Non-gaussian operations in different modes of pair coherent state
Anjali Jatwani, Amit Verma · Physica Scripta · 2025
Abstract A study of non-Gaussian operations in a single/two-mode quantum state is of great importance because of the enhancement of non-classicality. Experimental evidence of the generation of a Pair Coherent State (PCS) and the feasibility of non-Gaussian operations using beam splitters and nonlinear crystals motivated us to study non-Gaussian PCS. Recently, we studied various nonclassicality criteria in a particular case of non-Gaussian PCS. Here, we explore different combinations of photon addition/subtraction in either mode of PCS. For example, we studied photon addition and subtraction (PAS), photon subtraction and addition (PSA), photon addition and addition (PAA), and photon subtraction and subtraction (PSS) in two modes of PCS. We present a quantitative measure of nonclassicality in the form of inequality known as Klyshko’s criterion for the different combinations of PCS to show the nonclassical behavior of the states quantitatively. Here, we also present the corresponding coefficients (C n ) for each different case of PCS and analyze the effect of photon addition and subtraction on the photon-number distribution, linear entropy, single-photon source efficiency (SPS), Q-function, and fidelity for quantum teleportation. We illustrate our results through numerical simulations and compare them with standard PCS. We observe the changes induced by different combinations in PCS, leading to enhanced nonclassicality. Our results show that the PSA and PSS configurations demonstrate the strongest Klyshko nonclassicality, while the PAA state exhibits maximal entanglement via linear entropy and strong efficiency. In particular, the PAS state achieves the highest teleportation fidelity (F > 0.88). These findings establish photon-added/subtracted PCS as practical and tunable resources for quantum communication and metrology tasks.