Realizing that matter and energy are quantized is important, but quantum particles isn’t the full story; quantum fields are needed, too.
Category: quantum physics – Page 415
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It’s time we talked about loop quantum gravity. What exactly is it? What are the loops? And can it really defeat string theory in our quest for a Theory of Everything?
Hosted by Matt O’Dowd.
Written by Graeme Gossel & Matt O’Dowd.
Graphics by Leonardo Scholzer.
Directed by: Andrew Kornhaber.
Executive Producers: Eric Brown & Andrew Kornhaber.
End Credits Music by J.R.S. Schattenberg: https://www.youtube.com/channel/UCRl6-nb4iOnsij-vnpAjp0Q
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.
Circa 2021 face_with_colon_three
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.
Many theoretical physicists believe that bridging the gap between obvious reality (classical physics) and the wacky quantum realm could help us finally understand the true nature of our universe.
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.
Traditionally, “quantum supremacy” is sought from the point of view of raw computing power: we want to calculate (much) faster.
However, the question of its energy consumption could also now warrant research, with current supercomputers sometimes consuming as much electricity as a small town (which could in fact limit the increase in their computing power). Information technologies, at their end, accounted for 11% of global electricity consumption in 2020.
## Why focus on the energy consumption of quantum computers?
Since a quantum computer can solve problems in a few hours, whereas a supercomputer might take several tens of billions of years, it is natural to expect it will consume much less energy. However, manufacturing such powerful quantum computers will require that we solve many scientific and technological challenges, potentially over one to several decades of research.
“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.
At the nanoscale, the laws of classical physics suddenly become inadequate to explain the behavior of matter. It is precisely at this juncture that quantum theory comes into play, effectively describing the physical phenomena characteristic of the atomic and subatomic world. Thanks to the different behavior of matter on these length and energy scales, it is possible to develop new materials, devices and technologies based on quantum effects, which could yield a real quantum revolution that promises to innovate areas such as cryptography, telecommunications and computation.
The physics of very small objects, already at the basis of many technologies that we use today, is intrinsically linked to the world of nanotechnologies, the branch of applied science dealing with the control of matter at the nanometer scale (a nanometer is one billionth of a meter). This control of matter at the nanoscale is at the basis of the development of new electronic devices.
Among these, memristors are considered promising devices for the realization of new computational architectures emulating functions of our brain, allowing the creation of increasingly efficient computation systems suitable for the development of the entire artificial intelligence sector, as recently shown by Istituto Nazionale di Ricerca Metrologica (INRiM) researchers in collaboration with several international universities and research institutes.
Ultrasensitive matter-wave interferometer uses delocalization and entanglement to detect tiny accelerations.