Dynamical decoupling for quantum metrology with periodically driven Hamiltonians
Phys. Rev. A 114, 032418 – Published 8 September, 2026
DOI: https://doi.org/10.1103/lb42-hr34
Abstract
Quantum metrology exploits quantum resources to achieve measurement precision beyond classical scaling, but this advantage is often compromised by environmental decoherence. While dynamical decoupling is a powerful tool for eliminating non-Markovian noise, it has a fundamental conflict: The decoupling pulses often average out the parameter-dependent system Hamiltonian along with the noise, effectively erasing the signal to be measured. To overcome this trade-off, we propose a periodic Hamiltonian driving strategy in this work. By synchronizing the switching on and off of the system Hamiltonian with the dynamical decoupling pulses, this approach simultaneously preserves parameter encoding and suppresses environmental noise. We theoretically prove that this binary “bang-bang” modulation of the Hamiltonian is the optimal driving pattern, yielding the highest possible estimation precision within the periodic framework. Furthermore, we demonstrate that when integrated with optimal Hamiltonian control, this strategy successfully restores the Heisenberg scaling for estimation precision. The protocol is illustrated through some examples, where the pulse sequences are optimized to reduce the experimental complexity.
