One of the most puzzling discoveries in the history of science is the so-called quantum entanglement, that is to say, the invisible thread – “creepy connection at a distance”, Albert Einstein called it – that binds together subatomic particles, even if each is at the other end of the universe. It has been shown that if, for example, the spin or spin – technically, the angular momentum – of an electron is manipulated, this modification has an immediate effect on the spin of its partner, which opens the door to the possibility of teleportation; at least, of the quantum states of the particles .
The main problem is that controlling this phenomenon is extremely complicated, although it has already been possible to send information between entangled particles and hundreds of kilometers apart. The most spectacular achievement in this regard, announced last April, has been to link in this way two macroscopic objects, visible to the naked eye .
Objective: the quantum supercomputer
A team led by scientists from the Higher Council for Scientific Research (CSIC) has now advanced a step further in this promising field of research by developing a new protocol to transfer quantum information or electrons using nanometric-scale devices , according to a work published in the journal Nanotechnology . His innovation would improve the manipulation of artificial atoms or quantum bits (qubits), basic components of supercomputers – still in their infancy – that take advantage of the strange subatomic properties of matter.
The model created by the CSIC experts has the ability to transfer both the charge and the spin of the electrons between distant areas, without occupying the central region. This teleportation is carried out with a nanodevice that consists of a chain of artificial atoms or quantum dots , through which the electrons propagate.
This is how Gloria Platero, who works at the Madrid Institute of Materials, explains: “This transfer would be made by means of adiabatic electrical pulses (that is, low frequency) applied to the tunnel barriers that connect the quantum dots”. The downside of adiabatic protocols is that they are too slow, which increases the probability that the electron will interact with its environment and its electronic state will be altered. To solve the problem, the researchers have applied a theoretical model, based on reverse engineering, which speeds up the process and manages to isolate electrons from the environment .
CSIC scientists indicate that chains of up to 12 artificial atoms have already been developed , coupled together by electrostatic barriers. Electrons propagate through them thanks to a resonant tunneling effect. “Quantum processors, which need to keep data transfer intact over long distances, could benefit from this work”, has valued Gloria Platero.
Más información: Yue Ban, Xi Chen, Gloria Platero. Fast long-range charge transfer in quantum dot arrays. Nanotechnology. 29, 505201 (2018).
