In this paper, our focus is to explore the generation of a two-mode “squeezed cross-Kerr state (SCKS)” and its non-classical properties. We have thoroughly studied SCKS’s many non-classical characteristics, which have revealed its unique non-classical characteristics, throughout our investigation. One of the primary properties that we examined is higher-order squeezing, which reveals the degree to which the SCKS surpasses the limits of classical states in terms of the squeezing phenomenon. This higher-order squeezing signifies the presence of non-classical behavior in the state, offering valuable insights into its quantum nature. In addition to this, we looked at the Pearson correlation coefficient, which can be used as a measure of the state’s non-classical correlations. It enables us to have a better understanding of the non-classical entanglement present in the two-mode SCKS and how it differs from classical correlations. Furthermore, we explored the phenomenon of anti-bunching, a remarkable feature of non-classical light where photons tend to avoid arriving at the same point in time. Our investigation allowed us to assess the degree of photon antibunching in the SCKS, providing essential information about the state’s departure from classical behavior. Furthermore, we have calculated cumulants, which are statistical measures used to quantify the non-classical nature of the state. We obtained useful insights into the higher-order statistical correlations of the two-mode SCKS by analyzing cumulants, allowing us to distinguish them from classical statistical distributions.
In this paper, our focus is to explore the generation of a two-mode “squeezed cross-Kerr state (SCKS)” and its non-classical properties. We have thoroughly studied SCKS’s many non-classical characteristics, which have revealed its unique non-classical characteristics, throughout our investigation. One of the primary properties that we examined is higher-order squeezing, which reveals the degree to which the SCKS surpasses the limits of classical states in terms of the squeezing phenomenon. This higher-order squeezing signifies the presence of non-classical behavior in the state, offering valuable insights into its quantum nature. In addition to this, we looked at the Pearson correlation coefficient, which can be used as a measure of the state’s non-classical correlations. It enables us to have a better understanding of the non-classical entanglement present in the two-mode SCKS and how it differs from classical correlations. Furthermore, we explored the phenomenon of anti-bunching, a remarkable feature of non-classical light where photons tend to avoid arriving at the same point in time. Our investigation allowed us to assess the degree of photon antibunching in the SCKS, providing essential information about the state’s departure from classical behavior. Furthermore, we have calculated cumulants, which are statistical measures used to quantify the non-classical nature of the state. We obtained useful insights into the higher-order statistical correlations of the two-mode SCKS by analyzing cumulants, allowing us to distinguish them from classical statistical distributions.
Nonclassicality of optical fields are the key resources in quantum information processing.Recently, Agarwal [New J. Phys., 13, 073008(2011)] proposed a method for engineering of a two-mode vortex state, a non-Gaussian state, by subtracting a photon from a two-mode squeezed state produced by down-converter from idler mode via a beam splitter with low reflectivity and detection of one photon by the avalanche photo diode (APD), or even better by a single-photon detector.We study the nonclassicalities of this state in terms of squeezing, antibunching, photon number correlation and distribution of photon number.In addition, we study higher-order nonclassical properties, viz., sum squeezing.We find that the non-Gaussian state shows strong nonclassical effects.
A new class of non-classical state of the radiation field,called as two-mode squeezed superposed coherent state,is described in this paper.It is defined as ｜φ〉=CS(ξ)(｜α_1,α_2〉+e~(iφ)｜α~*_1,α~*_2〉).Calculating its normalized constant,its non-classical nature is discussed,including squeezed effect,sub-Poissonian distributing,anti-bunching effect,and the second-order cross correlation function between the two-mode.Numerical results demonstrate that the two-mode squeezed superposed coherent state possesses more obvious non-classical properties.Selecting suitable parameters α_1,α_2,φ,θandξ,the two-mode squeezed superposed coherent state can be reduced to the two-mode squeezed superposed vacuum state and the two-mode superposed coherent state.Therefore it is a kind of more generalized non-classical quantum state.
Abstract Two-mode nonlinear semi-coherent states and their even and odd superpositions are defined. Their non-classical properties, including photon statistics and squeezing, are then evaluated. We use the Mandel parameter and the second-order coherence function to study sub-Poissonian photon statistics and the photon antibunching effect. By calculating the variance of two-mode quadrature operators, we evaluate the squeezing effect for the introduced states. Next, we examine entanglement using concurrence. We have found that all states display non-classical properties within certain ranges of the parameters involved. The calculation of concurrence demonstrates that all states are entangled within specific ranges of parameters.
Non-Gaussian quantum states of light are essential resources for quantum information processing and precision metrology. Among them, generalized coherent states (GCS), which naturally arise from the evolution of a coherent state with a nonlinear medium, exhibit useful quantum features such as Wigner negativity and metrological advantages [Phys. Rev. Res. 5, 013165 (2023)]. Because these states remain coherent to all orders, their nonclassical character cannot be revealed through standard intensity-intensity correlation measurements. Here, we demonstrate that the intensity-field correlation function alone provides a simple and experimentally accessible witness of nonclassicality. For GCSs, any deviation of this normalized correlation from unity signals nonclassical behavior. We derive analytical results for Kerr-generated states and extend the analysis to statistical mixtures of GCSs. The proposed approach enables real-time, low-complexity detection of quantum signatures in non-Gaussian states, offering a practical tool for experiments across a broad range of nonlinear regimes.
Abstract Recently, experimental demonstrations of the pair coherent state of microwave photons in superconducting cavities (PRX QUANTUM 4, 020319, 2023) and experimental results of photon addition and subtraction in multimode entangled optical fields (Physical Review Research 6, 013065, 2024) were reported. Motivated by these results, we study the nonclassical properties of non-Gaussian photon-added and subtracted pair coherent states. More specifically, we explore quantum polarization, quadrature squeezing, sum and difference squeezing, Shchukin-Vogel Entanglement, EPR entanglement correlation, two-mode higher-order antibunching, and quasiprobability distribution function (Q function). The effect of photon addition and subtraction is visible in this study with different parameters, as we compared our results with the original pair coherent state (PCS). This study provides a deeper understanding of the quantum behavior of modified pair coherent states, with potential implications for advancements in quantum optics and information processing.
Entanglement is central to quantum physics, yet detecting and exploiting it in non-Gaussian systems remains a major challenge. In continuous variable platforms, standard inseparability criteria based on Gaussian statistics-such as the Duan-Simon criterion-fail when quantum correlations are encoded in higher moments of the field quadratures. Here we introduce a framework for detecting non-Gaussian entanglement using higher-order quadrature cumulants. In the Gaussian limit, the lowest order condition reduces to the Duan criterion, while higher-order violations reveal entanglement inaccessible to second-order methods. We experimentally demonstrate a tomography-free certification of inseparability in photon-subtracted squeezed states of light, where Gaussian witnesses fail despite the presence of entanglement. We further show that such higher-order inseparability enables enhanced quantum teleportation of Wigner negativity as compared to Gaussian protocols. These results identify higher-order cumulants as natural observables for non-Gaussian entanglement and open new routes to harnessing non-Gaussian resources in continuous variable quantum technologies.