Linnaeus Physics Colloquium: Sequential Protocols and Measurement Correlations

Title: Sequential Protocols and Measurement Correlations

Speaker: Giulio Foletto, KTH, Sweden

Abstract: Several quantum information protocols, often useful for cryptography, exploit nonclassical correlations between measurement outcomes to obtain (classical) resources. The paradigmatic example is the violation of a Bell inequality, which proves nonlocality and also guarantees the intrinsic randomness of the produced results. This is based only on the correlation between the outcomes of measurements on an entangled system, with only very general assumptions on how they are produced. This independence on the behavior of the physical devices generating the correlations is clearly attractive, as it weakens the requirements on the characterization of the devices themselves.

Finding ways to obtain these nonclassical correlations is therefore practically interesting and at the same time helps investigate the complex and fundamental relation between randomness and quantum properties. For this, sequential protocols have attracted some attention recently, as they allow producing stronger nonclassical correlations by measuring repeatedly the same quantum state. From the practical point of view, this means more resources, like random numbers, from the same physical system; from the fundamental point of view, this means that quantum properties can survive repeated measurements. This talk gives an overview of sequential protocols in this context and presents recent works that investigate them experimentally.

Organized within the Quantum Engineering: Science and Technology (QuEST) initiative by the LnU physics division

Part of the activities of the Advanced Materials knowledge environment

Zoom: https://lnu-se.zoom.us/j/416290322