Dephasing

It is an important effect in molecular and atomic spectroscopy, and in the condensed matter physics of mesoscopic devices.

When the temperature is lowered and the dimensions of the device are meaningfully reduced, this classical behaviour should disappear and the laws of quantum mechanics should govern the behavior of conducting electrons seen as waves that move ballistically inside the conductor without any kind of dissipation.

to uncover that the so-called dephasing time, that is the time it takes for the conducting electrons to lose their quantum behavior, becomes finite rather than infinite when the temperature approaches zero in mesoscopic devices violating the expectations of the theory of Boris Altshuler, Arkady Aronov and David E.

[1] This kind of saturation of the dephasing time at low temperatures is an open problem even as several proposals have been put forward.

The time constant T2 has been measured with ultrafast time-resolved spectroscopy directly, such as in photon echo experiments.