Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: particle physics – Page 433

Quantum entanglement is a process by which microscopic objects like electrons or atoms lose their individuality to become better coordinated with each other. Entanglement is at the heart of quantum technologies that promise large advances in computing, communications and sensing, for example detecting gravitational waves.

Entangled states are famously fragile: in most cases even a tiny disturbance will undo the entanglement. For this reason, current quantum technologies take great pains to isolate the microscopic systems they work with, and typically operate at temperatures close to absolute zero. The ICFO team, in contrast, heated a collection of atoms to 450 Kelvin, millions of times hotter than most atoms used for quantum technology. Moreover, the individual atoms were anything but isolated; they collided with each other every few microseconds, and each collision set their electrons spinning in random directions.

The researchers used a laser to monitor the magnetization of this hot, chaotic gas. The magnetization is caused by the spinning electrons in the atoms, and provides a way to study the effect of the collisions and to detect entanglement. What the researchers observed was an enormous number of entangled atoms — about 100 times more than ever before observed. They also saw that the entanglement is non-local — it involves atoms that are not close to each other. Between any two entangled atoms there are thousands of other atoms, many of which are entangled with still other atoms, in a giant, hot and messy entangled state.

Read more | >

Circa 2017

Einstein-Rosen or “ER” bridges, are equivalent to entangled quantum particles, also known as Einstein-Podolsky-Rosen or “EPR” pairs. The quantum connection between wormholes prevents their collapse without involving exotic matter.

The quantum-teleportation format precludes using these traversable wormholes as time machines. Anything that goes through the wormhole has to wait for Alice’s message to travel to Bob in the outside universe before it can exit Bob’s black hole, so the wormhole doesn’t offer any superluminal boost that could be exploited for time travel.

Researchers are working towards lab tests of quantum teleportation to verify their theories.

Continue reading “Teleportation and traversible wormholes are all real” | >

Physicists have measured the flight times of electrons emitted from a specific atom in a molecule upon excitation with laser light. This has enabled them to measure the influence of the molecule itself on the kinetics of emission.

Photoemission—the release of electrons in response to excitation by light—is one of the most fundamental processes in the microcosm. The kinetic energy of the emitted electron is characteristic for the atom concerned, and depends on the wavelength of the light employed. But how long does the process take? And does it always take the same amount of time, irrespective of whether the electron is emitted from an individual atom or from an atom that is part of a molecule? An international team of researchers led by laser physicists in the Laboratory for Attosecond Physics (LAP) at LMU Munich and the Max Planck Institute of Quantum Optics (MPQ) in Garching has now probed the influence of the molecule on photoemission time.

The theoretical description of photoemission in 1905 by Albert Einstein marked a breakthrough in , and the details of the process are of continuing interest in the world of science and beyond. How the motions of an elementary quantum particle such as the electron are affected within a molecular environment has a significant bearing on our understanding of the process of photoemission and the forces that hold molecules together.

Read more | >

O,.,o.

The weird world of quantum physics is being harnessed for some fascinating use cases. In the latest example, physicists have developed and demonstrated a “quantum radar” prototype that uses the quantum entanglement phenomenon to detect objects, a system which could eventually outperform conventional radar in some circumstances.

Quantum entanglement describes the bizarre state where two particles can become linked so tightly that they seem to communicate instantly, no matter how far apart they are. Measuring the state of one particle will instantly change the state of the other, hypothetically even if it’s on the other side of the universe. That implies that the information is moving faster than the speed of light, which is thought to be impossible – and yet, it’s clearly and measurably happening. The phenomenon even unnerved Einstein himself, who famously described it as “spooky action at a distance.”

While we still don’t entirely understand why or how it works, that’s not stopping scientists figuring out ways to use it to our advantage. Strides are being made towards creating quantum computers and a quantum internet, both of which would be super fast and nigh-unhackable. And now, in a new study by physicists at the Institute of Science and Technology Austria (IST Austria), MIT and the University of York, the phenomenon been applied to radar.

Continue reading ““Quantum radar” uses entangled photons to detect objects” | >

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object’s wake, greatly reducing its drag while simultaneously helping it avoid detection.

The idea originated at Duke University in 2011 when researchers outlined the general concept. By matching the acceleration of the surrounding water to an ’s movement, it would theoretically be possible to greatly increase its propulsion efficiency while leaving the surrounding sea undisturbed. The theory was an extension of the group’s pioneering work in metamaterials, where a material’s structure, rather than its chemistry, creates desired properties.

Six years later, Yaroslav Urzhumov, adjunct assistant professor of electrical and computer engineering at Duke, has updated the theory by detailing a potential approach. But rather than using a complex system of very small pumps as originally speculated, Urzhumov is turning to electromagnetic fields and the dense concentration of charged particles found in saltwater.

Read more | >

Linking multiple copies of these devices may lay the foundation for quantum computing.

Once unimaginable, transistors consisting only of several- atom clusters or even single atoms promise to become the building blocks of a new generation of computers with unparalleled memory and processing power. But to realize the full potential of these tiny transistors — miniature electrical on-off switches — researchers must find a way to make many copies of these notoriously difficult-to-fabricate components.

Now, researchers at the National Institute of Standards and Technology (NIST) and their colleagues at the University of Maryland have developed a step-by-step recipe to produce the atomic-scale devices. Using these instructions, the NIST-led team has become only the second in the world to construct a single-atom transistor and the first to fabricate a series of single electron transistors with atom-scale control over the devices’ geometry.

Read more | >

Using the Very Long Baseline Interferometry (VLBI) technique, astronomers have probed the parsec-scale jet of a neutrino-emitting blazar known as TXS 0506+056. Results of the new study, presented May 1 on arXiv.org, shed more light on the properties of this jet, which could improve the understanding of very-high energy (VHE) neutrinos.

Blazars, classified as members of a larger group of active galaxies that host (AGN), are powerful sources of emission across the from radio to very gamma frequencies. Their characteristic features are pointed almost exactly toward the Earth.

In general, blazars are perceived by astronomers as high-energy engines serving as natural laboratories to study , relativistic plasma processes, magnetic field dynamics and black hole physics. Therefore, high-resolution observations of blazars and their jets in different wavelengths could be essential for improving the understanding of these phenomena.

Read more | >

Rechargeable batteries are at the heart of many new technologies involving, for example, the increased use of renewable energies. More specifically, they are employed to power electric vehicles, cell phones, and laptops. Scientists at Johannes Gutenberg University Mainz (JGU) and the Helmholtz Institute Mainz (HIM) in Germany have now presented a non-contact method for detecting the state of charge and any defects in lithium-ion batteries. For this purpose, atomic magnetometers are used to measure the magnetic field around battery cells. Professor Dmitry Budker and his team usually use atomic magnetometry to explore fundamental questions of physics, such as the search for new particles. Magnetometry is the term used to describe the measurement of magnetic fields. One simple example of its application is the compass, which the Earth’s magnetic field causes to point north.

Non-contact quality assurance of batteries using atomic magnetometers

The demand for high-capacity is growing and so is the need for a form of sensitive, accurate diagnostic technology for determining the state of a battery cell. The success of many new developments will depend on whether batteries can be produced that can deliver sufficient capacity and a long effective life span. “Undertaking the quality assurance of rechargeable batteries is a significant challenge. Non-contact methods can potentially provide fresh stimulus for improvement in batteries,” said Dr. Arne Wickenbrock, a member of Professor Dmitry Budker’s work group at the JGU Institute of Physics and the Helmholtz Institute Mainz. The group has achieved a breakthrough by using atomic magnetometers to take measurements. The idea came about during a teleconference between Budker and his colleague Professor Alexej Jerschow of New York University. They developed a concept and, with close cooperation between the two groups, carried out the related experiments in Mainz.

Read more | >

According to the Wiedemann-Franz (WF) law, the electrical conductivity of a metal is linked to its thermal counterpart, provided that the heat carried by the phonons is negligible and the electrons do not suffer inelastic scattering. In a type II Weyl semimetal also known as a fourth fermion, the thermal dependence of the ratio between electrical and thermal conductivity highlights deviations from the Wiedemann-Franz law. Physicists have tested the WF law in numerous solids but intend to understand the extent of its relevance during anomalous transverse transport and investigate the topological nature of the wave function. In a new report, Liangcai Xu and an international research team in condensed matter physics in China, France, Israel and Germany, presented a study of the anomalous transverse response in a noncollinear antiferromagnetic Weyl semimetal, Mn3Ge. They varied the experimental conditions from room temperature down to sub-Kelvin temperature and observed finite-temperature violation of the WF correlation. They credited the outcome to a mismatch between the thermal and electrical summations of the Berry curvature (a geometric phase acquired within the course of a cycle) and not due to inelastic scattering. The team backed their interpretation with theoretical calculations to reveal a competition between the temperature and Berry curvature distribution. The work is now published on Science Advances.

The Berry curvature of electrons can result in the anomalous Hall effect (AHE) if the host solid lacks time-reversal symmetry (conservation of entropy). While the thermoelectric and thermal counterparts of the anomalous Hall effect are explored less frequently, they too arise from the same fictitious magnetic fields. It remains to be determined how the magnitudes of such anomalous off-diagonal coefficients correlate with each other and if the established correlations between ordinary transport coefficients continue to hold. It is currently laborious to form a semiclassical formula of the anomalous Hall effect (AHE), thereby making any intuitive picture of producing a transverse electric field even more challenging. In this work, the research team presented a study of a magnetic solid, focused on the relation between anomalous electrical and thermal Hall conductivities. Xu et al.

Read more | >