Mitigation of Scattering in a Quantum System Using an Integrating Sphere

Strong quantum-correlated sources are essential but delicate resources for quantum information science and technology protocols. Decoherence and loss are the two main disruptive processes that cause quantum correlations to lose their nonclassical behavior. In quantum systems, scattering can contribute to both decoherence and loss. In this work, we present an experimental scheme capable of significantly mitigating the adverse impact of scattering in quantum systems. Our quantum system is composed of a two-mode squeezed light generated with the four- wave mixing process in hot rubidium vapor, and a scatterer introduced to one of the two modes. An integrating sphere is then placed after the scatterer to recollect the scattered photons. We use mutual information between the two modes as the quantum correlation measure, and demonstrate a 47.5% mutual information recovery from scattering, despite an enormous photon loss of greater than 85%. Our scheme is the very first step towards recovering quantum correlations from disruptive random processes, thus has the potential to bridge the gap between proof-of-principle demonstrations and practical real-world implementations of quantum protocols.