ABSTRACT
The NMR quantum computer is one of the most established systems among many physical realizations of a quantum computer. In spite of its peculiar character associated with mixed states and lack of scalability, it still works as a prototypical quantum computer with at most 10 qubits. We should point out that it is the only quantum computer commercially available at the time of writing this book. For these reasons, an NMR quantum computer is introduced as one of the first examples of a physical system on which we can execute small-scale quantum algorithms. Qubits in this realization are nuclei with spin 1/2. Molecules with a certain number of such nuclei are employed as a quantum register. The system is made of a macroscopic number (∼ 1020) of moleclues in thermal equilibrium, and we have to take care of these aspects in preparation of a state and measurements as explained in this chapter. Our exposition follows [1] and [2]. Other useful review is [3].
