The scaling of NMR ensemble computers is currently one of the main obstacles to building larger-scale quantum computing devices. To achieve scalability, one needs a large number of highly polarized spins in liquid nuclear-spin systems at finite temperature. In quantum computing terminology, such spin-half states are (almost) pure qubit states. Producing highly polarized spins (almost pure qubit states) out of non-polarized spins (non-pure qubit states) is sometimes called "purification". From a thermodynamic point of view, purification can be viewed as cooling spins to a very low temperature. In this preliminary work, we study the optimality of purification as a tradeoff between the number of cooled spins and the closeness of their quantum state to the ideal pure state.

Date Published: 12 May 2006
PDF: 6 pages
Proc. SPIE 6244, Quantum Information and Computation IV, 624412 (12 May 2006); doi: 10.1117/12.666498

Published in SPIE Proceedings Vol. 6244:
Quantum Information and Computation IV
Eric J. Donkor; Andrew R. Pirich; Howard E. Brandt, Editor(s)