title: Algorithmic cooling and scalable NMR quantum computers.
abstract: We present here algorithmic cooling (via polarization heat bath)-a powerful method for obtaining a large number of highly polarized spins in liquid nuclear-spin systems at finite temperature. Given that spin-half states represent (quantum) bits, algorithmic cooling cleans dirty bits beyond the Shannon's bound on data compression, by using a set of rapidly thermal-relaxing bits. Such auxiliary bits could be implemented by using spins that rapidly get into thermal equilibrium with the environment, e.g., electron spins. Interestingly, the interaction with the environment, usually a most undesired interaction, is used here to our benefit, allowing a cooling mechanism. Cooling spins to a very low temperature without cooling the environment could lead to a breakthrough in NMR experiments, and our "spin-refrigerating" method suggests that this is possible. The scaling of NMR ensemble computers is currently one of the main obstacles to building larger-scale quantum computing devices, and our spin-refrigerating method suggests that this problem can be resolved.
authors.affiliation: Electrical Engineering Department, University of California, Los Angeles, CA 90095, USA.
authors.forename: P Oscar
authors.initials: PO
authors.lastname: Boykin
authors.forename: Tal
authors.initials: T
authors.lastname: Mor
authors.forename: Vwani
authors.initials: V
authors.lastname: Roychowdhury
authors.forename: Farrokh
authors.initials: F
authors.lastname: Vatan
authors.forename: Rutger
authors.initials: R
authors.lastname: Vrijen