Lifeboat Foundation

New particles sensitive to the strong interaction might be produced in abundance in the proton-proton collisions generated by the Large Hadron Collider (LHC) – provided that they aren’t too heavy. These particles could be the partners of gluons and quarks predicted by supersymmetry (SUSY), a proposed extension of the Standard Model of particle physics that would expand its predictive power to include much higher energies. In the simplest scenarios, these “gluinos” and “squarks” would be produced in pairs, and decay directly into quarks and a new stable neutral particle (the “neutralino”), which would not interact with the ATLAS detector. The neutralino could be the main constituent of dark matter.

The ATLAS Collaboration has been searching for such processes since the early days of LHC operation. Physicists have been studying collision events featuring “jets” of hadrons, where there is a large imbalance in the momenta of these jets in the plane perpendicular to the colliding protons (“missing transverse momentum,” E_T^miss). This missing momentum would be carried away by the undetectable neutralinos. So far, ATLAS searches have led to increasingly tighter constraints on the minimum possible masses of squarks and gluinos.

Is it possible to do better with more data? The probability of producing these heavy particles decreases exponentially with their masses, and thus repeating the previous analyses with a larger dataset only goes so far. New, sophisticated methods that help to better distinguish a SUSY signal from the background Standard Model events are needed to take these analyses further. Crucial improvements may come from increasing the efficiency for selecting signal events, improving the rejection of background processes, or looking into less-explored regions.

For years, scientists have looked for ways to cool molecules down to ultracold temperatures, at which point the molecules should slow to a crawl, allowing scientists to precisely control their quantum behavior. This could enable researchers to use molecules as complex bits for quantum computing, tuning individual molecules like tiny knobs to carry out multiple streams of calculations at a time.

While scientists have super-cooled atoms, doing the same for molecules, which are more complex in their behavior and structure, has proven to be a much bigger challenge.

Now MIT physicists have found a way to cool molecules of sodium lithium down to 200 billionths of a Kelvin, just a hair above absolute zero. They did so by applying a technique called collisional cooling, in which they immersed molecules of cold sodium lithium in a cloud of even colder sodium atoms. The ultracold atoms acted as a refrigerant to cool the molecules even further.

“Collisional cooling has been the workhorse for cooling atoms,” adds Nobel Prize laureate Wolfgang Ketterle, the John D. Arthur professor of physics at MIT. “I wasn’t convinced that our scheme would work, but since we didn’t know for sure, we had to try it. We know now that it works for cooling sodium lithium molecules. Whether it will work for other classes of molecules remains to be seen.” MIT School of Science, Harvard — MIT Center for Ultracold Atoms, RLE at MIT — Research Laboratory of Electronics at MIT, #research #supercooledatoms #nanokelvin #WolfgangKetterle

Technique may enable molecule-based quantum computing.

Dynamical fermionization involves velocity, as well as position.

The Belle II experiment finds no Z′ boson in its first results, but it does constrain how strongly the particle might interact with standard model particles.

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In novel concepts of magnetic data storage, it is intended to send small magnetic bits back and forth in a chip structure, store them densely packed and read them out later. The magnetic stray field generates problems when trying to generate particularly tiny bits. Now, researchers at the Max Born Institute (MBI), the Massachusetts Institute of Technology (MIT) and DESY were able to put an “invisibility cloak” over the magnetic structures. In this fashion, the magnetic stray field can be reduced in a fashion allowing for small yet mobile bits. The results were published in Nature Nanotechnology.

For physicists, magnetism is intimately coupled to rotating motion of electrons in atoms. Orbiting around the atomic nucleus as well as around their own axis, electrons generate the magnetic moment of the atom. The magnetic stray field associated with that magnetic moment is the property we know from e.g. a bar magnet we use to fix notes on pinboard. It is also the magnetic stray field that is used to read the information from a magnetic hard disk drive. In today’s hard disks, a single magnetic bit has a size of about 15 × 45 nanometer, about 1,000,000,000,000 of those would fit on a stamp.

One vision for a novel concept to store data magnetically is to send the magnetic bits back and forth in a memory chip via current pulses, in order to store them at a suitable place in the chip and retrieve them later. Here, the magnetic stray field is a bit of a curse, as it prevents that the bits can be made smaller for even denser packing of the information. On the other hand, the magnetic moment underlying the stray field is required to be able to move the structures around.

Accelerating electrons to such high energies in a laboratory setting, however, is challenging: typically, the more energetic the electrons, the bigger the particle accelerator. For instance, to discover the Higgs boson—the recently observed “God particle,” responsible for mass in the universe—scientists at the CERN laboratory in Switzerland used a particle accelerator nearly 17 miles long.

But what if there was a way to scale down particle accelerators, producing high-energy electrons in a fraction of the distance?

Particle chasing—it’s a game that so many physicists play. Sometimes the hunt takes place inside large supercolliders, where spectacular collisions are necessary to find hidden particles and new physics. For physicists studying solids, the game occurs in a much different environment and the sought-after particles don’t come from furious collisions. Instead, particle-like entities, called quasiparticles, emerge from complicated electronic interactions that happen deep within a material. Sometimes the quasiparticles are easy to probe, but others are more difficult to spot, lurking just out of reach.

New measurements show evidence for the presence of exotic Majorana particles on the surface of an unconventional superconductor, Uranium ditelluride. Graphic provided by Dr. E. Edwards, Managing Director of Illinois Quantum Information Science and Technology Center (IQUIST).

Now a team of researchers at the University of Illinois, led by physicist Vidya Madhavan, in collaboration with researchers from the National Institute of Standards and Technology, the University of Maryland, Boston College, and ETH Zurich, have used high-resolution microscopy tools to peer at the inner-workings of an unusual type of superconductor, uranium ditelluride (UTe₂). Their measurements reveal strong evidence that this material may be a natural home to an exotic quasiparticle that’s been hiding from physicists for decades. The study is published in the March 26 issue of Nature.