Quantum Simulation Exploiting the Haag-RuelleScattering Theory

The last years have seen a rapid development of applications of quantum computationto quantum field theory. The first quantum algorithms for simulation of scattering havebeen proposed in the context of scalar and fermionic theories, requiring thousands oflogical qubits.

These algorithms are not suitable to simulate scattering of incomingbound states, as the initial state preparation relies typically on adiabaticallytransforming wavepackets of the free theory into wavepackets of the interactingtheory. In this talk, I will present a strategy to excite wavepackets of the interacting theorydirectly from the vacuum of the interacting theory, allowing for preparation of statesof composite particles that can be taken as initial states of a scattering simulation.

Thisis the first step towards digital quantum simulation of scattering of bound states.The approach is based on the Haag-Ruelle scattering theory, which provides a way toconstruct creation and annihilation operators of a quantum field theory in a full, nonperturbative framework. As an example, I will consider a scalar theory in one spacedimension displaying a composite particle in its spectrum