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Category: particle physics – Page 173

A nitrogen-vacancy (NV) center is a defect in the crystal structure of diamond, where a nitrogen atom replaces a carbon atom in the diamond lattice and a neighboring site in the lattice is vacant. This and other fluorescent defects in diamond, known as color centers, have attracted researchers’ attention owing to their quantum properties, such as single-photon emission at room temperature and with long coherence time. Their many applications include quantum information encoding and processing, and cell marking in biological studies.

Microfabrication in diamond is technically difficult, and nanodiamonds with color centers have been embedded in custom-designed structures as a way of integrating these quantum emitters into photonic devices. A study conducted at the University of São Paulo’s São Carlos Institute of Physics (IFSC-USP) in Brazil has established a method for this, as described in an article published in the journal Nanomaterials.

“We demonstrated a method of embedding fluorescent nanodiamonds in designed for this purpose, using two-photon polymerization [2PP],” Cleber Mendonça, a professor at IFSC-USP and last author of the article, told Agência FAPESP. “We studied the ideal concentration of nanodiamond in the photoresist to achieve structures with at least one fluorescent NV center and good structural and optical quality.” The photoresist is a light-sensitive material used in the fabrication process to transfer nanoscale patterns to the substrate.

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Moore’s Law predicts that computers get faster every two years because of the evolution of semiconductor chips.

Researchers at Tohoku University and the University of California, Santa Barbara, have shown a proof-of-concept of energy-efficient computer compatible with current AI. It utilizes a stochastic behavior of nanoscale spintronics devices and is particularly suitable for probabilistic computation problems such as inference and sampling.

The team presented the results at the IEEE International Electron Devices Meeting (IEDM 2023) on December 12, 2023.

With the slowing down of Moore’s Law, there has been an increasing demand for domain-specific hardware. A probabilistic computer with naturally stochastic building blocks (probabilistic bits, or p-bits) is a representative example due to its potential capability to efficiently address various computationally hard tasks in machine learning (ML) and artificial intelligence (AI).

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In December 2022, NASA’s MAVEN mission observed a rare solar event causing the solar wind to “disappear.” This led to significant changes in Mars’ atmosphere and magnetosphere, including their expansion. Scientists, astounded by the data, formed a working group to study this phenomenon. Credit: SciTechDaily.com.

NASA ’s MAVEN detected a unique solar event that drastically affected Mars ’ atmosphere, offering vital insights into the planet’s interaction with solar phenomena.

In December 2022, NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) mission observed the dramatic and unexpected “disappearance” of a stream of charged particles constantly emanating off the Sun, known as the solar wind. This was caused by a special type of solar event that was so powerful, it created a void in its wake as it traveled through the solar system.

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If successful, the experiments would not only affirm some of the theories proposing the quantum nature of gravity but could also finally unify general relativity with theories of quantum mechanics.

Unifying General Relativity with Quantum Mechanics Has Proven Elusive

“General relativity and quantum mechanics are the two most fundamental descriptions of nature we have,” explains the press release announcing the new experiments. “General relativity explains gravity on large scales while quantum mechanics explains the behaviour of atoms and molecules.”

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SpaceX rockets are tearing holes in the Earth’s atmosphere as they make their return to the surface, triggering what scientists are calling “SpaceX auroras,” a newly coined term that refers to red, spherical spots in the night sky that can easily be seen with the naked eye.

As Spaceweather.com reports, the name isn’t entirely accurate as they’re technically not auroras. They’re the result of SpaceX rockets burning their engines in the Earth’s ionosphere, a part of the upper atmosphere where solar radiation ionizes atoms and molecules to create a protective layer of electrons.

That means that as the rocketmaker ratchets up its launch schedule, that could be a problem, because the ionosphere serves an important technical function by ensuring the stability of shortwave radio communication and GPS signals.

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The experiment mirrored the principles of the quantum bomb tester, where a photon’s wave-particle behavior was theorized to detect the presence of a bomb without directly interacting with it.

A new study demonstrated how a droplet’s behavior imitates certain behaviors predicted for quantum particles — particularly photons.

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Scientists from the Leibniz Institute for Astrophysics Potsdam (AIP) have discovered a new plasma instability that promises to revolutionize our understanding of the origin of cosmic rays and their dynamic impact on galaxies.

At the beginning of the last century, Victor Hess discovered a new phenomenon called that later on earned him the Nobel prize. He conducted high-altitude balloon flights to find that the Earth’s atmosphere is not ionized by the radioactivity of the ground. Instead, he confirmed that the origin of ionization was extra-terrestrial. Subsequently, it was determined that cosmic “rays” consist of charged from flying close to the speed of light rather than radiation. However, the name “cosmic rays” outlasted these findings.

In the new study, Dr. Mohamad Shalaby, scientists at AIP and the main author of this study, and his collaborators have performed to follow the trajectories of many cosmic ray particles and study how these interact with the surrounding plasma consisting of electrons and protons. The paper appears on the pre-print server arXiv.

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During their recent visit to CERN, Presidents Berset and Macron were given an introduction to the Laboratory by Fabiola. President Macron appeared to be really interested in the origins of the Universe, and explanations went way over time! The entourage were then whisked down to the LHC tunnel and through to the ATLAS cavern. It’s hard not be impressed, the LHC is the LHC and ATLAS is awe inspiring. What they didn’t see, however, was the near miraculous demonstration of technological prowess that underpins all of this. Taking a step back, it’s quite remarkable what we do here. One can weave a number of threads through the accelerator complex, from the chopper of Linac 4 to the PS RF system, the multi-cycling synchronisation of everything, the production of radioactive ion beams, the vacuum systems from ELENA to the LHC, the n_TOF target, stochastic cooling of antiprotons, the power converters, the magnets (from 1959 to 2023), beam instrumentation, the LHC transverse feedback system… and but wonder that it all comes together as well as it does. It’s worth reflecting on this, as we look back on another year in the life of an unparalleled collection of accelerators and facilities, a year that has been very good overall, although somewhat eventful for the LHC. Despite the sophisticated operations involved in producing the multiple beam configurations required for the down-stream machines, Linac4 maintained an impressive 98% availability, with stable running and optimal beam performance. The Proton Synchrotron Booster contributed significantly, as always, supplying beams to ISOLDE, HIE-ISOLDE and MEDICIS, as well as to the PS for the downstream users – all within tight user-dependent specifications. A large fraction of the protons at CERN are sent to ISOLDE, with 11.3e19 protons heading that way in 2023 and around 4.5e19 going on to the PS. To quote Erwin Siesling: “We (ISOLDE) had yet another very successful year, full of the usual issues and problems but with great physics results and lots of happy users!” The PS delivered beams to n_TOF, AD-ELENA, and the East Area experiments and irradiation facilities, which include CLOUD, CHARM, and IRRAD. The AD, back online since 30 July after repairs to a faulty quadrupole, compensated for the late start by extending their run to 12 November. Following optimisation, the AD achieved record intensity antiprotons for ELENA and the experiments. Throughout 2023, the SPS operated very well, with no major faults or prolonged downtimes while achieving an impressive transmission rate of about 95% to the North Area experiments with well optimised beam quality. Besides delivering beam to their regular users, work has continued in the Injectors on the high-intensity, high-brightness beams required by the HL-LHC (the primary mission of the LHC Injector Upgrade (LIU) during LS2). The injector teams have done a great job, with the LHC beams from PSB, PS and SPS meeting the LIU target beam parameters and even showing some margin to surpass the beam intensity and brightness required by HL-LHC. In the first part of the year, the LHC demonstrated outstanding luminosity performance, both peak and integrated. Operationally the teams have established impressive flexibility and sophisticated operational and system-level control. However, the excellent availability was punctuated by some singular faults – in particular, a helium leak into the insulation vacuum of the inner triplet assembly left of point 8 in the middle of July. This was a serious event, but reactivity was fantastic, and the leak repair and all that went with it were widely seen as a remarkable collaborative recovery. The adaptability of the cryogenics team was key to avoiding the need to warm up the adjacent sector. The leak, in an edge-welded bellows, was the result of a quench caused by an electrical disturbance on the grid. An availability analysis will be conducted at the Chamonix meeting in 2024 to address other potential non-conformities dating from construction. The prompt recovery enabled some special runs and the first LHC ion run in five years. Lead ions at the end of the year are always interesting, with preparation of the ion source, Linac3, and LEIR starting months before beam is sent to the PS and the downstream machines. Ions are principally destined for the North Area and the LHC. However, in the last two weeks of the four-week run, the PS provided lead ions to the East Area, where the CHIMERA facility irradiates electronics with high-energy heavy ions to study the effects of cosmic radiation on the electronics used in the CERN accelerators and experiments, as well as for space missions and avionics. In the SPS, the first operational use was made of a technique known as “momentum slip-stacking”, which involves injecting two batches of four lead-ion bunches separated by 100 nanoseconds to produce a single batch of eight lead-ion bunches separated by 50 nanoseconds, an impressive example of “RF gymnastics” and low-level RF control. In the LHC, the lead nuclei were colliding this year with an increased energy of 5.36 TeV per nucleon pair (compared to 5.02 TeV previously). A record number of bunches and high bunch intensities – thanks to the downstream machines – made for a challenging ion run. Again, with concerted effort and adaptability, the teams wrestled down the issues, delivered some record performance and paved the way for the rest of Run 3. As we look back on the year, we should bear in mind the phenomenal job that’s done in the exploitation of the complex. This is difficult stuff and it’s remarkable that it all works as well as it does. President Macron might not have seen it, but he surely sensed the spirit.

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Building a plane while flying it isn’t typically a goal for most, but for a team of Harvard-led physicists that general idea might be a key to finally building large-scale quantum computers.

Described in a new paper in Nature, the research team, which includes collaborators from QuEra Computing, MIT, and the University of Innsbruck, developed a new approach for processing quantum information that allows them to dynamically change the layout of atoms in their system by moving and connecting them with each other in the midst of computation.

This ability to shuffle the qubits (the fundamental building blocks of quantum computers and the source of their massive processing power) during the computation process while preserving their quantum state dramatically expands processing capabilities and allows for self-correction of errors. Clearing this hurdle marks a major step toward building large-scale machines that leverage the bizarre characteristics of quantum mechanics and promise to bring about real-world breakthroughs in material science, communication technologies, finance, and many other fields.

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On the highway of heat transfer, thermal energy is moved by way of quantum particles called phonons. But at the nanoscale of today’s most cutting-edge semiconductors, those phonons don’t remove enough heat. That’s why Purdue University researchers are focused on opening a new nanoscale lane on the heat transfer highway by using hybrid quasiparticles called “polaritons.” Credit: Purdue University photo/DALL-E.

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