Soliton

Lonely wave on a lab wave channel

A soliton envelope in water waves. The blue line is the bearer waves, while the red line is the envelope of the solitons.

A soliton is a solitary wave that propagates without deformation in a non-linear medium. It is found in physical phenomena as a solution to nonlinear differential equations.

History and applications

The associated phenomenon was first described by Scotsman John Scott Russell (1808-1882), who first observed it in the propagation of a wave along a water channel in 1834. It followed a wave for several kilometres. wave that did not seem to weaken going upstream. So on the water, it is synonymous with bar. It appears in various rivers in particular circumstances. It is famous in the Amazon for its dimensions and duration.

The use of solitons was proposed in 1973 by Akira Hasegawa of AT&T Bell Laboratories to improve transmission performance in optical telecommunications networks. In 1988 Linn Mollenauer and his team transmitted solitons over 4,000 km using the Raman effect (name of an Indian scientist who described a way to amplify signals in an optical fiber).^{[citation needed]} In 1991, Also at Bell Laboratories, a team transmitted solitons over 14,000 km using Erbium amplifiers.

In 1998 Thierry Georges and his team at France Télécom's research and development center combined solitons of different wavelengths to transmit at rates greater than 1 terabit per second (1,000,000,000,000 bit/s). ^{[citation required]}

In 2001 solitons found a practical application with early telecommunications equipment, which used them to transport actual signal traffic over a commercial network.^{[citation needed]}

Acetylene

An infinite polyacetylene chain, at a given temperature, will contain a certain number of solitons.

The soliton phenomenon can be illustrated by the case of the polyacetylene polymer chain. In its ground state, a polyacetylene chain will be in alternating double and single bonds, as shown in the figure. However, the succession of two single bonds, leaving an unpaired electron on the carbon on the left, has a very low energy cost, so that, except at very low temperatures, there will always be an appreciable population of these excitations. Through an electronic and nuclear rearrangement, it is easy to move these excitations along the chain. However, for fundamental reasons, during their propagation these excitations cannot undergo deformation or mitigation, although they do cancel if two of them collide it is possible to dissipate the energy to other subsystems. In other words, these excitations are solitons.