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ePaper created 2012-09-28, 09:46:25 | version 1.24.0
16 Research in Jülich 2|2012 Mathematical Prowess of a Quantum Computer T he future has already started. At least that is what some people may think when they read that the Ca- nadian company D-Wave has been mar- keting quantum computers since 2011. All conventional PCs, smartphones and supercomputers make use of bits as the smallest information units. These bits can only take on the values 0 and 1, but quantum computers operate with quan- tum bits, qubits for short, which consist of a large number of superimposed states. In contrast to conventional pro- cessors, quantum computers are basi- cally able to perform multiple operations simultaneously in one switching pro- cess. This is why physicists have been hoping since the 1980s that quantum computers would be able to solve cer- tain computational problems at an unim- aginable speed. NEW TWIST To date, experts have largely pursued a concept in which the qubits are formed of particles – for example, atomic nuclei – whose quantum mechanical angular momentum, the spin, can be selectively influenced. “In such quantum comput- ers, researchers try to transfer the logic that a normal computer uses for addi- tion, multiplication and other arithmetic procedures, to the rotation of the indi- vidual spins,” explains Thomas Neuhaus from the Jülich research group “Quan- tum Information Processing”. The prob- lem is that each individual spin must be very precisely adjusted, which is difficult enough for real systems of just four or eight qubits. In contrast, Neuhaus is concerned with the theory of a new and even more astounding variant of the quantum com- puter. This variant, the adiabatic quan- Quantum computers were long a mere utopian vision in the minds of physicists. But now they really exist. Theoretical studies can be made of the problems which they may in future help to solve. In his studies, the physicist Privatdozent Dr. Thomas Neuhaus makes use of conventional but extremely powerful computers – the Jülich supercomputers. Mathematical formulae and the Jülich supercomputers (in the background) are the tools of Privatdozent Dr. Thomas Neuhaus, who is investigating the po- tential performance of future quantum computers.