" The Bose-Einstein condensation of constituent particles results in
superfluidity in bosonic systems. Superconductivity in electronic systems is
attributed to the pairing of electrons into so called ""Cooper pairs"". Then,
how much of bosonic nature do Cooper pairs bear? Can one devise an setup to
test it quantitatively in real experiments?

In this talk, I review the basic properties of topological insulators, a
recently discovered new state of matter, and propose a Hanbury Brown and Twiss
experiment of Cooper pairs on the edge channels of quantum spin Hall
insulators to address the bosonic nature of Cooper pairs.

Surprisingly, the analysis reveals that the Cooper pairs do not bear a bosonic
nature at all once emitted from the superconductor. Crucial differences
between our work and previous similar works will be discussed.
"