Measuring the Renyi entropy of a two-site Fermi-Hubbard model on a trapped ion quantum computer

The efficient simulation of correlated quantum systems is the most promising near-term application of quantum computers. Here, we present a measurement of the second Renyi entropy of the ground state of the two-site Fermi-Hubbard model on a $5$-qubit programmable quantum computer based on trapped ions. Our work illustrates the extraction of a non-linear characteristic of a quantum state using a controlled-swap gate acting on two copies of the state. This scalable measurement of entanglement on a universal quantum computer will, with more qubits, provide insights into many-body quantum systems that are impossible to simulate on classical computers.
Comment: main text: 5 pages, 4 figures, 2 F-H systems, 2 qubits each, 1 ancilla; supplementary material: 4 pages, 7 figures