This content has been archived. It may no longer be relevant
Timothy Wogan writes that the erasure of data – the blanking of memory so that it can be used again – is a fundamental operation any computer must perform. In today’s computers, erasure generates heat, which not only wastes energy, but also causes problems for engineers trying to make smaller or more powerful computers, since the heat could damage the circuitry. But now theoretical physicists claim that, in the world of quantum computing, the act of erasing data might actually cool a computer.
A classical computer generates heat when erasing data because of entropy – a central concept in both thermodynamics and information theory that describes the amount of unknown information in a system. The entropy of the universe can never decrease; so if you reduce the entropy of a memory chip, then you inevitably increase the entropy of its surroundings, which causes them to heat up. In classical computing, data are stored as a long string of bits, which can read either one or zero. To erase these data, all the bits have to be set to zero, which means putting the memory into a zero-entropy state. Since this action normally means reducing the entropy, heat will be generated.
In information theory, however, the entropy of a particular set of data is conditional on how much the observer knows about the data. For an observer who has total knowledge of the data, the entropy is, by definition, zero. It is therefore theoretically possible for that observer to erase the data without decreasing the entropy and without generating any heat.
Associate Creative Director at bloomfield knoble
Associate Creative Director at bloomfield knoble