In an unreviewed preprint posted to arXiv, a team reports using IBM's 42-qubit ibm_boston processor to realize a quasiparticle collider for the one-dimensional Fermi-Hubbard model. The experiment encodes a 21-site half-filled chain and launches a doublon (a doubly-occupied site) and a holon (an empty site) toward each other, then measures the outcome of their collision. The authors claim this is the first direct measurement of Hubbard quasiparticle transmission probabilities on quantum hardware, with results agreeing with the Bethe-ansatz scattering matrix — an exact analytical solution — without any free fitting parameters.
Beyond reproducing known scattering probabilities, the paper reports a more subtle signature: the doublon-holon collision generates entanglement between the transmitted and reflected components, which the authors infer from particle-number fluctuations rather than full state tomography. As a control, collisions between two identical doublons show neither the interaction-dependent transmission nor the number fluctuations, consistent with the expected behavior of indistinguishable particles that simply pass through one another.
The authors argue that programmable digital quantum processors offer a qualitatively new handle on strongly correlated physics — one that allows experimenters to prepare quasiparticles of a chosen species, direct their motion, and probe the entanglement structure their collisions generate. Because this work has not yet undergone peer review, its claims about agreement with the Bethe ansatz and the entanglement inference method should be regarded as preliminary until independently scrutinized.