Colloquia

A remarkable property of one-dimensional conductors is the quantization of their resistance in units of Planck constant divided by the square of the elementary charge. This effect is well understood and readily observed in low-temperature experiments with relatively short one-dimensional conductors called the quantum point contacts. A puzzling feature of the transport through such contacts was reported a few years ago, when it was discovered that at somewhat higher temperatures the conduction drops to about 0.7 of its quantized value. This phenomenon, often referred to as the 0.7-anomaly, has been studied extensively in the last few years. I will discuss the latest experimental data and the theoretical attempts at understanding this effect.