180 research outputs found
Entropic uncertainty relations for Markovian and non-Markovian processes under a structured bosonic reservoir
The uncertainty relation is a fundamental limit in quantum mechanics and is
of great importance to quantum information processing as it relates to quantum
precision measurement. Due to interactions with the surrounding environment, a
quantum system will unavoidably suffer from decoherence. Here, we investigate
the dynamic behaviors of the entropic uncertainty relation of an atom-cavity
interacting system under a bosonic reservoir during the crossover between
Markovian and non-Markovian regimes. Specifically, we explore the dynamic
behavior of the entropic uncertainty relation for a pair of incompatible
observables under the reservoir-induced atomic decay effect both with and
without quantum memory. We find that the uncertainty dramatically depends on
both the atom-cavity and the cavity-reservoir interactions, as well as the
correlation time, , of the structured reservoir. Furthermore, we verify
that the uncertainty is anti-correlated with the purity of the state of the
observed qubit-system. We also propose a remarkably simple and efficient way to
reduce the uncertainty by utilizing quantum weak measurement reversal.
Therefore our work offers a new insight into the uncertainty dynamics for
multi-component measurements within an open system, and is thus important for
quantum precision measurements.Comment: 17 pages, 9 figures, to appear in Scientific Report
Controlling entropic uncertainty bound through memory effects
One of the defining traits of quantum mechanics is the uncertainty principle
which was originally expressed in terms of the standard deviation of two
observables. Alternatively, it can be formulated using entropic measures, and
can also be generalized by including a memory particle that is entangled with
the particle to be measured. Here we consider a realistic scenario where the
memory particle is an open system interacting with an external environment.
Through the relation of conditional entropy to mutual information, we provide a
link between memory effects and the rate of change of conditional entropy
controlling the lower bound of the entropic uncertainty relation. Our treatment
reveals that the memory effects stemming from the non-Markovian nature of
quantum dynamical maps directly control the lower bound of the entropic
uncertainty relation in a general way, independently of the specific type of
interaction between the memory particle and its environment.Comment: 5 pages, 3 figure
Quantum memory assisted entropic uncertainty and entanglement dynamics: Two qubits coupled with local fields and Ornstein Uhlenbeck noise
Entropic uncertainty and entanglement are two distinct aspects of quantum
mechanical procedures. To estimate entropic uncertainty relations, entropies
are used: the greater the entropy bound, the less effective the quantum
operations and entanglement are. In this regard, we analyze the entropic
uncertainty, entropic uncertainty lower bound, and concurrence dynamics in two
non-interacting qubits. The exposure of two qubits is studied in two different
qubit-noise configurations, namely, common qubit-noise and independent
qubit-noise interactions. To include the noisy effects of the local external
fields, a Gaussian Ornstein Uhlenbeck process is considered. We show that the
rise in entropic uncertainty gives rise to the disentanglement in the two-qubit
Werner type state and both are directly proportional. Depending on the
parameters adjustment and the number of environments coupled, different
classical environments have varying capacities to induce entropic uncertainty
and disentanglement in quantum systems. The entanglement is shown to be
vulnerable to current external fields; however, by employing the ideal
parameter ranges we provided, prolonged entanglement retention while preventing
entropic uncertainty growth can be achieved. Besides, we have also analyzed the
intrinsic behavior of the classical fields towards two-qubit entanglement
without any imperfection with respect to different parameter
Quantum-memory-assisted entropic uncertainty relations
Uncertainty relations take a crucial and fundamental part in the frame of
quantum theory, and are bringing on many marvelous applications in the emerging
field of quantum information sciences. Especially, as entropy is imposed into
the uncertainty principle, entropy-based uncertainty relations lead to a number
of applications including quantum key distribution, entanglement witness,
quantum steering, quantum metrology, and quantum teleportation. Herein, the
history of the development of the uncertainty relations is discussed,
especially focusing on the recent progress with regard to
quantum-memory-assisted entropic uncertainty relations and dynamical
characteristics of the measured uncertainty in some explicit physical systems.
The aims are to help deepen the understanding of entropic uncertainty relations
and prompt further explorations for versatile applications of the relations on
achieving practical quantum tasks.Comment: Review, 20 pages, published in Ann. Phys. (Berlin
Trade-off relations of quantum resource theory in Heisenberg models
Studying the relations between entanglement and coherence is essential in
many quantum information applications. For this, we consider the concurrence,
intrinsic concurrence and first-order coherence, and evaluate the proposed
trade-off relations between them. In particular, we study the temporal
evolution of a general two-qubit XYZ Heisenberg model with asymmetric
spin-orbit interaction under decoherence and analyze the trade-off relations of
quantum resource theory. For XYZ Heisenberg model, we confirm that the
trade-off relation between intrinsic concurrence and first-order coherence
holds. Furthermore, we show that the lower bound of intrinsic concurrence is
universally valid, but the upper bound is generally not. These relations in
Heisenberg models can provide a way to explore how quantum resources are
distributed in spins, which may inspire future applications in quantum
information processing.Comment: 8 pages, 3 figures. All comments are welcom
- …