| （英） |
We study adiabatic gate teleportation (AGT), a model of quantum computation recently proposed by D. Bacon and S. T. Flammia, Phys. Rev. Lett. 103, 120504 (2009), to investigate a new property of quantum computation, namely causal order manipulation. We develop parallelized adiabatic gate teleportation (PAGT) where a sequence of gate operations is performed in a single step of the adiabatic process by introducing a gate Hamiltonian implementing a single-qubit unitary gate. By parallelizing the AGT scheme, the neccessary time for the adiabatic evolution implementing a sequence of gates increases quadratically, however it allows us to map causal order of gate oprations to spatial order of interactions in the final Hamiltonian. Using this property, we also present controlled-PAGT scheme to manipulate the causal order of gate operations by a control-qubit. The scheme allows us to coherently perform two differently ordered unitary operations $U^{(2)}U^{(1)}$ and $U^{(1)}U^{(2)}$ depending on the state of a control-qubit by simultaneously applying the gate Hamiltonians of $U^{(1)}$ and $U^{(2)}$. |