Researchers from Japan and the Michigan Technological University have succeeded in building a molecular computer that, more than any previous project of its kind, can replicate the inner mechanisms of the human brain, repairing itself and mimicking the massive parallelism that allows our brains to process information like no silicon-based computer can.

A relatively new technology, molecular electronics is an interdisciplinary pursuit that may very well prove the long-term solution to validate Moore's law well into the next century. A molecular computer is made of organic molecules instead of silicon. Chips built this way are not only potentially much smaller but also, because of the way they can be networked, able to do things that no other traditional computer, regardless of its speed, can do.

"Modern computers are quite fast, capable of executing trillions of instructions a second, but they can't match the intelligent performance of our brain," Michigan Tech physicist Ranjit Pati commented. "Our neurons only fire about a thousand times per second. But I can see you, recognize you, talk with you, and hear someone walking by in the hallway almost instantaneously, a Herculean task for even the fastest computer."

The key lays in the massive parallelism and versatility of the human brain, as the electrical impulses that travel through it follow vast, dynamic neural paths that operate collectively, constantly communicating with each other. In digital computers, by contrast, information processing is done sequentially, with recent advancements such as multicore processors and GPU processing altering the picture only slightly.

The researchers built a molecular computer by placing DDQ — a hexagonal molecule made of nitrogen, oxygen, chlorine and carbon that self-assembles in two layers — on a gold substrate. Crucially, this molecule has the ability to easily switch among four conducting states (compared to the only two used by a standard computer), which simplifies the read/write mechanisms and speeds up the data crunching.

"The neat part is, approximately 300 molecules talk with each other at a time during information processing. We have mimicked how neurons behave in the brain," said Pati. But perhaps the most stunning similarity of the team's computer with the human brain comes from the self-organizing ability of the molecular layer, and is the ability to physically heal itself, just like brain cells are able to regenerate to some extent.

Because of these unique characteristics the team's processor can, despite its relative simplicity, solve problems for which algorithms are unknown. The researchers already demonstrated this capability by simulating two natural phenomena in the molecular layer — heat diffusion and the evolution of cancer cells. As their complexity grows, molecular computers may soon be able to solve the same problems that our brains face every day.

The team's work is detailed in the paper Massively Parallel Computing on an Organic Molecule Layer, published in the online version of the journal Nature Physics. The research is supported by the National Science Foundation.