Quantum transport goes ballistic for future computers

Article By : IBM Research

The technique fires electrons through nanowire without being scattered until they hit the opposed electrode, IBM researchers say.

IBM scientists have successfully shot an electron through an III-V semiconductor nanowire integrated on silicon, which could pave the way for sophisticated quantum wire devices for future integrated circuits used in advanced powerful computational systems.

For their research, published in the journal Nano Letters, the IBM team led by Dr. Johannes Gooth went "ballistic," but at the nanoscale.

To do this, the researchers fired electrons from one contact electrode, letting them fly through the nanowire without being scattered until they hit the opposed electrode. The nanowire acts as a perfect guide for electrons, such that the full quantum information of this electron (energy, momentum, spin) can be transferred without losses, Gooth explained.

"We can now do this in cross-junctions, which allows us to build up electron pipe networks, where quantum information can perfectly be transmitted. The challenge is to fabricate a geometrically very well defined material with no scatterers inside on the nanoscale. The template-assisted selective epitaxy or TASE process, which was developed here at the IBM Zurich Lab by my colleagues, makes this possible for the first time," he said.

The technique, according to Gooth, is scalable and compatible with standard electronics and CMOS processes.

Quantum transport for quantum computers

Gooth believes quantum transport will be an essential piece as the industry looks to build a universal computer.

"If you want to exercise the full power of quantum information technology, you need to connect everything ballistic: a quantum system that is fully ballistically (quantum) connected has an exponentially larger computational state space compared to classically connected systems," he explained. "Also, as stated above, the electronics are scalable. Moreover, combining our nanowire structures with superconductors allows for topological protected quantum computing, which enables fault tolerant computation. These are major advantages compared to other techniques."

The IBM team's next steps will involve the functionalisation of the crosses by attaching electronic quantum computational parts, according to Gooth.

"We will start to build superconducting/nanowire hybrid devices for Majorana building, and attach quantum dots," he said.

Universal quantum computer here we come.