Everyone likes new gadgets. What to buy for a multibillion dollar corporation that has everything? Google has bought a new quantum computer – a giant leap in computing that was only a physicist’s fantasy a decade ago. Over this piece we will look at what quantum computing is, and the possibilities for the technology into the future.

### What is a quantum computer?

Quantum computers can think in a much more complicated way than binary computers used today. It is as if, from two dimensional thinking, a quantum computer can think in “3-D”.

The machines you and I use work in binary code. A simple explanation of binary code can be found here. In its calculations every second all the activities we do on our PC are either 0 or 1 (and combinations thereof). We know about transistors on chips – they have capacitors on them, on which the binary code is registered as either “on” for 1 or “off” for 0. Each capacitor is known as a “bit”.

In quantum physics it has been shown that atoms can have two states of energy. Put simply, they can be at a high energy state and at a low energy state simultaneously. If they were capacitors on a transistor they could be on and off at the same time. Each atom on such a machine is known as a “qubit” or quantum bit.

According to the qubit foundation based in Oxford, England, “If we keep adding qubits to the register we increase its storage capacity exponentially i.e. three qubits can store 8 different numbers at once, four qubits can store 16 different numbers at once”.

The first time a computer was used in anger by a government was at Bletchley Park to crack the Nazi Enigma code in the 1940’s. In the 1980’s someone worked out that quantum computing would be even better at code breaking. From theoretical physics, so people got seriously interested in developing such computers.

According to the qubit foundation, factorization is a serious problem for computers. “Consider, for example, the following factorisation problem

? x ? = 29083.

How long would it take you, using paper and pencil, to find the two whole numbers which should be written into the two boxes (the solution is unique)? Probably about one hour. Solving the reverse problem

127 x 129 = ?,

again using paper and pencil technique, takes less than a minute. All because we know fast algorithms for multiplication but we do not know equally fast ones for factorisation.”

On current computers, the qubit foundation suggest, “No one can even conceive of how one might factorise, say, thousand-digit numbers; the computation would take much more that the estimated age of the universe.” A computer that can consider thousands of solutions at the same time would knock down the calculation times considerably. 