Premium
Impossibility of Determining the Unknown Quantum Wavefunction of a Single System: Quantum Non‐Demolition Measurements, Measurements without Entanglement and Adiabatic Measurements
Author(s) -
Alter Orly,
Xamamoto Yoshihisa
Publication year - 1998
Publication title -
fortschritte der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.469
H-Index - 71
eISSN - 1521-3978
pISSN - 0015-8208
DOI - 10.1002/(sici)1521-3978(199811)46:6/8<817::aid-prop817>3.0.co;2-y
Subject(s) - quantum entanglement , adiabatic process , observable , wave function , quantum , impossibility , quantum mechanics , physics , quantum discord , a priori and a posteriori , quantum system , quantum metrology , statistical physics , weak measurement , philosophy , epistemology , political science , law
We establish that the information which can be obtained in the measurement of a single system about the unknown quantum wavefunction of the system is limited to estimates of the expectation values of the measured observables, with the estimate errors satisfying the uncertainty principle. Only the fully a‐priori known wavefunction could be determined exactly. We consider specifically measurement schemes which may induce minimal change in the measured system, such as quantum non‐demolition measurements, measurements without entanglement and adiabatic measurements.