Quantum measurement paradox solved: weak and strong interactions in particle physics
Physicists have demonstrated how quantum particles can be observed without fully determining their state—a finding that resolves a decades-old measurement paradox. The work, using neutron-proton collisions, shows how interference effects during initial weak measurements can dramatically alter experimental outcomes, with potential implications for precision measurement technologies and quantum computing architectures.
Originaltitel: Compton scattering from proton pairs: illustrating weak and strong measurements
<p>Neutrons interacting with protons in Compton scattering is here chosen as an example of a non-trivial quantum measurement. It illustrates a situation where a probe particle makes an observation (a weak measurement) of the studied protons, preparing for a final state in which one of them takes up the recoil in the collision. The proton is ejected during a strong (projective) measurement that selects one particular momentum value out of the proton's initial distribution of momentum states. This course of events in the measurement process is evidenced by the observation that destructive interference appears during the weak interaction stage which leads to a strongly reduced neutron cross section for the proton system.</p>