Quantum lock-in detection (QLID) is crucial for extracting oscillating signals from noise, while quantum entanglement is vital to surpass the standard of quantum limit in precision measurement. Here, the authors experimentally realise entanglement-enhanced QLID using two trapped ions, achieving frequency measurement precision at the Heisenberg limit and demonstrating an improved inverse-quadratic temporal scaling.
- J.-W. Zhang
- M. Zhuang
- M. Feng
