Rotational Resonances and Regge Trajectories in Lightly Doped Antiferromagnets

Abstract

Understanding the nature of charge carriers in doped Mott insulators holds the key to unravelling puzzling properties of strongly correlated electron systems, including cuprate superconductors. Several theoretical models suggested that dopants can be understood as bound states of partons, the analogues of quarks in high-energy physics. The appearance and disappearance of bound states of partons, specifically spinons and chargons, may explain key features of the pseudogap phase and underly Fermi-surface reconstruction in cuprates. However, direct signatures of spinon-chargon bound states are lacking, both in experiment and theory. Here we numerically identify long-lived rotational resonances at low doping, which directly reveal the microscopic structure of spinon-chargon bound states. Similar to Regge trajectories reflecting the quark structure of mesons, we establish a linear dependence of the rotational energy on the super-exchange coupling. Rotational excitations are strongly suppressed in standard angle-resolved photo-emission (ARPES) spectra, but we propose a multi-photon rotational extension of ARPES where they have strong spectral weight. Our findings suggest that the rich physics of lightly doped cuprates may originate from an emergent parton structure.

Exploration of doped quantum magnets with ultracold atoms

“…The uniform-RVB state features similar sign flips of correlations and compares well also for larger dopings. ⇡-flux and the string model behave similarly and show agreement with our data for < 20 %, in line with [24]. Predictions for two-point correlations of di↵erent theoretical approaches are very similar at low doping, which calls for a comparison of higher-order spin-charge correlations.…”

“…The ability to perform lattice modulations and apply gradients will allow to go beyond the spectroscopic capabilities in solids, e.g. by studying rotational [24] or new time-dependent [176] variants of ARPES. On the other hand, the recent experiments pose new theoretical challenges.…”

“…Similarly, lattice modulations can be used as another way to perform spectroscopy [194,111,79], including in quantum gas microscope settings [26]. Local probes [125], the analogues of scanning tunneling microscopy (STM), and multi-photon spectroscopy [24] have also been proposed.…”

“…Recently new indications for the parton picture have been reported by advanced matrix product state (MPS) simulations [86,25,24]. Moreover, the string picture has been extended to include quantum fluctuations of the spin background [139] by introducing so-called geometric strings [87,86].…”

Electronic spectra with paramagnon fractionalization in the single band Hubbard model

“…[20][21][22]. But no theory of this bound state formation at non-zero hole density has yet been presented, although there have been some notable works [23][24][25][26].…”