Abstract:

Quantifying coherence is an essential endeavour for both quantum foundations and quantum technologies. Here the robustness of coherence is defined and proven a full monotone in the context of the recently introduced resource theories of quantum coherence. The measure is shown to be observable, as it can be recast as the expectation value of a coherence witness operator for any quantum state. The robustness of coherence is evaluated analytically on relevant classes of states, and an efficient semidefinite program that computes it on general states is given. An operational interpretation is finally provided: the robustness of coherence quantifies the advantage enabled by a quantum state in a phase-discrimination task.

Authors:

• Carmine Napoli
• Thomas R. Bromley
• Marco Cianciaruso
• Marco Piani
• Nathaniel Johnston
• Gerardo Adesso

Download:

• Official publication from Physical Review Letters
• Preprint from arXiv:1601.03781 [quant-ph]
• Local preprint [pdf]

Cite as:

• C. Napoli, T. R. Bromley, M. Cianciaruso, M. Piani, N. Johnston, and G. Adesso. Robustness of coherence: An operational and observable measure of quantum coherence, Physical Review Letters, 116:150502, 2016.

Supplementary material:

• MATLAB code for computing the robustness of coherence
• QETLAB function for computing the robustness of coherence

Related publications:

• Robustness of asymmetry and coherence of quantum states (longer publication containing proofs of the main mathematical results and their generalizations)