"Our Friend, the Atom" was a 1957 Disney film that was intended to improve the image of atomic physics, more specifically that of the atomic nucleus.

It has remained ambivalent.

But maybe the atom will still gain a reputation like the bit enjoys, the basis of our digital wonderland.

Two specialist articles in “Nature” now raise the prospect of this happening.

Ulf von Rauchhaupt

Editor in the “Science” section of the Frankfurter Allgemeine Sunday newspaper.

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There, research groups from Harvard and the University of Wisconsin in Madison succeeded in using atoms as so-called qubits and thus in constructing quantum computer circuits of practicable complexity for the first time.

While a bit is in only one of two states at a time, a qubit can assume both at the same time.

By suitably handling qubits, calculations can therefore be made that are only possible on digital computers with extreme expenditure of time, energy and hardware or not at all.

Considering how much binary computing has changed the world, it is clear why so many researchers, including those in the private sector, are now trying to build workable quantum computers.

Various approaches are being pursued to realize qubits in different physical systems.

So far, superconducting circuits have had the most headlines, particularly those from IBM and Google.

Ions trapped in electric and magnetic fields have one of the longest histories of research.

But experiments are also being carried out with molecules or defects in crystal lattices.

Monstrous inflated atomic shells intertwine

The research groups from Harvard and Wisconsin rely on neutral atoms that are held in lattices made of laser light.

Such systems do not have to be cooled to the lowest ambient temperatures, like the superconducting competition.

And unlike ions, atoms can be locked in when they take up little space, but their light cages can also be enlarged at will – scaled, as the physicists say.

And because of their electrical neutrality, atoms are fairly immune to perturbations of the fragile superposition state they are in when acting as qubits.

However, this insensitivity is a disadvantage when it comes to entangling the qubits.

This operation, which turns two or more quantum mechanical systems into one, whose components can no longer be described independently,

Both teams solved the problem of entangling neutral atoms by putting electrons in their shells into so-called Rydberg states, in which the atoms are millions of times larger and easily entangled with one another.

The group headed by Mikhail Lukin at Harvard started with pairs of atoms in adjacent places in the light lattice, converted them into Rydberg states and then pushed them to different places using special laser beams, so-called optical tweezers, in order to combine them there with others for the next calculation step , to initially entangle non-neighboring atoms.

They then succeeded in calculating a so-called NP-hard problem, which is notoriously complex for classical computers, on a small scale.

Now the two methods still have to prove that various sources of error can be adequately controlled.

The potential of neutral atoms for applications in so-called quantum simulations was already known, says Tommaso Calarco, who heads the Quantum Control Institute at Forschungszentrum Jülich.

"However, for the programmability of a universal quantum computer, the ability to individually manipulate and selectively couple any qubits is crucial.

This is convincingly demonstrated in the papers.” Neutral atoms have thus caught up with competing approaches, such as those being pursued by Google.

The atom might become our friend after all,