Laser radiation pressure is a basis of numerous applications in science and technology such as atom cooling, particle manipulation, material processing, etc. This light force for the case of scalar beams is proportional to the intensity-weighted wavevector known as optical current. The ability to design the optical current according to the considered application brings new promising perspectives to exploit the radiation pressure. However, this is a challenging problem because it often requires confinement of the optical current within tight light curves (circuits) and adapting its local value for a particular task. Here, we present a formalism to handle this problem including its experimental demonstration. It consists of a Nature-inspired circuit shaping with independent control of the optical current provided by a new kind of beam referred to as polymorphic beam. This finding is highly relevant to diverse optical technologies and can be easily extended to electron and x-ray coherent beams.
Category: particle physics
Assembly of the Plasma Liner Experiment (PLX) at Los Alamos National Laboratory is well underway with the installation of 18 of 36 plasma guns in an ambitious approach to achieving controlled nuclear fusion (Figure 1). The plasma guns are mounted on a spherical chamber, and fire supersonic jets of ionized gas inward to compress and heat a central gas target that serves as fusion fuel. In the meantime, experiments performed with the currently installed plasma guns are providing fundamental data to create simulations of colliding plasma jets, which are crucial for understanding and developing other controlled fusion schemes.
Most fusion experiments employ either magnetic confinement, which relies on powerful magnetic fields to contain a fusion plasma, or inertial confinement, which uses heat and compression to create the conditions for fusion.
The PLX machine combines aspects of both magnetic confinement fusion schemes (e.g. tokamaks) and inertial confinement machines like the National Ignition Facility (NIF). The hybrid approach, although less technologically mature than pure magnetic or inertial confinement concepts, may offer a cheaper and less complex fusion reactor development path. Like tokamaks, the fuel plasma is magnetized to help mitigate losses of particles and thermal energy. Like inertial confinement machines, a heavy imploding shell (the plasma liner) rapidly compresses and heats the fuel to achieve fusion conditions. Instead of NIF’s array of high-power lasers driving a solid capsule, PLX relies on supersonic plasma jets fired from plasma guns.
Grab a mixing bowl from your kitchen, throw in a handful of aluminum balls, apply some high voltage, and watch an elegant dance unfold where particles re-arrange themselves into a distinct “crystal” pattern. This curious behavior belongs to the phenomenon known as Wigner crystallization, where particles with the same electrical charge repel one another to form an ordered structure.
Wigner crystallization has been observed in variety of systems, ranging from particulates the size of sand grains suspended in small clouds of electrons and ions (called a dusty plasma) to the dense interiors of planet-sized stars, known as white dwarfs. Professor Alex Bataller of North Carolina State University has recently discovered that Wigner crystallization inside white dwarfs can be studied in the lab using a new class of classical systems, called gravity crystals.
For the curious behavior of Wigner crystallization to occur, there must be a system composed of charged particles that are both free to move about (plasma), that strongly interact with each other (strongly coupled particles), and has the presence of a confining force to keep the plasma particles from repulsively exploding away from each other.
Scientists at Stanford University and Fermilab are ready to introduce the world to the 100-meter-tall MAGIS-100 instrument.
More accurate clocks and sensors may result from a recently proposed experiment, linking an Einstein-devised paradox to quantum mechanics. University of Queensland physicist Dr Magdalena Zych said the international collaboration aimed to test Einstein’s twin paradox using quantum particles in a ‘superposition’ state.
In an effort to make robots more effective and versatile teammates for Soldiers in combat, Army researchers are on a mission to understand the value of the molecular living functionality of muscle, and the fundamental mechanics that would need to be replicated in order to artificially achieve the capabilities arising from the proteins responsible for muscle contraction.
Bionanomotors, like myosins that move along actin networks, are responsible for most methods of motion in all life forms. Thus, the development of artificial nanomotors could be game-changing in the field of robotics research.
Researchers from the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory have been looking to identify a design that would allow the artificial nanomotor to take advantage of Brownian motion, the property of particles to agitatedly move simply because they are warm.
A phenomenon that has previously been seen when researchers simulate the properties of planet cores at extreme pressures has now also been observed in pure titanium at atmospheric pressure. Chains of atoms dash around at lightning speeds inside the solid material.
“The phenomenon we have discovered changes the way we think about mass transport in metals. It explains properties of metals that we have, until now, not been able to understand. It’s too early to say what this means in practical terms, but the more we know about how materials function in different conditions, the better possibilities we have to develop materials with new or improved properties,” says Davide Sangiovanni, researcher in the Division of Theoretical Physics at LIU and principal author of an article that has been published in Physical Review Letters.
In response to the utter inadequacy of materialism to account for the mind, several philosophers have suggested panpsychism as a solution to the mind–body problem. Perhaps, they argue, all matter is inherently conscious but more primitive aggregates of matter may only have primitive consciousness. From that perspective, humans are very conscious and electrons are maybe just a little bit conscious.
Philosopher Philip Goff:
The panpsychist offers an alternative research programme: Rather than trying to account for consciousness in terms of utterly non-conscious elements, try to explain the complex consciousness of humans and other animals in terms of simpler forms of consciousness which are postulated to exist in simpler forms of matter, such as atoms or their sub-atomic components. This research project is still in its infancy. But a number of leading neuroscientists, such as Christof Koch and Giulio Tononi, are now finding that working within a panpsychist framework bears fruit. The more fruit is borne by this alternative research programme, the more reason we have to accept panpsychism.
For several years now, physicists at the European Organisation for Nuclear Research (CERN) have been running a landmark experiment, recording tens of billions of particles break apart in the hopes of catching a few oddballs. And they finally have some intriguing results to share.
This experiment, called NA62, has researchers building and destroying pairs of quarks called kaons, looking for examples of a one-in-10 billion event that could verify some of the predictions of the Standard Model of particle physics. Last year they found one. Now they’ve added another possible two.
The findings were presented at a recent CERN Seminar and were based on data collected in 2017; ten times the amount of data harvested the previous year.
These subatomic particles could make up dark matter in the cosmos. A mathematically similar phenomenon occurs in a solid material.