title: Conservation laws, uncertainty relations, and quantum limits of measurements.
abstract: The uncertainty relation between the noise operator and the conserved quantity leads to a bound on the accuracy of general measurements. The bound extends the assertion by Wigner, Araki, and Yanase that conservation laws limit the accuracy of "repeatable," or "nondisturbing," measurements to general measurements, and improves the one previously obtained by Yanase for spin measurements. The bound represents an obstacle to making a small quantum computer.
authors.affiliation: Center for Photonic Communication and Computing, Department of Electrical and Computer Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3118, USA.
authors.forename: Masanao
authors.initials: M
authors.lastname: Ozawa