How close are we to a useful quantum computer? We may be a step further, following the production of a quantum chip by the University of California, Santa Barbara.
The chip, which researchers showed off at the American Physical Society meeting in Dallas, contains four qubits - the quantum equivalent of the conventional binary bits found in silicon chips.
The difference between conventional bits (which represent either a one or a zero) and quantum bits is that the latter can be in two states at once - both a one and a zero - using a phenomenon known as 'superposition'. This ability to be both 'on' and 'off' is a unique feature of quantum mechanics. A quantum computer is one that is literally in two minds about everything, all the time.
The ability for qubits to represent both a one and a zero at the same time makes it possible for quantum computers to conduct calculations on different numbers at once, whereas a conventional computer has to process all of the numbers that it wants to calculate in sequence. Four bits gives a binary system enough digits for 16 numbers. The four-qubit system shown in Dallas could therefore calculate 16 numbers at the same time.
That isn't in itself a big deal. However, as researchers learn how to scale up the number of qubits in a chip, it will become very significant. With five qubits, the computer could process 32 numbers simultaneously. With ten, it could process 1024. With 20 bits, it could process 1,048,576 numbers in an instant.
As quantum computers get more qubits, they could be used to solve some mathematical problems that the IT industry has thus far relied on to be unsolveable.
It will be a while before we're truly in the quantum age, but this is a step in the right direction. When we finally get there, it will change everything.