Fig. 4: Influence of finite lifetime and temperature on the entanglement.
From: Protocol for certifying entanglement in surface spin systems using a scanning tunneling microscope
a shows \({{\mathcal{W}}}_{R}-O\) as function of temperature and decoherence time T2 (where T2 = 2 ⋅ T1). (b) slice of (a) showing \({{\mathcal{W}}}_{R}-O\) together with the concurrence \({\mathcal{C}}\) for T = 0.1 K as achievable by dilution refrigerators. (c) slice of (a) showing \({{\mathcal{W}}}_{R}-O\) together with \({\mathcal{C}}\) for T2 = 300 ns. Clearly, temperature is a critical factor and the concurrence drops drastically above 0.3 K. We also plot \({{\mathcal{W}}}_{R}\) such that the difference of subtracting O becomes apparent. d Relation of \({\mathcal{C}}\) and \({{\mathcal{W}}}_{R}-O\) for three different T2. Solid lines are linear fits. The dashed line represents the analytical limit for T2 → ∞ (e) relation of \({\mathcal{C}}\) and \({{\mathcal{W}}}_{R}-O\) for four different temperatures. Solid lines are logarithmic weighted power law fits. The dashed line represents the analytical limit for T → 0 The system parameters are as shown in Fig. 2a.
