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Category: computing – Page 333

Improved fabrication methods for qubits made from erbium-doped silicon waveguides give these qubits the key prerequisites for becoming a contender for future quantum computers.

From superconducting circuits to single atoms, there are many quantum-bit—or “qubit”—systems to choose from when building a quantum computer. New to the game are qubits made from individual erbium atoms implanted in silicon waveguides. Each of these qubits can be controlled and measured with telecom-wavelength light, making the platform practical to implement. But the platform has unfavorable properties that have put that implementation on hold. Now Andreas Reiserer of the Max Planck Institute of Quantum Optics in Germany and his colleagues have improved the qubit’s fabrication and detection methods, such that it is viable for near-future use in quantum computing technologies [1]. The results suggest that erbium-doped silicon waveguides could make more promising qubits than previously thought.

One problem with previous erbium-doped silicon waveguides came from the uneven clustering of erbium atoms around impurities in the waveguide. This clustering meant that the erbium atoms had different transition frequencies, making it difficult to simultaneously address multiple atoms and to perform basic operations between them—a necessary component of quantum information processing.

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In February 2019, JQI Fellow Alicia Kollár, who is also an assistant professor of physics at UMD, bumped into Adrian Chapman, then a postdoctoral fellow at the University of Sydney, at a quantum information conference. Although the two came from very different scientific backgrounds, they quickly discovered that their research had a surprising commonality. They both shared an interest in graph theory, a field of math that deals with points and the connections between them.

Chapman found graphs through his work in —a field that deals with protecting fragile quantum information from errors in an effort to build ever-larger quantum computers. He was looking for new ways to approach a long-standing search for the Holy Grail of quantum error correction: a way of encoding quantum information that is resistant to errors by construction and doesn’t require active correction. Kollár had been pursuing new work in graph theory to describe her photon-on-a-chip experiments, but some of her results turned out to be the missing piece in Chapman’s puzzle.

Their ensuing collaboration resulted in a new tool that aids in the search for new quantum error correction schemes—including the Holy Grail of self-correcting quantum error correction. They published their findings recently in the journal Physical Review X Quantum.

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The world wide web is not enough, because scientists have managed to transmit data at a staggering 1.84 petabits per second — nearly twice the amount of global internet traffic in the same interval.

That blows the previous record for data transmission using a single light source and optical chip of one petabit per second out the water. And to put that ridiculous amount into perspective, a petabit is equal to one million gigabits. A single gigabit, or 1,000 megabits, is about the fastest download speed money can buy for most households.

To achieve the astonishing feat, researchers from the Technical University of Denmark (DTU) and Chalmers University of Technology used a custom optical chip that can make use of a single infrared light by splitting it into hundreds of different frequencies that are evenly spaced apart. Collectively, they’re known as a frequency comb. Each frequency on the comb can discretely hold data by modulating the wave properties of light, allowing scientists to transmit far more bits than conventional methods.

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Physicists have created the first Bose-Einstein condensate—the mysterious fifth state of matter—made from quasiparticles, entities that do not count as elementary particles but that can still have elementary-particle properties like charge and spin. For decades, it was unknown whether they could undergo Bose-Einstein condensation in the same way as real particles, and it now appears that they can. The finding is set to have a significant impact on the development of quantum technologies including quantum computing.

A paper describing the process of creation of the substance, achieved at temperatures a hair’s breadth from absolute zero, was published in the journal Nature Communications.

Bose-Einstein condensates are sometimes described as the fifth state of matter, alongside solids, liquids, gases and plasmas. Theoretically predicted in the early 20th century, Bose-Einstein condensates, or BECs, were only created in a lab as recently as 1995. They are also perhaps the oddest state of matter, with a great deal about them remaining unknown to science.

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Reporting in Research Ideas and Outcomes, a Kyushu University researcher has developed a new technique for scanning various plants and animals and reconstructing them into highly detailed 3D models. To date, over 1,400 models have been made available online for public use.

Open any textbook or nature magazine and you will find stunning high-resolution pictures of the diverse flora and fauna that encompass our world. From the botanical illustrations in Dioscorides’ De materia medica (50−70 CE) to Robert Hooke’s sketches of the microscopic world in Micrographia (1665), scientists and artists alike have worked meticulously to draw the true majesty of nature.

The advent of photography has given us even more detailed images of animals and plants both big and small, in some cases providing new information on an organism’s morphology. As technology developed, digital libraries began to grow, giving us near unfettered access to valuable data, with methods like computer tomography, or CT, and MRI scanning becoming powerful tools for studying the internal structure of such creatures.

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A single chip has managed to transfer over a petabit-per-second according to research by a team of scientists from universities in Denmark, Sweden, and Japan. That’s over one million gigabits of data per second over a fibre optic cable, or basically the entire internet’s worth of traffic.

The researchers—A. A. Jørgensen, D. Kong, L. K. Oxenløwe—and their team successfully showed a data transmission of 1.84 petabits over a 7.9km fibre cable using just a single chip. That’s not quite as fast as some other alternatives with larger, bulkier systems, which have reached up to 10.66 petabits, but the key here is scale: the proposed system is very compact.

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Researchers at the University of Texas at Austin have developed a decoder that uses information from fMRI scans to reconstruct human thoughts. Jerry Tang, Amanda LeBel, Shailee Jain and Alexander Huth have published a paper describing their work on the preprint server bioRxiv.

Prior efforts to create technology that can monitor and decode them to reconstruct a person’s thoughts have all consisted of probes placed in the brains of willing patients. And while such technology has proven useful for research efforts, it is not practical for use in other applications such as helping people who have lost the ability to speak. In this new effort, the researchers have expanded on work from prior studies by applying findings about reading and interpreting brain waves to data obtained from fMRI scans.

Recognizing that attempting to reconstruct brainwaves into individual words using fMRI was impractical, the researchers designed a decoding device that sought to gain an overall understanding of what was going on in the mind rather than a word-for-word decoding. The decoder they built was a that accepted fMRI data and returned paragraphs describing general thoughts. To train their algorithm, the researchers asked two men and one woman to lie in an fMRI machine while they listened to podcasts and recordings of people telling stories.

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