Letters to Nature

Nature 393, 143-146 (14 May 1998) | doi:10.1038/30181; Received 21 January 1998; Accepted 18 March 1998

Experimental realization of a quantum algorithm

Isaac L. Chuang1, Lieven M. K. Vandersypen2, Xinlan Zhou2, Debbie W. Leung3 & Seth Lloyd4

  1. IBM Almaden Research Center, San Jose, California 95120, USA
  2. Solid State and Photonics Laboratory, Stanford University, Stanford, California 94305, USA
  3. Edward L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA
  4. MIT Department of Mechanical Engineering, Cambridge, Massachusetts 02139, USA

Correspondence to: Isaac L. Chuang1 Correspondence and requests for materials should be addressed to I.L. (e-mail: Email: ichuang@almaden.ibm.com.)

Quantum computers1, 2, 3, 4, 5 can in principle exploit quantum-mechanical effects to perform computations (such as factoring large numbers or searching an unsorted database) more rapidly than classical computers1,2,6, 7, 8. But noise, loss of coherence, and manufacturing problems make constructing large-scale quantum computers difficult9, 10, 11, 12, 13. Although ion traps and optical cavities offer promising experimental approaches14,15, no quantum algorithm has yet been implemented with these systems. Here we report the experimental realization of a quantum algorithm using a bulk nuclear magnetic resonance technique16, 17, 18, in which the nuclear spins act as 'quantum bits'19. The nuclear spins are particularly suited to this role because of their natural isolation from the environment. Our simple quantum computer solves a purely mathematical problem in fewer steps than is possible classically, requiring fewer 'function calls' than a classical computer to determine the global properties of an unknown function.