Variance-based uncertainty relation for incompatible observers

Abstract

Based on mixedness definition as M=1-tr(\r{ho}^2), we obtain a new variance-based uncertainty equality along with an inequality for Hermitian operators of a single-qubit system. The obtained uncertainty equality can be used as a measure of the system mixedness. A qubit system with feedback control is also exploited to demonstrate the new uncertainty.

10 pages;3 figures, in press in Quantum Inf Process

References in corpus (7)

• Stronger uncertainty relations for the sum of variances
• Stabilising entanglement by quantum jump-based feedback
• Controlling entanglement by direct quantum feedback
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• Implications and applications of the variance-based uncertainty equalities