Browsing by Author "Faujdar, Jyoti"

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    Bell�s inequality with biased experimental settings
    (Springer, 2022-04-30T00:00:00) Singh, Parvinder; Faujdar, Jyoti; Sarkar, Maitreyee; Kumar, Atul
    We analyse the efficiency of nonlocal correlations in comparison with classical correlations under biased experimental set-up, e.g. for a nonlocal game or a class of Bell-CHSH inequality where both Alice and Bob choose their measurements with a certain bias. We demonstrate that the quantum theory offers advantages over classical theory for the whole range of biasing parameters except for the limiting cases. Moreover, by using fine-grained uncertainty relations to distinguish between classical, quantum and superquantum correlations, we further confirm the underlined advantage of quantum correlations over classical correlations. Our results clearly show that all pure bi-partite entangled states violate the Bell-CHSH inequality under biased set-up. Although for the two-qubit mixed Werner state, the Horodecki state and a state proposed by Ma et al. (Phys Lett A 379:2802, 2015) the range of violation is same in both biased and unbiased scenarios, the extent of violation is different in both cases. We extend our analysis to detect nonlocal correlations using quantum Fisher information and demonstrate a necessary condition for capturing nonlocality in biased scenario. Furthermore, we also describe properties of nonlocal correlations under noisy conditions considering a biased experimental set-up. � 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
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    Nonlocality and efficiency of three-qubit partially entangled states
    (Birkhauser, 2022-09-08T00:00:00) Faujdar, Jyoti; Kaur, Hargeet; Singh, Parvinder; Kumar, Atul; Adhikari, Satyabrata
    We analyse nonlocal properties in three-qubit partially entangled Wn states to understand the efficiency of these states as entangled resources. Our results show that Wn states always violate the three-qubit Svetlichny inequality, and the degree of violation increases with the increase in degree of entanglement. We find that nonlocal correlations in W1 states are the highest in comparison to all other Wn states. We further demonstrate that within the limits of experimentally achievable measurements the W1 state proves to be a better quantum resource for specific protocols in comparison to standard W states, even though the degree of entanglement and nonlocality in the W1 state are less than the degree of entanglement and nonlocality in the standard W state. Moreover, we also consider superpositions of the Greenberger�Horne�Zeilinger (GHZ) state with W and W1 states to show that more entanglement is not a necessity for better efficiency in all protocols. In addition, we also demonstrate the preparation of three qubit quantum states represented as linear superpositions of the GHZ state with W and W1 states. � 2022, The Author(s) under exclusive license to Chapman University.