Fast quantum algorithm for numerical gradient estimation.
Given a black box for f, a smooth real scalar function of d real variables, one wants to estimate [symbol: see text]f at a given point with n bits of precision. On a classical computer this requires a minimum of d + 1 black box queries, whereas on a quantum computer it requires only one query regardless of d. The number of bits of precision to which f must be evaluated matches the classical requirement in the limit of large n.
Jordan
Stephen P
SP
Physics Department, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA. sjordan@mit.edu