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Category: quantum physics – Page 117

New study suggests that black holes may not be the featureless, structureless entities that Einstein’s general theory of relativity predicts them to be.

The frozen star is a recent proposal for a nonsingular solution of Einstein’s equations that describes an ultracompact object which closely resembles a black hole from an external perspective. The frozen star is also meant to be an alternative, classical description of an earlier proposal, the highly quantum polymer model. Here, we show that the thermodynamic properties of frozen stars closely resemble those of black holes: frozen stars radiate thermally, with a temperature and an entropy that are perturbatively close to those of black holes of the same mass. Their entropy is calculated using the Euclidean-action method of Gibbons and Hawking. We then discuss their dynamical formation by estimating the probability for a collapsing shell of “normal’’ matter to transition, quantum mechanically, into a frozen star.

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A Bose-Einstein condensate of cold atoms occupying a periodic lattice can flow like a superfluid. But if the atoms’ mutual repulsion is strengthened and the lattice potential deepened, the atoms can become immobilized in a state known as a Mott insulator. Now Hepeng Yao of the University of Geneva and his collaborators have examined the Mott transition of cold atoms trapped in a lattice that is quasiperiodic rather than periodic [1]. Given that quasiperiodicity and other kinds of disorder tend to trap particles, the researchers were surprised to discover that their quasiperiodic lattice sustained the superfluid state rather than weakening it.

Yao and his collaborators trapped potassium-39 atoms in a one-dimensional optical lattice formed by the standing waves of two lasers. If the ratio of the lasers’ wavelengths was a rational number, the lattice was periodic. Otherwise, the lattice was quasiperiodic. By adjusting various experimental parameters, they could control the depth of the confining potentials, the strength of the interatomic repulsion, and whether the lattice sites were fully occupied. To determine whether a given set of parameters yielded a static, insulating state or a mobile, superfluid one, they turned off the trap and observed how the atoms flew apart.

The team found that the Mott transitions for the periodic and quasiperiodic lattices were both characterized by a critical value of the interparticle repulsion, but the critical value in the quasiperiodic case was higher. Quantum Monte Carlo simulations pointed to the reason. The commensurability between the lattice period and the particle number is a key factor in pinning particles in a Mott insulator. However, the quasiperiodic lattice blurs this commensurate period, thereby destabilizing the Mott phase to the profit of the superfluid one.

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In the ever-evolving landscape of scientific discovery, certain paradigms periodically challenge the established norms, compelling us to reconsider the boundaries of what we deem as ‘science.’ One such paradigm is the intersection of quantum physics and metaphysical science. Despite skepticism, there is a growing body of evidence suggesting that these two fields are not only compatible but also complementary. This blog delves into how quantum physics supports metaphysical science and argues for its integration into mainstream scientific discourse, underpinned by historical precedents.

“The day science begins to study non-physical phenomena; it will make more progress in one decade than in all the previous centuries of its existence.” — Nikola Tesla

Quantum physics, the study of particles at the smallest scales of energy levels, has fundamentally altered our understanding of reality. The principles of quantum mechanics, such as superposition, entanglement, and wave-particle duality, have revealed a universe far more intricate and interconnected than classical physics ever suggested. These concepts resonate profoundly with metaphysical science, which explores the nature of reality, consciousness, and existence beyond the physical.

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Consciousness is famously unobservable. Therefore, to test for consciousness, we must study its absence rather than its presence. Stuart Hameroff here argues that by studying anesthesia we are able to understand what goes away in the brain when the light of consciousness is switched off. Hameroff finds the answer in quantum processes in the brain – recent studies suggest he is onto something.

This article is presented in association with Closer To Truth, a partner for HowTheLightGetsIn Festival 2024. The festival will feature the debate ‘The Consciousness Test’, featuring Sabine Hossenfelder, Yoshua Bengio, Nick Lane and Hilary Lawson.

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In recent years, a community of researchers from various universities and institutes across Europe and the United States set out to explore the physics of micro-and nano-mechanical devices coupled to light. The initial focus of these investigations was on demonstrating and exploiting uniquely quantum effects in the interaction of light and mechanical motion, such as quantum superposition, where a mechanical oscillator occupies two places simultaneously. The scope of this work quickly broadened as it became clear that these so-called optomechanical devices would open the door to a broad range of new applications.

Hybrid Optomechanical Technologies (HOT) is a research and innovation action funded by the European Commission’s FET Proactive program that supports future and emerging technologies at an early stage. HOT is laying the foundation for a new generation of devices that bring together several nanoscale platforms in a single hybrid system. It unites researchers from thirteen leading academic groups and four major industrial companies across Europe working to bring technologies to market that exploit the combination of light and motion.

One key set of advances made in the HOT consortium involves a family of non-reciprocal optomechanical devices, including optomechanical circulators. Imagine a device that acts like a roundabout for light or microwaves, where a signal input from one port emerges from a second port, and a signal input from that second port emerges from a third one, and so on. Such a device is critical to signal processing chains in radiofrequency or optical systems, as it allows efficient distribution of information among sources and receivers and protection of fragile light sources from unwanted back-reflections. It has however proven very tricky to implement a circulator at small scales without involving strong magnetic fields to facilitate the required unidirectional flow of signals.

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In recent years, these technological limitations have become far more pressing. Deep neural networks have radically expanded the limits of artificial intelligence—but they have also created a monstrous demand for computational resources, and these resources present an enormous financial and environmental burden. Training GPT-3, a text predictor so accurate that it easily tricks people into thinking its words were written by a human, costs $4.6 million and emits a sobering volume of carbon dioxide—as much as 1,300 cars, according to Boahen.

With the free time afforded by the pandemic, Boahen, who is faculty affiliate at the Wu Tsai Neurosciences Institute at Stanford and the Stanford Institute for Human-Centered AI (HAI), applied himself single mindedly to this problem. “Every 10 years, I realize some blind spot that I have or some dogma that I’ve accepted,” he says. “I call it ‘raising my consciousness.’”

This time around, raising his consciousness meant looking toward dendrites, the spindly protrusions that neurons use to detect signals, for a completely novel way of thinking about computer chips. And, as he writes in Nature, he thinks he’s figured out how to make chips so efficient that the enormous GPT-3 language prediction neural network could one day be run on a cell phone. Just as Feynman posited the “quantum supremacy” of quantum computers over traditional computers, Boahen wants to work toward a “neural supremacy.”

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Even those of us who aren’t physicists have an intuitive understanding of classical physics — we can predict what will happen when we throw a ball, use a salad spinner, or ease up on the gas pedal.

But atomic and subatomic particles don’t follow these ordinary rules of reality. “It turns out that at really small scales there are a different set of rules called quantum physics,” said Travis Nicholson. “These rules are bizarre and interesting.” (Think Schrodinger’s cat and Einstein’s “spooky action at a distance.”)

Nicholson is an assistant professor with joint appointments in Physics and Electrical and Computer Engineering. The physicist in him likes doing experiments to advance our knowledge of quantum mechanics; the engineer in him likes figuring out how to harness that knowledge to build quantum computers that will be vastly more powerful than today’s computers.

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