0000000000363181

AUTHOR

Alex Monras

showing 3 related works from this author

Measurement of damping and temperature: Precision bounds in Gaussian dissipative channels

2011

We present a comprehensive analysis of the performance of different classes of Gaussian states in the estimation of Gaussian phase-insensitive dissipative channels. In particular, we investigate the optimal estimation of the damping constant and reservoir temperature. We show that, for two-mode squeezed vacuum probe states, the quantum-limited accuracy of both parameters can be achieved simultaneously. Moreover, we show that for both parameters two-mode squeezed vacuum states are more efficient than either coherent, thermal or single-mode squeezed states. This suggests that at high energy regimes two-mode squeezed vacuum states are optimal within the Gaussian setup. This optimality result i…

PhysicsQuantum PhysicsOptimal estimationGaussianFOS: Physical sciencesQuantum entanglement01 natural sciencesLinear subspaceAtomic and Molecular Physics and Optics010305 fluids & plasmasCondensed Matter - Other Condensed Mattersymbols.namesakeMinimum-variance unbiased estimatorQuantum mechanics0103 physical sciencessymbolsDissipative systemCutoffStatistical physicsQuantum Physics (quant-ph)010306 general physicsQuantum information scienceOther Condensed Matter (cond-mat.other)
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Characterizing and Quantifying Frustration in Quantum Many-Body Systems

2011

We present a general scheme for the study of frustration in quantum systems. We introduce a universal measure of frustration for arbitrary quantum systems and we relate it to a class of entanglement monotones via an exact inequality. If all the (pure) ground states of a given Hamiltonian saturate the inequality, then the system is said to be inequality saturating. We introduce sufficient conditions for a quantum spin system to be inequality saturating and confirm them with extensive numerical tests. These conditions provide a generalization to the quantum domain of the Toulouse criteria for classical frustration-free systems. The models satisfying these conditions can be reasonably identifi…

frustrationmedia_common.quotation_subjectFOS: Physical sciencesGeneral Physics and AstronomyFrustrationQuantum capacityQuantum entanglement01 natural sciences010305 fluids & plasmasOpen quantum systemQuantum mechanics0103 physical sciencesQuantum operationStatistical physics010306 general physicsMathematical Physicsmedia_commonMathematicsQuantum PhysicsQuantum discordMathematical Physics (math-ph)Condensed Matter - Other Condensed MatterQuantum processQuantum algorithmCondensed Matter::Strongly Correlated ElectronsQuantum Physics (quant-ph)Other Condensed Matter (cond-mat.other)
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Information geometry of Gaussian channels

2009

We define a local Riemannian metric tensor in the manifold of Gaussian channels and the distance that it induces. We adopt an information-geometric approach and define a metric derived from the Bures-Fisher metric for quantum states. The resulting metric inherits several desirable properties from the Bures-Fisher metric and is operationally motivated from distinguishability considerations: It serves as an upper bound to the attainable quantum Fisher information for the channel parameters using Gaussian states, under generic constraints on the physically available resources. Our approach naturally includes the use of entangled Gaussian probe states. We prove that the metric enjoys some desir…

PhysicsQuantum PhysicsGaussianFOS: Physical sciencesMathematical Physics (math-ph)01 natural sciencesAtomic and Molecular Physics and Optics010305 fluids & plasmasStatistical manifoldIntrinsic metricCondensed Matter - Other Condensed Mattersymbols.namesakeQuantum mechanics0103 physical sciencesMetric (mathematics)symbolsApplied mathematicsInformation geometryFidelity of quantum statesQuantum Physics (quant-ph)010306 general physicsQuantum information scienceFisher information metricMathematical PhysicsOther Condensed Matter (cond-mat.other)
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