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- A. K. Rajagopal
- 1999

From this he went on to obtain several other identities in elegant ways which are all central in the development of quantum time evolution, Gibbsian ensembles in equilibrium quantum statistical mechanics, perturbation expansions, inequalities concerning correlation functions etc., all of which depend on the appearance of the exponential operator of the form… (More)

- A R Usha Devi, A. K. Rajagopal
- Physical review letters
- 2008

A novel measure, quantumness of correlations Q_AB is introduced here for bipartite states, by incorporating the required measurement scheme crucial in defining any such quantity. Quantumness coincides with the previously proposed measures in special cases and it vanishes for separable states--a feature not captured by the measures proposed earlier. It is… (More)

- A. R. Usha Devi, Sudha, A. K. Rajagopal
- Quantum Information Processing
- 2012

Given physical systems, counting rule for their statistical mechanical descriptions need not be unique, in general. It is shown that this nonuniqueness leads to the existence of various canonical ensemble theories, which equally arise from the definite microcanonical basis. Thus, the Gibbs theorem for canonical ensemble theory is not universal, and maximum… (More)

- Maria Kuruvilla, C R Chhallani, A. K. Rajagopal, F Salem Rakas
- The British journal of surgery
- 1987

The object of this study is to focus attention on the causes of intestinal obstruction in Libya. In this study, spread over 30 months and involving 114 patients, the most common cause was the entrapment of bowel in an external hernia. Postoperative adhesions accounted for obstruction in a third of our patients, and 59 per cent of them followed… (More)

- Sumiyoshi Abe, A. K. Rajagopal
- Physical review letters
- 2003

The second law of thermodynamics in nonextensive statistical mechanics is discussed in the quantum regime. Making use of the convexity property of the generalized relative entropy associated with the Tsallis entropy indexed by q, Clausius' inequality is shown to hold in the range q in (0, 2]. This restriction on the range of the entropic index, q, is purely… (More)

- Avijit Misra, Uttam Kumar Singh, Manabendra Nath Bera, A. K. Rajagopal
- Physical review. E, Statistical, nonlinear, and…
- 2015

We formulate a complete theory of quantum thermodynamics in the Rényi entropic formalism exploiting the Rényi relative entropies, starting from the maximum entropy principle. In establishing the first and second laws of quantum thermodynamics, we have correctly identified accessible work and heat exchange in both equilibrium and nonequilibrium cases. The… (More)

The Lévy-type distributions are derived using the principle of maximum Tsallis nonextensive entropy both in the full and half spaces. The rates of convergence to the exact Lévy stable distributions are determined by taking the N -fold convolutions of these distributions. The marked difference between the problems in the full and half spaces is elucidated… (More)

- A. R. Usha Devi, Rashmi Prabhu, A. K. Rajagopal
- Physical review letters
- 2007

We show that higher order intergroup covariances involving even number of qubits are necessarily positive semidefinite for N-qubit separable states, which are completely symmetric under permutations of the qubits. This identification leads to a family of sufficient conditions of inseparability based on the negativity of 2kth order intergroup covariance… (More)

- A. K. Rajagopal
- 2003

The foundations of the Boltzmann-Gibbs (BG) distributions for describing equilibrium statistical mechanics of systems are examined. Broadly, they fall into: (i) probabilistic approaches based on the principle of equal a priori probability (counting technique and method of steepest descents), law of large numbers, or the state density considerations and (ii)… (More)