Experimental quantification of the entanglement of noisy twin beams

Continuous variable quantum teleportation with sculptured and noisy non-Gaussian resources

We investigate continuous variable (CV) quantum teleportation using relevant classes of non-Gaussian states of the radiation field as entangled resources. First, we introduce the class two-mode squeezed symmetric superposition of Fock states, including finite truncations of twin-beam Gaussian states as special realizations. These states depend on a set of free independent parameters that can be adjusted for the optimization of teleportation protocols, with an enhancement of the success probability of teleportation both for coherent and Fock input states. We show that the optimization procedure…

Quantification of Quantum Correlations in Two-Beam Gaussian States Using Photon-Number Measurements

Identification, and subsequent quantification of quantum correlations, is critical for understanding, controlling, and engineering quantum devices and processes. We derive and implement a general method to quantify various forms of quantum correlations using solely the experimental intensity moments up to the fourth order. This is possible as these moments allow for an exact determination of the global and marginal impurities of two-beam Gaussian fields. This leads to the determination of steering, tight lower and upper bounds for the negativity, and the Kullback-Leibler divergence used as a q…

统一不确定性量化框架：跨越变分量子算法和量子信号处理中的噪声量子后端

Unified Uncertainty Quantification Framework Bridging Noisy Quantum Backends Across Variational Quantum Algorithms and Quantum Signal Processing

该研究提出统一不确定性量化框架，在同一统计管道下比较NISQ变分量子算法和基于QSVT的格林函数重建两类工作负载，结合多种分析方法，能识别相关特性，为不同工作负载提供通用基准来衡量后端可靠性。

Binary optical communication in single-mode and entangled quantum noisy channels

We address binary optical communication in single-mode and entangled quantum noisy channels. For single-mode we present a systematic comparison between direct photodetection and homodyne detection in realistic conditions, i.e. taking into account the noise that occurs both during the propagation and the detection of the signals. We then consider entangled channels based on twin-beam state of radiation, and show that with realistic heterodyne detection the error probability at fixed channel energy is reduced in comparison to the single-mode cases for a large range of values of quantum efficienc…

Interplay of nonclassicality and entanglement of two-mode Gaussian fields generated in optical parametric processes

The behavior of general nonclassical two-mode Gaussian states at a beam splitter is investigated. Single-mode nonclassicality as well as two-mode entanglement of both input and output states are analyzed suggesting their suitable quantifiers. These quantifiers are derived from local and global invariants of linear unitary two-mode transformations such that the sum of input (or output) local nonclassicality measures and entanglement measure gives a global invariant. This invariant quantifies the global nonclassicality resource. Mutual transformations of local nonclassicalities and entanglement …

Experimentally friendly bounds on non-Gaussian entanglement from second moments

We demonstrate that the entanglement in a class of two-mode non-Gaussian states obtained by subtracting photons from Gaussian twin beams can be bounded from above and from below by functionals of the second moments only. Knowledge of the covariance matrix thus suffices for an entanglement quantification with appreciable precision. The absolute error in the entanglement estimation scales with the non-Gaussianity of the considered states.

Degradation of continuous variable entanglement in a phase-sensitive environment

We address the propagation of twin-beam of radiation through Gaussian phase-sensitive channels, i.e. noisy channels with squeezed fluctuations. We find that squeezing the environment always reduces the survival time of entanglement in comparison to the case of simple dissipation and thermal noise. We also show that the survival time is further reduced if the squeezing phase of the fluctuations is different from the twin-beam phase.

Nonclassicality and entanglement criteria for bipartite optical fields characterized by quadratic detectors

Numerous inequalities involving moments of integrated intensities and revealing nonclassicality and entanglement in bipartite optical fields are derived using the majorization theory, non-negative polynomials, the matrix approach, as well as the Cauchy-Schwarz inequality. Different approaches for deriving these inequalities are compared. Using the experimental photocount histogram generated by a weak noisy twin beam monitored by a photon-number-resolving iCCD camera the performance of the derived inequalities is compared. A basic set of ten inequalities suitable for monitoring the entanglement…

带噪声探针的量子照明：非高斯性的条件优势

Quantum illumination with noisy probes: Conditional advantages of non-Gaussianity

本文研究在热噪声和局部高斯噪声影响下，光子增加/减去非高斯态作为量子照明探针的性能层级，发现其优势依赖于Chernoff界比较条件，且高斯态整体性能最优。

量子开关的涌现非马尔可夫性与动力学量化

Emergent non-Markovianity and dynamical quantification of the quantum switch

该研究探究量子开关的动力学特性，发现其会诱导特殊量子记忆，推导信息损失与该记忆的不确定关系，证实开关诱导记忆会涌现非马尔可夫性，为将量子开关理解为涌现非马尔可夫量子记忆奠定基础。