Decoherence in quantum walks and quantum computers

Understand

Decoherence is the major stumbling block in the realization of a large-scale quantum computer.

• Ingenious methods have been devised to overcome decoherence, but their success has been proven only for over-simplified models of system-environment interaction.
• Whether such methods will be reliable in the face of more realistic models is a fundamental open question.
• In this partly pedagogical article, we study two toy models of quantum information processing, using the language of \emph{quantum walks}.