# Cross-Platform Verification of Intermediate Scale Quantum Devices

### Citation:

Andreas Elben, Benoît Vermersch, Rick Van Bijnen, Christian Kokail, Tiff Brydges, Christine Maier, Manoj K. Joshi, Rainer Blatt, Christian F. Roos, and Peter Zoller. 2020. “Cross-Platform Verification of Intermediate Scale Quantum Devices.” Physical Review Letters, 124, Pp. 010504.

### 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.