Dancing with Qubits

1 Why Quantum Computing?

Nature isn’t classical, dammit, and if you want to make a simulation of nature, you’d better make it quantum mechanical.

Richard Feynman [5]

In his 1982 paper ‘‘Simulating Physics with Computers,’’ Richard Feynman, 1965 Nobel Laureate in Physics, said he wanted to ‘‘talk about the possibility that there is to be an exact simulation, that the computer will do exactly the same as nature.’’ He then went on to make the statement above, asserting that nature doesn’t especially make itself amenable for computation via classical binary computers.

In this chapter we begin to explore how quantum computing is different from classical computing. Classical computing is what drives smartphones, laptops, Internet servers, mainframes, ...