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Category: quantum physics – Page 1,032

Black hole hologram appears in a graphene flake

Much research on black holes is theoretical since it is difficult to make actual measurements on real black holes. Such experiments also need to be undertaken over decades or longer. Physicists are therefore keen to create laboratory systems that are analogous to these cosmic entities. New theoretical calculations by a team in Canada, the US, UK and Israel have now revealed that a material as simple as a graphene flake with an irregular boundary subjected to an intense external magnetic field can be used to create a quantum hologram that faithfully reproduces some of the signature characteristics of a black hole. This is because the electrons in the carbon material behave according to the Sachdev-Ye-Kitaev model.

Some of the most important unresolved mysteries in modern physics come from the “incompatibility” between Einstein’s theory of general relativity and the theory of quantum mechanics. General relativity describes the physics of the very big (the force of gravity and all that it affects: spacetime, planets, galaxies and the expansion of the Universe). The theory of quantum mechanics is the physics of the very small – and the other three forces, electromagnetism and the two nuclear forces.

“In recent years, physicists have gleaned important new insights into these questions through the study of the SYK model,” explains Marcel Franz of the University of British Columbia in Canada, who led this research effort. “This model is an illustration of a type of ‘holographic duality’ in which a lower-dimensional system can be represented by a higher dimensional one. In our calculations, the former is N graphene electrons in (0+1) dimensions and the latter the dilation gravity of a black hole in (1+1) dimensional anti-de Sitter (AdS2) space.

These 9 Incredible Images Are a Mind-Boggling Remind of How Far Technology Has Come

Sometimes, while waiting for quantum computers to become a thing, or complaining that your stupid laptop keeps dying on 5 percent battery, it’s easy to forget just how far technology has come over the past 50 years.

Sure, we can all list off a whole bunch of innovations that have changed the way the world works — the Internet, smartphones, radio telescopes — but it’s hard to really put that kind of change into perspective.

Thankfully, pictures often speak louder than words, and so below are nine photos that’ll make you stop and raise your *praise hand* emojis to the sky in honour of the scientists and engineers that have got us where we are today.

Nanocrystals emit light

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.

Uncovering the interplay between two famous quantum effects

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 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 . 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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