Figure 1.

In our schematic conception of a programmable, autonomous Maxwell’s demon, a fixed set of binary gates defines a reference sequence. As the demon interacts one bit at a time with an incoming sequence of memory bits, it is able to lift a small mass against gravity if the incoming bit sequence matches the reference sequence. As the demon writes information onto the memory bits, the outgoing sequence becomes less correlated with the reference sequence. To highlight the correlation between each bit–gate pair, we use blue when the pair are in the same state and red when the pair are in the opposite state. Conversely, if the mass is large and falls against gravity, then this energy can be used to copy the reference sequence to the memory bits.