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Category: quantum physics – Page 236

The surprising behavior of black holes in an expanding universe

A physicist investigating black holes has found that, in an expanding universe, Einstein’s equations require that the rate of the universe’s expansion at the event horizon of every black hole must be a constant, the same for all black holes. In turn this means that the only energy at the event horizon is dark energy, the so-called cosmological constant. The study is published on the arXiv preprint server.

“Otherwise,” said Nikodem Popławski, a Distinguished Lecturer at the University of New Haven, “the pressure of matter and curvature of spacetime would have to be infinite at a horizon, but that is unphysical.”

Black holes are a fascinating topic because they are about the simplest things in the universe: their only properties are mass, electric charge and angular momentum (spin). Yet their simplicity gives rise to a fantastical property—they have an event horizon at a critical distance from the black hole, a nonphysical surface around it, spherical in the simplest cases. Anything closer to the black hole, that is, inside the event horizon, can never escape the black hole.

Understanding quantum states: New research shows importance of precise topography in solid neon qubits

Quantum computers have the potential to be revolutionary tools for their ability to perform calculations that would take classical computers many years to resolve.

But to make an effective quantum computer, you need a reliable quantum bit, or , that can exist in a simultaneous 0 or 1 state for a sufficiently long period, known as its coherence time.

One promising approach is trapping a on a solid surface, called an electron-on-solid-neon qubit. A study led by FAMU-FSU College of Engineering Professor Wei Guo that was published in Physical Review Letters shows new insight into the that describes the condition of electrons on such a qubit, information that can help engineers build this innovative technology.

Researchers capture detailed picture of electron acceleration in one shot

Adjusting experimental methods achieved the first “single-shot” diagnosis of electron acceleration through a laser wakefield accelerator along a curved trajectory, according to a recent study led by University of Michigan researchers. The findings are published in the journal Physical Review Letters.

This optical-based technique could help engineers develop more powerful electron accelerators for fundamental studies of quantum and —or more compact accelerators for use in medicine and industry.

Compared to traditional accelerators which can be kilometers long, laser wakefield accelerators can apply 1,000 times more energy per meter, allowing a vastly more compact design able to fit into a large room.

Time-compression in electron microscopy: Terahertz light controls and characterizes electrons in space and time

Scientists at the University of Konstanz in Germany have advanced ultrafast electron microscopy to unprecedented time resolution. Reporting in Science Advances, the research team presents a method for the all-optical control, compression, and characterization of electron pulses within a transmission electron microscope using terahertz light. Additionally, the researchers have discovered substantial anti-correlations in the time domain for two-electron and three-electron states, providing deeper insight into the quantum physics of free electrons.

Ultrafast electron microscopy is a cutting-edge technique that combines the spatial resolution of traditional electron microscopy with the of ultrafast femtosecond laser pulses. This powerful combination allows researchers to observe atoms and electrons in motion, capturing dynamic processes in materials with unparalleled clarity. By visualizing these rapid events in space and time, scientists can gain deeper insights into the fundamental mechanisms that govern and transitions, helping to create advancements in research fields such as nanotechnology, optics, materials science, and .

Although ultrafast electron microscopy enables, in principle, the observation of atomic and electronic motions on fundamental spatial and temporal scales, capturing these rapid dynamics has remained challenging due to the limitations in electron pulse duration. The current standard electron pulses, lasting about 200 femtoseconds, are too long to resolve many fundamental reaction processes in materials and molecules. Pulses ten times shorter would be required to observe basic reaction paths and collective atomic motions, so-called phonon modes, in real time.

Engineers produce the world’s first practical Titanium-sapphire laser on a chip

As lasers go, those made of Titanium-sapphire (Ti: sapphire) are considered to have “unmatched” performance. They are indispensable in many fields, including cutting-edge quantum optics, spectroscopy, and neuroscience. But that performance comes at a steep price. Ti: sapphire lasers are big, on the order of cubic feet in volume. They are expensive, costing hundreds of thousands of dollars each. And they require other high-powered lasers, themselves costing $30,000 each, to supply them with enough energy to function.

As a result, Ti: lasers have never achieved the broad, real-world adoption they deserve—until now. In a dramatic leap forward in scale, efficiency, and cost, researchers at Stanford University have built a Ti: sapphire laser on a chip. The prototype is four orders of magnitude smaller (10,000x) and three orders less expensive (1,000x) than any Ti: sapphire laser ever produced.

“This is a complete departure from the old model,” said Jelena Vučković, the Jensen Huang Professor in Global Leadership, a professor of electrical engineering, and senior author of the paper introducing the chip-scale Ti: sapphire laser published in the journal Nature.

Raphael Bousso — Is Information Fundamental?

Watch more interviews on the deep laws of nature: https://shorturl.at/P6tIr Does information work at the deep levels of physics, including quantum theory, undergirding the fundamental forces and particles? But what is the essence of information—describing how the world works or being how the world works. There is a huge difference. Could information be the most basic building block of reality? Support the show with Closer To Truth merchandise: https://bit.ly/3P2ogje Follow us on Instagram for news, giveaways, announcements, and more: https://shorturl.at/dnA39 Raphael Bousso is a theoretical physicist and string theorist. He is a professor at Department of Physics, UC Berkeley. He is known for the proposal of Bousso’s holographic bound, also known as the covariant entropy bound. For members-only benefits, register for a free CTT account today: https://shorturl.at/ajRZ8 Closer To Truth, hosted by Robert Lawrence Kuhn and directed by Peter Getzels, presents the world’s greatest thinkers exploring humanity’s deepest questions. Discover fundamental issues of existence. Engage new and diverse ways of thinking. Appreciate intense debates. Share your own opinions. Seek your own answers.

Exploring the Fabric of the Universe: Hadrons to Cosmological Constant

Within the vast tapestry of the universe, where the microscopic building blocks of matter intertwine with the cosmic dance of galaxies, lies a story of profound discovery. Venture into a realm where the laws of physics as we know them are both challenged and confirmed, where the invisible forces that hold the very fabric of our reality together are brought into the light. This narrative isn’t born from the pages of a science fiction novel but emerges from the cutting-edge explorations at the heart of quantum physics. At this frontier, scientists embark on a rigorous inquiry to understand the origins of particle mass, revealing insights that connect the infinitesimal to the immense, from the atoms in our bodies to the distant stars.

On quantum computing for artificial superintelligence

Artificial intelligence algorithms, fueled by continuous technological development and increased computing power, have proven effective across a variety of tasks. Concurrently, quantum computers have shown promise in solving problems beyond the reach of classical computers. These advancements have contributed to a misconception that quantum computers enable hypercomputation, sparking speculation about quantum supremacy leading to an intelligence explosion and the creation of superintelligent agents. We challenge this notion, arguing that current evidence does not support the idea that quantum technologies enable hypercomputation. Fundamental limitations on information storage within finite spaces and the accessibility of information from quantum states constrain quantum computers from surpassing the Turing computing barrier.

Gold nanomembrane coaxes secrets out of surfaces

“Surfaces were invented by the devil” — this quote is attributed to the theoretical physicist Wolfgang Pauli, who taught at ETH Zurich for many years and in 1945 received the Nobel Prize in physics for his contributions to quantum mechanics. Researchers do, indeed, struggle with surfaces. On the one hand they are extremely important both in animate and inanimate nature, but on the other hand it can be devilishly difficult to study them with conventional methods.

An interdisciplinary team of materials scientists and electrical engineers led by Lukas Novotny, Professor of Photonics at ETH Zurich, together with colleagues at Humboldt-Universität zu Berlin has now developed a method that will make the characterization of surfaces considerably easier in the future.

They recently published the results of their research, which is based on an extremely thin gold membrane, in the scientific journal Nature Communications (“Bulk-suppressed and surface-sensitive Raman scattering by transferable plasmonic membranes with irregular slot-shaped nanopores”).