Computer chips are made by etching microscopic patterns into silicon using light and chemicals in a technique called photo lithography. For even smaller circuits, like those needed for quantum dots and quantum devices, electrons replace the light in a technique known as electron beam lithography. The problem with electron beam lithography is that it is a laboriously slow process.
Teams of researchers from Cambridge University in England and the Massachusetts Institute of Technology have modified a scanning tunnelling microscope (STM) to create quantum devices in a matter of hours rather than weeks. Their technique is known as erasable electrostatic lithography.
The microscope draws charge patterns on a semiconducting piece of gallium arsenide and erases the patterns with red light. The surface charge creates working quantum devices and has been used to make quantum wires, dots and hills.