Two-state Q-system: Qubit representations

Abstract

Obviously the simplest q-systems are the two-state systems. Typical realizations are an atom with its ground state and one of its excited states, a photon with its two polarization states, or an electronic spin with its "up" and "down" states. The smallest unit of q-information, i.e. the qubit, is an abstract two-state q-system. This chapter is technical: you learn standard mathematics of a single abstract qubit. © 2011 Springer-Verlag Berlin Heidelberg.