Quantum Discord Underlies the Optimal Scheme for Modifying the Overlap between Two States

Roa, Luis; Maldonado-Trapp, Alejandra; Jara-Figueroa, Cristian; Guevara, M. L. Ladrón de

doi:10.7566/jpsj.83.044006

Cited by 4 publications

(4 citation statements)

References 54 publications

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“…Numerous are the quantum protocols, which can be performed with quantum discord [4][5][6][7][8][9][10] instead of entanglement [11,12]. As a measure of non-classical correlation, quantum discord is also recognized as a fundamental property of quantum systems [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Analytical solutions and criteria for the quantum discord of two-qubit X-states

Maldonado-Trapp

Roa

2015

Quantum Inf Process

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Except for a few special states, computing quantum discord remains a complicated optimization process. In this paper, we present analytical solutions for computing quantum discord of the most general class of X -states and the criteria for each analytical solution to be valid. We discuss parameter regions that correspond to different analytical solutions and explain the underlying reasons for such structure to exist. We apply our formalism to study both arbitrary X -states and X -states with certain symmetries. We find that our analytical formalism is in excellent agreement with numerical calculation of quantum discord in both cases.

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Section: Introductionmentioning

confidence: 99%

Analytical solutions and criteria for the quantum discord of two-qubit X-states

Maldonado-Trapp

Roa

2015

Quantum Inf Process

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“…Quantum discord [3,4] measures the difference between the total quantum mutual information and the classical mutual information of a system [5]. Although entanglement has been widely used as a measure of a given stateʼs potential quantum advantage, recent studies have suggested that quantum discord can be a richer resource [6][7][8][9][10][11][12][13][14]. Gu et al [15] studied the relationship between quantum advantage and quantum discord in an encoding/decoding protocol.…”

Section: Introductionmentioning

confidence: 99%

“…[3][4][5] Although entanglement has been widely used as a measure of a given state's potential quantum advantage, recent studies suggest that quantum discord is a richer resource. [6][7][8][9][10] The maximum quantum advantage that can be harvested with optimal encoding is equal to the initial quantum discord. This has been shown using continuous variable and Gaussian discord, 11 and quantum discord for a particular discrete state.…”

Section: Introductionmentioning

confidence: 99%

Realizing quantum advantage without entanglement in single-photon states

Maldonado-Trapp

Solano

et al. 2017

New J. Phys.

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We propose an optical circuit for attaining quantum measurement advantage in a system that has no quantum entanglement. Our device produces symmetric two-qubit X-states with controllable antidiagonal elements, and does not require entangled states as input. We discuss the use of this device in a two-qubit quantum game. When entanglement is absent, the maximum quantum advantage in this game is 1/3 bit. A slightly diminished quantum advantage, 0.311 bit, can be realized with a simplified transaction protocol.

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“…The original proposals considered schemes in which nonorthogonal states were first orthogonalised, and then measured with a suitable detection scheme [8,9]. However, for a valid implementation, these steps must be combined [10][11][12][13][14][15][16][17][18][19][20][21], such that orthogonalisation is post-selected on the appropriate measurement outcome, non-destructive [22,23] or otherwise. Yet, in some cases it may be necessary to orthogalise the input states without a post-selected measurement.In this paper, we develop a practical scheme for heralded, non-destructive state orthogonalisation of continuous-variable states, namely weak coherent states of opposite phase.…”

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confidence: 99%

Heralded orthogonalisation of coherent states and their conversion to discrete-variable superpositions

Kruse

Silberhorn

Bartley

2017

Quantum Measurements and Quantum Metrology

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Abstract:The nonorthogonality of coherent states is a fundamental property which prevents them from being perfectly and deterministically discriminated. Here, we present an experimentally feasible protocol for the probabilistic orthogonalisation of a pair of coherent states, independent of their amplitude and phase. In contrast to unambiguous state discrimination, a successful operation of our protocol is heralded without measuring the states. As such, they remain suitable for further manipulation and the obtained orthogonal states serve as a discretevariable basis. Therefore, our protocol doubles as a simple continuous-to-discrete variable converter, which may nd application in hybrid continuous-discrete quantum information processing protocols.

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Quantum Discord Underlies the Optimal Scheme for Modifying the Overlap between Two States

Cited by 4 publications

References 54 publications

Analytical solutions and criteria for the quantum discord of two-qubit X-states

Analytical solutions and criteria for the quantum discord of two-qubit X-states

Realizing quantum advantage without entanglement in single-photon states

Heralded orthogonalisation of coherent states and their conversion to discrete-variable superpositions

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