Entanglement Detection with Non-Ideal Ferromagnetic Detectors
P. Rożeka, P. Busz a, W. Kłobus b, D. Tomaszewski a, A. Grudka b, A. Baumgartner c, C. Schönenberger c and J. Martinek a
aInstitute of Molecular Physics, Polish Academy of Science, 60-179 Poznan, Poland
bFaculty of Physics, Adam Mickiewicz University, 61-614 Poznan, Poland
cDepartment of Physics, University of Basel, CH-4056 Basel, Switzerland
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Entangled states are essential in basics quantum communication protocols and quantum cryptography. Ferromagnetic contacts can work as a spin detector, giving possibility of converting information about electron spin to the electric charge, and therefore, detection of entangled states with the electric current measurements is possible. Method of confirming entanglement with non-ideal detectors is presented, the impact of decoherence and noise on states and quality of entanglement is discussed. Entanglement witness (EW) operator method is compared with the CHSH inequalities approach. Required spin polarization for the EW is lower than for the CHSH inequalities. System with asymmetric spin polarizations of detectors was analyzed, including the CHSH inequalities and the EW method.

DOI: 10.12693/APhysPolA.127.493
PACS numbers: 03.67.Mn, 03.67.Bg, 73.23.-b