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Noise-Resilient Heisenberg-Limited Quantum Sensing via Indefinite-Causal-Order Error Correction
Hang Xu1, Xiaoyang Deng1, Ze Zheng1
1Shanghai Jiao Tong University, State Key Laboratory of Photonics and Communications, Institute for Quantum Sensing and Information Processing, Shanghai 200240, People's Republic of China.
None:
Quantum resources can, in principle, enable Heisenberg-limited sensing, yet no-go theorems imply that Heisenberg-limited scaling is generically unattainable in realistic noisy devices. While quantum error correction (QEC) can suppress noise, its use in quantum sensing is constrained by stringent requirements, including prior noise characterization, restrictive signal-noise compatibility conditions, and measurement-based syndrome extraction with global control. Here we introduce a QEC protocol based on indefinite causal order (ICO), providing the first application of ICO to QEC. By coherently placing auxiliary controls and noisy evolution in an indefinite causal order, the resulting noncommutative interference enables an auxiliary system to herald and correct errors in real time, avoiding the entanglement encoding and entanglement readout required by traditional QEC. Furthermore, within the time-reversal regime of the Hamiltonian, our protocol extends correctability to parallel noises where traditional protocols may fail. We rigorously establish the protocol for single-noise and multinoise scenarios and demonstrate its performance in single-qubit, many-body, and continuous-variable platforms. We further identify regimes in which error correction can be implemented entirely by unitary control, without measurements. Our results reveal ICO as a powerful resource for metrological QEC and provide a broadly applicable framework for noise-resilient quantum information processing.
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