2011/01/01 by Avshalom C. Elitzur, Eliahu Cohen, Daniel P. Sheehan · 2 citations
Computer Science · Mathematics · Physics and Astronomy · #Computer science #Erasure #Mathematics #Measurement problem #Observer (physics) #Physics #Quantum #Quantum Information and Cryptography #Quantum Mechanics and Applications #Quantum mechanics #Quantum state #Spectroscopy and Quantum Chemical Studies #State vector #Statistical physics #Superposition principle #Theoretical physics #Uncertainty principle #Weak measurement
paper · doi:10.1063/1.3663720
openalex publication_date 2011/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
Quantum measurement is sometimes more effective when its result is not definite. Partial measurement turns the initial superposition not into a certain state but to a greater probability for it, enabling probing the quantum state in cases where complete measurement makes the noncommuting variables inaccessible. It also enables full quantum erasure that, unlike prevailing method, can be carried out even on recorded results. Aharonov's weak measurement is another method of imprecisely measuring quantum variables, outsmarting the uncertainty principle in even subtler ways. Happily, the two methods complement and corroborate one another in several interesting ways. We gedankenly apply these measurements to the EPR case. A pair of entangled particles undergoes more than one pair of partial and weak measurements, which, unlike complete measurements, leave them partially correlated. Their erasure is then shown to be as nonlocal as measurement itself. Surprisingly, the temporal relations between such measurements in the EPR setting do not follow the temporal sequence perceived by an external observer. For each particle, the measurements performed on the other operate as if they occurred (with signs reversed) in its own past, and in reversed order. This fully accords with Cramer's transactional interpretation and Aharonov's two state‐vector formalism.