TECHNOLOGY
Living fuel cells to squeeze juice from jellyfish protein power the jellyfish device without the need for an external light source. They concocted a mixture of light-emitting pigments – the luciferase enzymes found in fireflies and sea pansies – and the molecule ATP, which provides
STEAMPUNK, the re-imagining of modern-day technology through a Victorian perspective, could find its way into modern jet engines. A retro logic gate, built in the style of Victorian inventor Charles Babbage, works at temperatures that standard transistors cannot stand, and so could be used in jet engine electronics. Babbage famously designed mechanical computers, in which steam-driven pistons turned cogs and levers, but his unwieldy contraptions were quickly superseded by electronic computers, through which data is processed by vast arrays of transistors. In a transistor, the voltage applied to one of the terminals, the gate, determines whether a current flows through it. But above 250 °C, the device is so awash with thermally generated electrons that the current leaks through the gate when it is closed. Even silicon carbide, a semiconductor material –Sea power– hardy against heat, isn’t immune to the problem. That prompted Te-Hao Lee’s team at Case Western Reserve University in be used to chill the qubits in a Cleveland, Ohio, to consider returning to quantum computer, cutting out the mechanical logic. His team has developed thermal noise that can upset their a mechanical version of an inverter – the delicate quantum properties. building block for many types of logic However, to reach super-cool gate, which themselves are fundamental the 101 and 010 group states are temperatures within a quantum components of digital circuitry within exactly equal in energy, meaning the computer the fridge would need computers. The device uses an system can swap between the two a super-hot heat bath. Raymond arrangement of nanoscale levers instead easily. Next, the team imagined that Laflamme’s team at the University of the first qubit is attached to a heat Waterloo in Ontario, Canada, has made of transistors (Science, DOI: 10.1126/ science.1192511). Like a telegraph bath, providing it with a constant operator’s Morse key, these levers source of energy that should increase “The fridge could chill physically make or break contact to pass the probability that the qubits will the qubits in a quantum or block currents. take on the 101 state. However, the computer, cutting out Application of a voltage makes qubits interact on a quantum level thermal noise” the levers move under electrostatic with the unexpected consequence attraction. At 550 °C Lee’s team managed that the probabilities flip, making a quantum refrigeration system that the 010 state more likely. As the runs on similar principles to the Bristol to get the inverter to switch on and off 500,000 times a second. The faster the probability of the third qubit being team’s blueprint, but the cooling is switching speed, the zippier the in state 0 increases, its temperature driven by an external magnet acting computing. Lee predicts that switching falls. Increasing the probability is on the qubits rather than heat. They easy: turn up the heat on the first have used their fridge to cool a carbon speeds of a billion times a second (1 gigahertz) will eventually be possible qubit. The work will appear in Physical atom to -95°C, but they intend to – high enough to run engine control Review Letters. approach absolute zero in future systems. Paul Marks n The team says that the fridge could experiments. Kate McAlpine n
World’s smallest fridge takes aim at absolute zero A QUANTUM trick could pave the way for the world’s smallest fridge – one built on the atomic scale. The small but mighty cooler could brush the ultimate chill of absolute zero to keep quantum computers running smoothly, according to a team of theoretical physicists. Blueprints for the device, designed by Noah Linden at the University of Bristol, UK, and colleagues, suggest that the fridge would consist of two quantum bits, or qubits, which interact with a third qubit in such a way that it would cool. Each qubit has two possible energy states: high, or “1”, and low, or “0”. The three qubits together share a group state, such as 110. The team’s theoretical system is chosen so that 22 | NewScientist | 18 September 2010
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Who wants a dead battery? Dollops of green goo made of the material of life – from jellyfish to fireflies – are now being recruited to produce electricity. Zackary Chiragwandi at Chalmers University of Technology in Gothenburg, Sweden, and colleagues have built a fuel cell powered by stuff taken from living cells. First, they made a photovoltaic device based on green fluorescent protein (GFP) from the jellyfish Aequorea victoria. They deposited two aluminium electrodes with a tiny gap between them onto a silicon dioxide substrate and then added a droplet of GFP on top, whereupon the protein assembled itself into strands between the electrodes. When ultraviolet light shone on it, the GFP absorbed photons and emitted electrons, which travelled around a circuit to produce electricity. Next, the team found a way to
Steampunk chip could take the heat in jet engines
living cells with energy. The mixture produces light, so when it was placed alongside the GFP inside a fuel cell, the jellyfish goo produced its juice. The team’s fuel cell, which they will describe in the journal Energy and Environmental Science, could power nano-devices embedded in humans or animals, says Chiragwandi, for example to diagnose disease. Helen Knight n