  Nuclear magnetic resonance is arguably both the best available quantum
technology for implementing simple quantum computing experiments and the worst
technology for building large scale quantum computers that has ever been
seriously put forward. After a few years of rapid growth, leading to an
implementation of Shor's quantum factoring algorithm in a seven-spin system,
the field started to reach its natural limits and further progress became
challenging. Rather than pursuing more complex algorithms on larger systems,
interest has now largely moved into developing techniques for the precise and
efficient manipulation of spin states with the aim of developing methods that
can be applied in other more scalable technologies and within conventional NMR.
However, the user friendliness of NMR implementations means that they remain
popular for proof-of-principle demonstrations of simple quantum information
protocols.
