Some physicists claim the popular landscape of universes in string theory may not exist.
Using advanced fabrication techniques, engineers at the University of California San Diego have built a nanosized device out of silver crystals that can generate light by efficiently “tunneling” electrons through a tiny barrier. The work brings plasmonics research a step closer to realizing ultra-compact light sources for high-speed, optical data processing and other on-chip applications.
The work is published July 23 in Nature Photonics.
The device emits light by a quantum mechanical phenomenon known as inelastic electron tunneling. In this process, electrons move through a solid barrier that they cannot classically cross. And while crossing, the electrons lose some of their energy, creating either photons or phonons in the process.
The Casimir force and superconductivity are two well-known quantum effects. These phenomena have been thoroughly studied separately, but what happens when these effects are combined in a single experiment? Now, Delft University of Technology have created a microchip on which two wires were placed in close proximity in order to measure the Casimir forces that act upon them when they become superconducting.
Is vacuum really empty? Quantum mechanics tells us that it’s actually swarming with particles. In the 1940s, Dutch physicists Hendrik Casimir and Dirk Polder predicted that when two objects are placed in very close proximity, about a thousandth of the diameter of a human hair, this sea of ‘vacuum particles’ pushes them together – a phenomenon known as the Casimir effect. This attractive force is present between all objects and even sets fundamental limits to how closely we can place components together on microchips.
Superconductivity is another well-known quantum phenomenon, also discovered by a Dutchman, Heike Kamerlingh Onnes, in the early 20th century. It describes how certain materials, such as aluminum or lead, allow electricity to flow through them without any resistance at cryogenic temperatures. Over the last 100 years, superconductors have revolutionized our understanding of physics and are responsible for magnetically levitated trains, MRI scans and even mobile phone stations.
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Quantum communication and cryptography are the future of high-security communication. But many challenges lie ahead before a worldwide quantum network can be set up, including propagating the quantum signal over long distances. One of the major challenges is to create memories with the capacity to store quantum information carried by light. Researchers at the University of Geneva (UNIGE), Switzerland, in partnership with CNRS, France, have discovered a new material in which an element, ytterbium, can store and protect the fragile quantum information even while operating at high frequencies. This makes ytterbium an ideal candidate for future quantum networks, where the aim is to propagate the signal over long distances by acting as repeaters. These results are published in the journal Nature Materials.
Quantum cryptography today uses optical fibre over several hundred kilometres and is marked by its high degree of security: it is impossible to copy or intercept information without making it disappear.
However, the fact that it is impossible to copy the signal also prevents scientists from amplifying it to diffuse it over long distances, as is the case with the Wi-Fi network.
Researchers have created the fastest man-made rotor in the world, which they believe will help them study quantum mechanics.
At more than 60 billion revolutions per minute, this machine is more than 100,000 times faster than a high-speed dental drill.
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