This study investigates the nonclassical and non-gaussian features of twomode squeezed vacuum state and photon-subtracted squeezed vacuum state generated with a partially temporally coherent pump which could be useful for long-distance quantum communication.
Recent studies show that quantum non-Gaussian states or using non-Gaussian operations can improve entanglement distillation, quantum swapping, teleportation, and cloning. In this work, employing a strategy of non-Gaussian operations (namely subtracting and adding a single photon), we propose a scheme to generate non-Gaussian quantum states named single-photon-added and -subtracted coherent (SPASC) superposition states by implementing Bell measurements, and then investigate the corresponding nonclassical features. By squeezed the input field, we demonstrate that robustness of non-Gaussianity can be improved. Controllable phase space distribution offers the possibility to approximately generate a displaced coherent superposition states (DCSS). The fidelity can reach up to F ≥ 0.98 and F ≥ 0.90 for size of amplitude z = 1.53 and 2.36, respectively.
Abstract In this paper, we aim to introduce a new state called photon-subtracted-then-added squeezing-enhanced coherent state (PSASECS) by multiple photon subtraction and then addition to a squeezing-enhanced coherent state. We investigate the non-Gaussianity and nonclassicality of this new state in detail, including its Wigner function, sub-Poissonian statistics, Q -function, squeezing, and antibunching properties. The obtained results indicate that these non-Gaussian and nonclassical characteristics have been enhanced by appropriately changing between photon subtraction l and photon addition k . Additionally, the non-Gaussianity and nonclassicality of PSASECS are enhanced compared to cases involving only the addition or subtraction of photons. This demonstrates the importance of subtracting and then adding photons to the squeezing-enhanced coherent state, and introducing a significant state for application in quantum optics, particularly in mitigating phase noise fluctuations in quantum devices.
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.