On a New Class of Self-Referencing, 1/τ Atomic Clocks

The merit of a modern atomic clock is measured by its phase stability. A clock＇s absolute time-keeping uncertainty typically worsens over its operating time τ as Δτα√τ, with an Allan deviation of sy σy（τ）=Δτ/τατ^-1/2. Here we analyze a new class of self-referencing clocks, whose phase is locked to itself after a certain time delay. We show that the Allan deviation of such clocks decreases as 1/τ over a long and controllable operating time. This class of clocks can maintain synchronization over a prolonged period with only a fixed, almost non-increasing, absolute uncertainty, forming an ideal time-piece.