Wednesday 3 August 2016

Study Opens New Realms of Light-Matter Interaction

Light-Matter Interaction

Interaction between Light & Matter – Within Fractions of a Second

A latest MIT research could reveal new areas of technology depending on the forms of light emanation which had been presumed to be restricted or at least unlikely to be almost inaccessible. According to the researchers, the new approach may cause some kind of interactions between light and matter that would generally take billions of years to occur, will take place instead within fractions of a second under special circumstances.Based on theoretical analysis, the conclusions were reported recently in the journal Science in a paper by MIT doctoral student Nicholas Rivera, Department of Physics Professor Marin Soljacic, Francis Wright Davis Professor of Physics John Joannopoulos and post docs Ido Kaminer and Bo Zhen.

Defined by the laws of quantum electro dynamic, the interactions between light and matter seem to be the basis of an extensive range of technologies comprising of lasers, LEDs and atomic clocks. Soljacic explains that, from a theoretical point of view, `most of the light matter interaction processes tend to be forbidden by electronic selection rules that restricts the number of transitions between the levels of energy we have access to. For instance, spectrograms that are utilised in probing the essential conformation of substances indicate a few bright lines against a typically dark background.

Electrons in Atom Have Distinct Energy Levels

Kaminer says that with this new research, they demonstrate theoretically that these constraints could be raised, utilising confined waves within atomically thin, 2-D materials. He added that `we display that some of the changes which normally take the age of the universe to happen could be made to happen within nanoseconds.
Owing to this, several of the dark regions of a spectrogram tends to become bright when an atom is positioned near a 2-D material’. Electrons in an atom is said to have distinct energy levels and when they step from one level to another, they tend to give off a photon of light which is a development known as impulsive emission. However, the atom in itself seems to be much smaller than the wavelength of the light which gets emitted, around 1/1,000 to 1/10,000 as big, considerably impairing the interactions between the two.

Shrink Light to Match Scale of Atom

The researchers have shown in their study that the habit is to shrink the light so that it tends to match the scale of the atom. The significance of enabling a complete range of interactions specially transitions in atomic shows that transmit of absorbing or emitting light; it is the use of a two-dimensional material known as graphene wherein light can intermingle with matter in the form of plasmons, which is a kind of electromagnetic oscillation in the material.

These plasmons that look like photons though have wavelengths which are shorter hundreds of time, seems to be confined narrowly in the graphene which makes some type of interactions with the matter in several kinds of magnitude than they would in ordinary resources. This supports various phenomena which are generally considered unreachable like the simultaneous emission of various plasmons, or two-step light emitting transition between energy levels, according to the team.

This system could assist in simultaneous emission of two photons which are entangled which means that they share the same quantum state although they seem separated and such generation of entangled photons seems to be an important element in quantum devices like those which could be utilised for cryptography.

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