Quantum clocks are more precise than classical ones

Understand

A clock is, from an information-theoretic perspective, a system that emits information about time.

• One may therefore ask whether the theory of information imposes any constraints on the maximum precision of clocks.
• Here we show a quantum-over-classical advantage for clocks or, more precisely, the task of generating information about what time it is.
• The argument is based on information-theoretic considerations: we analyse how the precision of a clock scales with its size, measured in terms of the number of bits that could be stored in it.