The Singularity is Near: When Humans Transcend Biology

by Ray Kurzweil

As with the DNA computer described above, a key to successful quantum computing is a careful statement of the problem, including a precise way to test possible answers. The quantum computer effectively tests every possible combination of values for the qubits. So a quantum computer with one thousand qubits would test 21,000 (a number approximately equal to one followed by 301 zeroes) potential solutions simultaneously. A thousand-bit quantum computer would vastly outperform any conceivable DNA computer, or for that matter any conceivable nonquantum computer. There are two limitations to the process, however. The first is that, like the DNA and optical computers discussed above, only a special set of problems is amenable to being presented to a quantum computer. In essence, we need to be able to test each possible answer in a simple way.