The quantum-memory-assisted entropic uncertainty relation (QMA-EUR) plays an important role in quantum information theory, as it provides insights into the fundamental limits of measurement accuracy in entangled quantum systems. This paper investigates the QMA-EUR, which is activated by the entanglement between two quantum dots (QDs) confined in semiconductor microcavities that are coupled by an optical fiber. The investigation focuses on the dynamic characteristics of the QMA-EUR under the effects of dissipation. Moreover, two distinct initial states of the two QDs are examined: correlated and uncorrelated. In the initial uncorrelated state, the evolution of the QMA-EUR and entanglement is influenced by the coupling strengths between the QDs and cavities, as well as between the fiber and cavities, and by the detuning. In contrast, if the two QDs are initially in a maximally correlated state, these couplings and the detuning considerably increase the stability of both the entanglement and the QMA-EUR. They also extend the time intervals during which Alice can precisely predict the measurement results. Notably, strong couplings, in conjunction with an initially maximally entangled state, increase the robustness of the quantum memory mechanism.
The quantum-memory-assisted entropic uncertainty relation (QMA-EUR) plays an important role in quantum information theory, as it provides insights into the fundamental limits of measurement accuracy in entangled quantum systems. This paper investigates the QMA-EUR, which is activated by the entanglement between two quantum dots (QDs) confined in semiconductor microcavities that are coupled by an optical fiber. The investigation focuses on the dynamic characteristics of the QMA-EUR under the effects of dissipation. Moreover, two distinct initial states of the two QDs are examined: correlated and uncorrelated. In the initial uncorrelated state, the evolution of the QMA-EUR and entanglement is influenced by the coupling strengths between the QDs and cavities, as well as between the fiber and cavities, and by the detuning. In contrast, if the two QDs are initially in a maximally correlated state, these couplings and the detuning considerably increase the stability of both the entanglement and the QMA-EUR. They also extend the time intervals during which Alice can precisely predict the measurement results. Notably, strong couplings, in conjunction with an initially maximally entangled state, increase the robustness of the quantum memory mechanism.
Abstract This study investigates the dynamics of two‐qubit quantum‐memory‐assisted (QMA) entropic uncertainty relation and entanglement in a system comprising two strongly coupled semiconductor pair quantum dots (SPQD). The influences of detuning, tunnel coupling, dipole‐dipole interaction, and intrinsic decoherence on the system's behavior are explored. Without decoherence, periodic fluctuations in entropic uncertainty driven by the inter‐dot coupling parameter , are observed, while entanglement remains negligible, reflecting the separable nature of the initial two‐qubit states. Introducing decoherence significantly alters these dynamics, with even low decoherence rates, an increased uncertainty and accelerated loss of coherence are observed when coupled with strong dipole interactions. The findings elucidate the complex interplay between entropic uncertainty and entanglement under intrinsic decoherence, highlighting challenges in maintaining quantum coherence. This work enhances the understanding of quantum dynamics in strongly coupled qubit systems and opens the doors for research to mitigate decoherence effects and improve quantum information processing.
Abstract Based on a simple cavity‐engineered architecture, the dynamics of quantum memory–assisted entropic uncertainty relation (QMA‐EUR) for two qubits initially prepared in a generic Werner state is investigated. The effects of cavity decay rate, qubit–cavity couplings, and cavity–cavity couplings on the uncertainty are explored. It is found that the damped oscillation of uncertainty can be induced by the increase of two types of coupling strengths mentioned above. It is demonstrated that the maximum value of uncertainty is closely related to the purity of the initial state. The uncertainty can be either increased or decreased, depending on the threshold value of coupling strength between the two cavities. Finally, in agreement with a recent observation, an asynchronous relation between uncertainty and mixedness is found during the initial time evolution.
In a system of two charge-qubits that are initially prepared in a maximally entangled Bell's state, the dynamics of quantum memory-assisted entropic uncertainty, purity, and negative entanglement are investigated. Isolated external cavity fields are considered in two different configurations: coherent-even coherent and even coherent cavity fields. For different initial cavity configurations, the temporal evolution of the final state of qubits and cavities is solved analytically. The effects of intrinsic decoherence and detuning strength on the dynamics of bipartite entropic uncertainty, purity and entanglement are explored. Depending on the field parameters, nonclassical correlations can be preserved. Nonclassical correlations and revival aspects appear to be significantly inhibited when intrinsic decoherence increases. Nonclassical correlations stay longer and have greater revivals due to the high detuning of the two qubits and the coherence strength of the initial cavity fields. Quantum memory-assisted entropic uncertainty and entropy have similar dynamics while the negativity presents fewer revivals in contrast.
Abstract We analyze the quantum correlations, the quantum-memory-assisted entropic uncertainty (QMA-EUR), and its lower bound in a quadruple quantum dot device for two charge qubits. Herein, we select incompatible Pauli operators σ ^ x and σ ^ z as a pair of observables of interest for the measurement of particle A, and the uncertainty can be predicted from the entanglement of particle A with quantum memory B . We explore the dynamics of quantum discord and QMA-EUR, taking into account the effects of electron temperature, energy offsets, tunneling coupling, and the strength of coupling (i.e., the Coulomb interaction between electrons). Interestingly, our results indicate that there are certain adjustable parameters that can be tuned to suppress the entropy uncertainty bound and enhance quantum correlations.
This paper investigates the intrinsic decoherence effect on quantum memory and coherence dynamics of two dipole-coupled qubits in a non-degenerate bimodel cavity. Entropic uncertainty, entropy, and concurrence are utilized to examine the dynamics of quantum-memory-assisted entropic uncertainty relations, mixedness, and entanglement. The results indicate that the nonlinear interactions between the two qubits and the cavity generate quantum-memory-assisted entropic uncertainty, mixedness, and entanglement, which are reliant not only on the qubit–qubit interaction but also on the intrinsic decoherence and coherence intensity of the initial two-mode cavity states. For specific values of the dipole–dipole interaction, non-classical correlations can be enhanced By reducing the initial intensity coherence, the stability of the quantum memory-assisted entropic uncertainty relations, as well as the two-qubit mixedness of the intrinsic decoherence, are accelerated.
Abstract The uncertainty principle offers a bound to show accuracy of the simultaneous measurement outcome for two incompatible observables. In this letter, we investigate quantum-memory-assisted entropic uncertainty relation (QMA–EUR) when the particle to be measured stays at an open system, and another particle is treated as quantum memory under a noninertial frame. In such a scenario, the collective influence of the unital and nonunital noise environment, and of the relativistic motion of the system, on the QMA–EUR is examined. By numerical analysis, we conclude that, firstly, the noises and the Unruh effect can both increase the uncertainty, due to the decoherence of the bipartite system induced by the noise or Unruh effect; secondly, the uncertainty is more affected by the noises than by the Unruh effect from the acceleration; thirdly, unital noises can reduce the uncertainty in long-time regime. We give a possible physical interpretation for those results: that the information of interest is redistributed among the bipartite, the noisy environment and the physically inaccessible region in the noninertial frame. Therefore, we claim that our observations provide an insight into dynamics of the entropic uncertainty in a noninertial frame, and might be important to quantum precision measurement under relativistic motion.