By Alexander Hellemans
If a practical quantum computer is going to become an everyday thing, qubits have to remain in two states at one time for much longer than they do now. One of the possible candidates for a longer lasting qubit is a copper ion embedded in a large molecule.
A quick primer on qubits is in order. Certain ions have unpaired electrons whose spins can assume either of two spin states, up or down—or in computer speak, 0 or 1. But when struck with a microwave pulse, the unpaired electron can be coerced into assuming both the 0 and 1 state simultaneously. The two states are said to be in superposition. All the qubits created up to now stay in a superposition state for very short periods because the spin states of neighboring atoms quickly destroy the coherent state, making the life of the qubit too short for it to perform the desired number of quantum computations. But researchers have been looking high and low for suitable qubits and for ways to lengthen the periods over which they remain in superposition. …[Read more]