{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,1]],"date-time":"2026-07-01T19:22:43Z","timestamp":1782933763011,"version":"3.54.5"},"reference-count":15,"publisher":"National Academy of Sciences","issue":"6","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2002,3,19]]},"abstract":"<jats:p>We present here algorithmic cooling (via polarization heat bath)\u2014a 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 \u201cspin-refrigerating\u201d 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.<\/jats:p>","DOI":"10.1073\/pnas.241641898","type":"journal-article","created":{"date-parts":[[2002,7,26]],"date-time":"2002-07-26T10:37:36Z","timestamp":1027679856000},"page":"3388-3393","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":173,"title":["Algorithmic cooling and scalable NMR quantum computers"],"prefix":"10.1073","volume":"99","author":[{"given":"P. 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