X-Message-Number: 9499 Date: Thu, 16 Apr 1998 10:21:32 -0700 (PDT) From: John K Clark <> Subject: Quantum Computer Hardware -----BEGIN PGP SIGNED MESSAGE----- - From PHYSICS NEWS UPDATE The American Institute of Physics Bulletin of Physics News Number 367 April 15, 1998 by Phillip F. Schewe and Ben Stein A SEARCH ENGINE THAT EMPLOYS QUANTUM WEIRDNESS has been experimentally demonstrated, allowing researchers to successfully find one of four possible pieces of data in a single computational step, rather than the 2.25 steps it takes traditional computers on average. Executing a quantum search algorithm proposed by Bell Labs physicist Lov Grover (Physical Review Letters, 14 July 1997; Physics Today, October 1997), an IBM-MIT-Berkeley team (Isaac Chuang, IBM-Almaden, 408-927-8245) employed an "NMR" quantum computer (Update 310), a device in which the binary digits 0 and 1 are represented by an atomic nucleus respectively aligned with and opposed to an external magnetic field. Starting with a solution of liquid chloroform molecules, and using radio pulses to manipulate the inner magnets of the carbon and hydrogen nucleus in each molecule, the researchers first put each carbon and hydrogen nucleus into a combination or "superposition" of 0 and 1 states, for a total of four possibilities in each molecule. Because quantum systems can be in many states at the same time, each molecule would then respond for all 4 possible states at once. Then they fired one of four possible sequences of radio pulses. By measuring the response of the collection of molecules, the researchers were then able to deduce the pulse sequence in a single step. Equivalent to finding one of 4 items in a database, this is the first experimental demonstration of a quantum computation requiring fewer steps than on a classical computer. (Chuang et al., Phys. Rev. Lett., 13 April 1998.) -----BEGIN PGP SIGNATURE----- Version: 2.6.i iQCzAgUBNTYMTH03wfSpid95AQGNpQTuOvY42JXIwI2i/DZtRezrFsGNinSQUZUl u6Or2roCFrF6ZCUiQGxbjJgyMQQu/iiIUPa5OwcmaS6YjzRJH1WA8g5C+YKQMk0p ze2Ka796X3+BWAxx191YEHqOM4A5jOtM3MI1fDiMcrQJQO0bHQyzaIORUO1zOpcX qHCrsk+BlmXMOTnv/lPDL1pVjwVcBSPgCCSBUcPY+pl8Ui9n0y4=96J8 -----END PGP SIGNATURE----- Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=9499