NMR based quantum information processing: Achievements and prospects

Nuclear magnetic resonance (NMR) provides an experimental setting to explor e physical implementations of quantum information processing (QIP), Here we introduce the basic background for understanding applications of NMR to QI P and explain their current successes, limitations and potential. NMR spect roscopy is well known for its wealth of diverse coherent manipulations of s pin dynamics. Ideas and instrumentation from liquid state NMR spectroscopy have been used to experiment with QIP. This approach has carried the field to a complexity of about 10 qubits, a small number for quantum computation but large enough for observing and better understanding the complexity of t he quantum world. While liquid state NMR is the only present-day technology about to reach this number of qubits. further increases in complexity will require new methods. We sketch one direction leading towards a scalable qu antum computer using spin 1/2 particles. The next step of which is a solid stare NMR-based QIP capable of reaching 10-30 qubits.