Archive for the ‘quantum physics’ category: Page 491

Oct 4, 2015

Signals from empty space

Posted by in category: quantum physics

What are the properties of the vacuum, the absolute nothingness? So far, physicists have assumed that it is impossible to directly access the characteristics of the ground state of empty space. Now, a team of physicists led by Prof. Alfred Leitenstorfer at the University of Konstanz (Germany) has succeeded in doing just that. They demonstrated a first direct observation of the so-called vacuum fluctuations by using short light pulses while employing highly precise optical measurement techniques. The duration of their light pulses was ensured to be shorter than half a cycle of light in the spectral range investigated. According to quantum physics, these oscillations exist even in total darkness, when the intensity of light and radio waves completely disappears. These findings are of fundamental importance for the development of quantum physics and will be published in the journal Science; an advance online version has appeared on October 1, 2015.

The existence of vacuum fluctuations is already known from theory as it follows from Heisenberg’s uncertainty principle, one of the main pillars of quantum physics. This principle dictates that electric and magnetic fields can never vanish simultaneously. As a consequence, even total darkness is filled with finite fluctuations of the electromagnetic field, representing the quantum ground state of light and radio waves. However, until now direct experimental proof of this basic phenomenon has been considered impossible. Instead, it is usually assumed that vacuum fluctuations are manifested in nature only indirectly. From spontaneous emission of light by excited atoms e.g. in a fluorescent tube to influences on the structure of the universe during the Big Bang: these are just some of the instances that highlight the ubiquitous role the concept of vacuum fluctuations plays in the modern physical description of the world.

An experimental setup to measure electric fields with extremely high temporal resolution and sensitivity has now made it possible to directly detect vacuum fluctuations, despite all contrary assumptions. World-leading optical technologies and ultrashort pulsed laser systems of extreme stability provide the know-how necessary for this study. The research team at the University of Konstanz developed these technologies in-house and also an exact description of the results based on quantum field theory. The temporal precision achieved in their experiment is in the femtosecond range — a millionth of a billionth of a second. The sensitivity is limited only by the principles of quantum physics. “This extreme precision has enabled us to see for the first time that we are continuously surrounded by the fields of electromagnetic vacuum fluctuations” sums up Alfred Leitenstorfer.

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Oct 2, 2015

Google, NASA using quantum computing to push A.I., machine learning

Posted by in categories: computing, quantum physics, robotics/AI, space

Google and NASA are continuing to test quantum computers and this week entered into a new agreement to work with a series of updated systems.

D-Wave Systems, a quantum computing company based in Burnaby, British Columbia, announced this week that it had signed a deal to install a succession of D-Wave systems at NASA’s Ames Research Center in Moffett Field, California. NASA and Google on Wednesday also confirmed the deal.

NASA and the Universities Space Research Association (USRA) are collaborating on the project, which is focused on advancing artificial intelligence and machine learning.

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Oct 1, 2015

Did Google’s quantum computer just get the biggest processor upgrade in history?

Posted by in categories: computing, quantum physics

If all the claims are true, this highly specialized processor is unimaginably fast at certain specific operations.

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Sep 30, 2015

Pushing computers towards petahertz, with femtosecond lasers and weird dielectrics

Posted by in categories: computing, electronics, materials, quantum physics

New findings published by quantum scientists in Germany could pave the way towards computer chips that use light instead of electricity to control their internal logic. Where today’s silicon-based electrical computer chips are capable of speeds in the gigahertz range, the German light-based chips would be some 1,000,000 times faster, operating in the petahertz range.

Rather than focusing on an exciting new semiconductor, or some metamaterial that manipulates light in weird and wonderful ways, this research instead revolves around dielectrics. In the field of electronics, materials generally fall into one of three categories: charge carriers (conductors), semiconductors, and dielectrics (insulators). As the name suggests, a semiconductor only conduct electricity some of the time (when it receives a large enough jolt of energy to get its electrons moving). In a dielectric, the electrons are basically immobile, meaning electricity can’t flow across them. Apply too much energy, and you destroy the dielectric. As a general rule, there’s no switching: A dielectric either insulates, or it breaks.

Basically, the Max Planck Institute and Ludwig Maximilian University in Germany have found that dielectrics, using very short bursts of laser light, can be turned into incredibly fast switches. The researchers took a small triangle of silica glass (a strong insulator), and then coated two sides with gold, leaving a small (50nm) gap in between (see below). By shining a femtosecond infrared laser at the gap, the glass started conducting and electricity flowed across the gap. When the laser is turned off, the glass becomes an insulator again.

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Sep 28, 2015

Google, NASA sign 7-year deal to test D-Wave quantum computers as artificial brains

Posted by in categories: computing, quantum physics, robotics/AI

The deal with D-Wave Systems will see a steady stream of D-Wave quantum chips used as the foundation of an artificial intelligence lab.

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Sep 27, 2015

Time Travel Could Become Reality Sooner Than You Think

Posted by in categories: particle physics, quantum physics, space, time travel

According to scientists photons can travel through time. They already have simulated directing quantum light particles to the past for the first time in the history. University of Queensland scientists learned that a simulation of two wormhole-travelling photons might interrelate; signifying hopping through time is conceivable at smallest scales. Their study might help to comprehend how time-travel could be conceivable in the quantum realm. PhD student Martin Ringbauer spoke to The Speaker: “For the first, ‘photon one’ would travel through a wormhole into the past and interact with its older version. In the second, ‘photon two’ travels through normal space-time but interacts with a photon that is stuck in a time-travelling loop through a wormhole, known as a closed timelike curve (CTC).”

Tim Ralph, UQ Physics Professor, said: “We used single photons to do this, but the time-travel was simulated by using a second photon to play the part of the past incarnation of the time travelling photon.”

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Sep 23, 2015

Cambridge Physicists Find Wormhole Proof

Posted by in categories: energy, quantum physics, space, time travel

Calculations show that if the wormhole’s throat is orders of magnitude longer then the width of its mouth, it does indeed create Casimir energy at its centre.

Cambridge Physicists Find Wormhole Proof:-Physicists at the University of Cambridge have established a theoretical groundwork for the reality of wormholes, which are pipes that join two different points in space-time. If a part of information or physical object could pass through the wormhole, it might open the door to time travel or immediate communication through huge distances. “But there’s a problem: Einstein’s wormholes are extremely unsteady, and they don’t stay open long enough for something to pass over.” In 1988, physicists reached the deduction that a type of negative energy called Casimir energy might keep wormholes open.

The hypothetical solution established at Cambridge has to do with the properties of quantum energy, which conveys that even vacuums are teaming by means of waves of energy. If you visualize two metal plates in a vacuum, some waves of energy would be excessively big enogh to fit between the plates, meaning that the space-time among the plates would have negative energy. “Under the right circumstances, could the tube-like shape of the wormhole itself generate Casimir energy? Calculations show that if the wormhole’s throat is orders of magnitude longer then the width of its mouth, it does indeed create Casimir energy at its centre.”

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Sep 23, 2015

What are Quantum Dots?

Posted by in categories: media & arts, quantum physics

NIBIB’s 60 Seconds of Science explains how quantum dots work and why they glow.

Music by longzijun ‘Chillvolution.’

Continue reading “What are Quantum Dots?” »

Sep 23, 2015

Scientists shatter distance record for teleporting quantum data

Posted by in categories: computing, encryption, internet, quantum physics

Quantum teleportation, the act of reconstructing quantum data somewhere else, is impressive just by itself. However, scientists at the US’ National Institute of Standards and Technology have managed to one-up that feat. They’ve broken the distance record for quantum teleportation by transferring the information from one photon to another across 63 miles of optical fiber. That may not sound like much, but it’s an achievement just to beam that data in the first place — 99 percent of photons would never make the complete trip. It was only possible thanks to newer detectors that could pick up the faint signal of the lone light particle.

You’d clearly need to send much more information before this teleportation becomes practical, but the achievement does open the door to many possibilities in quantum computing. You could use unbreakable quantum encryption at inter-city distances, for instance. The biggest challenge may simply be to extend the range to the point where quantum data transfers work on the scale of the internet, where there are occasionally thousands of miles between connections.

[Image credit: Getty Images/iStockphoto].

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Sep 22, 2015

Physicists Discovered New State of Matter

Posted by in categories: materials, particle physics, quantum physics

I remember the time when states of matter were pretty simple: Solid, liquid and gas. Then came plasma state, supercritical fluid, Bose –Einstein condensate and more. Now this list of states of matter has grown by one more, with the surprising discovery of a new state dubbed “dropletons” that shows some similarity to liquids but occur under very unlike circumstances.

The discovery of new state of matter occurred when a team of scientists at the University of Colorado Joint Institute for Lab Astrophysics were concentrating laser light on gallium arsenide (GaAs) to generate excitons.

Excitons are made when a photon strikes a material, mostly a semiconductor. If an electron is knocked loose, or excited, it leaves what is labelled as “electron hole” behind. If the forces of other charges at very close distance keep the electron close enough to the hole in order to feel an attraction, a certain state forms called as an Exciton. Excitons are also called quasiparticles because the holes and electrons act together as if they were like a single particle.

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