Quantum uncertainty relation using coherence

TL;DR

This paper introduces a new quantum uncertainty relation based on quantum coherence, distinguishing quantum unpredictability from classical predictability, and derives analytical bounds for qubits using multiple coherence measures.

Contribution

It proposes a novel quantum uncertainty relation using coherence as a measure, providing analytical results for qubits with various coherence quantifiers.

Findings

Quantum coherence can quantify quantum uncertainty.

Derived analytical uncertainty relations for qubits.

Applicable to multiple coherence measures.

Abstract

Measurement outcomes of a quantum state can be genuinely random (unpredictable) according to the basic laws of quantum mechanics. The Heisenberg-Robertson uncertainty relation puts constrains on the accuracy of two noncommuting observables. The existing uncertainty relations adopt variance or entropic measures, which are functions of observed outcome distributions, to quantify the uncertainty. According to recent studies of quantum coherence, such uncertainty measures contain both classical (predictable) and quantum (unpredictable) components. In order to extract out the quantum effects, we define quantum uncertainty to be the coherence of the state on the measurement basis. We discover a quantum uncertainty relation of coherence between two measurement non-commuting bases. Furthermore, we analytically derive the quantum uncertainty relation for the qubit case with three widely adopted coherence measures, the relative entropy using coherence, the coherence of formation, and the $l_1$ norm of coherence.