THE QUANTUM FUTURE
THE QUANTUM FUTURE
The next generation of solar cells may employ tiny bits of semiconductor material called quantum dots. These can be turned to quantum wires – made with carbon nanotubes. But things get even better and efficient with superconductors – thus helping power companies to reduce the loss of energy to heat, which is typically about 7 percent.
THE DUAL NATURE OF LIGHT
Quantum physics tells us that light acts both as a wave and particle – a mysterious duality that has puzzled scientists for more than a century.
To detail this further, the double-slit experiment – that looks on the behavior of light – shows how light or electrons are aimed at a solid plate with two parallel cuts in it, thus offering two choices. One would be to go through the slit on the left and the other, to go through the slit on the right. Strangely enough, subatomic particles might break the rules and go through both slits, just as a wave would behave. Now, the most bizarre aspect of this duality is that it depends on how much the observer pays attention. Specifically, the more carefully it measures whether it went through the left or right slit, the more the object in question chooses a single slit – just as a particle would.
This dual nature is utilized in solar power technology. Incoming sunlight is concentrated by mirrors and lenses that rely on the wave-like properties of light. Once inside the solar cell, however, the focused light collides with electrons in a particle-like way. This way, it frees the electrons to create an electric current.
QUANTUM WIRES VERSUS SUPERCONDUCTORS
Quantum dots are nanometer-sized devices so small that only a handful (1 to 1,000) of free electrons can reside inside. In these cramped quarters, a quantum dot behaves like an artificial atom in that its electrons can reside only at specific energy levels – which define exactly what wavelengths of light the dot will absorb. The solar cell manufacturers may one day be able to combine dots of different sizes to absorb sunlight from a wide range of wavelengths.
Now, a quantum wire is like a quantum dot stretched out along one direction. This is 10,000 times thinner than human hair and it can be very good at conducting electricity. Using carbon nanotubes is a good way to make quantum wires. These rolled-up sheets of hexagonally bound carbon were discovered in 1991, now being present in many types of applications, including better energy storage. Building an ultracapacitor from several nanotubes can secure the storing of up to 50 percent of the electricity that a battery of the same size can, the scientists claim. Such a device might be successfully used in electric cars.
But although these quantum wires can be fairly good conductors, research has found that another quantum substance is the best: superconductors. These are materials in which the electrons pair up to carry the current. This pairing is very unusual because electrons typically repel each other, but quantum physics overcomes this. Thus, it reduces the electrical resistance in the superconductor very close to zero.
While power companies typically lose about 7 percent of their energy to heat caused by resistance in transmission wires. But superconducting wires could help reduce this waste. But superconductors work only at extremely low temperatures – typically minus 330 degrees Fahrenheit.
Superconducting wires can be used in offshore wind turbines, so making them smaller and much more efficient.