We theoretically study the statistical properties of non-Gaussian states generated by inputting coherent state, single-mode squeezed vacuum state and thermal state to the displacement-based single-side quantum scissor. Compared to the case without the displacement, it is shown that the displacement-based single-side quantum scissor with large coherent amplitudes can not only effectively enhance the success probability of quantum state preparation in the high-transmittance range, but also improve the statistical properties of the generated states involving the average photon number, the signal to noise ratio and the nonclassicality. These results indicate that the usage of the displacement-based single-side quantum scissor may have potential applications for the optical interferometry.
We theoretically study the statistical properties of non-Gaussian states generated by inputting coherent state, single-mode squeezed vacuum state and thermal state to the displacement-based single-side quantum scissor. Compared to the case without the displacement, it is shown that the displacement-based single-side quantum scissor with large coherent amplitudes can not only effectively enhance the success probability of quantum state preparation in the high-transmittance range, but also improve the statistical properties of the generated states involving the average photon number, the signal to noise ratio and the nonclassicality. These results indicate that the usage of the displacement-based single-side quantum scissor may have potential applications for the optical interferometry.
We investigate the properties of non-Gaussian quantum states generated by a three-photon quantum scissor (3-QS). Three different types of inputs to the 3-QS are considered: coherent state (CS), squeezed vacuum state (SVS), and optical field thermal state (TS). We discuss both the detection probability and fidelity of the output states. Our results demonstrate that when the input states have a smaller mean photon number, the output non-Gaussian state can exhibit high detection probability and high fidelity by selecting an appropriate transmissivity. Additionally, we calculate the Wigner functions for the various output states and analyze the non-classical properties by comparing the negative volume of the Wigner functions. The results indicate that the output non-Gaussian states display significant non-classical behavior, particularly when the transmissivity is high, with SVS as the input state showing the strongest effect. Moreover, we compare the performance of the 3-QS with that of the two-photon quantum scissors (2-QS). The findings demonstrate that the non-Gaussian states prepared by the 3-QS possess stronger non-classical characteristics. These results have potential implications for advancing the practical application of the 3-QS in quantum information technology.
Abstract Based on the quantum scissor device proposed by Pegg et al , this paper implements a non-Gaussian quantum state preparation scheme. When considering the quantum photocatalysis of single-photon input and single-photon detection, the equivalent operator of catalytic quantum scissors is given in order to understand the physical nature of quantum scissors. When the coherent state is taken as the input state, for an asymmetric beam splitter, the output state can be truncated to zero photon, single photon and two photon components; for a symmetric beam splitter, the output state is only truncated to zero photon and two photon components. The non-classicality of the prepared non-Gaussian quantum states is discussed by the average photon number, signal-to-noise ratio, squeezing effcet and Wigner function. These results show that the output states can present strong non-classicality when modulating the amplitude of the coherent state and transmissivity of beam splitter.
Abstract Recently, photon subtraction from the single-mode squeezed vacuum state (SVS) has been explored as a technique to enhance its squeezing strength (SS). Notably, the enhancement is observed only when an even number of photons is subtracted, and this effect is limited to a specific range of the squeezing parameter r. In this paper, we introduce a novel class of single-mode nonclassical states, termed as qubit superposed SVSs (qSSVSs), via the coherent superposition of a SVS and a single-photon-subtracted SVS. The primary objective of this work is to enhance the SS for any r > 0 through the creation of these superposed states. Our analysis reveals that the qSSVSs not only improve the SS but also exhibit enhanced nonclassical features such as the negativity of Wigner function, single-mode antibunching effect, photon-number distribution, and sub-Poissonian photon statistics. Furthermore, we demonstrate that the qSSVSs provide superior phase sensitivity in a quantum Mach–Zehnder interferometer compared to the original SVS. Importantly, the generation of qSSVSs is feasible using readily available optical devices, including a beam splitter, a photodetector, and an amplitude displacement. These states hold significant potential for practical applications in quantum information science, particularly for tasks such as information encoding and processing in quantum computing systems.
Abstract Conditional measurement schemes, which employ linear optical elements and photon detectors, have recently become powerful tools for generating and enriching nonclassical states in single- and multi-mode scenarios. Here, the nonclassical resourcefulness of a simple single-mode conditional measurement (CM) setup, with a coherent state as one input state, is examined. Studying the output of this setup in the form of displaced qudits (DQ) simplifies the complete characterization of nonclassical resources. The figures of merit of the prepared states are evaluated through quadrature squeezing and some of the non-Gaussian measures such as the Hilbert–Schmidt distance, the quantum relative entropy and the Wigner negativity to identify the squeezing and non-Gaussianity of the states, respectively. The squeezing capacity of the DQ output is compared with the achievable squeezing in finite superposed Fock states, since DQ also constitute a finite-dimensional representation. This optimal squeezing is attained when the detector detects the single photons in the CM setup. All the studied non-Gaussian measures confirm the qualitative agreement that the non-Gaussianity of the setup is limited and does not exceed that of the input number state. The interplay of nonclassical resources between non-Gaussianity and squeezing is exemplified, showing that states exhibiting non-Gaussianity do not exhibit squeezing, and vice versa. In addition, experimental imperfections, such as photon-source impurities and detector inefficiencies, are accommodated to analyze the realistic preparation of DQ. The calculated success probabilities are around 15 % to create the maximally squeezed states under experimental conditions. It demonstrates the potential of nonclassical state generation with minimal nonclassical inputs through the CM scheme.
The entanglement improvement is theoretically investigated when applying a single-side quantum scissors (SSQS) with a local squeezing operation and two-asymmetrical beam splitters (BSs) to one mode of an input two-mode squeezed vacuum state (TMSV). It is found that the gain factor can be significantly enhanced with the increasing of local squeezing parameter at the expense of the success probability. The entanglement can also be further improved adjusting the local-squeezing or the transmissivity of BSs in a small initial squeezing region. In addition, our scheme is robust against the photon loss in TMSV. The improved effect becomes more obvious due to the presence of local squeezing. However, the case is not true for a more realistic SSQS. In both cases, the asymmetric BSs play a positive role for the entanglement improvement. These results suggest that the squeezing-based SSQS at single-photon level is beneficial to effectively improve the entanglement, which may have potential applications in quantum communication.
Abstract We analyze the quantum properties for the output state of the superposition coherent states with the opposite phase using a quantum scissor. From the perspectives of theoretical calculation and numerical analysis, we discuss the effects of the parameters of the quantum scissors device on different superposition coherent states, such as the probability of successful photon scissor, fidelity, signal gain and squeezing. An interesting finding is that when the input quantum states are even/odd coherent states, signal gain and squeezing for the output quantum state only depend on the amplitude and are independent of the parameters of the quantum scissors. In addition, the quantum properties for other superposition coherent states which are dependent of the amplitude of coherent and the transmittance of beam splitters are also discussed.