Faster, smaller & biocompatible? Excitonic logic could supercharge computing

A roadmap to challenging conventional computing through excitonic logic has been published by Australian researchers in the journal Nature Reviews Chemistry.

The authors, members of the ARC Centre of Excellence in Exciton Science, propose harnessing the power and potential of quasi-particles known as excitons to provide an alternative to existing inorganic logic elements.

Studied closely by both chemists and physicists, excitons are formed when a material is ‘excited’ by photons of light or another source of energy. They have no net charge and exist for mere nanoseconds but have many interesting properties that make them useful for a variety of applications.

Excitons already power important technologies such as solar panels and light-emitting diodes (LEDs). In the future, they could also be used to give computers around the world a significant upgrade.

Computing devices are currently made from semiconducting electronic chips and function through binary logic, where high or low voltages are used to encode information in ‘bits’ – 0 or 1.

In the proposed alternative, excitons would instead be used to encode information, offering a number of major advantages. Excitonic circuit components could be constructed using single molecules, allowing them to be significantly smaller than contemporary transistors and diodes.

Multiexcitonic processes occur on extraordinarily fast timescales, from femtoseconds (one quadrillionth of a second) onwards. Conducting logical operations with excitons could help to build devices that operate much faster than modern computers.

Unlike silicon-based electronics, excitonic logical devices made using organic semiconductor molecules also have the potential to be biocompatible and could be used in brain implants, skin monitors and other medical devices. Excitonic logic could even have the potential to control molecular scale machines.

And while the researchers focused on the capacity of excitonic logic to improve conventional binary computing, other forms of excitonic logic are also theoretically feasible.

For example, quantum excitonic computing could represent information as 1, 0 or a superposition of these values, and converting between different types of excitons could encode information in a ternary information basis (0, 1 or 2).

However, practical implementation of quantum excitonic logic may prove challenging to achieve for many years to come.  

Nevertheless, using excitons to perform logical, binary operations in our computers offers the tantalising prospect of an information technology landscape advanced beyond recognition.