Robin Kothari: Quantum Linear Systems Algorithms with Exponentially Improved Dependence on Precision
Robin Kothari (MIT)
Quantum Linear Systems Algorithms with Exponentially Improved Dependence on Precision
QuICS Workshop on the Frontiers of Quantum Information and Computer Science (September 28, 2015)
Consider the linear system of equations Ax=b. Harrow, Hassidim, and Lloyd showed that if A and b satisfy appropriate conditions, it is possible to output a quantum state whose entries are proportional to the entries of x. Their algorithm runs in time polynomial in log N and 1⁄ϵ, where N is the size of A, and ϵ is the desired precision in the output state. We present an improved algorithm whose running time is polynomial in log N and log(1⁄ϵ), exponentially improving the dependence on precision while keeping the same dependence on other parameters.