Speaker
Description
We present a lattice calculation of the parton distribution function (PDF) of the lightest positronium system employing the 1+1D Schwinger model in the Hamiltonian formulation, implemented within a quantum computational framework on an IBM quantum computer. Our setup employs a total of 11 qubits: 10 qubits represent stagger fermions sites, which correspond to five spatial lattice sites and one ancillary qubit for determination of matrix element of a bilinear operator via Hadamad test. The PDF is obtained as the Fourier transform of this bilinear operator, which is measured along the light-cone direction. This approach offers a key advantage over traditional Euclidean lattice calculations, which require various approximations such as the LaMET framework. Compared with classical methods, quantum computation offers the advantage of not being limited in the accessible range of parton momentum fraction $x$ due to renormalon ambiguity particularly at $x=0$ and $x=1$, and the difficulty of accessing non-valence partons. A PDF calculation with 3+1 dimensional QCD near $x=0$ or $x=1$ will be a clear demonstration of the quantum advantage on a problem with great scientific impact. The real quantum computer and simulator results match well within the estimated statistical error, although the error remains sizable. Our study demonstrates that meaningful PDF extraction is feasible on current quantum devices by reducing the two-qubit gate depth from 5000 to 500. Future generations of quantum hardware will be capable of maintaining greater circuit depth and hold promise for achieving precise PDF calculations.
| Parallel Session (for talks only) | Quantum computing and quantum information |
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