Abstract:

We describe a protocol for cross-platform verification of quantum simulators and quantum computers. We show how to measure directly the overlap Tr[$\rho$1$\rho$2] and the purities Tr[$\rho$1,22], and thus a fidelity of two, possibly mixed, quantum states $\rho$1 and $\rho$2 prepared in separate experimental platforms. We require only local measurements in randomized product bases, which are communicated classically. As a proof of principle, we present the measurement of experiment-theory fidelities for entangled 10-qubit quantum states in a trapped ion quantum simulator.