  The second quantum technological revolution started around 1980 with the
control of single quantum particles and their interaction on an individual
basis. These experimental achievements enabled physicists and engineers to
utilize long-known quantum features - especially superposition and entanglement
of single quantum states - for a whole range of practical applications. We use
a publication set of 54,598 papers from the Web of Science published between
1980 and 2018 to investigate the time development of four main subfields of
quantum technology in terms of numbers and shares of publication as well as the
occurrence of topics and their relation to the 25 top contributing countries.
Three successive time periods are distinguished in the analyses by their short
doubling times in relation to the whole Web of Science. The periods can be
characterized by the publication of pioneering works, the exploration of
research topics, and the maturing of quantum technology, respectively. Compared
to the US, China has a far over proportional contribution to the worldwide
publication output, but not in the segment of highly-cited papers.
