Phys.org March 4, 2024
The coherence time of the quantum system surpasses that of the oscillator probing the system. Correlation spectroscopy overcomes this limitation by probing two quantum systems with the same noisy oscillator for a measurement of their transition frequency difference enabling very precise comparisons of atomic clocks. An international team of researchers (Austria, Israel, USA – Caltech) extended correlation spectroscopy to the case of multiple quantum systems undergoing strong correlated dephasing. They modelled Ramsey correlation spectroscopy with N particles as a multiparameter phase estimation problem and demonstrated that multiparticle correlations could assist in reducing the measurement uncertainties even in the absence of entanglement. Using one- and two-dimensional ion Coulomb crystals with up to 91 qubits, they experimentally demonstrated the advantage of measuring multiparticle correlations for reducing phase uncertainties and applied correlation spectroscopy to measure ion-ion distances, transition frequency shifts, laser-ion detunings, and path-length fluctuations. According to the researchers their method can be implemented in experimental setups with globally coherent qubit control and qubit-resolved single-shot readout and hence it is applicable to other physical systems such as neutral atoms in tweezer arrays… read more. Open Access TECHNICAL ARTICLEÂ
Measurement scenario… Credit: Phys. Rev. X 14, 011033, 29 February 2024