Quantum Clocks and Stopwatches

R. Sala Mayato, Daniel Alonso, I. L. Egusquiza

Yuxiang Yang, Giulio Chiribella, Masahito Hayashi

Yuxiang Yang, Giulio Chiribella, Masahito Hayashi

Atomic clocks are our most accurate indicators of time. Their applications range from GPS systems to synchronization of electronics, astronomical observations, and tests of fundamental physics. Here we propose a protocol that combines an atomic clock with a quantum memory, realizing a stopwatch that can be paused and resumed on demand. Taking advantage of the quantum memory, the stopwatch can measure the total time elapsed in a sequence of time intervals with the ultimate precision allowed by quantum mechanics, outperforming stopwatches that use only classical memories. The working principle of the quantum stopwatch is a new type of information compression,tailored to store the state of the quantum clock into a quantum memory of exponentially smaller size. Our protocol can be used to generate quantum states with Heisenberg limited sensitivity and to efficiently synchronize clocks in quantum communication networks.

P. Kómár, E. M. Kessler, Michael Bishof +4 more

Maximilian P. E. Lock, Ivette Fuentes

J. Muñoz, Ion Lizuain, Juan Gonzalo Muga

Fundamental low-energy limits to the accuracy of quantum clock and stopwatch models in which the clock hand motion is activated by the presence of a particle in a region of space have been studied in the past, but their relevance for actual atomic clocks had not been assessed. In this work we address the effect of slow atomic quantum motion on Rabi and Ramsey resonance fringe patterns, as a perturbation of the results based on classical atomic motion. We find the dependence of the fractional error of the corresponding atomic clocks on the atomic velocity and interaction parameters.