%0 Journal Article %J Physical Review A %D 2003 %T Lower bounds on the complexity of simulating quantum gates %A Andrew M. Childs %A Henry L. Haselgrove %A Michael A. Nielsen %X We give a simple proof of a formula for the minimal time required to simulate a two-qubit unitary operation using a fixed two-qubit Hamiltonian together with fast local unitaries. We also note that a related lower bound holds for arbitrary n-qubit gates. %B Physical Review A %V 68 %8 2003/11/18 %G eng %U http://arxiv.org/abs/quant-ph/0307190v1 %N 5 %! Phys. Rev. A %R 10.1103/PhysRevA.68.052311