Entanglement from Tensor Networks on a Trapped-Ion Quantum Computer
Michael Foss‐Feig, Stephen Ragole, Andrew C. Potter, Joan Dreiling, Caroline Figgatt, John Gaebler, Alex Hall, Steven A. Moses, Juan Miguel Rey Pino, Ben Spaun, Brian Neyenhuis, David Hayes
Abstract
The ability to selectively measure, initialize, and reuse qubits during a quantum circuit enables a mapping of the spatial structure of certain tensor-network states onto the dynamics of quantum circuits, thereby achieving dramatic resource savings when simulating quantum systems with limited entanglement. We experimentally demonstrate a significant benefit of this approach to quantum simulation: the entanglement structure of an infinite system-specifically the half-chain entanglement spectrum-is conveniently encoded within a small register of "bond qubits" and can be extracted with relative ease. Using Honeywell's model H0 quantum computer equipped with selective midcircuit measurement and reset, we quantitatively determine the near-critical entanglement entropy of a correlated spin chain directly in the thermodynamic limit and show that its phase transition becomes quickly resolved upon expanding the bond-qubit register.