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Random access codes are important for a wide range of applications in quantum information. However, their implementation with quantum theory can be made in two very different ways: (i) by distributing data with strong spatial correlations violating a Bell inequality, or (ii) using quantum communication channels to create stronger-than-classical sequential correlations between state preparation and measurement outcome. Here, we study this duality of the quantum realization. We present a family of Bell inequalities tailored to the task at hand and study their quantum violations. Remarkably, we show that the use of spatial and sequential quantum correlations imposes different limitations on the performance of quantum random access codes. We also show that there exist random access codes for which spatial quantum correlations offer no gain over classical strategies, whereas sequential quantum correlations can yield an advantage. We discuss the physics behind the observed discrepancy between spatial and sequential quantum correlations.
Quantum information protocols can be realized using the `prepare and measure setups which do not require sharing quantum correlated particles. In this work, we study the equivalence between the quantumness in a prepare and measure scenario involving
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Random access coding is an information task that has been extensively studied and found many applications in quantum information. In this scenario, Alice receives an $n$-bit string $x$, and wishes to encode $x$ into a quantum state $rho_x$, such that