Physical implementation of three-qubit gates on a separate quantum particle
A. R. Kessel, Vladimir L. Ermakov · Journal of Experimental and Theoretical Physics Letters · 2000
A virtual spin formalism is suggested to demonstrate that a single quantum particle possessing eight suitable discrete energy levels can be used for storing three information qubits and organizing on them a universal set of logical operations that are necessary for constructing an arbitrary quantum algorithm. The formalism can be practically implemented on a nuclear spin 7/2 subjected to resonance rf pulses. A single-pulse realization is found for all quantum gates of a universal set, including a three-qubit gate.