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According to the Standard Model of Particle Physics, the Universe is governed by four fundamental forces: electromagnetism, the weak nuclear force, the strong nuclear force, and gravity. Whereas the first three are described by Quantum Mechanics, gravity is described by Einstein’s Theory of General Relativity. Surprisingly, gravity is the one that presents the biggest challenges to physicists. While the theory accurately describes how gravity works for planets, stars, galaxies, and clusters, it does not apply perfectly at all scales.

While General Relativity has been validated repeatedly over the past century (starting with the Eddington Eclipse Experiment in 1919), gaps still appear when scientists try to apply it at the quantum scale and to the Universe as a whole. According to a new study led by Simon Fraser University, an international team of researchers tested General Relativity on the largest of scales and concluded that it might need a tweak or two. This method could help scientists to resolve some of the biggest mysteries facing astrophysicists and cosmologists today.

The team included researchers from Simon Fraser, the Institute of Cosmology and Gravitation at the University of Portsmouth, the Center for Particle Cosmology at the University of Pennsylvania, the Osservatorio Astronomico di Roma, the UAM-CSIC Institute of Theoretical Physics, Leiden University’s Institute Lorentz, and the Chinese Academy of Sciences (CAS). Their results appeared in a paper titled “Imprints of cosmological tensions in reconstructed gravity,” recently published in Nature Astronomy.

Realizing that matter and energy are quantized is important, but quantum particles isn’t the full story; quantum fields are needed, too.

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Continue reading “Loop Quantum Gravity Explained” »

Researchers at Penn Engineering have created a chip that outstrips the security and robustness of existing quantum communications hardware. Their technology communicates in “qudits,” doubling the quantum information space of any previous on-chip laser.

Liang Feng, Professor in the Departments of Materials Science and Engineering (MSE) and Electrical Systems and Engineering (ESE), along with MSE postdoctoral fellow Zhifeng Zhang and ESE Ph.D. student Haoqi Zhao, debuted the technology in a recent study published in Nature. The group worked in collaboration with scientists from the Polytechnic University of Milan, the Institute for Cross-Disciplinary Physics and Complex Systems, Duke University and the City University of New York (CUNY).

A team of German and Spanish researchers from Valencia, Münster, Augsburg, Berlin and Munich have succeeded in controlling individual light quanta to an extremely high degree of precision. In Nature Communications, the researchers report how, by means of a soundwave, they switch individual photons on a chip back and forth between two outputs at gigahertz frequencies. This method, demonstrated here for the first time, can now be used for acoustic quantum technologies or complex integrated photonic networks.

Light waves and soundwaves form the technological backbone of modern communications. While glass fibers with laser light form the World Wide Web, nanoscale soundwaves on chips process signals at gigahertz frequencies for wireless transmission between smartphones, tablets or laptops. One of the most pressing questions for the future is how these technologies can be extended to quantum systems, to build up secure (i.e., tap-free) quantum communication networks.

“Light quanta or photons play a very central role in the development of quantum technologies,” says physicist Prof. Hubert Krenner, who heads the study in Münster and Augsburg. “Our team has now succeeded in generating individual photons on a chip the size of a thumbnail and then controlling them with unprecedented precision, precisely clocked by means of soundwaves,” he says.

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We don’t know very much about our universe. We’re fairly certain it exists, but we don’t know how it got here, how long it’s been here, or how big it is. Heck, we don’t even know if our universe is unique.

Ever since Albert Einstein came up with the theory of relativity and other scientists realized that classical physics and quantum mechanics don’t really line up, we’ve been trying to reconcile those worlds.

Continue reading “New superstring theory says black holes may be portals to other universes” »

Could energy efficiency be quantum computers’ greatest strength yet?

Quantum computers have attracted considerable interest of late for their potential to crack problems in a few hours where they might take the age of the universe (i.e., tens of billions of years) on the best supercomputers. Their real-life applications range from drug and materials design to solving complex optimization problems. They are, therefore, primarily intended for scientific and industrial research.

Continue reading “Les Ordinateurs Quantiques” »

Can quantum theory explain consciousness?

“It’s a novel contribution that uses different methods compared to what most people have been doing,” said Steffen Gielen, a cosmologist at the University of Sheffield in the United Kingdom.

The provocative conclusion rests on a mathematical trick involving switching to a clock that ticks with imaginary numbers. Using the imaginary clock, as Hawking did in the ’70s, Turok and Boyle could calculate a quantity, known as entropy, that appears to correspond to our universe. But the imaginary time trick is a roundabout way of calculating entropy, and without a more rigorous method, the meaning of the quantity remains hotly debated. While physicists puzzle over the correct interpretation of the entropy calculation, many view it as a new guidepost on the road to the fundamental, quantum nature of space and time.