The Economist is gazing into the pretty colors…not of quantum computers, but quantum television screens:
An LCD screen works with a backlight shining through red, blue or green filters to produce the pixels which make up an image. Many televisions use light-emitting diodes (LEDs) as the backlight because they are brighter and use less power than fluorescent bulbs. Sony’s new televisions uses quantum dots with conventional LEDs to produce a hybrid backlight of greater intensity. In time, though, quantum dots might be used directly as the coloured pixels on screens.
When a voltage is applied to a quantum dot it causes electrons contained in the crystal to release energy in the form of light. Changing the size of the dots changes the amount of energy released, which in turn determines the wavelength, and therefore the colour of the emitted light. This means they can be made into nanoscopic LEDs and, in principle, be tailored to generate any colour of the rainbow from red (long wavelenghts) to violet (short wavelengths).