Molecular logic gate, conceptual illustration. Molecular logic gates are molecules that perform a Boolean operation using one or more inputs to produce a single logic output. The inputs may be changes to the molecule's environment, such as a change in pH or the addition of other molecules, or a change in the energy state of the molecule itself. The output is usually a change in the way the molecule interacts with light. Molecular logic gates could be used in situations where silicon logic gates cannot, such as inside living tissues and cells.