Quantum of storage: Scientists develop smallest ever storage device

Scientists have developed the smallest ever storage device - inside an atom.

Scientists have developed the smallest ever storage device - inside an atom.

In a step towards quantum computing - the Holy Grail of data processing and storage - scientists from Oxford University, the US Department of Energy and Princeton University were able to successfully store and retrieve information using the nucleus of an atom.

In a paper entitled "Solid-state quantum memory using the 31P nuclear spin", the team described an experiment in which exceptionally pure and isotopically controlled crystals of silicon were precisely doped with phosphorus atoms.

Quantum information was processed in phosphorus electrons, transferred to phosphorus nuclei, then subsequently transferred back to the electrons.

This is the first demonstration that a single atomic nucleus can serve as quantum computational memory.

Another step towards quantum computing was taken when a team of scientists processed information in the electron spin (blue) and stored it in the nuclear spin (yellow) of phosphorus atoms through a combination of microwave and radio-frequency pulses.

The immediate lure of quantum computing is blinding speed: a quantum computer would be able to perform certain mathematical tasks, such as factoring, many billions of times faster than the most powerful supercomputers of today.

Beyond that, quantum computing should make it possible to engage calculations that cannot be considered with current "classical" computing technology.

In classical computing, information is processed and stored based on the charge of an electron, and represented in a binary digit or "bit."

Each bit carries a value of 0 (no charge) or 1 (charge). Quantum computing uses an intrinsic quantum property called "spin", in which certain particles can act as if they were tiny bar magnets.

Spin is assigned a directional state of either up or down, which can be used to encode data in 0s and 1s. However, unlike charge in classical computing, which is either present or not, spin can be up, down or both, thanks to a quantum effect called superposition.

Superpositioning exponentially expands the storage capabilities of a quantum data bit or qubit. Whereas a byte of classical data, made up of three bits, can represent only one of the eight possible combinations of 0s and 1s, a quantum equivalent (sometimes called a qubyte) can represent all eight combinations at once.

Furthermore, thanks to another quantum property called entanglement, operations on all eight combinations can be performed simultaneously.

Of the many challenges facing quantum computing, one of the biggest has been finding a way to preserve the integrity of data while it is stored.

Although the spin of electrons has proven well suited for data processing, it is too fragile to be used as memory - the data quickly becomes corrupted by the influence of other electrons. To overcome this obstacle, the co-authors of this experiment turned to the more protected environs of the atomic nucleus.

More on quantum computing:

"Solid-state quantum memory using the 31P nuclear spin", Nature

The future of quantum IT (Computer Weekly)

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