# Quantum Computers

Around 2030 computers might not have any transistors and chips. Think of a computer that is much faster than a common classical silicon computer. This might be a quantum computer. Theoretically it can run without energy consumption and billion times faster than today’s PIII computers. Scientists already think about a quantum computer, as a next generation of classical computers.

Gershenfeld says that if making transistors smaller and smaller is continued with the same rate as in the past years, then by the year of 2020, the width of a wire in a computer chip will be no more than a size of a single atom. These are sizes for which rules of classical physics no longer apply. Computers designed on today’s chip technology will not continue to get cheaper and better. Because of its great power, quantum computer is an attractive next step in computer technology.

A technology of quantum computers is also very different. For operation, quantum computer uses quantum bits (qubits). Qubit has a quaternary nature. Quantum mechanic’s laws are completely different from the laws of a classical physics. A qubit can exist not only in the states corresponding to the logical values 0 or 1 as in the case of a classical bit, but also in a superposition state.

A qubit is a bit of information that can be both zero and one simultaneously (Superposition state). Thus, a computer working on a qubit rather than a standard bit can make calculations using both values simultaneously. A qubyte, is made up of eight qubits and can have all values from zero to 255 simultaneously. “Multi-qubyte systems have a power beyond anything possible with classical computers.”

Forty qubits could have the same power as modern supercomputers. According to Chuang a supercomputer needs about a month to find a phone number from the database consisting of world’s phone books, where a quantum computer is able to solve this task in 27 minutes.

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