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The National Physical Laboratory (NPL) has published research in Nature Communications that updates one of the most fundamental concepts in the physics of quantum electronic devices - the standard tunnelling model (STM).
 
The STM was introduced in the 1970s to describe the thermal properties of glass at temperatures close to absolute zero. At these low temperatures quantum mechanics takes over from classical physics and strange properties begin to emerge. Quantum tunnelling is one such property and describes how atoms can cross barriers that they should not be able to according to classical physics.
 
The performance of many electronic devices is hampered by a type of low frequency noise known as 1/f noise, or flicker noise. This is thought to be caused by two-level states, quantum systems where an atom, for example, can exist in exactly two states simultaneously. The STM predicts that, as temperatures decrease, this noise should also decrease and eventually vanish completely.
 
New measurements made in this research, over longer time scales than previously possible, contradict this prediction, showing an increase in noise at low temperatures. The measurements were made possible by implementing an ultra-stable frequency-tracking technique used in atomic clocks and by producing a superconducting resonator insensitive to fluctuations in temperature.

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