A
quantum
computer is a device for computation that makes direct use of quantummechanical
phenomena, such as superposition and entanglement,
to perform operations on data. The basic principle of quantum computation is that quantum properties can be used to represent data and
perform operations on these data.

Computing
using quantum
effects, especially to solve untractable problems (like factorization or
breaking cryptosystems). See the Centre for Quantum
Computation for more information.

A
computer that exploits the quantummechanical
nature of particles, such as electrons
or atomic nuclei, to manipulate information as quantum
sized bits (qubit)