Valance bond shadows of quantum spin liquids

More than 50 years have passed since Phil Anderson hypothesized the resonating valence bond picture of quantum spin liquids, yet this phase presents numerous theoretical and experimental challenges. Quantum spin liquids are highly entangled phases of matter that are believed to host a variety of exotic quasiparticles, such as spinons, visons, and photons. The advent of quantum computing promises to bring us closer to understanding quantum spin liquids and their connection to high-temperature superconductivity. While preparing ground states on a quantum computer is challenging, characterizing their behavior also faces a significant challenge because Landau's paradigm of symmetry breaking does not describe them. We introduce valence bond (VB) shadows, a non-projective measurement technique in an overcomplete S=0 valence bond basis, large enough to be tomographically complete. Shots measured on this basis enable efficient detection of quasiparticles, estimation of vison loop observables, and visualization of the resonating valance bond state. The development of quantum computers and simulators capable of preparing quantum spin liquid states and shadow tomography methods like ours can shed more light on their elusive nature.