Development of quantum technologies and quantum information processing in particular, dictates the necessity of finding a proper physical system that could satisfy stringent requirements on quantum coherence of individual components, their scalability, good controllability of device parameters, ease of fabrication, etc. Superconducting nanoelectronic devices are among the most promising for many applications in which quantum behaviour becomes important and may satisfy all the requirements imposed. Superconductors possess two properties that are crucial prerequisites for the observation of quantum effects: (i) they can carry dc current with zero resistance and (ii) have a gap in the energy spectrum. While the first property ensures dissipationless charge transport in the material, the second property protects charge carriers, the Cooper pairs, from low-energy excitations. This gives a possibility to prepare, manipulate and measure quantum states in superconducting circuits and use them for practical purposes. Also, the fabrication process for superconducting electronics is well established.
In my talk I will present the basics of superconducting qubits and compare their various realisations. Besides explaining the physics of the superconducting devices, I will also pay attention to some technical issues involved.