Scientists at the National Center for Quantum Technology (CQT) at the National University of Singapore have revealed that the shape of a photon can affect its absorption by a single atom. They say the finding is significant, suggesting that the photon's energy, or 5mw laser pointer wavelength, is no longer the only factor determining photonic behavior.

CQT chief scientist Christian Kurtsiefer and his research team have mastered how to accurately control the photon shape. "We usually do not think that photons will spread in space and time, and have a certain shape, but the photons we use in our experiments are four meters long," he commented.

The results were published in the November 29 issue of Nature Communications, using rubidium atoms and infrared photons. Each emitting a photon to a single alkali metal atom. "Our experiments study the most fundamental interaction of light and matter," commented Victor Leong, a Ph.D. student who participated in the study.

It takes 13 nanoseconds for a 4-meter photon to pass through such atoms. Whenever a photon passes through an atom, the team looks at whether or not the atom is excited. By recording the excitation time, the researchers can get the photon atomic absorption of the probability of time-varying relationship.

Two kinds of photons with different shapes of brightness increase and attenuation are studied. Hundreds of millions of 200mw laser pointer measurements lasting more than 1500 hours show that for both types of photons they are just over 4% absorbed by rubidium atoms. However, if the time scale from nanoseconds, each time the photon absorption probability and the shape of the photon.

CQT's team found that if the photon reaches the atom, the photon intensity after the first weak and strong, then the peak atomic excitation probability than the photon brightness of the first strong case of more than 50% higher than weak.

Researchers envisioned atoms more likely to absorb energy-boosting photons, explains Matthias Steiner, co-author of the paper, explaining that "the natural process of releasing photons by stimulated atomic decay causes this phenomenon. Atoms release an attenuated photon, In turn, imagine that the form of the equation does not change and that atoms will naturally encounter photons with increased brightness, and that the photons we choose to shape are inspired by the time - reversal symmetry of quantum mechanics.

The research team believes that their work helps to understand the use of 400mw laser pointer light and material interaction technology, "such as quantum communication, sensors, computing and other quantum technology involved in the process, usually need to use information into the photon atoms. "In order to design reliable quantum devices, scientists need to control this interaction, and you can use it only if you understand the interaction," says Alessandro Cerè, co-author of the paper.

The main conclusions are as follows: "We found that the process of light scattering is related to the photon's envelope.With the exponential decay of the envelope shape of the photon with time exponentially increasing with time, the envelope shape of the photon can more effectively excite the atoms.Using the exponential rise Shape of the photon excited atoms, which in a narrower time interval to produce a higher peak excitation probability of such synchronization will help the quantum communication network connection.