401 research outputs found
Optimal state estimation for d-dimensional quantum systems
We establish a connection between optimal quantum cloning and optimal state
estimation for d-dimensional quantum systems. In this way we derive an upper
limit on the fidelity of state estimation for d-dimensional pure quantum states
and, furthermore, for generalized inputs supported on the symmetric subspace.Comment: 3 page
Optimal cloning for two pairs of orthogonal states
We study the optimal cloning transformation for two pairs of orthogonal
states of two-dimensional quantum systems, and derive the corresponding optimal
fidelities.Comment: 4 pages, 3 figure
Experimental generation of pseudo bound entanglement
We use Nuclear Magnetic Resonance (NMR) to experimentally generate a bound
entangled (more precisely: pseudo bound entangled) state, i.e. a quantum state
which is non-distillable but nevertheless entangled. Our quantum system
consists of three qubits. We characterize the produced state via state
tomography to show that the created state has a positive partial transposition
with respect to any bipartite splitting, and we use a witness operator to prove
its entanglement.Comment: 5 page
Multipartite entanglement in quantum algorithms
We investigate the entanglement features of the quantum states employed in
quantum algorithms. In particular, we analyse the multipartite entanglement
properties in the Deutsch-Jozsa, Grover and Simon algorithms. Our results show
that for these algorithms most instances involve multipartite entanglement
Multipartite entanglement in quantum algorithms
We investigate the entanglement features of the quantum states employed in
quantum algorithms. In particular, we analyse the multipartite entanglement
properties in the Deutsch-Jozsa, Grover and Simon algorithms. Our results show
that for these algorithms most instances involve multipartite entanglement
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