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Parameter Estimation of Quantum Channels
It is found that programmable parameters obey the standard quantum limit strictly; hence, no speedup is possible in its estimation and a class of nonunitary quantum channels is constructed whose parameter can be estimated in a way that thestandard quantum limit is broken.
Zero-Error Communication via Quantum Channels, Noncommutative Graphs, and a Quantum Lovász Number
A quantum version of Lovász' famous ϑ function on general operator systems is defined, as the norm-completion of a “naive” generalization of ϑ, in terms of which the zero-error capacity of a quantum channel, as well as the quantum and entanglement-assisted zero- error capacities can be formulated.
Semidefinite Programming Converse Bounds for Quantum Communication
The authors' SDP strong converse bound is weaker than the Rains information, but it is efficiently computable for general quantum channels, which means the fidelity of any sequence of codes with a rate exceeding this bound will vanish exponentially fast as the number of channel uses increases.
Four locally indistinguishable ququad-ququad orthogonal maximally entangled states.
It is shown that a 2⊗2 maximally entangled state can be used to locally distinguish this set of states without being consumed, thus demonstrating a novel phenomenon of entanglement discrimination catalysis.
An algebra of quantum processes
We introduce an algebra qCCS of pure quantum processes in which communications by moving quantum states physically are allowed and computations are modeled by super-operators, but no classical data
Multiple-copy entanglement transformation and entanglement catalysis
We prove that any multiple-copy entanglement transformation [S. Bandyopadhyay, V. Roychowdhury, and U. Sen, Phys. Rev. A 65, 052315 (2002)] can be implemented by a suitable entanglement-assisted
Locally indistinguishable subspaces spanned by three-qubit unextendible product bases
We study the local distinguishability of general multiqubit states and show that local projective measurements and classical communication are as powerful as the most general local measurements and
Bisimulation for quantum processes
A novel notion of bisimulation for quantum processes is introduced and it is proved that it is congruent with respect to various process algebra combinators including parallel composition even when both classical and quantum communications are present.
Tensor rank and stochastic entanglement catalysis for multipartite pure states.
A remarkable consequence of these results is that certain multipartite transformations, impossible even probabilistically, can become possible when performed in multiple-copy bunches or when assisted by some catalyzing state.
Tripartite entanglement transformations and tensor rank.
This work shows that for tripartite systems, there is no easy general criterion to determine the feasibility of quantum entangled states, and in fact, the problem is NP hard.