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Category: quantum physics

Ultra-low-loss metal films with high-quality single crystals are in demand as the perfect surface for nanophotonics and quantum information processing applications. Silver is by far the most preferred material due to low-loss at optical and near infrared (near-IR) frequencies. In a recent study now published on Scientific Reports, Ilya A. Rodionov and an interdisciplinary research team in Germany and Russia reported a two-step approach for electronic beam evaporation of atomically smooth single crystalline metal films. They proposed a method to establish thermodynamic control of the film growth kinetics at the atomic level in order to deposit state-of-the-art metal films.

The researchers deposited 35 to 100 nm thick, single-crystalline silver with sub-100 picometer (pm) with theoretically limited optical losses to form ultrahigh-Q nanophotonic devices. They experimentally estimated the contribution of material purity, material grain boundaries, surface roughness and crystallinity to the optical properties of metal films. The team demonstrated a fundamental two-step approach for single-crystalline growth of silver, gold and aluminum films to open new possibilities in nanophotonics, biotechnology and superconductive quantum technologies. The research team intends to adopt the method to synthesize other extremely low-loss single-crystalline metal films.

Optoelectronic devices with plasmonic effects for near-field manipulation, amplification and sub-wavelength integration can open new frontiers in nanophotonics, quantum optics and in quantum information. Yet, the ohmic losses associated in metals are a considerable challenge to develop a variety of useful plasmonic devices. Materials scientists have devoted research efforts to clarify the influence of metal film properties to develop high performance material platforms. Single-crystalline platforms and nanoscale structural alterations can prevent this problem by eliminating material-induced scattering losses. While silver is one of the best known plasmonic metals at optical and near-IR frequencies, the metal can be challenging for single-crystalline film growth.

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If you’ve ever been wakened by the roar of a freight train – or waited at a level crossing for one to trundle by – you’ll be glad to know that these noisy vehicles have a new and potentially life-saving purpose: predicting earthquakes. As Hamish Johnston explains on this week’s podcast, freight trains generate surprisingly strong seismic waves, and changes in the velocity of these waves is an early sign of hazardous earthquake activity. Researchers in France, Belgium and the US studied the rumblings of freight trains running through California’s Coachella Valley and found that they could, in principle, be used to monitor the nearby San Jacinto fault.

Next on the podcast is Chris Monroe, an atomic physicist and quantum technologist whose start-up firm, Ion Q, is developing a quantum computer that uses trapped ions as qubits. In an interview with Physics World’s industry editor Margaret Harris, Monroe explains how Ion Q’s technology differs from classical computers, and describes how trapped ions execute quantum gates.

The third segment of the podcast focuses on the persistent lack of diversity in physics. In an interview, Jess Wade, a physicist at Imperial College London, discusses the scientific impact of this poor diversity and suggests ways to make the field more welcoming to members of underrepresented groups. Afterwards, our features editor Sarah Tesh, who commissioned Wade and Maryam Zarainghalam to write about this topic in the August issue of Physics World, talks about the portraits of white male scientists that adorn walls in many physics departments. These so-called “dude walls” honour important historical figures, but they also send out subtle signals about what a “great” physicist looks like.

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Light and sound waves are at the basis of energy and signal transport and fundamental to some of our most basic technologies—from cell phones to engines. Scientists, however, have yet to devise a method that allows them to store a wave intact for an indefinite period of time and then direct it toward a desired location on demand. Such a development would greatly facilitate the ability to manipulate waves for a variety of desired uses, including energy harvesting, quantum computing, structural-integrity monitoring, information storage, and more.

In a newly published paper in Science Advances, a group of researchers led by Andrea Alù, founding director of the Photonics Initiative at the Advanced Science Research Center (ASRC) at The Graduate Center, CUNY, and by Massimo Ruzzene, professor of Aeronautics Engineering at Georgia Tech, have experimentally shown that it is possible to efficiently capture and store a wave intact then guide it towards a specific location.

“Our experiment proves that unconventional forms of excitation open new opportunities to gain control over and scattering,” said Alù. “By carefully tailoring the time dependence of the excitation, it is possible to trick the wave to be efficiently stored in a cavity, and then release it on demand towards the desired direction.”

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In a study published in Scientific Reports, a group of researchers affiliated with São Paulo State University (UNESP) in Brazil describes an important theoretical finding that may contribute to the development of quantum computing and spintronics (spin electronics), an emerging technology that uses electron spin or angular momentum rather than electron charge to build faster, more efficient devices.

The study was supported by São Paulo Research Foundation—FAPESP. Its principal investigator was Antonio Carlos Seridonio, a professor in UNESP’s Department of Physics and Chemistry at Ilha Solteira, São Paulo State. His graduate students Yuri Marques, Willian Mizobata and Renan Oliveira also participated.

The researchers observed that molecules with the capacity to encode information are produced in systems called Weyl semimetals when is broken.

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Then again, maybe not.

In a previous post, I explained why quantum mechanics predicts that there are countless versions of you running around in what could be an infinite number of parallel universes.

This time, I’m going to introduce a controversial proposal by MIT physicist Max Tegmark, that uses these parallel universes to argue that you might actually be immortal.

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Gravity was the first fundamental force that humanity recognized, yet it remains the least understood. Physicists can predict the influence of gravity on bowling balls, stars and planets with exquisite accuracy, but no one knows how the force interacts with minute particles, or quanta. The nearly century-long search for a theory of quantum gravity — a description of how the force works for the universe’s smallest pieces — is driven by the simple expectation that one gravitational rulebook should govern all galaxies, quarks and everything in between. [Strange Quarks and Muons, Oh My! Nature’s Tiniest Particles Dissected (Infographic)].

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A new high definition radar system that could change the nature of warfare has been demonstrated for the first time. The result, quantum radar, is a high definition detection system that provides a much more detailed image of targets while itself remaining difficult to detect. Quantum radars could provide users with enough detail to identify aircraft, missiles, and other aerial targets by specific model.

According to the MIT Technology Review, researchers at Austria’s Institute of Science and Technology used entangled microwaves to create the world’s first quantum radar system.

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Two researchers at Harvard University, Aavishkar A. Patel and Subir Sachdev, have recently presented a new theory of a Planckian metal that could shed light on previously unknown aspects of quantum physics. Their paper, published in Physical Review Letters, introduces a lattice model of fermions that describes a Planckian metal at low temperatures (Tà 0).

Metals contain numerous , which carry . When physicists consider the electrical resistance of metals, they generally perceive it as arising when the flow of current-carrying electrons is interrupted or degraded due to electrons scattering off impurities or off the crystal lattice in the metal.

“This picture, put forth by Drude in 1900, gives an equation for the electrical resistance in terms of how much time electrons spend moving freely between successive collisions,” Patel told Phys.org. “The length of this time interval between collisions, called the ‘,’ or ‘electron liftetime,’ is typically long enough in most common metals for the electrons to be defined as distinct, mobile objects to a microscopic observer, and the Drude picture works remarkably well.”

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