Mechanisms of decoherence at low temperatures

Pritiraj Mohanty

Alexander Dementsov

One mechanism of decoherence of anyon qubit due to interaction with edge states is considered. The calculations are made at low temperature in Markovian and "short-time" approximation. Two approximations are compared.

Pritiraj Mohanty, R. A. Webb

We report low-temperature measurements of electron decoherence time in a series of pure gold wires, 18 nm thick and 30 nm wide. At fields up to 15 T, large enough to polarize any concentration of magnetic impurity spins, conductance fluctuation measurements show almost no temperature dependence of the decoherence time below 300 mK, both in the correlation field for interference and the root-mean-square value of the fluctuations. Combined with previous low-field weak localization measurements on samples from similar material, our experiment suggests that the ubiquitous saturation of decoherence time in these samples is not due to any mechanism based on magnetic impurity spins.

J. M. Raimond

Victor V. Makhro, Ya. A. Padamanov

A mesoscopic CrNi 6 system is used to demonstrate the possibility of transitions from quantum to classical behavior in thermally stimulated tunneling processes. The main mechanism responsible for these transitions is assumed to be quantum decoherence produced as a result of thermal interaction between the spin system and its neighborhood. Results are presented of calculations of the disruption probability for a mesoscopic system as a function of temperature. It is shown that the main characteristic which can reveal the decoherence effect is the nonmonotonic behavior of the disruption probability at low temperatures.

Maximilian Schlosshauer