18 research outputs found
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
Experimental implementation of encoded logical qubit operations in a perfect quantum error correcting code
Large-scale universal quantum computing requires the implementation of
quantum error correction (QEC). While the implementation of QEC has already
been demonstrated for quantum memories, reliable quantum computing requires
also the application of nontrivial logical gate operations to the encoded
qubits. Here, we present examples of such operations by implementing, in
addition to the identity operation, the NOT and the Hadamard gate to a logical
qubit encoded in a five qubit system that allows correction of arbitrary single
qubit errors. We perform quantum process tomography of the encoded gate
operations, demonstrate the successful correction of all possible single qubit
errors and measure the fidelity of the encoded logical gate operations
Determination of nutrient salts by automatic methods both in seawater and brackish water: the phosphate blank
9 páginas, 2 tablas, 2 figurasThe main inconvenience in determining nutrients in seawater by automatic methods is simply solved:
the preparation of a suitable blank which corrects the effect of the refractive index change on the recorded
signal. Two procedures are proposed, one physical (a simple equation to estimate the effect) and the other
chemical (removal of the dissolved phosphorus with ferric hydroxide).Support for this work came from CICYT (MAR88-0245 project) and
Conselleria de Pesca de la Xunta de GaliciaPeer reviewe