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| A Wafer of the D-Wave Quantum Computer. By Steve Jurvetson from Menlo Park, USA |
We have been speaking about quantum computers for a few decades. These
computers would work with qubits
(quantum bits) instead of bits, and would perform certain operations much
faster than ordinary computers.
It has been known since the thirties that quantum computers cannot solve
problems that cannot be solved by ordinary computers. Those problems are called
non-computable.
What they would do, in principle, is solve certain problems (not all) much
faster than ordinary computers. That higher speed, which in some cases should
be enormous, is called quantum supremacy.
Let's give an example: we know that the decomposition of a composite
number into its prime factors can be difficult. It’s trivial if the factors are
small, but if the composite number is the result of multiplying two prime
numbers of 100 digits each (for example) it is almost impossible to break it
down, if we don’t know ay least one of the prime numbers.
