Browsing by Author "Sarker, P."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Circuit Complexity in Z2 EEFT
    (MDPI, 2023) Adhikari, K.; Choudhury, S.; Kumar, S.; Mandal, S.; Pandey, N.; Roy, A.; Sarkar, S.; Sarker, P.; Shariff, S.S.
    Motivated by recent studies of circuit complexity in weakly interacting scalar field theory, we explore the computation of circuit complexity in (Formula presented.) Even Effective Field Theories ((Formula presented.) EEFTs). We consider a massive free field theory with higher-order Wilsonian operators such as (Formula presented.), (Formula presented.), and (Formula presented.) To facilitate our computation, we regularize the theory by putting it on a lattice. First, we consider a simple case of two oscillators and later generalize the results to N oscillators. This study was carried out for nearly Gaussian states. In our computation, the reference state is an approximately Gaussian unentangled state, and the corresponding target state, calculated from our theory, is an approximately Gaussian entangled state. We compute the complexity using the geometric approach developed by Nielsen, parameterizing the path-ordered unitary transformation and minimizing the geodesic in the space of unitaries. The contribution of higher-order operators to the circuit complexity in our theory is discussed. We also explore the dependency of complexity on other parameters in our theory for various cases. © 2022 by the authors.
  • No Thumbnail Available
    Item
    Entanglement in interacting quenched two-body coupled oscillator system
    (American Physical Society, 2022) Choudhury, S.; Gharat, R.M.; Mandal, S.; Pandey, N.; Roy, A.; Sarker, P.
    In this work, we explore the effects of a quantum quench on the entanglement measures of a two-body coupled oscillator system having quartic interaction. We use the invariant operator method, under a perturbative framework, for computing the ground state of this system. We give the analytical expressions for the total and reduced density matrix of the system having non-Gaussian, quartic interaction terms. Using this reduced density matrix, we show the analytical calculation of two entanglement measures viz., Von Neumann entanglement entropy using replica trick and Renyi entanglement entropy. Further, we give a numerical estimate of these entanglement measures with respect to the dimensionless parameter (t/δt) and show its behavior in the three regimes, i.e., late time behavior, around the quench point and the early time behavior. We comment on the variation of these entanglement measures for different orders of coupling strength. The variation of Renyi entropy of different orders has also been discussed. © 2022 authors. Published by the American Physical Society.