Experimental quantum compressed sensing for a seven-qubit system

Understand

Well-controlled quantum devices with their increasing system size face a new roadblock hindering further development of quantum technologies: The effort of quantum tomography---the characterization of processes and states within a quantum device---scales unfavorably to the point that state-of-the-art systems can no longer be treated.

• Quantum compressed sensing mitigates this problem by reconstructing the state from an incomplete set of observables.
• In this work, we present an experimental implementation of compressed tomography of a seven qubit system---the largest-scale realization to date---and we introduce new numerical methods in order to scale the reconstruction to this dimension.
• Originally, compressed sensing has been advocated for density matrices with few non-zero eigenvalues.