One laser can help halt another.
A crystal that holds light could facilitate quantum computing.
Researchers in the United States and Korea have brought light to a complete standstill in a crystal. The pulse is effectively held within the solid, ready to be released at a later stage.
Light moves at 186,000 miles per second through empty space, and was first stopped in its tracks at the beginning of last year. In that experiment, a vapour of metal atoms cooled close to absolute zero was shown to act like molasses on a passing light beam2,3.
Now Philip Hemmer, of the Air Force Research Laboratory at Hanscom Air Force Base in Massachusetts, and his colleagues have halted light in a crystal of yttrium silicate containing a few atoms of the element praseodymium.
Light-stopping solids would be much easier to incorporate into faster, more powerful computers than extremely cold gases. So the advance could aid information technology in much the same way that solid-state diodes and transistors made electronics more compact and robust than it could be with vacuum tubes.
Light slows down very slightly when it passes into any substance from a vacuum. The greater the refractive index of the material, the slower the light becomes. To make laser light travel very slowly, researchers create substances with immense refractive indices.
Hemmer’s team use a second laser beam to excite atoms in a substance to new energy states. Light can be considered to propagate through a material by being sequentially absorbed and re-emitted by atoms. The second beam manipulates this process so that it becomes more and more difficult for the light to make the step from one atom to the next.
The second beam couples the light pulse to the atoms. When shackled to these heavy objects, the pulse slows down. If this coupling is strong enough, the pulse comes to rest and all its energy is transferred to the atoms.
A light pulse that is brought to a standstill is not destroyed. The atoms ’remember’ it, so the pulse can be regenerated by changing the intensity of the coupling laser to allow the atoms to re-emit photons - the particles of which light is composed.
PHILIP BALL | © Nature News Service
Quantum computers by AQT and University of Innsbruck leverage Cirq for quantum algorithm development
16.09.2019 | Universität Innsbruck
Artificial Intelligence speeds up photodynamics simulations
12.09.2019 | University of Vienna
Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Hamburg and the European Molecular Biology Laboratory (EMBL) outstation in the city have developed a new method to watch biomolecules at work. This method dramatically simplifies starting enzymatic reactions by mixing a cocktail of small amounts of liquids with protein crystals. Determination of the protein structures at different times after mixing can be assembled into a time-lapse sequence that shows the molecular foundations of biology.
The functions of biomolecules are determined by their motions and structural changes. Yet it is a formidable challenge to understand these dynamic motions.
At the International Symposium on Automotive Lighting 2019 (ISAL) in Darmstadt from September 23 to 25, 2019, the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, a provider of research and development services in the field of organic electronics, will present OLED light strips of any length with additional functionalities for the first time at booth no. 37.
Almost everyone is familiar with light strips for interior design. LED strips are available by the metre in DIY stores around the corner and are just as often...
Later during this century, around 2060, a paradigm shift in global energy consumption is expected: we will spend more energy for cooling than for heating....
Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Potsdam (both in Germany) and the University of Toronto (Canada) have pieced together a detailed time-lapse movie revealing all the major steps during the catalytic cycle of an enzyme. Surprisingly, the communication between the protein units is accomplished via a water-network akin to a string telephone. This communication is aligned with a ‘breathing’ motion, that is the expansion and contraction of the protein.
This time-lapse sequence of structures reveals dynamic motions as a fundamental element in the molecular foundations of biology.
Two research teams have succeeded simultaneously in measuring the long-sought Thorium nuclear transition, which enables extremely precise nuclear clocks. TU Wien (Vienna) is part of both teams.
If you want to build the most accurate clock in the world, you need something that "ticks" very fast and extremely precise. In an atomic clock, electrons are...
10.09.2019 | Event News
04.09.2019 | Event News
29.08.2019 | Event News
18.09.2019 | Materials Sciences
17.09.2019 | Materials Sciences
17.09.2019 | Health and Medicine