On the generation of sequential unitary gates from continuous time Schrodinger equations driven by external fields
Claudio Altafini
Quantum Information Processing, 1(3):207-224, 2002.
In all the various proposals for quantum computers, a common feature is that the quantum circuits are expected to be made of cascades of unitary transformations acting on the quantum states.
A framework is proposed to express these elementary quantum gates directly in terms of the control inputs entering into the continuous time forced Schrodinger equation.
pdf file