6,491 research outputs found
Prediction-error of Prediction Error (PPE)-based Reversible Data Hiding
This paper presents a novel reversible data hiding (RDH) algorithm for
gray-scaled images, in which the prediction-error of prediction error (PPE) of
a pixel is used to carry the secret data. In the proposed method, the pixels to
be embedded are firstly predicted with their neighboring pixels to obtain the
corresponding prediction errors (PEs). Then, by exploiting the PEs of the
neighboring pixels, the prediction of the PEs of the pixels can be determined.
And, a sorting technique based on the local complexity of a pixel is used to
collect the PPEs to generate an ordered PPE sequence so that, smaller PPEs will
be processed first for data embedding. By reversibly shifting the PPE histogram
(PPEH) with optimized parameters, the pixels corresponding to the altered PPEH
bins can be finally modified to carry the secret data. Experimental results
have implied that the proposed method can benefit from the prediction procedure
of the PEs, sorting technique as well as parameters selection, and therefore
outperform some state-of-the-art works in terms of payload-distortion
performance when applied to different images.Comment: There has no technical difference to previous versions, but rather
some minor word corrections. A 2-page summary of this paper was accepted by
ACM IH&MMSec'16 "Ongoing work session". My homepage: hzwu.github.i
Cavity-based architecture to preserve quantum coherence and entanglement
Quantum technology relies on the utilization of resources, like quantum
coherence and entanglement, which allow quantum information and computation
processing. This achievement is however jeopardized by the detrimental effects
of the environment surrounding any quantum system, so that finding strategies
to protect quantum resources is essential. Non-Markovian and structured
environments are useful tools to this aim. Here we show how a simple
environmental architecture made of two coupled lossy cavities enables a switch
between Markovian and non-Markovian regimes for the dynamics of a qubit
embedded in one of the cavity. Furthermore, qubit coherence can be indefinitely
preserved if the cavity without qubit is perfect. We then focus on entanglement
control of two independent qubits locally subject to such an engineered
environment and discuss its feasibility in the framework of circuit quantum
electrodynamics. With up-to-date experimental parameters, we show that our
architecture allows entanglement lifetimes orders of magnitude longer than the
spontaneous lifetime without local cavity couplings. This cavity-based
architecture is straightforwardly extendable to many qubits for scalability.Comment: 12 pages, 9 figures, 1 table. To appear on Nature Scientific Report
Harnessing non-Markovian quantum memory by environmental coupling
Controlling the non-Markovian dynamics of open quantum systems is essential
in quantum information technology since it plays a crucial role in preserving
quantum memory. Albeit in many realistic scenarios the quantum system can
simultaneously interact with composite environments, this condition remains
little understood, particularly regarding the effect of the coupling between
environmental parts. We analyze the non-Markovian behavior of a qubit
interacting at the same time with two coupled single-mode cavities which in
turn dissipate into memoryless or memory-keeping reservoirs. We show that
increasing the control parameter, that is the two-mode coupling, allows for
triggering and enhancing a non-Markovian dynamics for the qubit starting from a
Markovian one in absence of coupling. Surprisingly, if the qubit dynamics is
non-Markovian for zero control parameter, increasing the latter enables
multiple transitions from non-Markovian to Markovian regimes. These results
hold independently on the nature of the reservoirs. This work highlights that
suitably engineering the coupling between parts of a compound environment can
efficiently harness the quantum memory, stored in a qubit, based on
non-Markovianity.Comment: 8 pages, 5 figures. To appear in Phys. Rev.
A probabilistic data association based MIMO detector using joint detection of consecutive symbol vectors
A new probabilistic data association (PDA) approach is proposed for symbol detection in spatial multiplexing multiple-input multiple-output (MIMO) systems. By designing a joint detection (JD) structure for consecutive symbol vectors in the same transmit burst, more a priori information is exploited when updating the estimated posterior marginal probabilities for each symbol per iteration. Therefore the proposed PDA detector (denoted as PDA-JD detector) outperforms the conventional PDA detectors in the context of correlated input bit streams. Moreover, the conventional PDA detectors are shown to be a special case of the PDA-JD detector. Simulations and analyses are given to demonstrate the effectiveness of the new method
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