A new theory of quantum gravity, which attempts to unite quantum physics with Einstein’s relativity, could help solve the puzzle of the universe’s expansion, a theoretical paper suggests.
Category: quantum physics – Page 239
Does quantum gravity exist?
Several thousand sensors distributed over a square kilometer near the South Pole are tasked with answering one of the large outstanding questions in physics: does quantum gravity exist?
The sensors monitor neutrinos —particles with no electrical charge and almost without mass—arriving at the Earth from outer space. A team from the Niels Bohr Institute (NBI) at the University of Copenhagen have contributed to developing the method which exploits neutrino data to reveal if quantum gravity exists.
“If as we believe, quantum gravity does indeed exist, this will contribute to unite the current two worlds in physics. Today, classical physics describes the phenomena in our normal surroundings such as gravity, while the atomic world can only be described using quantum mechanics. The unification of quantum theory and gravitation remains one of the most outstanding challenges in fundamental physics. It would be very satisfying if we could contribute to that end,” says Tom Stuttard, assistant professor at NBI.
Neuromorphic nanoelectronic materials
Memristive and nanoionic devices have recently emerged as leading candidates for neuromorphic computing architectures. While top-down fabrication based on conventional bulk materials has enabled many early neuromorphic devices and circuits, bottom-up approaches based on low-dimensional nanomaterials have shown novel device functionality that often better mimics a biological neuron. In addition, the chemical, structural and compositional tunability of low-dimensional nanomaterials coupled with the permutational flexibility enabled by van der Waals heterostructures offers significant opportunities for artificial neural networks. In this Review, we present a critical survey of emerging neuromorphic devices and architectures enabled by quantum dots, metal nanoparticles, polymers, nanotubes, nanowires, two-dimensional layered materials and van der Waals heterojunctions with a particular emphasis on bio-inspired device responses that are uniquely enabled by low-dimensional topology, quantum confinement and interfaces. We also provide a forward-looking perspective on the opportunities and challenges of neuromorphic nanoelectronic materials in comparison with more mature technologies based on traditional bulk electronic materials.
New research uncovers hidden phenomena in ultra-clean quantum materials
In a paper published today in Nature Communications, researchers unveiled previously unobserved phenomena in an ultra-clean sample of the correlated metal SrVO3. The study offers experimental insights that challenge the prevailing theoretical models of these unusual metals.
The international research team—from the Paul Drude Institute of Solid State Electronics (PDI), Germany; Oak Ridge National Laboratory (ORNL); Pennsylvania State University; University of Pittsburgh; the Pittsburgh Quantum Institute; and University of Minnesota—believes their findings will prompt a re-evaluation of current theories on electron correlation effects, shedding light on the origins of valuable phenomena in these systems, including magnetic properties, high-temperature superconductivity, and the unique characteristics of highly unusual transparent metals.
The perovskite oxide material SrVO3 is classified as a Fermi liquid—a state describing a system of interacting electrons in a metal at sufficiently low temperatures.
Faster Than the Speed of Light: Information Transfer Through “Spooky Action at a Distance” at the Large Hadron Collider
Physicists have demonstrated quantum entanglement in top quarks and their antimatter partners, a discovery made at CERN. This finding extends the behavior of entangled particles to distances beyond the reach of light-speed communication and opens new avenues for exploring quantum mechanics at high energies.
An experiment by a group of physicists led by University of Rochester physics professor Regina Demina has produced a significant result related to quantum entanglement—an effect that Albert Einstein called “spooky action at a distance.”
Entanglement concerns the coordinated behavior of minuscule particles that have interacted but then moved apart. Measuring properties—like position or momentum or spin—of one of the separated pair of particles instantaneously changes the results of the other particle, no matter how far the second particle has drifted from its twin. In effect, the state of one entangled particle, or qubit, is inseparable from the other.
Untangling the entangled: Quantum study shines fresh light on how neutrinos fuel supernovae
“At this point, the neutrinos go from passive particles—almost bystanders—to major elements that help drive the collapse,” Savage said. “Supernovae are interesting for a variety of reasons, including as sites that produce heavy elements such as gold and iron. If we can better understand neutrinos and their role in the star’s collapse, then we can better determine and predict the rate of events such as a supernova.”
Scientists seldom observe a supernova close-up, but researchers have used classical supercomputers such as ORNL’s Summit to model aspects of the process. Those tools alone wouldn’t be enough to capture the quantum nature of neutrinos.
“These neutrinos are entangled, which means they’re interacting not just with their surroundings and not just with other neutrinos but with themselves,” Savage said.
Silicon Magic: Powering the Quantum Internet of the Future
Building the quantum internet could be significantly simplified by leveraging existing telecommunications technologies and infrastructure. In recent years, researchers have identified defects in silicon—a widely used semiconductor material—that hold the potential for transmitting and storing quantum information across the prevalent telecommunications wavelengths. These silicon defects might just be the prime contenders to host qubits for efficient quantum communications.
Exploring Quantum Defects in Silicon
“It’s still a Wild West out there,” said Evelyn Hu, the Tarr-Coyne Professor of Applied Physics and of Electrical Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). “Even though new candidate defects are a promising quantum memory platform, there is often almost nothing known about why certain recipes are used to create them, and how you can rapidly characterize them and their interactions, even in ensembles. And ultimately, how can we fine-tune their behavior so they exhibit identical characteristics? If we are ever to make a technology out of this wide world of possibilities, we must have ways to characterize them better, faster, and more efficiently.”
The Cosmological Constant Problem: a Crisis in Physics
What is Dark Energy? A mysterious substance that fills space and causes it to expand is Dark Energy .70% of the universe’s energy is in the form of ‘dark energy’
Comparison of Discrete Variable and Continuous Variable Quantum Key Distribution Protocols with Phase Noise in the Thermal-Loss Channel
Sebastian P. Kish1,2, Patrick J. Gleeson2, Angus Walsh2, Ping Koy Lam3,2, and Syed M. Assad3,2
1Data61, CSIRO, Marsfield, NSW, Australia. 2 Centre of Excellence for Quantum Computation and Communication Technology, Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT, Australia. 3 Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore, 138,634, Singapore.
Get full text pdfRead on arXiv VanityComment on Fermat’s library.
Twisting Light Unlocks New Quantum Realms
A research team is studying how light moves through special circuits called optical waveguides, using a concept called topology. They’ve made an important discovery that combines stable light paths with light particle interactions, which could make quantum computers more reliable and lead to new technological advancements.
Scientific innovation often arises as synthesis from seemingly unrelated concepts. For instance, the reciprocity of electricity and magnetism paved the way for Maxwell’s theory of light, which, up until now, is continually being refined and extended with ideas from quantum mechanics.
Similarly, the research group of Professor Alexander Szameit at the Institute of Physics at the University of Rostock explores light evolution in optical waveguide circuits in the presence of topology. This abstract mathematical concept was initially developed to classify solid geometries according to their global properties. Szameit explains: “In topological systems, light only follows the global characteristics of the waveguide system. Local perturbations to the waveguides such as defects, vacancies, and disorder cannot divert its path.”