Chaos Boosts Quantum Sensing Accuracy

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A superconducting quantum processor, architected with nine transmon qubits, explores the limits of sensitivity through a protocol leveraging information scrambling - specifically, an engineered ‘butterfly state’ entangled from a polarized foundation $|0\rangle^{\otimes 9}$ and a scrambled counterpart $|\psi_{\textrm{sc}}\rangle$ - to approach a sensitivity scaling of half the Heisenberg limit by imprinting a global phase signal $\phi$ analogous to a quantum-enhanced Mach-Zehnder interferometer, and ultimately measured through projective measurement of a central qubit following a localized perturbation and time-dependent unitary evolution.

Researchers have harnessed the principles of quantum chaos to significantly improve the precision of quantum sensors, bringing them closer to the fundamental limits of measurement.