Quantum Stopwatch: How To Store Time in a Quantum Memory

Abstract

Quantum mechanics imposes a fundamental tradeoff between the accuracy of time measurements and the size of the systems used as clocks. When the measurements of different time intervals are combined, the errors due to the finite clock size accumulate, resulting in an overall inaccuracy that grows with the complexity of the setup. Here we introduce a method that in principle eludes the accumulation of errors by coherently transferring information from a quantum clock to a quantum memory of the smallest possible size. Our method could be used to measure the total duration of a sequence of events with enhanced accuracy, and to reduce the amount of quantum communication needed to stabilize clocks in a quantum network.

arXiv comment10 + 5 pages, 3 figures

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• Quantum adaptive agents with efficient long-term memories
• Efficient algorithms for quantum information bottleneck
• Quantum metrology in the finite-sample regime
• Communication Cost of Quantum Processes
• Quantum coarse-graining for extreme dimension reduction in modelling stochastic temporal dynamics
• Quantum Compression of Tensor Network States
• Compression of quantum shallow-circuit states
• Compression for Qubit Clocks