A new algorithm can organize hundreds of atoms into pristine patterns—including a honeycomb lattice, a fractal called a Sierpiński triangle, and a lion’s head.
Strongly correlated systems are systems made of particles that strongly interact with one another, to such an extent that their individual behavior depends on the behavior of all other particles in the system. In states that are far from equilibrium, these systems can sometimes give rise to fascinating and unexpected physical phenomena, such as many-body localization.
Many-body localization occurs when a system made of interacting particles fails to reach thermal equilibrium even at high temperatures. In many-body localized systems, particles thus remain in a state of non-equilibrium for long periods of time, even when a lot of energy is flowing through them.
Theoretical predictions suggest that the instability of the many-body localized phase is caused by small thermal inclusions in the strongly interacting system that act as a bath. These inclusions prompt the delocalization of the entire system, through a mechanism that is known as avalanche propagation.
Most people only encounter turbulence as an unpleasant feature of air travel, but it’s also a notoriously complex problem for physicists and engineers. The same forces that rattle planes are swirling in a glass of water and even in the whorl of subatomic particles. Because turbulence involves interactions across a range of distances and timescales, the process is too complicated to be solved through calculation or computational modeling—there’s simply too much information involved.
Scientists have attempted to tackle the issue by studying the turbulence that occurs in superfluids, which is formed by tiny identical whirls called quantized vortices. A key question is how turbulence happens on the quantum scale and how is it linked to turbulence at larger scales.
Researchers at Aalto University have brought that goal closer with a new study of quantum wave turbulence. Their findings, published in Nature Physics, demonstrate a new understanding of how wave-like motion transfers energy from macroscopic to microscopic length scales, and their results confirm a theoretical prediction about how the energy is dissipated at small scales.
One of the first practical applications of the much-hyped but little-used quantum computing technology is now within reach, thanks to a unique approach that sidesteps the major problem of scaling up such prototypes.
The invention, by a University of Bristol physicist, who gave it the name “counterportation,” provides the first-ever practical blueprint for creating in the lab a wormhole that verifiably bridges space, as a probe into the inner workings of the universe.
By deploying a novel computing scheme, revealed in the journal Quantum Science and Technology, which harnesses the basic laws of physics, a small object can be reconstituted across space without any particles crossing. Among other things, it provides a “smoking gun” for the existence of a physical reality underpinning our most accurate description of the world.
Imagine a universe with extremely strong gravity. Stars would be able to form from very little material. They would be smaller than in our universe and live for a much shorter amount of time. But could life evolve there? It took human life billions of years to evolve on Earth under the pleasantly warm rays from the Sun after all.
Now imagine a universe with extremely weak gravity. Its matter would struggle to clump together to form stars, planets and—ultimately—living beings. It seems we are pretty lucky to have gravity that is just right for life in our universe.
This isn’t just the case for gravity. The values of many forces and particles in the universe, represented by some 30 so-called fundamental constants, all seem to line up perfectly to enable the evolution of intelligent life. But there’s no theory explaining what values the constants should have—we just have to measure them and plug their numbers into our equations to accurately describe the cosmos.
For decades, various physicists have theorized that even the slightest changes in the fundamental laws of nature would make it impossible for life to exist. This idea, also known as the “fine-tuned universe” argument, suggests that the occurrence of life in the universe is very sensitive to the values of certain fundamental physics. Alter any of these values (as the logic goes), and life would not exist, meaning we must be very fortunate to be here.
But can this really be the case, or is it possible that life can emerge under different physical constants, and we just don’t know it? This question was recently tackled by Luke A. Barnes, a postdoctoral researcher at the Sidney Institute for Astronomy (SIA) in Australia. In his book, “A Fortunate Universe: Life in a Finely Tuned Cosmos,” he and Sydney astrophysics professor Geraint F. Lewis argued that a fine-tuned universe makes sense from a physics standpoint.
The authors also summarized these arguments in an invited contribution paper, which appeared in the Routledge Companion to Philosophy of Physics (1st ed.) In this paper, titled “The Fine-Tuning of the Universe for Life,” Barnes explains how “fine-tuning” consists of explaining observations by employing a “suspiciously precise assumption.” This, he argues, has been symptomatic of incomplete theories throughout history and is a common feature of modern cosmology and particle physics.
For decades physicists have been perplexed about why our cosmos appears to have been precisely tuned to foster intelligent life. It is widely thought that if the values of certain physical parameters, such as the masses of elementary particles, were tweaked, even slightly, it would have prevented the formation of the components necessary for life in the universe—including planets, stars, and galaxies. But recent studies, detailed in a new report by the Foundational Questions Institute, FQXi, propose that intelligent life could have evolved under drastically different physical conditions. The claim undermines a major argument in support of the existence of a multiverse of parallel universes.
“The tuning required for some of these physical parameters to give rise to life turns out to be less precise than the tuning needed to capture a station on your radio, according to new calculations,” says Miriam Frankel, who authored the FQXi report, which was produced with support from the John Templeton Foundation. “If true, the apparent fine tuning may be an illusion,” Frankel adds.
Over the last few decades, the subject of fine tuning has attracted some of the sharpest minds in physics. By probing the universe’s physical laws and precisely pinning down the values of physical constants—such as the masses of elementary particles and the strengths of forces—physicists have discovered that surprisingly small variations in these values would have rendered the universe lifeless. This led to a puzzle: why are physical conditions seemingly tailored towards human existence?
The Higgs boson doesn’t stick around for long. Once it is created in particle collisions, the famed particle lives for a mere less than a trillionth of a billionth of a second or, more precisely, 1.6 × 10-22 seconds. According to theory, that is, for so far experiments have only been able to set bounds on the value of the particle’s lifetime or to determine this property with a large uncertainty. Until now. In a new study, the CMS collaboration reports a value for the particle’s lifetime that has a small enough uncertainty to confirm that the Higgs boson does have such a short lifetime.
Measuring the Higgs boson’s lifetime is high on the wish list of particle physicists, because an experimental value of the lifetime would allow them not only to better understand the nature of the particle but also to find out whether or not the value matches the value predicted by the Standard Model of particle physics. A deviation from the prediction could point to new particles or forces not predicted by the Model, including new particles into which the Higgs boson would decay.
But it isn’t easy to measure the Higgs boson’s lifetime. For one, the predicted lifetime is too short to be measured directly. A possible solution entails measuring a related property called the mass width, which is inversely proportional to the lifetime and represents the small range of possible masses around the particle’s nominal mass of 125 GeV. But this isn’t easy either, as the predicted mass width of the Higgs boson is too small to be easily measured by experiments.
How can we combat data theft, which is a real issue for society? Quantum physics has the solution. Its theories make it possible to encode information (a qubit) in single particles of light (a photon) and to circulate them in an optical fiber in a highly secure way. However, the widespread use of this telecommunications technology is hampered in particular by the performance of the single-photon detectors.
A team from the University of Geneva (UNIGE), together with the company ID Quantique, has succeeded in increasing their speed by a factor of twenty. This innovation, published in the journal Nature Photonics, makes it possible to achieve unprecedented performances in quantum key distribution.
Buying a train ticket, booking a taxi, getting a meal delivered: these are all transactions carried out daily via mobile applications. These are based on payment systems involving an exchange of secret information between the user and the bank. To do this, the bank generates a public key, which is transmitted to their customer, and a private key, which it keeps secret. With the public key, the user can modify the information, make it unreadable and send it to the bank. With the private key, the bank can decipher it.
In 2022, the physics Nobel prize was awarded for experimental work showing that the quantum world must break some of our fundamental intuitions about how the Universe works.
Many look at those experiments and conclude that they challenge “locality” – the intuition that distant objects need a physical mediator to interact. And indeed, a mysterious connection between distant particles would be one way to explain these experimental results.
Others instead think the experiments challenge “realism” – the intuition that there’s an objective state of affairs underlying our experience. After all, the experiments are only difficult to explain if our measurements are thought to correspond to something real.
