Even a single atom can be turned into a mirror
Four Austrian physicists succeeded in developing an experimental scheme in which a single atom becomes one of the mirrors of a Fabry – Perot resonator.
The design of an ordinary Fabry – Perot resonator consists of two mirrors, the main thing is that these mirrors are parallel to each other. This is necessary in order for the laser beam to pass through the space between the mirror. With each reflection of the beam, some of it will be lost due to the fact that it comes out. In this experiment, the distance that light travels in the cavity is not a multiple of the wavelength of the light. But if this parameter is changed, then in the prototype one can observe the phenomenon of constructive interference and, naturally, the transmission will also be maximum. But if the interval value changes, the destructive interference that appears in this case will lead to a drop in the bandwidth level. Based on this, we can conclude that the parameters of the transmission of radiation are in direct proportion to the distance between the mirrors.
In the process of carrying out a new experiment, the role of one of the mirrors was played by the Ba + ion, which was placed in the Paul trap. In order to accurately maintain the distance between the mirrors, the ion was cooled using a laser using the Doppler technique. After the atom was cooled, it did not move more than 20 Nm from the center of the trap.
Then, weak laser radiation with a wavelength of 493 nm, which fully corresponds to the 6S1 / 2-6P1 / 2 transition in barium, was directed towards the cavity. After a detailed analysis of the results of the study, it was found that the fraction of radiation passing through the cavity will change by approximately 6%. It should be emphasized that such resonators give more significant variations in the bandwidth, but the assumption that the ion is able to perform the same functions as the mirror has been experimentally confirmed.
The authors of the study believe that such a technique will make it possible to create optical switches based on ions.