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Category: particle physics – Page 138

Physicists in the MIT-Harvard Center for Ultracold Atoms (CUA) have developed a new approach to control the outcome of chemical reactions. This is traditionally done using temperature and chemical catalysts, or more recently with external fields (electric or magnetic fields, or laser beams).

MIT CUA physicists have now added a new twist to this: They have used minute changes in a magnetic field to make subtle changes to the quantum mechanical wavefunction of the colliding particles during the chemical reaction. They show how this technique can steer reactions to a different outcome: enhancing or suppressing reactions.

This was only possible by working at ultralow temperatures at a millionth of a degree above absolute zero, where collisions and chemical reactions occur in single quantum states. Their research was published in Science on March 4.

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New insights into near-Earth space’s hazardous environment could revolutionize space weather prediction, driven by collaborative international research.

A challenge to space scientists to better understand our hazardous near-Earth space environment has been set in a new study led by the University of Birmingham.

The research represents the first step towards new theories and methods that will help scientists predict and analyze the behavior of particles in space. It has implications for theoretical research, as well as for practical applications such as space weather forecasting.

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The results, continuing the legacy of late Columbia professor Aron Pinczuk, are a step toward a better understanding of gravity.

A team of scientists from Columbia, Nanjing University, Princeton, and the University of Munster, writing in the journal Nature, have presented the first experimental evidence of collective excitations with spin called chiral graviton modes (CGMs) in a semiconducting material.

A CGM appears to be similar to a graviton, a yet-to-be-discovered elementary particle better known in high-energy quantum physics for hypothetically giving rise to gravity, one of the fundamental forces in the universe, whose ultimate cause remains mysterious.

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A nanoresonator trapped in ultrahigh vacuum features an exceptionally high quality factor, showing promise for applications in force sensors and macroscopic tests of quantum mechanics.

Nanomechanical oscillators could be used to build ultrasensitive sensors and to test macroscopic quantum phenomena. Key to these applications is a high quality factor (Q), a measure of how many oscillation cycles can be completed before the oscillator energy is dissipated. So far, clamped-membrane nanoresonators achieved a Q of about 1010, which was limited by interactions with the environment. Now a team led by Tracy Northup at the University of Innsbruck, Austria, reports a levitated oscillator—a floating particle oscillating in a trap—competitive with the best clamped ones [1]. The scheme offers potential for order-of-magnitude improvements, the researchers say.

Theorists have long predicted that levitated oscillators, by eliminating clamping-related losses, could reach a Q as large as 1012. Until now, however, the best levitated schemes, based on optically trapped nanoparticles, achieved a Q of only 108. To further boost Q, the Innsbruck researchers devised a scheme that mitigated two important dissipation mechanisms. First, they replaced the optical trap with a Paul trap, one that confines a charged particle using time-varying electric fields instead of lasers. This approach eliminates the dissipation associated with light scattering from the trapped particle. Second, they trapped the particle in ultrahigh vacuum, where the nanoparticle collides with only about one gas molecule in each oscillation cycle.

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The full collection of top quark mass measurements by the CMS experiment! 🗝

What’s the best way to pin down the exact mass of this enigmatic particle? Discover the diverse strategies perfected by CMS over the last decade:

When it comes to top quark mass measurements, the CMS collaborati on has the largest and most complete collection of publication-quality results, cov ering a wide range of methods and approaches. In a recent review paper, an overview is given of all top quark mass measurements published by CMS so far. In the quest to pin down the exact mass of this enigmatic particle, different methods were developed and perfected over the last decade.

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Southwest Research Institute has invested in research to enhance the capabilities of spacecraft instruments. Consequently, they have developed more effective conversion surfaces for the detection and analysis of low-energy particles in outer space.

Led by Dr. Jianliang Lin of Mechanical Engineering and Dr. Justyna Sokół of the Space Science Division, the project could potentially change our understanding of space physics and exploration.

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🔗 Top quark and top antiquark entanglement 🔗

The CMS experiment has just reported the observation and confirms the existence of #entanglement between the top #quark and its #Antiparticle beyond reasonable doubt.

The CMS experiment has just reported the observation of quantum entanglement between a top quark and a top antiquark, simultaneously produced at the LHC.

In quantum mechanics, a system is said to be entangled if its quantum state cannot be described as a simple superposition of the states of its constituents. If two particles are entangled, we cannot describe one of them independently of the other, even if the particles are separated by a very large distance. When we measure the quantum state of one of the two particles, we instantly know the state of the other. The information is not transmitted via any physical channel; it is encoded in the correlated two-particle system.

Quantum information is a field of physics that was born with the work of John Bell, a CERN physicist, in the mid 1960’s. Soon after, Aspect, Clouser, and other physicists did important pioneering experimental work to test “Bell’s theorem”, and in 2007 Zeilinger’s team convincingly demonstrated the existence of entanglement between two photons, too far away from each other for the information to travel between them at the speed of light. This breakthrough brought Aspect, Clauser, and Zeilinger the 2022 Nobel Prize in Physics, “for experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science”. Quantum entanglement was mostly examined for states of photons and electrons until 2023, when ATLAS reported the observation of entanglement in the top quark-antiquark system.

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