Quantum computers – dream and realization
Institute for Experimental Physics,
Institute for Quantum Optics and Quantum Information,
Computational operations always rely on real physical processes, which are data input, data representation in a memory, data manipulation using algorithms and finally, the data output. With conventional computers all the processes are classical processes and can be described accordingly. Theoretically, it is known for several years now that certain computations could be processed much more efficiently using quantum mechanical operations. This requires the implementation of quantum bits (qubits), quantum registers and quantum gates and the development of quantum algorithms. Several approaches for the implementation of quantum computers will be presented, with special emphasis on the ion storage techniques. Experimental realizations of quantum registers and quantum gate operations using strings of trapped ions in a linear Paul trap will be discussed.
With a small ion-trap quantum
computer based on two and three trapped Ca+ ions as qubits we have
generated in a pre-programmed way specific quantum states. In particular,
entangled states of two particles, i.e.