Dephasing of Entangled Electron-Hole Pairs in a Degenerate Electron Gas

Authors: J. L. VAN VELSEN, M. KINDERMANN, C. W. J. BEENAKKER

Abstract: A tunnel barrier in a degenerate electron gas was recently discovered as a source of entangled electron-hole pairs. Here, we investigate the loss of entanglement by dephasing. We calculate both the maximal violation E_{max} of the Bell inequality and the degree of entanglement (concurrence) C. If the initially maximally entangled electron-hole pair is in a Bell state, then the Bell inequality is violated for arbitrary strong dephasing. The same relation E_{max} = 2 \sqrt{1 + C^2} then holds as in the absence of dephasing. More generally, for a maximally entangled superposition of Bell states, the Bell inequality is satisfied for a finite dephasing strength and the entanglement vanishes for somewhat stronger (but still finite) dephasing strength. There is then no one-to-one relation between E_{max} and C.

Keywords: Entanglement, Bell inequality, Nonlocality, Decoherence

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