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The giant CMS detector at the Large Hadron Collider will search for double-Higgs events.
IMAGE: MICHAEL HOCH AND MAXIMILIEN BRICE
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Quantum particles can be difficult to characterize, and almost impossible to control if they strongly interact with each other—until now.
An international team of researchers led by Princeton physicist Zahid Hasan has discovered a quantum state of matter that can be “tuned” at will—and it’s 10 times more tuneable than existing theories can explain. This level of manipulability opens enormous possibilities for next-generation nanotechnologies and quantum computing.
“We found a new control knob for the quantum topological world,” said Hasan, the Eugene Higgins Professor of Physics. “We expect this is tip of the iceberg. There will be a new subfield of materials or physics grown out of this. … This would be a fantastic playground for nanoscale engineering.”
Graphene — an ultrathin material consisting of a single layer of interlinked carbon atoms — is considered a promising candidate for the nanoelectronics of the future. In theory, it should allow clock rates up to a thousand times faster than today’s silicon-based electronics. Scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) and the University of Duisburg-Essen (UDE), in cooperation with the Max Planck Institute for Polymer Research (MPI-P), have now shown for the first time that graphene can actually convert electronic signals with frequencies in the gigahertz range — which correspond to today’s clock rates — extremely efficiently into signals with several times higher frequency. The researchers present their results in the scientific journal Nature.
A system made of just a handful of particles acts just like larger systems, allowing scientists to study quantum behaviour more easily.
Most substances physicists study are made up of huge numbers of particles—so large that there is essentially no difference between the behavioural properties of a drop or a swimming pool’s worth of pure water. Even a single drop can contain more than a quadrillion particles.
This makes understanding their collective behaviour relatively easy. For example, both the water in the drop and in the pool will freeze at 0C and boil at 100C.
Austrian physicist Erwin Schrödinger (1887−1961), one of the giants of contemporary science, considered entanglement the most interesting property in quantum mechanics. In his view, it was this phenomenon that truly distinguished the quantum world from the classical world. Entanglement occurs when groups of particles or waves are created or interact in such a way that the quantum state of each particle or wave cannot be described independently of the others, however far apart they are. Experiments performed at the University of São Paulo’s Physics Institute (IF-USP) in Brazil have succeeded in entangling six light waves generated by a simple laser light source known as an optical parametric oscillator.
Articles about these experiments have been published in Physical Review Letters and Physical Review A. The experiments are highlighted in a special news feature posted online.
“Our platform is capable of generating a massive entanglement of many optical modes with different but well-defined frequencies, as if connecting the nodes of a large network. The quantum states thus produced can be controlled by a single parameter: the power of the external laser that pumps the system,” said Marcelo Martinelli, one of the coordinators of the experiments. Martinelli is a professor at IF-USP and the principal investigator for the project.
Rice University atomic physicists have verified a key prediction from a 55-year-old theory about one-dimensional electronics that is increasingly relevant thanks to Silicon Valley’s inexorable quest for miniaturization.
“Chipmakers have been shrinking feature sizes on microchips for decades, and device physicists are now exploring the use of nanowires and nanotubes where the channels that electrons pass through are almost one-dimensional,” said Rice experimental physicist Randy Hulet. “That’s important because 1D is a different ballgame in terms of electron conductance. You need a new model, a new way of representing reality, to make sense of it.”
With IBM and others committed to incorporating one-dimensional carbon nanotubes into integrated circuits, chip designs will increasingly need to account for 1D effects that arise from electrons being fermions, antisocial particles that are unwilling to share space.
Aug. 28 (UPI) — Particle physicists have finally witnessed the decay of a Higgs boson particle into two bottom quarks.
Models predict Higgs boson particles decay into two bottom quarks 60 percent of the time. Bottom quarks, or b quarks, are the second heaviest of the six types of quarks.
Scientists have struggled to directly observe the predicted decay. Several types of proton-proton collisions can produce bottom quarks, making it difficult to link quarks produced by particle collisions with decaying Higgs boson particles.
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After their recent pioneering experiments to couple light and matter to an extreme degree, Rice University scientists decided to look for a similar effect in matter alone. They didn’t expect to find it so soon.
Rice physicist Junichiro Kono, graduate student Xinwei Li and their international colleagues have discovered the first example of Dicke cooperativity in a matter-matter system, a result reported in Science this week.
The discovery could help advance the understanding of spintronics and quantum magnetism, Kono said. On the spintronics side, he said the work will lead to faster information processing with lower power consumption and will contribute to the development of spin-based quantum computing. The team’s findings on quantum magnetism will lead to a deeper understanding of the phases of matter induced by many-body interactions at the atomic scale.
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