Simulation of n-qubit quantum systems. I. Quantum registers and quantum gates

Unusual features of the program:The Feynman program has been designed for interactive simulations on n-qubit quantum registers with no other restriction than given by the size and time resources of the computer. Apart from the standard quantum gates, as discussed in the literature [M.A. Nielsen, I.L. Chuang, Quantum Computation and Quantum Information, Cambridge University Press, Cambridge, 2000], it provides all the necessary tools to generalize these gates for n-qubits (in any given order of the individual qubits). Both common representations of the quantum registers in terms of their state vectors and/or density matrices are equally supported by the program whenever possible. In addition, the program also facilitates the composition of two or more quantum registers into a combined one as well as their decomposition into subsystems by using the partial trace and the use of the reduced density matrix for the individual parts.