We investigate the performance of quantum Fisher information (QFI) under the Unruh-Hawking effect, where one of the observers (e.g., Rob) is uniformly accelerated with respect to other partners. In the context of relativistic quantum information theory, we demonstrate that quantum Fisher information, as an important measure of the information content of quantum states, has a rich and subtle physical structure compared with entanglement or Bell nonlocality. In this work, we mainly focus on the parametrized (and arbitrary) pure two-qubit states, where the weight parameter $\ensuremath{\theta}$ and phase parameter $\ensuremath{\phi}$ are naturally introduced. Intriguingly, we prove that QFI with respect to $\ensuremath{\theta}$ (${\mathcal{F}}_{\ensuremath{\theta}}$) remains unchanged for both scalar and Dirac fields. Meanwhile, we observe that QFI with respect to $\ensuremath{\phi}$ (${\mathcal{F}}_{\ensuremath{\phi}}$) decreases with the increase of acceleration $r$ but remains finite in the limit of infinite acceleration. More importantly, our results show that the symmetry of ${\mathcal{F}}_{\ensuremath{\phi}}$ (with respect to $\ensuremath{\theta}=\ensuremath{\pi}/4$) has been broken by the influence of the Unruh effect for both cases.We investigate the performance of quantum Fisher information (QFI) under the Unruh-Hawking effect, where one of the observers (e.g., Rob) is uniformly accelerated with respect to other partners. In the context of relativistic quantum information theory, we demonstrate that quantum Fisher information, as an important measure of the information content of quantum states, has a rich and subtle physical structure compared with entanglement or Bell nonlocality. In this work, we mainly focus on the parametrized (and arbitrary) pure two-qubit states, where the weight parameter $\ensuremath{\theta}$ and phase parameter $\ensuremath{\phi}$ are naturally introduced. Intriguingly, we prove that QFI with respect to $\ensuremath{\theta}$ (${\mathcal{F}}_{\ensuremath{\theta}}$) remains unchanged for both scalar and Dirac fields. Meanwhile, we observe that QFI with respect to $\ensuremath{\phi}$ (${\mathcal{F}}_{\ensuremath{\phi}}$) decreases with the increase of acceleration $r$ but remains finite in the limit of infinite acceleration. More importantly, our results show that the symmetry of ${\mathcal{F}}_{\ensuremath{\phi}}$ (with respect to $\ensuremath{\theta}=\ensuremath{\pi}/4$) has been broken by the influence of the Unruh effect for both cases.

arXiv:1401.0596Physical Review AApr 30, 2014110 citations

Probing multipartite entanglement, coherence and quantum information preservation under classical Ornstein–Uhlenbeck noise

Atta Ur Rahman, Muhammad Javed, Zhaoxu Ji +1 more

Abstract We address entanglement, coherence, and information protection in a system of four non-interacting qubits coupled with different classical environments, namely: common, bipartite, tripartite, and independent environments described by Ornstein–Uhlenbeck (ORU) noise. We show that quantum information preserved by the four qubit state is more dependent on the coherence than the entanglement using time-dependent entanglement witness, purity, and Shannon entropy. We find these two quantum phenomena directly interrelated and highly vulnerable in environments with ORU noise, resulting in the pure exponential decay of a considerable amount. The current Markovian dynamical map, as well as suppression of the fluctuating character of the environments, are observed to be entirely attributable to the Gaussian nature of the noise. The increasing number of environments are witnessed to speed up the amount of decay. Unlike other noises, the current noise parameter’s flexible range is readily exploitable, ensuring long enough preserved memory properties. The four-qubit GHZ state, besides having a large information storage potential, stands partially entangled and coherent in common environments for an indefinite duration. In addition, we derive computational values for each system-environment interaction, which will help quantum practitioners to optimize the related classical environments.Abstract We address entanglement, coherence, and information protection in a system of four non-interacting qubits coupled with different classical environments, namely: common, bipartite, tripartite, and independent environments described by Ornstein–Uhlenbeck (ORU) noise. We show that quantum information preserved by the four qubit state is more dependent on the coherence than the entanglement using time-dependent entanglement witness, purity, and Shannon entropy. We find these two quantum phenomena directly interrelated and highly vulnerable in environments with ORU noise, resulting in the pure exponential decay of a considerable amount. The current Markovian dynamical map, as well as suppression of the fluctuating character of the environments, are observed to be entirely attributable to the Gaussian nature of the noise. The increasing number of environments are witnessed to speed up the amount of decay. Unlike other noises, the current noise parameter’s flexible range is readily exploitable, ensuring long enough preserved memory properties. The four-qubit GHZ state, besides having a large information storage potential, stands partially entangled and coherent in common environments for an indefinite duration. In addition, we derive computational values for each system-environment interaction, which will help quantum practitioners to optimize the related classical environments.

arXiv:2107.11251Journal of Physics A Mathematical and TheoreticalNov 17, 202127 citations

Quantum Fisher information flow and entanglement in pair coherent states

S. Abdel‐Khalek

Optical and Quantum ElectronicsNov 15, 201336 citations

Dynamics of entanglement and quantum Fisher information for N-level atomic system under intrinsic decoherence

Syed Jamal Anwar, Muhammad Asif Ramzan, Majid Khan

Quantum Information ProcessingApr 17, 201727 citations

Non-classical Correlations of Accelerated Observers Interacting with a Classical Stochastic Noise

Mahmoud Youssef Abd‐Rabbou, Mahmood Shamirzaie, Salman Naeem Khan

Abstract The influence of a classical environment on the behaviour of the Wigner function and the concurrence of an accelerated two-qubit system interacting is discussed. The negative values of the Wigner function verify the non-classicality, while the concurrence shows the entanglement degree of the quantum system. We assume one or both observers are accelerated (s) and interact with a common or independent environment. Suppression of the coherence rises due to acceleration effect, noise strength, and noise frequency are pointed. The amount of quantum entanglement is investigated by using the quantum concurrence, where its positive values are consistent with what the negative Wigner function shows. We found that the degradation of coherence of the initial system reduces when observers interact with their environments independently more than when it interacts with a common one. It is also sensitive to the acceleration status of both observers. Additionally, the correlation and entanglement pertinent to the situation with common or independent noise agents behave contrarily for the two regimes of Markovian and non-Markovian noises.Abstract The influence of a classical environment on the behaviour of the Wigner function and the concurrence of an accelerated two-qubit system interacting is discussed. The negative values of the Wigner function verify the non-classicality, while the concurrence shows the entanglement degree of the quantum system. We assume one or both observers are accelerated (s) and interact with a common or independent environment. Suppression of the coherence rises due to acceleration effect, noise strength, and noise frequency are pointed. The amount of quantum entanglement is investigated by using the quantum concurrence, where its positive values are consistent with what the negative Wigner function shows. We found that the degradation of coherence of the initial system reduces when observers interact with their environments independently more than when it interacts with a common one. It is also sensitive to the acceleration status of both observers. Additionally, the correlation and entanglement pertinent to the situation with common or independent noise agents behave contrarily for the two regimes of Markovian and non-Markovian noises.

Jan 17, 20230 citations

r

but remains finite in the limit of infinite acceleration. More importantly, our results show that the symmetry of ${\mathcal{F}}_{\ensuremath{\phi}}$ (with respect to $\ensuremath{\theta}=\ensuremath{\pi}/4$) has been broken by the influence of the Unruh effect for both cases.