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

Laser Physics

A quantum beat of quantum discord induced by the number of qubits in non-Markovian environments

Qi-Wen He, Zhi He, Yu Chen

Published Dec 14, 2020• 4 citations
Publisher

Abstract

Abstract We investigate the protection of the quantum discord of two qubits, individually originated by two generalized amplitude-damping models. Here, each generalized amplitude-damping model consists of N non-interacting qubits interacting with a common zero-temperature reservoir. First, for initial states with extended Werner-like states, we find that the robust quantum discord of two qubits against decoherence can be obtained by controlling the number of qubits in the reservoir. More interestingly, we find that a quantum beat for quantum discord can occur when both the number of qubits in each reservoir is large and when the number of qubits have a tiny difference, even in the resonant case. Our results shed new light on the protection of quantum discord by means of a quantum-reservoir engineering approach in quantum-information processing.

DOI
10.1088/1555-6611/abca34

Related papers

Non-Markovian effect on the quantum discord

Bo Wang, Zhenyu Xu, Zeqian Chen +1 more

We study the non-Markovian effect on the dynamics of the quantum discord by exactly solving a model consisting of two independent qubits subject to two zero-temperature non-Markovian reservoirs, respectively. Considering the two qubits initially prepared in Bell-like or extended Werner-like states, we show that there is no occurrence of the sudden death, but only instantaneous disappearance of the quantum discord at some time points, in comparison to the entanglement sudden death in the same range of the parameters of interest. This implies that the quantum discord is more useful than the entanglement to describe the quantum correlation involved in quantum systems.

arXiv:0911.1845•Physical Review A•Jan 8, 2010•290 citations

Amplification of quantum discord between two uncoupled qubits in a common environment by phase decoherence

Ji-Bing Yuan, Le‐Man Kuang, Jie‐Qiao Liao

We study analytically the dynamic behaviours of quantum correlation measured by a quantum discord between two uncoupled qubits, which are immersed in a common Ohmic environment. We show that the quantum discord of the two non-interacting qubits can be greatly amplified or protected for certain initially prepared X -type states in the time evolution. In particular, it is found that stable amplification of the quantum discord exists for the case of two identical qubits, and the quantum discord can be protected for the case of two different qubits with a large detuning. It is also indicated that in general a sudden change of the quantum discord occurs in the time evolution at a critical time point t c , and the discord amplification and protection may occur only in the time interval for certain X -type states. This sheds new light on the creation and protection of quantum correlation.

arXiv:1005.4204•Journal of Physics B Atomic Molecular and Optical Physics•Aug 4, 2010•55 citations

Robustness of quantum discord to sudden death

T. Werlang, S. Souza, F. F. Fanchini +1 more

We calculate the dissipative dynamics of two-qubit quantum discord under Markovian environments. We analyze various dissipative channels such as dephasing, depolarizing, and generalized amplitude damping, assuming independent perturbation, in which each qubit is coupled to its own channel. Choosing initial conditions that manifest the so-called sudden death of entanglement, we compare the dynamics of entanglement with that of quantum discord. We show that in all cases where entanglement suddenly disappears, quantum discord vanishes only in the asymptotic limit, behaving similarly to individual decoherence of the qubits, even at finite temperatures. Hence, quantum discord is more robust than the entanglement against decoherence so that quantum algorithms based only on quantum discord correlations may be more robust than those based on entanglement.

arXiv:0905.3376•Physical Review A•Aug 31, 2009•543 citations

Quantum Discord Persistence under dissipative processes

T. Werlang, Simone R. S. Souza, F. F. Fanchini +1 more

We calculate the dissipative dynamics of two-qubit quantum discord under Markovian environments. We analyze various dissipative channels such as dephasing, depolarizing, and generalized amplitude damping, assuming independent perturbation, in which each qubit is coupled to its own channel. Choosing initial conditions that manifest the so-called sudden death of entanglement, we compare the dynamics of entanglement with that of quantum discord. We show that in all cases where entanglement suddenly disappears, quantum discord vanishes only in the asymptotic limit, behaving similarly to individual decoherence of the qubits, even at finite temperatures. Hence, quantum discord is more robust than the entanglement against to decoherence so that quantum algorithms based only on quantum discord correlations may be more robust than those based on entanglement.

•May 20, 2009•0 citations

Quantum Discord Dynamics of Three Qubits in Non-Markovian Environments

Yan Zhang, Jin‐Ming Liu, Yan-Jie Li

We investigate the dynamics of pairwise quantum discord (QD) for a mixed three-qubit W-type state in three independent non-Markovian reservoirs at zero temperature, each of which is modeled by a leaky cavity with Lorentzian spectral density. The influence of the environment's amount of non-Markovianity, the detuning between the qubit frequency and the cavity centre frequency, and the purity of the initial state on the QD dynamics are analyzed in detail. It is found that in the non-Markovian regime the system-reservoir interactions induce QD revivals and oscillations no matter whether the detuning is zero or not. Moreover, QD can be preserved for a long time if the non-Markovian condition and the detuning condition are satisfied simultaneously.

Communications in Theoretical Physics•Jun 1, 2014•8 citations

Protecting quantum correlations of two qubits in independent non-Markovian environments by bang-bang pulses

Hang-Shi Xu, Jing‐Bo Xu

We investigate how to protect quantum correlations for two qubits each locally interacting with its own non-Markovian environment by making use of bang-bang pulses. It is shown that the quantum discord dynamics presents the phenomenon of sudden change for some certain initial states. We also find that the amount of quantum correlation between two qubits can be improved by applying a train of pulses and protected more effectively with shorter interval pulses or longer reservoir correlation time.

arXiv:1208.5387•Journal of the Optical Society of America B•Jul 20, 2012•11 citations
Abstract We investigate the protection of the quantum discord of two qubits, individually originated by two generalized amplitude-damping models. Here, each generalized amplitude-damping model consists of N non-interacting qubits interacting with a common zero-temperature reservoir. First, for initial states with extended Werner-like states, we find that the robust quantum discord of two qubits against decoherence can be obtained by controlling the number of qubits in the reservoir. More interestingly, we find that a quantum beat for quantum discord can occur when both the number of qubits in each reservoir is large and when the number of qubits have a tiny difference, even in the resonant case. Our results shed new light on the protection of quantum discord by means of a quantum-reservoir engineering approach in quantum-information processing.
We study the non-Markovian effect on the dynamics of the quantum discord by exactly solving a model consisting of two independent qubits subject to two zero-temperature non-Markovian reservoirs, respectively. Considering the two qubits initially prepared in Bell-like or extended Werner-like states, we show that there is no occurrence of the sudden death, but only instantaneous disappearance of the quantum discord at some time points, in comparison to the entanglement sudden death in the same range of the parameters of interest. This implies that the quantum discord is more useful than the entanglement to describe the quantum correlation involved in quantum systems.
We study analytically the dynamic behaviours of quantum correlation measured by a quantum discord between two uncoupled qubits, which are immersed in a common Ohmic environment. We show that the quantum discord of the two non-interacting qubits can be greatly amplified or protected for certain initially prepared X -type states in the time evolution. In particular, it is found that stable amplification of the quantum discord exists for the case of two identical qubits, and the quantum discord can be protected for the case of two different qubits with a large detuning. It is also indicated that in general a sudden change of the quantum discord occurs in the time evolution at a critical time point t c , and the discord amplification and protection may occur only in the time interval for certain X -type states. This sheds new light on the creation and protection of quantum correlation.
We calculate the dissipative dynamics of two-qubit quantum discord under Markovian environments. We analyze various dissipative channels such as dephasing, depolarizing, and generalized amplitude damping, assuming independent perturbation, in which each qubit is coupled to its own channel. Choosing initial conditions that manifest the so-called sudden death of entanglement, we compare the dynamics of entanglement with that of quantum discord. We show that in all cases where entanglement suddenly disappears, quantum discord vanishes only in the asymptotic limit, behaving similarly to individual decoherence of the qubits, even at finite temperatures. Hence, quantum discord is more robust than the entanglement against decoherence so that quantum algorithms based only on quantum discord correlations may be more robust than those based on entanglement.
We calculate the dissipative dynamics of two-qubit quantum discord under Markovian environments. We analyze various dissipative channels such as dephasing, depolarizing, and generalized amplitude damping, assuming independent perturbation, in which each qubit is coupled to its own channel. Choosing initial conditions that manifest the so-called sudden death of entanglement, we compare the dynamics of entanglement with that of quantum discord. We show that in all cases where entanglement suddenly disappears, quantum discord vanishes only in the asymptotic limit, behaving similarly to individual decoherence of the qubits, even at finite temperatures. Hence, quantum discord is more robust than the entanglement against to decoherence so that quantum algorithms based only on quantum discord correlations may be more robust than those based on entanglement.
We investigate the dynamics of pairwise quantum discord (QD) for a mixed three-qubit W-type state in three independent non-Markovian reservoirs at zero temperature, each of which is modeled by a leaky cavity with Lorentzian spectral density. The influence of the environment's amount of non-Markovianity, the detuning between the qubit frequency and the cavity centre frequency, and the purity of the initial state on the QD dynamics are analyzed in detail. It is found that in the non-Markovian regime the system-reservoir interactions induce QD revivals and oscillations no matter whether the detuning is zero or not. Moreover, QD can be preserved for a long time if the non-Markovian condition and the detuning condition are satisfied simultaneously.