Electrons in atoms sometimes behave in surprising ways.
Thanks to very precise simulations, researchers from the Universities of Vienna and China have managed to observe in detail how two electrons bond quantumly in just a few attoseconds, an ultra-short time scale where entanglement between particles appears.
This quantum entanglement creates such an intimate connection between two particles that they can no longer be described separately. This phenomenon is essential for technologies like quantum computers and cryptography. In this study, the researchers' objective was to understand how this entanglement is created from the first fractions of secondby observing interactions between a laser and atoms. To carry out this research, scientists used a very high frequency laser to remove a electron of the atom ofhéliuma process which can excite a second. This then remains attached to the nucleus, but in a different energy state. This phenomenon creates a link between the two electrons: they are now entangled, which means that by studying one of them, we can deduce information about the other.
The researchers were able to show that the “moment of birth” of the ejected electron, that is to say the moment when it leaves the atom under the impulse of the laser, is intimately linked to the state of the electron remained in the atom. In quantum terms, this moment has no existence: it is a superposition of several possible moments.
This superposition indicates that the moment when the electron leaves the atom depends on the energy of the remaining electron. If it is in a higher energy state, it is likely that the electron was ejected earlier. Conversely, lower energy suggests a later start, in average of the order of 232 attoseconds, or a billionth of a billionth of a second.
This time frame is incredibly short, but it allows researchers to precisely measure the bond that forms between the two electrons as they separate. This temporal aspect is essential: the ejection of the electron occurs gradually, in the form of a wave which “flows” out of the atom, and it is in this phase that the entanglement between the electrons occurs. product.
The researchers now hope to reproduce these observations in the laboratory with other teams to validate this model. This work makes it possible to explore new frontiers in quantum physics, where phenomena that were thought to be instantaneous actually turn out to be much more complex and structured.
