The title of this post, “Breakthrough will lead to further entanglements” should be taken literally…and figuratively. An experiment by L. G. Herrmann in France, working with colleagues in France, Spain, and Germany, and published in Physical Review Letters has demonstrated for the first time in a solid state device the property of quantum mechanics called entanglement. With entanglement a single particle (photon or electron) can be two separate entities, as in split in two, and yet change in the behavior of one entity instantaneously affects the other entity. This is not an atomic version of cloning, it’s much more fundamental – the two particles can be identified as separated, yet they behave like communication between them is occurring as if tied together – that is to say, instantly. Measurement of one particle simultaneously affects the other. If the status of one particle is changed, the other particle instantly reflects that change. Sounds impossible – like being in two places at the same time – but that’s quantum physics. The challenge for scientists has been to provide the evidence that there are, in fact, two different entities and then show that they are, in fact, entangled. This was first done in the 1980’s with photonic particles (light) of one kind or another; now it has been done with electrons in a solid-state environment.
By ‘solid-state’ is meant metallic electron particles in a super-cold, superconducting environment, an environment similar to that used by some supercomputers. This experiment used carbon nanotubes to split electrons, a significant advantage because the nanotube’s tiny diameter retains the charge of each electron at higher energy than other techniques. As the nanotubes split what are called Cooper pairs (already entangled electrons), the particles that remain entangled are deposited on one or the other of two quantum dots (semiconductors with the capability of quantum confinement). Because the quantum dots are physically separated, it demonstrates that two particles are involved, and the instant communication property of entanglement occurs over a measurable distance.
More work needs to be done to verify the entanglement properties of the particles in the quantum dots, and there are many variations yet to be tried for types and configurations of nanotubes (especially metallic carbon nanotubes). This means that practical applications are speculative, but the potential is enhanced by the solid-state entanglement. This is an environment, such as supercomputing, where the conditions for creating and monitoring super-cold, superconducting particle activity is already part of engineering. As one analyst put it:
…electrons entangled in a superconducting Cooper pair can be spatially separated into different arms of a carbon nanotube, a material thought favorable for the efficient injection and transport of split, entangled pairs. This work may help pave the way for tests of nonlocal effects [quantum entanglement] in solid-state systems, as well as applications such as quantum teleportation and ultrasecure communication.
[Source: American Physical Society]