Scientists discovered in 1937 that liquid helium-4, when chilled to extremely low temperatures, became a superfluid that could leak through glass, overflow its containers or eternally gush like a fountain. Future Nobel laureate Lev Landau came along in 1941, predicting that superfluid helium-4 should contain an exotic, particle-like excitation called a roton.
While the mysterious, unseen forces magnets project are now (mostly) well understood, they can still occasionally surprise us. For instance, thin films of cobalt have been observed to spontaneously switch their poles: something that typically doesn’t happen in the absence of an external magnetic field. Physicists at NIST and the Univ. of Maryland have measured this phenomenon on the largest scale yet.
Birds are unwitting masters of fluid dynamics: They manipulate airflow each time they flap their wings, pushing air in one direction and moving themselves in another. Two New York Univ. researchers have taken inspiration from avian locomotion strategies and created a pump that moves fluid using vibration instead of a rotor.
A little detective work by nuclear physicists has uncovered hidden uncertainties in a popular method for precisely measuring radioactive nuclides, often used to make reference materials for forensic analyses such as radioactive dating. The much-used method, called α/β-γ anticoincidence counting, has long relied on simplified assumptions. Now researchers from NIST have produced a more realistic model.
Far from being a defect, a winding thread of odd rings at the border of two sheets of graphene has qualities that may prove valuable to manufacturers, according to Rice Univ. scientists. Graphene rarely appears as a perfect lattice of chicken wire-like six-atom rings. When grown via chemical vapor deposition, it usually consists of “domains,” or separately grown sheets that bloom outward from hot catalysts until they meet up.
A new study by a team of physicists at Rice Univ., Zhejiang Univ., Los Alamos National Laboratory, Florida State Univ. and the Max Planck Institute adds to the growing body of evidence supporting a theory that strange electronic behaviors arise from quantum fluctuations of strongly correlated electrons.
Quantum computers are experimental devices that promise exponential speedups on some computational problems. Where a bit in a classical computer can represent either a 0 or a 1, a quantum bit, or qubit, can represent 0 and 1 simultaneously, letting quantum computers explore multiple problem solutions in parallel. But such “superpositions” of quantum states are, in practice, difficult to maintain.
Ever since Einstein proposed his special theory of relativity in 1905, physics and cosmology have been based on the assumption that space looks the same in all directions: that it’s not squeezed in one direction relative to another. A new experiment by Univ. of California, Berkeley physicists used partially entangled atoms to demonstrate more precisely than ever before that this is true, to one part in a billion billion.
Earth’s magnetic field is crucial for our existence, as it shields the life on our planet’s surface from deadly cosmic rays. It is generated by turbulent motions of liquid iron in Earth’s core. Iron is a metal, which means it can easily conduct a flow of electrons that makes up an electric current. New findings show a missing piece of the traditional theory explaining why metals become less conductive when they are heated.
A technology developed by Stanford Univ. scientists for passively probing the seafloor using weak seismic waves generated by the ocean could revolutionize offshore oil and natural gas extraction by providing real-time monitoring of the subsurface while lessening the impact on marine life.
A sun-like star with orbiting planets, dating back to the dawn of the galaxy, has been discovered by an international team of astronomers. At 11.2 billion years old it is the oldest star with Earth-sized planets ever found and proves that such planets have formed throughout the history of the universe. The discovery used observations made by NASA's Kepler satellite.
In a marathon, everyone starts at roughly the same place at roughly the same time. But the faster runners will gradually increase their lead, and in the end, the distribution of runners on the street will be very broad. Something similar happens to a pulse of light sent through a medium. The pulse is a combination of different colors (or wavelengths), and when they are sent through a medium like glass, they travel at different speeds.
A potential avenue to quantum computing currently generating quite the buzz in the high-tech industry is “valleytronics,” in which information is coded based on the wavelike motion of electrons moving through certain 2-D semiconductors. Now, a promising new pathway to valleytronic technology has been uncovered by researchers with the Lawrence Berkeley National Laboratory.
The idea of computing systems based on controlling atomic spins just got a boost from new research performed at MIT and Brookhaven National Laboratory. By constructing tiny "mirrors" to trap light around impurity atoms in diamond crystals, the team dramatically increased the efficiency with which photons transmit information about those atoms' electronic spin states, which can be used to store quantum information.
Scientists have demonstrated a nanoscale memory technology for superconducting computing that could hasten the advent of an urgently awaited, low-energy alternative to power-hungry conventional data centers and supercomputers. In recent years, the stupendous and growing data demands of cloud computing, expanded Internet use, mobile device support and other applications have prompted the creation of large, centralized computing facilities.
Understanding this electronic effect in organic molecules is crucial for their use in optoelectronic applications. In their article published in Nature Physics, the research team demonstrates measurements on the organic molecule cobalt phthalocyanine (CoPC) that can be explained only by taking into consideration how electrons in the molecule interact with each other.
NIST scientists have developed a novel method to rapidly and accurately calibrate gas flow meters, such as those used to measure natural gas flowing in pipelines, by applying a fundamental physical principle: When a sound wave travels through a gas containing temperature gradients, the sound wave's average speed is determined by the average temperature of the gas.
Graphene has many desirable properties. Magnetism alas is not one of them. Magnetism can be induced in graphene by doping it with magnetic impurities, but this doping tends to disrupt graphene's electronic properties. Now a team of physicists at the Univ. of California, Riverside has found an ingenious way to induce magnetism in graphene while also preserving graphene's electronic properties.
Unlike Bilbo's magic ring, which entangles human hearts, engineers have created a new microring that entangles individual particles of light, an important first step in a whole host of new technologies. Entanglement is one of the most intriguing and promising phenomena in all of physics. Properly harnessed, entangled photons could revolutionize computing, communications and cyber security.
Since the beginning of recorded time, humans have used materials found in nature to improve their lot. Since the turn of this century, scientists have studied metamaterials, artificial materials engineered to bend electromagnetic, acoustic and other types of waves in ways not possible in nature. Now, a discovery has been made with these synthetic materials that may take engineers one step closer to building microscopes with superlenses.
Scientists at the Univ. of Liverpool have controlled the structure of a material to simultaneously generate both magnetization and electrical polarization, an advance which has potential applications in information storage and processing. The researchers demonstrated that it's possible to unlock these properties in a material which initially displayed neither by making designed changes to its structure.
Theoretical physicists at Rice Univ. are living on the edge as they study the astounding properties of graphene. In a new study, they figure out how researchers can fracture graphene nanoribbons to get the edges they need for applications. New research shows it should be possible to control the edge properties of graphene nanoribbons by controlling the conditions under which the nanoribbons are pulled apart.
One of the reasons solar cells are not used more widely is cost: The materials used to make them most efficient are expensive. Engineers are exploring ways to print solar cells from inks, but the devices don’t work as well. A team of engineers has developed a technique to increase the performance and electrical conductivity of thin films that make up these materials using nanotechnology.
Scientists have long known that the speed of light can be slowed slightly as it travels through materials such as water or glass. However, it has generally been thought impossible for particles of light, known as photons, to be slowed as they travel through free space, unimpeded by interactions with any materials.
New laser-driven compression experiments reproduce the conditions deep inside exotic super-Earths and giant planet cores, and the conditions during the violent birth of Earth-like planets, documenting the material properties that determined planet formation and evolution processes. The experimentsreveal the unusual properties of silica under the extreme pressures and temperatures relevant to planetary formation and interior evolution.