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Category: particle physics

Structured light beams can serve as vortex beams carrying optical angular momentum and have been used to enhance optical communications and imaging. Rego et al. generated dynamic vortex pulses by interfering two incident time-delayed vortex beams with different orbital angular momenta through the process of high harmonic generation. A controlled time delay between the pulses allowed the high harmonic extreme-ultraviolet vortex beam to exhibit a time-dependent angular momentum, called self-torque. Such dynamic vortex pulses could potentially be used to manipulate nanostructures and atoms on ultrafast time scales.

Science, this issue p. eaaw9486.

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Physicists at the National Institute of Standards and Technology (NIST) have teleported a computer circuit instruction known as a quantum logic operation between two separated ions (electrically charged atoms), showcasing how quantum computer programs could carry out tasks in future large-scale quantum networks.

Quantum teleportation transfers data from one quantum system (such as an ion) to another (such as a second ion), even if the two are completely isolated from each other, like two books in the basements of separate buildings. In this real-life form of teleportation, only quantum information, not matter, is transported, as opposed to the Star Trek version of “beaming” entire human beings from, say, a spaceship to a planet.

Teleportation of quantum data has been demonstrated previously with ions and a variety of other quantum systems. But the new work is the first to teleport a complete quantum logic operation using ions, a leading candidate for the architecture of future quantum computers. The experiments are described in the May 31 issue of Science.

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In conventional imaging methods, a beam of photons (or other particles) is reflected off the object to be imaged. After the beam travels to a detector, the information gathered there is used to create a photograph or other type of image. In an alternative imaging technique called “ghost imaging,” the process works a little differently: an image is reconstructed from information that is detected from a beam that never actually interacts with the object.

The key to is to use two or more correlated beams of particles. While one interacts with the object, the second beam is detected and used to reconstruct the image, even though the second beam never interacts with the object. The only aspect of the first beam that is detected is the arrival time of each photon on a separate detector. But because the two beams are correlated, the image of the object can be fully reconstructed.

While two beams are usually used in ghost imaging, recent research has demonstrated higher-order correlations—that is, correlations among three, four, or five beams. Higher-order ghost imaging can lead to improvements in image visibility, but it comes with the drawback that higher-order correlated events have a lower probability of detection, which causes lower resolution.

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Circa 2014

A team of researchers from Princeton University has started doing some very strange things with light. Instead of letting it zip by at incredibly high speed, they’re stopping it dead: freezing it into crystal.

Crucially, they’re not shining light through crystal; rather, they making light into crystal. It’s a process that involves fixing the particles of light known as photons in a single spot, freezing them permanently in one place. It’s never been done before, and it could help develop new exotic materials with weird and wonderful properties.

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Particle physicists might seem like a dry bunch, but they have their fun. Why else would there be such a thing as a “strange quark”? When it comes to the fundamental nuclear forces, though, they don’t mess around: the strongest force in nature is known simply as the “strong force,” and it’s the force that literally holds existence together.

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The Standard Model is a remarkably successful but incomplete theory. Supersymmetry (SUSY) offers an elegant solution to the Standard Model’s limitations, extending it to give each particle a heavy “superpartner” with different spin properties (an important quantum number distinguishing matter particles from force particles and the Higgs boson). For example, sleptons are the spin 0 superpartners of spin 1/2 electrons, muons and tau leptons, while charginos and neutralinos are the spin 1/2 counterparts of the spin 0 Higgs bosons (SUSY postulates a total of five Higgs bosons) and spin 1 gauge bosons.

If these superpartners exist and are not too massive, they will be produced at CERN’s Large Hadron Collider (LHC) and could be hiding in data collected by the ATLAS detector. However, unlike most processes at the LHC, which are governed by strong force interactions, these superpartners would be created through the much weaker electroweak interaction, thus lowering their production rates. Further, most of these new SUSY particles are expected to be unstable. Physicists can only search for them by tracing their decay products—typically into a known Standard Model particle and the lightest supersymmetric particle (LSP), which could be stable and non-interacting, thus forming a natural dark matter candidate.

On 20 May, 2019, at the Large Hadron Collider Physics (LHCP) conference in Puebla, Mexico, and at the SUSY2019 conference in Corpus Christi, U.S., the ATLAS Collaboration presented numerous new searches for SUSY based on the full LHC Run 2 dataset (taken between 2015 and 2018), including two particularly challenging searches for electroweak SUSY. Both searches target particles that are produced at extremely low rates at the LHC, and decay into Standard Model particles that are themselves difficult to reconstruct. The large amount of data successfully collected by ATLAS in Run 2 provides a unique opportunity to explore these scenarios with new analysis techniques.

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One of the essential features required for the realization of a quantum computer is quantum entanglement. A team of physicists from the University of Vienna and the Austrian Academy of Sciences (ÖAW) introduces a novel technique to detect entanglement even in large-scale quantum systems with unprecedented efficiency. This brings scientists one step closer to the implementation of reliable quantum computation. The new results are of direct relevance for future generations of quantum devices and are published in the current issue of the journal Nature Physics.

Quantum computation has been drawing the attention of many scientists because of its potential to outperform the capabilities of standard computers for certain tasks. For the realization of a quantum computer, one of the most essential features is quantum entanglement. This describes an effect in which several quantum particles are interconnected in a complex way. If one of the entangled particles is influenced by an external measurement, the state of the other entangled particle changes as well, no matter how far apart they may be from one another. Many scientists are developing new techniques to verify the presence of this essential quantum feature in quantum systems. Efficient methods have been tested for systems containing only a few qubits, the basic units of quantum information. However, the physical implementation of a quantum computer would involve much larger quantum systems.

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Nuclear magnetic resonance (NMR) spectroscopy is one of the most important methods of physicochemical analysis. It can be used to determine precise molecular structures and dynamics. The importance of this method is also evidenced by the recognition of ETH Zurich’s two latest Nobel laureates, Richard Ernst and Kurt Wüthrich, for their contributions to refining the method.

The technique is based on , which takes advantage of the fact that certain atomic nuclei interact with a magnetic field. A key factor here is nuclear spin, which can be compared with the spinning of a child’s top. Similar to a top that begins to wobble, a phenomenon called precession, nuclear spins that are exposed to a magnetic field begin to precess. This generates an electromagnetic signal that can be measured using an induction coil.

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Physicists have spotted the highest-energy light ever seen. It emanated from the roiling remains left behind when a star exploded.

This light made its way to Earth from the Crab Nebula, a remnant of a stellar explosion, or supernova, about 6,500 light-years away in the Milky Way. The Tibet AS-gamma experiment caught multiple particles of light — or photons — from the nebula with energies higher than 100 trillion electron volts, researchers report in a study accepted in Physical Review Letters. Visible light, for comparison, has just a few electron volts of energy.“This energy regime has not been accessible before,” says astrophysicist Petra Huentemeyer of Michigan Technological University in Houghton, who was not involved with the research. For physicists who study this high-energy light, known as gamma rays, “it’s an exciting time,” she says.

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