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Category: particle physics – Page 365

The prospects for directly testing a theory of quantum gravity are poor, to put it mildly. To probe the ultra-tiny Planck scale, where quantum gravitational effects appear, you would need a particle accelerator as big as the Milky Way galaxy. Likewise, black holes hold singularities that are governed by quantum gravity, but no black holes are particularly close by — and even if they were, we could never hope to see what’s inside. Quantum gravity was also at work in the first moments of the Big Bang, but direct signals from that era are long gone, leaving us to decipher subtle clues that first appeared hundreds of thousands of years later.

But in a small lab just outside Palo Alto, the Stanford University professor Monika Schleier-Smith and her team are trying a different way to test quantum gravity, without black holes or galaxy-size particle accelerators. Physicists have been suggesting for over a decade that gravity — and even space-time itself — may emerge from a strange quantum connection called entanglement. Schleier-Smith and her collaborators are reverse-engineering the process. By engineering highly entangled quantum systems in a tabletop experiment, Schleier-Smith hopes to produce something that looks and acts like the warped space-time predicted by Albert Einstein’s theory of general relativity.

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The Mu2e experiment at Fermilab will look for a never-before-seen subatomic phenomenon that, if observed, would transform our understanding of elementary particles: the direct conversion of a muon into an electron. An international collaboration of over 200 scientists is building the Mu2e precision particle detector that will hunt for new physics beyond the Standard Model.

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A gas made of particles of light, or photons, becomes easier to compress the more you squash it. This strange property could prove useful in making highly sensitive sensors.

While gases are normally made from atoms or molecules, it is possible to create a gas of photons by trapping them with lasers. But a gas made this way doesn’t have a uniform density – researchers say it isn’t homogeneous, or pure – making it difficult to study properly.

Now Julian Schmitt at the University of Bonn, Germany, and his colleagues have made a homogeneous photon gas for the first time by trapping photons between two nanoscale mirrors.

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The double-slit experiment is one of the most famous experiments in physics and definitely one of the weirdest. It demonstrates that matter and energy (such as light) can exhibit both wave and particle characteristics — known as the particle-wave duality of matter — depending on the scenario, according to the scientific communication site Interesting Engineering.

According to the University of Sussex, American physicist Richard Feynman referred to this paradox as the central mystery of quantum mechanics.

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Transmutex is reinventing nuclear energy from first principles using a process that uses radioactive waste as a fuel source.

Transmutex, a Swiss company, states on its website that it is “reinventing nuclear energy from first principles” by using a process that uses radioactive waste as a fuel source.

Its transmitter is a particle accelerator that produces nuclear energy with fewer contaminants than any reactor on the market today. The technology represents a valuable tool in the transition to intermittent renewables by providing baseload energy-producing alternatives to fossil-fuel thermal power stations.

The particle accelerator rather than the radioactive fuel creates a controlled nuclear reaction. Turn off the particle beam and the reaction stops immediately. The technology is designed to use a wide range of nuclear fuels including the radioactive waste from existing reactors.

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A team of researchers affiliated with multiple institutions in China and the U.S. has found that it is possible to track the sliding of grain boundaries in some metals at the atomic scale using an electron microscope and an automatic atom tracker. In their paper published in the journal Science, the group describes their study of platinum using their new technique and the discovery they made in doing so.

Scientists have been studying the properties of metals for many years. Learning more about how crystal grains in certain metals interact with one another has led to the development of new kinds of metals and applications for their use. In their recent effort, the researchers took a novel approach to studying the sliding that occurs between grains and in so doing have learned something new.

When crystalline metals are deformed, the grains that they are made of move against one another, and the way they move determines many of their properties, such as malleability. To learn more about what happens between grains in such metals during deformity, the researchers used two types of technologies: and automated atom-tracking.

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As scientists prepared in 2010 to collapse the first particles in the Large Hadron Collider (LHC), media representatives imagined that the EU-wide experiment could create a black hole that could swallow and destroy our planet. How on earth, columnists rage, could scientists justify such a dangerous indulgence for the pursuit of abstract, theoretical knowledge?

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The researchers simulated the molecules H4, molecular nitrogen, and solid diamond. These involved as many as 120 orbitals, the patterns of electron density formed in atoms or molecules by one or more electrons. These are the largest chemistry simulations performed to date with the help of quantum computers.

A classical computer actually handles most of this fermionic quantum Monte Carlo simulation. The quantum computer steps in during the last, most computationally complex step—calculating the differences between the estimates of the ground state made by the quantum computer and the classical computer.

The prior record for chemical simulations with quantum computing employed 12 qubits and a kind of hybrid algorithm known as a variational quantum eigensolver (VQE). However, VQEs possess a number of limitations compared with this new hybrid approach. For example, when one wants a very precise answer from a VQE, even a small amount of noise in the quantum circuitry “can cause enough of an error in our estimate of the energy or other properties that’s too large,” says study coauthor William Huggins, a quantum physicist at Google Quantum AI in Mountain View, Calif.

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The problem is that transitions from one s-orbital to another are forbidden, quantum mechanically. There’s no way to emit one photon from an s-orbital and have your electron wind up in a lower energy s-orbital, so the transition we talked about earlier, where you emit a Lyman-series photon, can only occur from the 2 p state to the 1s state.

But there is a special, rare process that can occur: a two-photon transition from the 2s state (or the 3s, or 4s, or even the 3 d orbital) down to the ground (1s) state. It occurs only about 0.000001% as frequently as the Lyman-series transitions, but each occurrence nets us one new neutral hydrogen atom. This quantum mechanical quirk is the primary method of creating neutral hydrogen atoms in the Universe.

If it weren’t for this rare transition, from higher energy spherical orbitals to lower energy spherical orbitals, our Universe would look incredibly different in detail. We would have different numbers and magnitudes of acoustic peaks in the cosmic microwave background, and hence a different set of seed fluctuations for our Universe to build its large-scale structure out of. The ionization history of our Universe would be different; it would take longer for the first stars to form; and the light from the leftover glow of the Big Bang would only take us back to 790,000 years after the Big Bang, rather than the 380,000 years we get today.

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