Quantum entropies and lossless quantum data compression

BELLOMO, GUIDO

Florencio Varela

Jornada; 2da Jornada de LoCIC; 2017

Universidad Nacional Arturo Jauretche

One of the main concerns in classical and quantum information theories is the problem of encoding information by using fewest resources as possible. This task is known as data compression and it can be carried out either in a lossy or a lossless way, depending on whether the original data can be recovered with or without errors, respectively. Based on the problem of quantum data compression in a lossless way, we present here an operational interpretation for the family of quantum Rényi entropies. In order to do this, we appeal to a very general quantum encoding scheme that satisfies a quantum version of the Kraft-McMillan inequality. Then, in the standard situation, where one is intended to minimize the usual average length of the quantum codewords, we recover the known results, namely that the von Neumann entropy of the source bounds the average length of the optimal codes. Otherwise, we show that by invoking an exponential average length, related to an exponential penalization over large codewords, the quantum Rényi entropies arise as the natural quantities relating the optimal encoding schemes with the source description, playing an analogous role to that of von Neumann entropy.