Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Chinese Physics B

Dynamics of super-quantum discord and direct control with weak measurement in open quantum system

Yinghua Ji

Published Dec 1, 2015• 8 citations
Publisher

Abstract

Super-quantum discord (SQD) with weak measurement is regarded as a kind of quantum correlation in quantum information processing. We compare and analyze the dynamical evolutions of SQD, quantum discord (QD), and quantum entanglement (QE) between two qubits in the correlated dephasing environmental model. The results indicate that (i) owing to the much smaller influence of weak measurement on the coherence of the system than that of von Neumann projection measurement, SQD with weak measurement is larger than QD, and (ii) dynamical evolution of QD or QE monotonically goes to zero with time, while SQD monotonically tends to a stable value and a freezing phenomenon occurs. The stable value after freezing mainly depends on the measurement strength and the purity of the initial quantum state.

DOI
10.1088/1674-1056/24/12/120302

Related papers

Weak-measurement induced quantum discord and monogamy of X states

Asutosh Kumar

Weak-measurement induced quantum discord or super quantum discord (SQD) is a generalization of the normal quantum discord and is defined as the difference between quantum mutual information and classical correlation obtained by weak measurements in a given quantum system. This correlation is an information-theoretic measure and is, in general, different from entanglement-separability measures such as entanglement. Super quantum discord may be nonzero even for certain separable states. So far, SQD has been calculated explicitly only for a limited set of two-qubit quantum states and expressions for more general quantum states are not known. In this article, we derive explicit expressions for SQD for X states, a seven real-parameter family of two-qubit states and investigate its monogamy properties. The monogamy behaviour of SQD depends on the measurement strength. The formalism can be easily extended to N-qubit X states.

•Jan 1, 2013•0 citations

Dynamics of the Quantum Discord with Weak Measurement for a Two-atom System in Thermal Reservoirs

Mei Bai, Hong Jia Xu, Xue Qun Yan

Weak measurement is a kind of state partial collapse measurement developed on the basis of von Neumann measurement and positive operator value measurement, which allows us to explore the quantum world which has the least influence on the research system. Based on the weak measurement theory, the dynamics of quantum discord for two isolated atoms in their own thermal reservoirs is presented. We examine the time evolution of both standard quantum discord and quantum discord with weak measurement for the two-atom system, and analyzes the differences between the standard quantum discord and quantum discord with weak measurement in the evolution process with time, as well as the general role of the strength parameter in determing the discord and affecting its dynamic evolution. We show that quantum discords depend on how weak or strong one perturbs the quantum system. We also show that the difference of the standard quantum discord and the quantum discord with weak measurements increases as the strength parameter decreases. This means that the weak measurements can capture more quantum discord of a bipartite system. Our results show that the weak measurement performed on one of the subsystems can lead to the quantum discord that is a more natural measure of quantum correlations than the standard quantum discord captured by the projective measurements.

American Journal of Modern Physics•Jan 1, 2020•2 citations

Super quantum discord for a class of two-qubit states with weak measurement

H. Eftekhari, E. Faizi

So far, super quantum discord has been calculated explicitly only for Bell-diagonal states and expressions for more general quantum states are not known. In this paper, we derive explicit expressions for super quantum discord for a larger class of two-qubit states, namely, a 4-parameter family of two-qubit states. We observe that, weak measurements obtain more quantumness of correlations than strong measurements. As an application, the dynamic behavior of the super quantum discord under decoherence channel is investigated. We find that, the super quantum discord decreases monotonically as a function of the measurement strength parameter.

arXiv:1409.4329•Sep 15, 2014•1 citation

Dynamics of quantum discord and geometric quantum discord in multiqubit interacting system

Xiao-Di 晓迪 Cheng 程, Ya‐Jun Zheng, Meng-Jie 梦杰 Ran 冉 +1 more

Abstract Using quantum discord (QD) and geometric quantum discord (GQD), quantum correlation dynamics is investigated for two coupled qubits within a multiqubit interacting system in the zero-temperature bosonic reservoir, under both weak and strong qubit-reservoir coupling regimes. The multiqubit system is connected with either a common bosonic reservoir (CBR) or multiple independent bosonic reservoirs (IBRs). In the CBR case, our findings indicate that both QD and GQD can be strengthened by increasing the number of qubits in the multiqubit system. Furthermore, we study the steady state QD and GQD in the strong coupling regime, and find that the stable value in the long-time limit is determined exclusively by the number of qubits. The evolution period of QD and GQD gets longer as the dipole–dipole interaction (DDI) strength increases, which helps prolong the correlation time and thus preserves the quantum correlation under the weak coupling regime. Further analysis reveals notable differences between the CBR and IBRs scenarios. In the IBRs case, the decay of QD and GQD becomes slower compared to the CBR case, with both measures tending to zero at a reduced rate. Moreover, GQD consistently exhibits lower values than QD in both scenarios. These findings provide valuable insights into the selection of appropriate correlation measurement techniques for quantifying quantum correlations.

Chinese Physics B•Apr 8, 2025•0 citations

Dynamics super quantum discord and quantum discord teleportation in the Jaynes–Cummings model

Фороузан Мирмасоуди, Sodeif Ahadpour

The aim of this paper is investigation on dynamics of super quantum discord (SQD) and quantum discord (QD) teleportation in the Jaynes–Cummings model. In order to teleport one and two qubit states, a scheme is proposed for quantum channel where is induced from an atom-field interaction. The initial state of the atom is its excited state while the state of field starts in a coherent one. The model reveals that the dynamics of quantum correlations depends crucially on atom-field initial conditions and the field parameters can be utilized as control parameters for optimal teleportation. Interestingly, we find that QD teleportation and SQD teleportation are not always zero when the entanglement falls to zero for a teleported state. This result clearly illustrates that in some cases we can only get a truly quantum teleportation by QD and SQD if we use a suitable field parameters and initial state, which have no entanglement. The results reveal that QD and SQD for teleported states are much robuster than entanglement in the process of communication. According to the results, the proposed scheme can greatly reduce the cost of quantum communication. We also obtain that the behaviour of the QD and SQD teleportation are similar to average fidelity. So, QD and SQD can be used to analyse teleported state as average fidelity.

Journal of Modern Optics•Nov 24, 2017•16 citations

Dynamics of super quantum discord and optimal dense coding in quantum channels

Фороузан Мирмасоуди, Sodeif Ahadpour

Abstract Quantum discord (QD), super quantum discord (SQD) and optimal dense coding at entangled states of three types of quantum channels, are investigated. The used models include: two-qubit spin squeezing, the two-qubit Heisenberg XYZ model with decoherency and the Jaynes–Cummings model. In the first two models the quantum correlations and the optimal dense coding capacity are calculated in terms of channel parameters, system initial conditions and decoherency rate. It has been found that valid dense coding can exist, although there is no trace of entanglement in the quantum channel. In contrast, despite the presence of entanglement states in the system, there may be no dense coding capacity. We investigate the effects of cavity Fock states on quantum correlations and optimal dense coding in the Jaynes–Cummings model. Cavity Fock states are found to be effective for quantum correlations and optimal dense coding. The common result of all three models is that the dynamic properties of SQD on our channel enable us to determine when and under what conditions the system is suitable for dense coding capacity.

Journal of Physics A Mathematical and Theoretical•Jun 18, 2018•24 citations
Super-quantum discord (SQD) with weak measurement is regarded as a kind of quantum correlation in quantum information processing. We compare and analyze the dynamical evolutions of SQD, quantum discord (QD), and quantum entanglement (QE) between two qubits in the correlated dephasing environmental model. The results indicate that (i) owing to the much smaller influence of weak measurement on the coherence of the system than that of von Neumann projection measurement, SQD with weak measurement is larger than QD, and (ii) dynamical evolution of QD or QE monotonically goes to zero with time, while SQD monotonically tends to a stable value and a freezing phenomenon occurs. The stable value after freezing mainly depends on the measurement strength and the purity of the initial quantum state.
Weak-measurement induced quantum discord or super quantum discord (SQD) is a generalization of the normal quantum discord and is defined as the difference between quantum mutual information and classical correlation obtained by weak measurements in a given quantum system. This correlation is an information-theoretic measure and is, in general, different from entanglement-separability measures such as entanglement. Super quantum discord may be nonzero even for certain separable states. So far, SQD has been calculated explicitly only for a limited set of two-qubit quantum states and expressions for more general quantum states are not known. In this article, we derive explicit expressions for SQD for X states, a seven real-parameter family of two-qubit states and investigate its monogamy properties. The monogamy behaviour of SQD depends on the measurement strength. The formalism can be easily extended to N-qubit X states.
Weak measurement is a kind of state partial collapse measurement developed on the basis of von Neumann measurement and positive operator value measurement, which allows us to explore the quantum world which has the least influence on the research system. Based on the weak measurement theory, the dynamics of quantum discord for two isolated atoms in their own thermal reservoirs is presented. We examine the time evolution of both standard quantum discord and quantum discord with weak measurement for the two-atom system, and analyzes the differences between the standard quantum discord and quantum discord with weak measurement in the evolution process with time, as well as the general role of the strength parameter in determing the discord and affecting its dynamic evolution. We show that quantum discords depend on how weak or strong one perturbs the quantum system. We also show that the difference of the standard quantum discord and the quantum discord with weak measurements increases as the strength parameter decreases. This means that the weak measurements can capture more quantum discord of a bipartite system. Our results show that the weak measurement performed on one of the subsystems can lead to the quantum discord that is a more natural measure of quantum correlations than the standard quantum discord captured by the projective measurements.
So far, super quantum discord has been calculated explicitly only for Bell-diagonal states and expressions for more general quantum states are not known. In this paper, we derive explicit expressions for super quantum discord for a larger class of two-qubit states, namely, a 4-parameter family of two-qubit states. We observe that, weak measurements obtain more quantumness of correlations than strong measurements. As an application, the dynamic behavior of the super quantum discord under decoherence channel is investigated. We find that, the super quantum discord decreases monotonically as a function of the measurement strength parameter.
Abstract Using quantum discord (QD) and geometric quantum discord (GQD), quantum correlation dynamics is investigated for two coupled qubits within a multiqubit interacting system in the zero-temperature bosonic reservoir, under both weak and strong qubit-reservoir coupling regimes. The multiqubit system is connected with either a common bosonic reservoir (CBR) or multiple independent bosonic reservoirs (IBRs). In the CBR case, our findings indicate that both QD and GQD can be strengthened by increasing the number of qubits in the multiqubit system. Furthermore, we study the steady state QD and GQD in the strong coupling regime, and find that the stable value in the long-time limit is determined exclusively by the number of qubits. The evolution period of QD and GQD gets longer as the dipole–dipole interaction (DDI) strength increases, which helps prolong the correlation time and thus preserves the quantum correlation under the weak coupling regime. Further analysis reveals notable differences between the CBR and IBRs scenarios. In the IBRs case, the decay of QD and GQD becomes slower compared to the CBR case, with both measures tending to zero at a reduced rate. Moreover, GQD consistently exhibits lower values than QD in both scenarios. These findings provide valuable insights into the selection of appropriate correlation measurement techniques for quantifying quantum correlations.
The aim of this paper is investigation on dynamics of super quantum discord (SQD) and quantum discord (QD) teleportation in the Jaynes–Cummings model. In order to teleport one and two qubit states, a scheme is proposed for quantum channel where is induced from an atom-field interaction. The initial state of the atom is its excited state while the state of field starts in a coherent one. The model reveals that the dynamics of quantum correlations depends crucially on atom-field initial conditions and the field parameters can be utilized as control parameters for optimal teleportation. Interestingly, we find that QD teleportation and SQD teleportation are not always zero when the entanglement falls to zero for a teleported state. This result clearly illustrates that in some cases we can only get a truly quantum teleportation by QD and SQD if we use a suitable field parameters and initial state, which have no entanglement. The results reveal that QD and SQD for teleported states are much robuster than entanglement in the process of communication. According to the results, the proposed scheme can greatly reduce the cost of quantum communication. We also obtain that the behaviour of the QD and SQD teleportation are similar to average fidelity. So, QD and SQD can be used to analyse teleported state as average fidelity.
Abstract Quantum discord (QD), super quantum discord (SQD) and optimal dense coding at entangled states of three types of quantum channels, are investigated. The used models include: two-qubit spin squeezing, the two-qubit Heisenberg XYZ model with decoherency and the Jaynes–Cummings model. In the first two models the quantum correlations and the optimal dense coding capacity are calculated in terms of channel parameters, system initial conditions and decoherency rate. It has been found that valid dense coding can exist, although there is no trace of entanglement in the quantum channel. In contrast, despite the presence of entanglement states in the system, there may be no dense coding capacity. We investigate the effects of cavity Fock states on quantum correlations and optimal dense coding in the Jaynes–Cummings model. Cavity Fock states are found to be effective for quantum correlations and optimal dense coding. The common result of all three models is that the dynamic properties of SQD on our channel enable us to determine when and under what conditions the system is suitable for dense coding capacity.