A team of researchers from Japan and Michigan Technological University has built a molecular computer using lessons learned from the human brain.

“Modern computers are quite fast, capable of executing trillions of instructions a second, but they can’t match the intelligent performance of our brain. 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,” said physicist Ranjit Pati of Michigan Technological University.

That happens because information processing is done sequentially in digital computers. Once a current path is established along a circuit, it does not change. By contrast, the electrical impulses that travel through our brains follow vast, dynamic, evolving networks of neurons that operate collectively.

The researchers made their different kind of computer with DDQ, a hexagonal molecule made of nitrogen, oxygen, chlorine and carbon that self-assembles in two layers on a gold substrate.

The DDQ molecule can switch among four conducting states – 0, 1, 2 and 3 – unlike the binary switches – 0 and 1 – used by computers.

The researchers have demonstrated an assembly of molecular switches that simultaneously interact to perform a variety of computational tasks including conventional digital logic, calculating Voronoi diagrams, and simulating natural phenomena such as heat diffusion and cancer growth. As well as representing a conceptual shift from serial-processing with static architectures, our parallel, dynamically reconfigurable approach could provide a means to solve otherwise intractable computational problems.

“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. The evolving neuron-like circuit network allows us to address many problems on the same grid, which gives the device intelligence. As a result, their tiny processor can solve problems for which algorithms on computers are unknown, especially interacting many-body problems, such as predictions of natural calamities and outbreaks of disease,” explained Mr. Pati.

The molecular processor heals itself if there is a defect. This property comes from the self-organizing ability of the molecular monolayer. No existing man-made computer has this property, but our brain does, if a neuron dies, another neuron takes over its function.

“This is very exciting, a conceptual breakthrough. This could change the way people think about molecular computing,” said Mr. Pati.

An abstract of “Massively Parallel Computing on an Organic Molecule Layer” is available at Nature Physics. Additional coauthors are Satyajit Sahu and Daisuke Fujita of the National Institute for Materials Science, Japan, and Ferdinand Peper of the National Institute of Information and Communications Technology, Japan.