Projects per year
Quantum states may exhibit asymmetry with respect to the action of a given group. Such an asymmetry of states can be considered as a resource in applications such as quantum metrology, and it is a concept that encompasses quantum coherence as a special case. We introduce explicitly and study the robustness of asymmetry, a quantifier of asymmetry of states that we prove to have many attractive properties, including efficient numerical computability via semidefinite programming, and an operational interpretation in a channel discrimination context. We also introduce the notion of asymmetry witnesses, whose measurement in a laboratory detects the presence of asymmetry. We prove that properly constrained asymmetry witnesses provide lower bounds to the robustness of asymmetry, which is shown to be a directly measurable quantity itself. We then focus our attention on coherence witnesses and the robustness of coherence, for which we prove a number of additional results; these include an analysis of its specific relevance in phase discrimination and quantum metrology, an analytical calculation of its value for a relevant class of quantum states, and tight bounds that relate it to another previously defined coherence monotone.
- quantum states
- asymmetry of states
- quantum information processing
Research Output per year
12 Apr 2016, In : Physical Review Letters. 116, 15, 6 p., 150502.
Research output: Contribution to journal › Letter
Piani, M., Cianciaruso, M., Bromley, T. R., Napoli, C., Johnston, N., & Adesso, G. (2016). Robustness of asymmetry and coherence of quantum states. Physical Review A, 93(4), . https://doi.org/10.1103/PhysRevA.93.042107