute, University of Copenhagen, researchers have realized the swap of electron spins between distant quantum dots. The discovery brings us a step closer to future applications of quantum information, as the tiny dots have to leave enough room on the microchip for delicate control electrodes. The distance between the dots has now become big enough for integration with traditional microelectronics and perhaps, a future quantum computer.

The result is achieved via a multinational collaboration with Purdue University and the University of Sydney, Australia, now published in Nature Communications .

Quantum information can be stored and exchanged using electron spin states. The electrons' charge can be manipulated by gate-voltage pulses, which also controls their spin. It was believed that this method can only be practical if quantum dots touch each other; if squeezed too close together the spins will react too violently, if placed too far apart the spins will interact far too slowly. This creates a dilemma, because if a quantum computer is ever going to see the light of day, we need both, fast spin exchange and enough room around quantum dots to accommodate the pulsed gate electrodes.

Normally, the left and right dots in the linear array of quantum dots are too far apart to exchange quantum information with each other. Frederico Martins, postdoc at the University of New South Wales (UNSW), Sydney, Australia, explained: "We encode quantum information in the electrons' spin states, which have the desirable property that they don't interact much with the noisy environment, making them useful as robust and long-lived quantum memories. But when you want to actively process quantum information, the lack of interaction is counterproductive - because now you want the spins to interact." What to do? You can't have both long lived information and information exchange - or so it seems. "We discovered that by placing a large, elongated quantum dot between the left dots and right dots, it can mediate a coherent swap of spin states, within a billionth of a second, without ever moving electrons out of their dots. In other words, we now have both fast interaction and the necessary space for the pulsed gate electrodes", stated Ferdinand Kuemmeth, associate professor at the Niels Bohr Institute.

The collaboration between researchers with diverse expertise was key to success. Internal collaborations constantly advance the reliability of nanofabrication processes and the sophistication of low-temperature techniques. In fact, at the Center for Quantum Devices, major contenders for the implementation of solid-state quantum computers are currently intensely studied, namely semiconducting spin qubits, superconducting gatemon qubits, and topological Majorana qubits.

All of them are voltage-controlled qubits, allowing researchers to share tricks and solve technical challenges together. But Ferdinand Kuemmeth was quick to add that "all of this would be futile if we didn't have access to extremely clean semiconducting crystals in the first place". Michael Manfra, Professor of Materials Engineering, agreed: "Purdue has put a lot of work into understanding the mechanisms that lead to quiet and stable quantum dots. It is fantastic to see this work yield benefits for Copenhagen's novel qubits".

The theoretical framework of the discovery is provided by the University of Sydney, Australia. Stephen Bartlett, a professor of quantum physics at the University of Sydney, stated: "What I find exciting about this result as a theorist, is that it frees us from the constraining geometry of a qubit only relying on its nearest neighbours." His team performed detailed calculations, providing the quantum mechanical explanation for the counterintuitive discovery.

Overall, the demonstration of fast spin exchange constitutes not only a remarkable scientific and technical achievement, but may have profound implications for the architecture of solid-state quantum computers. The reason is the distance: "If spins between non-neighboring qubits can be controllably exchanged, this will allow the realization of networks in which the increased qubit-qubit connectivity translates into a significantly increased computational quantum volume", predicted Ferdinand Kuemmeth.

Source: University of Copenhagen

Back to Table of contents

Primeur weekly 2019-03-25

Special

Meeting the challenges of tomorrow - at scale ...

FocusCoE to support HPC Centres of Excellence for outreach to the broader European HPC community ...

Focus

University of Maribor and XENYA signed contract for an HPC system as part of the national research infrastructure project HPC - RIVR, readying Slovenia for EuroHPC participation ...

Exascale supercomputing

U.S. Department of Energy and Intel to deliver first exascale supercomputer ...

Argonne deepens the Department of Energy's footprint in high-impact computing ...

Crowd computing

NVIDIA announces Jetson Nano: $99 tiny, yet mighty NVIDIA CUDA-X AI computer that runs all AI models ...

Quantum computing

In a new quantum simulator, light behaves like a magnet ...

Long-distance quantum information exchange - success at the nanoscale ...

Middleware

NERSC and NVIDIA to partner on compiler development for Perlmutter system ...

Hardware

DDN to unveil transformative solutions for accelerating AI, analytics and Deep Learning at NVIDIA GTC 2019 ...

NVIDIA introduces new breed of high-performance workstations for millions of data scientists ...

Global computer companies announce NVIDIA-powered enterprise servers optimized for data science ...

Mellanox HDR 200G InfiniBand deep learning acceleration engines demonstrates two times higher performance for Artificial Intelligence (AI) platforms with NVIDIA ...

Altair OptiStruct runs up to 10x faster on NVIDIA GPUs ...

Pure Storage unveils NVIDIA-powered solutions for full spectrum of AI initiatives ...

Preferred Networks builds MN-2, a state-of-the-art supercomputer powered with NVIDIA GPUs ...

Supermicro offers end-to-end portfolio of NVIDIA GPU systems ...

Applications

H5 Data Centers completes a High-Performance Compute (HPC) suite in partnership with Forced Physics Data Center Technology ...

Supercomputers to help supercharge ceramic matrix composite manufacturing ...

A surprising, cascading earthquake ...

Brain-inspired AI inspires insights about the brain and vice versa ...

Supercomputer simulations shed light on how liquid drops combine ...

Novel MD simulation sheds light on mystery of hydrated electron's structure ...

Kicking neural network automation into high gear ...

DOE extends University PPPL contract ...

The Cloud

NVIDIA teams with Amazon Web Services to bring AI to millions of connected devices ...