Researchers from Yale University and the University of Auckland were able to register and prevent quantum jumps of electrons in a three-level system. The results of the experiment were published in the journal Nature.
“Quantum leaps of an electron are similar to a volcanic eruption. However, we have learned to track and prevent a catastrophe,”said lead author of the article, Yale University employee Zlatko Minev.
The Bohr model of the atom, which was born in 1913, says that electrons are located around the atomic nucleus in certain stationary states - in orbitals. A specific electron can pass from one state to another, but a quantum transition occurs instantly and with a change in the energy of the system. So, when jumping to a higher energetically higher orbital, energy is absorbed, and to a lower one, it is emitted. For a long time, scientists were confident that quantum jumps differ from gradual classical transitions in the absence of a trajectory between two states.
To better understand this phenomenon, a thought experiment was introduced, called "Schrödinger's cat." A certain cat is locked in a chamber with a machine that is triggered by the decay of a radioactive atom. An atom may or may not disintegrate with equal probability. However, if disintegration does occur, the device will throw prussic acid vapors into the chamber, which will kill the cat. Until someone looks into the box, the cat is a superposition (combination) of the states "alive" and "dead". According to this view, the quantum leap is discrete under the gaze of an observer.
In the 1980s, the scientific theory of quantum trajectories emerged. According to her, during the leap, the state of the system evolves continuously and the leap is always preceded by a latent period, during which it can be predicted and prevented.
The last hypothetical property of the system was used by physicists for a three-level system of a superconducting artificial atom (qubit) with a V-shaped structure of energy levels, cooled to a temperature of absolute zero (-273 ° C). The transition of an electron from the ground state to an excited state was recorded by the scientists by observing the change in the resonant frequency of the connected oscillatory circuit. The resonance frequency dropped sharply when the atom jumped into an auxiliary, intermediate state. The moment of transition to an excited state was recorded by freezing the evolution of the system and measuring the state using tomography. Finally, the transition was prevented by registering the absence of detecting photons, which each time preceded the quantum jump to an excited state.
The researchers showed that for intermediate times, the state of the atom changed continuously: the evolution of each completed jump was continuous, sequential and deterministic. The experiment is consistent with the predictions of the theory of quantum trajectories.