The transistor is the foundation for the semiconductor industry and all of our modern electronic miracles. The ability to shrink transistors has led to cheaper and faster electronic devices, as well as solid state storage and digital photography.

Australian researchers have now created the world's smallest transistor, consisting of only seven atoms arranged into a single silicon crystal. It is fully functional and can regulate and control the flow of electrical current, despite being only 4nm across.

"The significance of this achievement is that we are not just moving atoms around or looking at them through a microscope," says Professor Michelle Simmons, a co-author of a paper on the subject that is being published by Nature Nanotechnology. The paper is entitled "Spectroscopy of Few-Electron Single-Crystal Silicon Quantum Dots".

"We are manipulating individual atoms and placing them with atomic precision, in order to make a working electronic device," elaborated Simmons. "We have replaced just seven individual silicon atoms with phosphorus atoms. That is amazing exactness".

The research was primarily conducted at the University of New South Wales' Centre for Quantum Computer Technology (CQCT) in Sydney, with the assistance of researchers from the University of Wisconsin-Madison. Simmons currently works as the Director of the CQCT.

The atoms were placed using a scanning tunneling microscope, which operates on the concept of quantum tunneling. Although it was first developed in 1981, it uses extremely challenging techniques that require highly clean and stable surfaces, exceptional vibration control, and sophisticated electronics. Simmons' team is now applying those techniques towards their first quantum computer.

Quantum computing is expected to be the next big scientific leap, and could revolutionize cryptography, weather forecasting, and nuclear modeling amongst other fields.