17,073 research outputs found
Multi-party zero-error classical channel coding with entanglement
We study the effects of quantum entanglement on the performance of two
classical zero-error communication tasks among multiple parties. Both tasks are
generalizations of the two-party zero-error channel-coding problem, where a
sender and a receiver want to perfectly communicate messages through a one-way
classical noisy channel. If the two parties are allowed to share entanglement,
there are several positive results that show the existence of channels for
which they can communicate strictly more than what they could do with classical
resources. In the first task, one sender wants to communicate a common message
to multiple receivers. We show that if the number of receivers is greater than
a certain threshold then entanglement does not allow for an improvement in the
communication for any finite number of uses of the channel. On the other hand,
when the number of receivers is fixed, we exhibit a class of channels for which
entanglement gives an advantage. The second problem we consider features
multiple collaborating senders and one receiver. Classically, cooperation among
the senders might allow them to communicate on average more messages than the
sum of their individual possibilities. We show that whenever a channel allows
single-sender entanglement-assisted advantage, then the gain extends also to
the multi-sender case. Furthermore, we show that entanglement allows for a
peculiar amplification of information which cannot happen classically, for a
fixed number of uses of a channel with multiple senders.Comment: Some proofs have been modifie
Classical capacities of quantum channels with environment assistance
A quantum channel physically is a unitary interaction between the information
carrying system and an environment, which is initialized in a pure state before
the interaction. Conventionally, this state, as also the parameters of the
interaction, is assumed to be fixed and known to the sender and receiver. Here,
following the model introduced by us earlier [Karumanchi et al.,
arXiv[quant-ph]:1407.8160], we consider a benevolent third party, i.e. a
helper, controlling the environment state, and how the helper's presence
changes the communication game. In particular, we define and study the
classical capacity of a unitary interaction with helper, indeed two variants,
one where the helper can only prepare separable states across many channel
uses, and one without this restriction. Furthermore, the two even more powerful
scenarios of pre-shared entanglement between helper and receiver, and of
classical communication between sender and helper (making them conferencing
encoders) are considered.Comment: 28 pages, 9 figures. To appear in "Problems of Information
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A quantum-like model for complementarity of preferences and beliefs in dilemma games
We propose a formal model to explain the mutual influence between observed behavior and subjects' elicited beliefs in an experimental sequential prisoner's dilemma. Three channels of interaction can be identified in the data set and we argue that two of these effects have a non-classical nature as shown, for example, by a violation of the sure thing principle. Our model explains the three effects by assuming preferences and beliefs in the game to be complementary. We employ non-orthogonal subspaces of beliefs in line with the literature on positive-operator valued measure. Statistical fit of the model reveals successful predictions
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