Reliable Quantum State Tomography

Philippe Faist, Cyril Stark, Matthias Christandl, Renato Renner

Institute for Theoretical Physics, ETH Zurich

Quantum State Tomography is the task of estimating the state of a quantum system based on measurements of several copies of the system. Methods currently being used lack reliable error bars or rely on a prior. A new method based on the idea of reporting regions in state space, rather than single states, is proposed. The reported regions contain the true state almost certainly and thus provide reliable error bars. This method is practical and can be used to reconstruct states from actual experimental data.