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IPFS News Link • Science, Medicine and Technology

Quad-storage method writes data to a single atom in four different ways

•, By Michael Irving

The method unlocks more powerful quantum computers that are easier to control.

Where traditional computers can process and store information as either a 0 or a 1, quantum computers can do the same plus a superposition of both at the same time. This gives them exponentially more power as you add quantum bits (qubits), allowing them to tackle problems that are simply too complex for regular machines.

The problem is, manipulating those qubits can be tricky, especially as quantum computers start using more and more of them. But now, scientists at the University of New South Wales (UNSW) Sydney have shown how data can be written to a qubit – in this case, a single atom – in four different ways, depending on what's needed each time.

The atom in question is of an element called antimony, which can be implanted into a silicon chip where it replaces one of the silicon atoms. This heavy atom was chosen for the job because its nucleus already contains eight separate quantum states that can be used to encode quantum data. Plus, it has an electron that itself has two quantum states, which doubles the total on offer in the antimony atom to 16 (each of the original eight, paired in turn with each of the electron's two). If you were going to use other materials to create a quantum computer with 16 states, you'd need four qubits coupled together.

But the real breakthrough of the study was in how the team was able to manipulate the data on the atom, using four different methods. The electron could be controlled with an oscillating magnetic field. A magnetic resonance method, like that used in MRI machines, could manipulate the spin of the atom's nucleus. An electric field could also be used to control the nucleus. And finally, a technique called "flip-flop qubits" allowed the nucleus and electron to be controlled in opposition to each other, with the help of an electric field.