Proposal of an Experimentally Accessible Measure of Many-Fermion Entanglement

We propose an experimentally accessible measure of entanglement in many-fermion systems that characterizes interaction-induced ground state correlations. It is formulated in terms of cross correlations of currents through resonant fermion levels weakly coupled to the probed system. The proposed entanglement measure vanishes in the absence of many-body interactions at zero temperature and it is related to measures of occupation number entanglement. We evaluate it for two examples of interacting electronic nanostructures.

Figure 1

System $\mathcal{S}$ contacted by resonant levels $j=0,\dots ,n$ that emit electron currents $I_j$, ${\tilde{I}}_j$ into two reservoirs each.

Figure 2

Large quantum dot opened up by $N$ conduction channels coupled to two resonant levels implemented by small dots.

Figure 3

Normal metal (N) tunnel coupled (transmission $T\ll 1$) to a superconductor (SC).