Parton Physics on a Quantum Computer

TL;DR

This paper explores algorithms for computing parton distribution functions and hadronic tensors on quantum computers, demonstrating potential advantages over traditional methods and estimating the computational costs involved.

Contribution

It introduces quantum algorithms for calculating parton physics quantities and discusses their extension to QCD, highlighting a new fitting approach for PDFs.

Findings

Parton distribution functions can be obtained by fitting the hadronic tensor.

Quantum algorithms may compute lepton-hadron cross sections more cheaply.

Estimated quantum computational costs for realistic parameters.

Abstract

Parton distribution functions and hadronic tensors may be computed on a universal quantum computer without many of the complexities that apply to Euclidean lattice calculations. We detail algorithms for computing parton distribution functions and the hadronic tensor in the Thirring model. Their generalization to QCD is discussed, with the conclusion that the parton distribution function is best obtained by fitting the hadronic tensor, rather than direct calculation. As a side effect of this method, we find that lepton-hadron cross sections may be computed relatively cheaply. Finally, we estimate the computational cost of performing such a calculation on a digital quantum computer, including the cost of state preparation, for physically relevant parameters.