Editing Travelling Ballot Based Protocol (section)

==Outline==
We consider N voters who wish to cast their vote secretly. The election authority prepares an entangled state, keeps one of the qudits, and passes the other one as the ballot qudit. Each voter receives the ballot qudit from the previous voter, casts her vote by applying a unitary and then forwards the qudit to the next voter. In the end, the authority obtains the election outcome by measuring the two qudits.