The ‘quasiparticles’ defy the categories of ordinary particles and herald a potential way to build quantum computers.
Category: quantum physics
In a paper that made the cover of the journal Applied Physics Letters, an international team of researchers has demonstrated an innovative technique for increasing the intensity of lasers. This approach, based on the compression of light pulses, would make it possible to reach a threshold intensity for a new type of physics that has never been explored before: quantum electrodynamics phenomena.
Researchers Jean-Claude Kieffer of the Institut national de la recherche scientifique (INRS), E. A. Khazanov of the Institute of Applied Physics of the Russian Academy of Sciences and in France Gérard Mourou, Professor Emeritus of the Ecole Polytechnique, who was awarded the Nobel Prize in Physics in 2018, have chosen another direction to achieve a power of around 1023 watts (W). Rather than increasing the energy of the laser, they decrease the pulse duration to only a few femtoseconds. This would keep the system within a reasonable size and keep operating costs down.
To generate the shortest possible pulse, the researchers are exploiting the effects of non-linear optics. “A laser beam is sent through an extremely thin and perfectly homogeneous glass plate. The particular behavior of the wave inside this solid medium broadens the spectrum and allows for a shorter pulse when it is recompressed at the exit of the plate,” explains Jean-Claude Kieffer, co-author of the study published online on 15 June 2020 in the journal Applied Physics Letters.
URu2Si2 is a metal that belongs to the family of heavy-fermion compounds in which several quantum phases (e.g., magnetism and superconductivity) can compete or coexist. These metals exhibit small energy scales that are easy to tune, a characteristic that makes them ideal for testing new physical ideas and concepts.
For instance, researchers have often used these compounds to test theories related to quantum phase transitions, quantum criticality and unconventional superconductivity. Studying heavy-fermion metals could ultimately unveil new physical properties of other correlated-electron materials that have shown promise for a wide range of applications, such as high-temperature superconductors.
A research team at the National Laboratory of High Magnetic Fields (LNCMI/CNRS) in France and Université Grenoble Alpes, in collaboration with researchers at Okayama University and Tohoku University in Japan, recently carried out a systematic investigation of URu2Si2 under a combination of high pressures and high magnetic fields. Their paper, published in Nature Physics, maps out a phase in the material that is so far poorly understood, delineating a complex three-dimensional phase diagram.
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Scientists have been able to generate the world’s fastest laser pulse with a beam shot for 67 attoseconds (0.000000000000000067 seconds). This breaks the previous record of 80 attoseconds that was established in 2008. This could help engineers see extremely rapid quantum mechanical processes, like the movements of electrons during chemical reactions.
The researchers published their findings in the journal Optics Letters. This will allow the study of electron motions with attosecond pulses. The blast was obtained by sending pulses from a titanium-sapphire near-infrared laser through a system known as double optical gating (DOG) in which the gate concentrates the energy of extreme ultraviolet light pulses and focuses them on a cell filled with neon gas.
As researchers worldwide work toward a potential quantum internet, a major roadblock remains: How to build a device called a quantum repeater.
In a world’s first, researchers in France and the U.S. have performed a pioneering experiment demonstrating “hybrid” quantum networking. The approach, which unites two distinct methods of encoding information in particles of light called photons, could eventually allow for more capable and robust communications and computing.
Similar to how classical electronics can represent information as digital or analog signals, quantum systems can encode information as either discrete variables (DVs) in particles or continuous variables (CVs) in waves. Researchers have historically used one approach or the other—but not both—in any given system.
“DV and CV encoding have distinct advantages and drawbacks,” says Hugues de Riedmatten of the Institute of Photonic Sciences in Barcelona, who was not a part of the research. CV systems encode information in the varying intensity, or phasing, of light waves. They tend to be more efficient than DV approaches but are also more delicate, exhibiting stronger sensitivity to signal losses. Systems using DVs, which transmit information by the counting of photons, are harder to pair with conventional information technologies than CV techniques. They are also less error-prone and more fault-tolerant, however. Combining the two, de Riedmatten says, could offer “the best of both worlds.”
China is even developing a satellite-based laser surveillance system aimed at detecting vessels submerged as deep as five hundred meters.
Here’s What You Need To Remember: Time will tell which, if any, of these technologies can be developed into practical operational systems.
Scientists suggest a desktop quantum computer based on nuclear magnetic resonance (NMR) could soon be on its way to a classroom near you. Although the device might not be suited to handle large quantum applications, the makers say it could help students learn about quantum computing.
SpinQ Chief Scientist Prof. Bei Zeng from University of Guelph, announced the SpinQ Gemini, a two-qubit desktop quantum computer, at the industry session of the Quantum Information Processing (QIP2020) conference, which is held recently in Shenzhen, China. It is the first time that a desktop quantum computer is commercially available, according to the researchers.
SpinQ Gemini is built by the state-of-the-art technology of permanent magnets, providing 1T magnetic field, running at room temperature, and maintenance free. It demonstrates quantum algorithms such as Deutsch’s algorithm and Grover’s algorithm for teaching quantum computing to university and high school students, also provides advanced models for quantum circuit design and control sequence design for researchers.
Tiny satellites could be the key to a global quantum internet network. That could mean internet from space on Earth, and communication between spacecraft.
Ever tried defrosting your dinner by popping it in one identical freezer after another? Strange as it sounds, recent studies of indefinite causal order—in which different orders of events are quantum superposed—suggest this could actually work for quantum systems. Researchers at the University of Oxford show how the phenomenon can be put to use in a type of quantum refrigeration.