Characterizing the multipartite continuous-variable entanglement structure from squeezing coefficients and the Fisher information
Authors: Qin ZZ., Gessner M., Ren ZH., Deng XW., Han DM., Li WD., Su XL., Smerzi A., Peng KC.
Autors Affiliation: Shanxi Univ, Inst Optoelect, State Key Lab Quantum Opt & Quantum Opt Devices, Taiyuan 030006, Shanxi, Peoples R China; Shanxi Univ, Collaborat Innovat Ctr Extreme Opt, Taiyuan 030006, Shanxi, Peoples R China; INO CNR, QSTAR, Largo Enrico Fermi 2, I-50125 Florence, Italy; LENS, Largo Enrico Fermi 2, I-50125 Florence, Italy; Shanxi Univ, Inst Theoret Phys, Taiyuan 030006, Shanxi, Peoples R China; Shanxi Univ, Dept Phys, Taiyuan 030006, Shanxi, Peoples R China; Shanxi Univ, Inst Laser Spect, Taiyuan 030006, Shanxi, Peoples R China
Abstract: Understanding the distribution of quantum entanglement over many parties is a fundamental challenge of quantum physics and is of practical relevance for several applications in the field of quantum information. The Fisher information is widely used in quantum metrology since it is related to the quantum gain in metrology measurements. Here, we use methods from quantum metrology to microscopically characterize the entanglement structure of multimode continuous-variable states in all possible multi-partitions and in all reduced distributions. From experimentally measured covariance matrices of Gaussian states with 2, 3, and 4 photonic modes with controllable losses, we extract the metrological sensitivity as well as an upper separability bound for each partition. An entanglement witness is constructed by comparing the two quantities. Our analysis demonstrates the usefulness of these methods for continuous-variable systems and provides a detailed geometric understanding of the robustness of cluster-state entanglement under photon losses.
Journal/Review: NPJ QUANTUM INFORMATION
Volume: 5 Pages from: 3-1 to: 3-6
KeyWords: QUANTUM-NOISE; CRITERION; BEAMSDOI: 10.1038/s41534-018-0119-6Citations: 8data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2021-02-28References taken from IsiWeb of Knowledge: (subscribers only)Connecting to view paper tab on IsiWeb: Click hereConnecting to view citations from IsiWeb: Click here