The notion of a quantum computer was first put forth by Richard
Feynman in 1982. He suggested that the only way to effectively simulate
a quantum system was with another quantum system. The question of
whether quantum computation could be more powerful than classical
computation in general was first pioneered by David Deutsch in the
mid1980’s. He developed the notion of a universal quantum
computer as well as the first quantum algorithm, as opposed to a
simulation. It was not until 1994, when Peter Shor published an
algorithm that could factorize large numbers into prime numbers
exponentially faster than ever before, that the field of quantum
computation really began to flourish.
The reason Shor’s factoring algorithm is so responsible for
the burgeoning of the field of quantum computation is security.
The most popular encryption schemes for digital information, i.e.,
the encryption used to prevent people from stealing your credit
card information when you buy something on the internet, are safe
because people cannot factor a large number into two primes in any
amount of reasonable time. Shor’s algorithm, if we had a quantum
computer, could solve this problem in an instant. Though still not
known for sure, many people speculate that a quantum computer could
solve an entire class of problems that today’s computers find
impossible to solve.
Besides the enormous computational power a quantum computer
seems to offer, the systems that could make up quantum computers
also present fascinating physics and engineering challenges. The
fundamental unit of information in today’s computers is the
bit. In a quantum computer these bits would be replaced by their
quantum cousins, qubits. An accurately manipulated and wellbehaved
single qubit is the most fundamental component of a quantum computer,
and it is an extremely interesting and challenging problem. For
a quantum computer you would also need to couple lots of qubits
together, which is another fascinating challenge. And of course
all these sensitive qubits must be shielded from all the microscopic
noise that constantly surrounds us but doesn’t bother us,
but which would ruin all hope of computing with the qubits.
