SWARNAMALA SIRSI
Articles written in Pramana – Journal of Physics
Volume 59 Issue 2 August 2002 pp 175-179
Spin squeezing and quantum correlations
KS Mallesh Swarnamala Sirsi Mahmoud AA Sbaih PN Deepak G Ramachandran
We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-
Volume 83 Issue 2 August 2014 pp 279-287
Entangling capabilities of symmetric two-qubit gates
Swarnamala Sirsi Veena Adiga Subramanya Hegde
Our work addresses the problem of generating maximally entangled two spin-1/2 (qubit) symmetric states using NMR, NQR, Lipkin–Meshkov–Glick Hamiltonians. Time evolution of such Hamiltonians provides various logic gates which can be used for quantum processing tasks. Pairs of spin-1/2s have modelled a wide range of problems in physics. Here, we are interested in two spin-1/2 symmetric states which belong to a subspace spanned by the angular momentum basis $\{|j = 1,\mu\langle; \mu = + 1, 0, -12\}$. Our technique relies on the decomposition of a Hamiltonian in terms of $SU$(3) basis matrices. In this context, we define a set of linearly independent, traceless, Hermitian operators which provides an alternate set of $SU(n)$ generators. These matrices are constructed out of angular momentum operators
Volume 91 Issue 2 August 2018 Article ID 0024 Research Article
Trivariate analysis of two qubit symmetric separable state
One of the main problems of quantum information theory is developing the separability criterion which is both necessary and sufficient in nature. Positive partial transposition test (PPT) is one such criterion which is both necessary and sufficient for $2 \times 2$ and $2 \times 3$ systems but not otherwise. We express this strong PPT criterion for a system of 2-qubit symmetric states in terms of the well-known Fano statistical tensor parameters and prove that a large set of separable symmetric states are characterised by real statistical tensor parameters only. The physical importance of these states are brought out by employing trivariate representation of density matrix wherein the components of J, namely $J_{x} , J_{y} , J_{z}$ are considered to be the three variates.We prove that this set of separable states is characterised by the vanishing average expectation value of $J_{y}$ and its covariance with $J_{x}$ and $J_{z}$ . This allows us to identify a symmetric separable state easily. We illustrate our criterion using 2-qubit system as an example.
Volume 94, 2020
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