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    Close to Absolute Zero, Electrons exhibit their Quantum Nature

    November 8, 2016, Categories  Physics, Technology/Electronics

    Keeping a close eye on everything: Christian Ast checks the connections of the scanning tunneling microscope (top). Researchers in the Nanoscale Science Department conduct their experiments in this instrument at lowest temperatures of a fifteen thousandth of a degree above absolute zero. The principle is always the same (bottom): A tunneling current (illustrated by the transparent bar) flows between an ultrafine tip and the sample, providing information about the properties of the sample. At these low temperatures the tunneling current reveals all of its quantum properties.

    Keeping a close eye on everything: Christian Ast checks the connections of the scanning tunneling microscope (top). Researchers in the Nanoscale Science Department conduct their experiments in this instrument at lowest temperatures of a fifteen thousandth of a degree above absolute zero. The principle is always the same (bottom): A tunneling current (illustrated by the transparent bar) flows between an ultrafine tip and the sample, providing information about the properties of the sample. At these low temperatures the tunneling current reveals all of its quantum properties. Credit: Tom Pingel (top), MPI for Solid State Research (bottom)

    What would happen if an electric current no longer flowed, but trickled instead? This was the question investigated by researchers working with Christian ...

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    Major Advance in Solar Cells made from Cheap, Easy-to-use Perovskite

    November 8, 2016, Categories  Technology/Electronics, Chemistry/Nanotechnology, Physics

    Major advance in solar cells made from cheap, easy-to-use perovskite

    This first version of a new layered perovskite solar cell already achieves an efficiency of more than 20 percent, rivaling many commercial solar cells. Flexible and easy to make, it can produce more than half a volt of electricity. Credit: Onur Ergen, UC Berkeley

    Solar cells made from an inexpensive and increasingly popular material called perovskite can more efficiently turn sunlight into electricity using a new technique to sandwich 2 types of perovskite into a single photovoltaic cell. Perovskite solar cells are made of a mix of organic molecules and inorganic elements that together capture light and convert it into electricity, just like today’s more common silicon-based solar cells...

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    Lasers + Anti-lasers: Marriage opens door to Development of Single Device with Exceptional Optical Capabilities

    November 7, 2016, Categories  Physics, Technology/Electronics

    Schematics above show light input (green) entering opposite ends of a single device. When the phase of light input 1 is faster than that of input 2 (left panel), the gain medium dominates, resulting in coherent amplification of the light, or a lasing mode. When the phase of light input 1 is slower than input 2 (right panel), the loss medium dominates, leading to coherent absorption of the input light beams, or an anti-lasing mode. (Credit: Zi Jing Wong/UC Berkeley)

    Scanning electron microscope image of the single device capable of lasing and anti-lasing. Indium gallium arsenide phosphide (InGaAsP) material functions as the gain medium, while the chromium (Cr) and germanium (Ge) structures introduce the right amount of loss to satisfy the condition of parity-time symmetry that is required for lasing and anti-lasing. (Credit: Zi Jing Wong/UC Berkeley)(From left) Berkeley researchers Xiang Zhang, Zi Jing Wong, Jeongmin Kim and Yuan Wang stand next to the optical setup they designed to demonstrate both lasing and anti-lasing in a single device. (Credit: Marilyn Chung/Berkeley Lab)

    1. Schematics above show light input (green) entering opposite ends of a single device. When the phase of light input 1 is faster than that of input 2 (left panel), the gain medium dominates, resulting in coherent amplification of the light, or a lasing mode. When the phase of light input 1 is slower than input 2 (right panel), the loss medium dominates, leading to coherent absorption of the input light beams, or an anti-lasing mode. (Credit: Zi Jing Wong/UC Berkeley)
    2. Scanning electron microscope image of the single device capable of lasing and anti-lasing...
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    Scientists present the most Accurate time Measurements of Quantum Jumps to date

    November 7, 2016, Categories  Physics, Technology/Electronics

    Ein kurzer Laserpuls ionisiert ein Helium-Atom und kann den Zustand des verbleibenden Elektrons verändern.

    A short laser pulse can ionize a helium atom and change the quantum state of the remaining electron.

    When a quantum system changes its state, this is called a quantum jump. Usually, these quantum jumps are considered to be instantaneous. Now, new methods for high-precision measurements allow us to study the time evolution of these quantum jumps. On a time scale of attoseconds, there time structure becomes visible. It is he most accurate time measurement of quantum jumps to date. Quantum particles can change their state very quickly, ie “quantum jump”. An atom, for example, can absorb a photon, thereby changing into a state of higher energy. With new methods, developed at TU Wien (Vienna), it is now possible to study the time structure of such extremely fast state changes...

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