Due to their nonlocality, qubits nested in Majorana bound states may be the
key to realize decoherence-free quantum computation. Majorana bound states
could be achieved at the ends of a one-dimensional topological superconductor.
However, when the bound states couple directly to electron reservoirs their
nonlocal correlation is quenched by local Andreev reflections. Here we propose
a scheme to generate nonlocal noise cross correlation between two
well-separated quantum dots, mediated by a pair of Majorana bound states. Both
positive and negative cross correlations can be obtained by tuning the gate
voltages applied to the dots. Within a limited range of finite temperatures,
the cross correlation is not suppressed by thermal fluctuations. Furthermore,
we show how the local Andreev reflections suppress the noise cross correlation
when multiple dot energy levels are coupled to the Majorana bound states. The
measurable cross correlation is expected to serve as a sensitive indicator for
the generation of Majorana fermions.Comment: 8 pages, 5 figure
