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Introducing the 'nano-ear'



Bulging fibre excels at storing light


Ohm's law holds down to atomic scale

The result comes as a surprise because conventional wisdom suggests that quantum effects should cause large deviations from Ohm's law for such tiny wires. How to turn darkness into light. Quantum mechanics tells us that the vacuum is not empty but is filled with virtual particles that pop into and out of existence.

How to turn darkness into light


Three electrons for the price of one. Researchers have created a new material that can produce three or more free electrons every time it absorbs a single photon.

Three electrons for the price of one


Solar cells work by absorbing photons, each of which liberates an electron and positively charged hole that travel in opposite directions, thereby creating a voltage and current that can do work. However, when an electron is liberated, a lot of its kinetic energy is lost to the semiconductor as heat, rather than being available as useful electrical energy. Researchers are therefore keen to develop new materials in which some or all of this energy is captured rather than wasted. Stable, yet conducting. New 'light transistor' for optical circuits. A gadget that boosts a laser signal by a factor of 60 - based on the transfer of photons rather than electrons - could seed a new generation of ultrafast components for optical circuits.

New 'light transistor' for optical circuits

Junji Tominaga of the National Institute of Advanced Industrial Science in Japan and colleagues developed the device, which paves the way for all-optical circuits that transmit information at - literally - the speed of light. (J Tominaga et al 2001 Appl. Phys. Lett. 78 2417). The new 'photonic transistor' would be just nanometres thick, unlike existing devices that rely on long optical fibres to produce the gain. Optical signals in conventional optoelectronic devices have to be converted into electronic signals when they are amplified or manipulated. Nanoantenna separates light of different colours.


Nanoantenna separates light of different colours



Electrons surf between qubits

Both schemes involve using sound waves on the surface of a material to propel electrons between the quantum dots – which are sub-micron-sized pieces of semiconductor. The teams are confident that they will soon be able to show that electrons arrive at their destination with their quantum information intact, making the system a viable "quantum data bus" for a quantum computer. Quantum computers, which exploit purely quantum phenomena such as superposition and entanglement, should in principle be able to outperform classical computers at certain tasks. But building a practical quantum computer remains a challenge because the physical entities that store and transfer quantum bits (qubits) of information are tricky to implement and are easily destroyed.


Graphene tunes in to terahertz radiation


Physicists in tune with neurons


Hitting the right notes How humans and animals perceive sound has long fascinated scientists because of the brain's amazing ability to process auditory signals. As examples, Spagnolo cites two things that musicians take for granted: the "pitch perception" and the "perception of consonance and dissonance". On board the "spike trains" Senses and sensibility. Black holes act as galactic thermostats. The supermassive black hole at the centre of a massive galaxy or galaxy cluster acts as a furnace, pumping heat into its surroundings. But astronomers have struggled to understand how a steady temperature is maintained throughout the whole galaxy when the black hole only appears to interact with nearby gas.

Now, researchers in Canada and Australia believe the answer could be a feedback loop in which gravity causes gas to accumulate around the black hole until its density reaches a tipping point. Calcium ions simulate the quantum world. The first digital "quantum simulator" based on trapped ions has been built by physicists in Austria.


Analogue to digital Easily scalable. Introducing the 'antimagnet' Plasmonic metamaterials could make 'gecko toes' A material that promises to stick to smooth surfaces and then release on demand has been designed by scientists in the UK. Light propagates as if 'space is missing' Flipping spins, one proton at a time.