Dissonance is Required for Assisted Optimal State Discrimination

Roa, Luis; Retamal, J. C.; Alid-Vaccarezza, M.

doi:10.1103/physrevlett.107.080401

Cited by 117 publications

(160 citation statements)

References 27 publications

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“…Further, unambiguous state discrimination with a priori classical probabilities [12][13][14], can be considered as a special case our procedure.…”

Section: Discussionmentioning

confidence: 99%

“…We refer to this task as unambiguous sub-state discrimination (USSD), to differentiate with the case with a priori classical probabilities studied in [12][13][14]. In fact, such process exists in specific quantum information protocols, for instance the probabilistic teleportation [15,16] which will be shown as a part of our results.…”

Section: Introductionmentioning

confidence: 97%

“…Our basic idea to study the intrinsic coherence in USSD comes from the researches about quantum correlations in unambiguous state discrimination with a priori classical probabilities [12][13][14]. This process can be implemented successfully in the absence of quantum entanglement and is conjectured to be aided by quantum discord.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Intrinsic coherence in assisted sub-state discrimination

Zhang

Wang

2017

EPL

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We study intrinsic coherence in the tripartite process to unambiguously discriminate two nonorthogonal states of a qubit, entangled with another one, and assisted by an auxiliary system. The optimal success probability is found to be benefited by initial intrinsic coherence, but no extra one is required. The transformations among different contributions of intrinsic coherence are necessary in this procedure, which increase with the overlap between the states to recognize. Such state discrimination is a key step of the probabilistic teleportation protocol. Entanglement of the quantum channel decreases the coherence characterizing the reliance on an ancilla.

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“…Further, unambiguous state discrimination with a priori classical probabilities [12][13][14], can be considered as a special case our procedure.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Intrinsic coherence in assisted sub-state discrimination

Zhang

Wang

2017

EPL

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“…Our methodology, along with the traditional QD and QWD, is applicable also to the geometric measures that require an optimization. Motivated by the usefulness of QD and QWD in certain quantum protocols [5][6][7]41], we choose these measures for the purpose of demonstration.…”

Section: Constrained Quantum Correlations: Error In Estimationmentioning

confidence: 99%

Reducing computational complexity of quantum correlations

et al. 2015

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We address the issue of reducing the resource required to compute information-theoretic quantum correlation measures like quantum discord and quantum work deficit in two qubits and higher dimensional systems. We show that determination of the quantum correlation measure is possible even if we utilize a restricted set of local measurements. We find that the determination allows us to obtain a closed form of quantum discord and quantum work deficit for several classes of states, with a low error. We show that the computational error caused by the constraint over the complete set of local measurements reduces fast with an increase in the size of the restricted set, implying usefulness of constrained optimization, especially with the increase of dimensions. We perform quantitative analysis to investigate how the error scales with the system size, taking into account a set of plausible constructions of the constrained set. Carrying out a comparative study, we show that the resource required to optimize quantum work deficit is usually higher than that required for quantum discord. We also demonstrate that minimization of quantum discord and quantum work deficit is easier in the case of two-qubit mixed states of fixed ranks and with positive partial transpose in comparison to the corresponding states having non-positive partial transpose. Applying the methodology to quantum spin models, we show that the constrained optimization can be used with advantage in analyzing such systems in quantum information-theoretic language. For bound entangled states, we show that the error is significantly low when the measurements correspond to the spin observables along the three Cartesian coordinates, and thereby we obtain expressions of quantum discord and quantum work deficit for these bound entangled states.

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“…Quantum discord can be activated into distillable entanglement [16,17], and has been shown to be a resource in quantum state discrimination [18] and quantum locking [19]. It has been also shown [20,21] that discord quantifies the minimum damage made by a decoherence process to the performance of many quantum information processing protocols, including teleportation, distillation and dense coding.…”

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confidence: 99%

Discording Power of Quantum Evolutions

et al. 2013

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We introduce the discording power of a unitary transformation, which assesses its capability to produce quantum discord, and analyze in detail the generation of discord by relevant classes of two-qubit gates. Our measure is based on the Cartan decomposition of two-qubit unitaries and on evaluating the maximum discord achievable by a unitary upon acting on classical-classical states at fixed purity. We found that there exist gates which are perfect discorders for any value of purity, and that they belong to a class of operators that includes the √ SWAP. Other gates, even those universal for quantum computation, do not posses the same property: the CNOT, for example, is a perfect discorder only for states with low or unit purity, but not for intermediate values. The discording power of a two-qubit unitary also provides a generalization of the corresponding measure defined for entanglement to any value of the purity. The primary aim of the science of quantum information is the exploitation of the quantum structure of nature for information processing and communication tasks. Among the quantum features of a physical system, entanglement is usually considered the prominent resource, providing speed-up in various quantum information and communication tasks [1]. In the realm of mixed-state quantum-information, however, instances are known where quantum advantages are obtained in the presence of little or no entanglement. In fact, quantum discord [2,3] has been proposed as the source behind this enhancement [4], and some indications in this direction have been given [5][6][7][8]. The notion of nonclassicality springing from information theory has been also discussed in comparison with that coming from phase-space constraints [9].Although introduced in the context of environment induced decoherence, quantum discord has been then related to the performance of quantum and classical Maxwell's demons [10] and to the thermodynamic efficiency of a photo-Carnot engine [11], as well as the total entanglement consumption [12], and the minimum possible increase of quantum communication cost [13] in state merging protocols. Furthermore, its propagation properties have been studied in [14] in connection with micro-causality and in [15] for quantum spin channels.Quantum discord can be activated into distillable entanglement [16,17], and has been shown to be a resource in quantum state discrimination [18] and quantum locking [19]. It has been also shown [20,21] that discord quantifies the minimum damage made by a decoherence process to the performance of many quantum information processing protocols, including teleportation, distillation and dense coding.In continuous variable systems, Gaussian quantum discord [22,23] has been experimentally measured [24][25][26] and represents a measure of the advantage provided by coherent quantum systems over their classical counterpart. It has been also suggested [27] that the geometric quantum discord [28] is the optimal resource for remote quantum state preparation, though the interpretation of ...

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Dissonance is Required for Assisted Optimal State Discrimination

Cited by 117 publications

References 27 publications

Intrinsic coherence in assisted sub-state discrimination

Intrinsic coherence in assisted sub-state discrimination

Reducing computational complexity of quantum correlations

Discording Power of Quantum Evolutions

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