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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 18:08 |
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Conference: Bucharest University Faculty of Physics 2023 Meeting
Section: Theoretical Physics and Applied Mathematics
Title:
Entanglement and steering witnesses for unknown Gaussian states
Authors:
Drd. TATAIANA MIHAESCU, Prof. Dr. AURELIAN ISAR
*
Affiliation:
1) Faculty of Physics, University of Bucharest, RO-077125 Bucharest-Magurele,
Romania
2) Department of Theoretical Physics, National Institute of Physics and Nuclear
Engineering, RO-077125 Bucharest-Magurele, Romania
E-mail
mihaescu92tatiana@gmail.com
Keywords:
entanglement witnesses, steering witnesses, Gaussian states, covariance matrices
Abstract:
We define and fully characterize the witnesses based on second moments
detecting steering in Gaussian states by means of Gaussian measurements. All such
tests, which arise from linear combination of variances or second moments of canonical operators, are easily implemented in experiments. We propose also a set of linear constraints fully characterizing steering witnesses when the steered party has one bosonic mode, while in the general case the constraints restrict the set of tests detecting steering. Given an unknown quantum state we implement a semidefinite program providing the appropriate steering test with respect to the number of random measurements performed. Thus, it is a ”repeat-until-success” method allowing for steering detection with less measurements than in full tomography. We study the efficiency of steering detection for two-mode squeezed vacuum states, for two-mode general unknown states, and for three-mode continuous variable GHZ states. In addition, we discuss the robustness of this method to statistical errors.
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