2019/10/31 by Yiming Pan, Jie Zhang, Eliahu Cohen +5
Computer Science · Physics and Astronomy · #Asymptote #Atomic physics #Cold Atom Physics and Bose-Einstein Condensates #Dimensionless quantity #Mechanical and Optical Resonators #Open quantum system #Physics #Quantum #Quantum Information and Cryptography #Quantum entanglement #Quantum mechanics #Quantum state #Quantum system #Quantum technology #Trapped ion quantum computer #Weak measurement #cond-mat.other #physics.atm-clus #physics.hist-ph #physics.optics #quant-ph
paper · pdf · doi:10.1038/s41567-020-0973-y
published as Nat. Phys. 16, 1206 - 1210 (2020) · 6 pages, 3 figures, accepted by Nature Physics
openalex publication_date 2020/09/14 · arxiv created 2020/09/17 · arxiv updated 2020/12/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Quantum measurement remains a puzzle through its stormy history from the birth of quantum mechanics to state-of-the-art quantum technologies. Two complementary measurement schemes have been widely investigated in a variety of quantum systems: von Neumann's projective 'strong' measurement and Aharonov's weak measurement. Here, we report the observation of a weak-to-strong measurement transition in a single trapped 40Ca+ ion system. The transition is realized by tuning the interaction strength between the ion's internal electronic state and its vibrational motion, which play the roles of the measured system and the measuring pointer, respectively. By pre- and post-selecting the internal state, a pointer state composed of two of the ion's motional wavepackets is obtained, and its central-position shift, which corresponds to the measurement outcome, demonstrates the transition from the weak-value asymptotes to the expected-value asymptotes. Quantitatively, the weak-to-strong measurement transition is characterized by a universal transition factor e-Γ2, where Γ is a dimensionless parameter related to the system-apparatus coupling. This transition, which continuously connects weak measurements and strong measurements, may open new experimental possibilities to test quantum foundations and prompt us to re-examine and improve the measurement schemes of related quantum technologies.