Quantum algorithm
양자 알고리즘
A way of solving a problem that makes use of the properties of a quantum computer.
Overview
Running an ordinary computer's program as it is on a quantum computer does not make it faster. You need a special method, built with superposition and entanglement, so that wrong answers cancel each other out and only the right answer stands out clearly. This is a quantum algorithm.
Shor's algorithm, published in 1994, can break a large number into a product of primes much faster. A lot of today's encryption relies on that being hard, so it came as a big shock. Grover's algorithm, published in 1996, searches for what you want in jumbled data quickly. But only some problems get faster this way.
An everyday example
Just as there are tricks like "keep one hand on the wall" for solving a maze, a quantum computer has its own tricks that fit its properties. On a problem with no such trick, a quantum computer cannot show its strength either.
Why it matters
This is where the point that a quantum computer is not an all-purpose machine that does everything fast comes from. It is strong only on problems that have a useful quantum algorithm, and finding such methods is as important as building the machines.