2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/21772A 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.7 pages with 3 figures, special style file included; To appear in a special issue on "Quantum Computation at the Atomic Scale" in Turkish Journal of PhysicsCondensed MatterQuantum Physicstext