6,357 research outputs found
Local Hidden Variable Theoretic Measure of Quantumness of Mutual Information
Entanglement, a manifestation of quantumness of correlations between the
observables of the subsystems of a composite system, and the quantumness of
their mutual information are widely studied characteristics of a system of
spin-1/2 particles. The concept of quantumness of correlations between the
observables of a system is based on incommensurability of the correlations with
the predictions of some local hidden variable (LHV) theory. However, the
concept of quantumness of mutual information does not invoke the LHV theory
explicitly. In this paper, by invoking explicitly the local hidden variable
theory, a measure of quantumness of mutual information, , for a system
of two spin-1/2 particles is proposed. It is based on finding the difference
between the quantum and classical mutual informations in which the classical
mutual information corresponds to the joint probability of the eigenvalues of
the spins each along a specified direction. The proposed measure circumvents
the need of optimization when the Bloch vector of each spin is non-zero; the
optimization is needed but can be performed analytically exactly when the Bloch
vector of each spin vanishes and is simplified when the Bloch vector of only
one of the spins is zero. In essence, the proposed measure is identical with
the measurement induced disturbance when the Bloch vector of each of the spins
is non-zero. However, whereas the measurement induced disturbance is non-unique
when the Bloch vector of one or both the spins is zero, the proposed measure
even then determines the quantumness of mutual information unambiguously. The
is identical with the symmetric discord if the Bloch vector of each
spin vanishes. It is same as the quantum discord if the Bloch vector of only
one spin is zero and if the state in question possesses certain additional
properties.Comment: 12 page
Study of non-equilibrium effects and thermal properties of heavy ion collisions using a covariant approach
Non-equilibrium effects are studied using a full Lorentz-invariant formalism.
Our analysis shows that in reactions considered here, no global or local
equilibrium is reached. The heavier masses are found to be equilibrated more
than the lighter systems. The local temperature is extracted using hot Thomas
Fermi formalism generalized for the case of two interpenetrating pieces of
nuclear matter. The temperature is found to vary linearly with bombarding
energy and impact parameter whereas it is nearly independent of the mass of the
colliding nuclei. This indicates that the study of temperature with medium size
nuclei is also reliable. The maximum temperatures obtained in our approach are
in a nice agreement with earlier calculations of other approaches. A simple
parametrization of maximal temperature as a function of the bombarding energy
is also given.Comment: LaTex-file, 17 pages, 8 figures (available upon request), Journal of
Physics G20 (1994) 181
Dynamical Casimir Effect in two-atom cavity QED
We study analytically and numerically the dynamical Casimir effect in a
cavity containing two stationary 2-level atoms that interact with the resonance
field mode via the Tavis-Cummings Hamiltonian. We determine the modulation
frequencies for which the field and atomic excitations are generated and study
the corresponding dynamical behaviors in the absence of damping. It is shown
that the two-atom setup allows for monitoring of photon generation without
interrupting the growth, and different entangled states can be generated during
the process.Comment: 4+ pages, 2 figure
Investigating the ‘mission and profit’ paradox: Case study of an ecopreneurial organisation in India
Based on a case study of a waste management services provider in India, this paper sets out to investigate how an ecopreneurial organisation balances the competing demands of environmental mission and profit generation. Results indicate that two internal organisational mechanisms, namely Leadership, and Organisational Processes, are instrumental in achieving the dual goals. The paper highlights the role of contextual factors in supporting such organisations, and in doing so, it responds to the call for research to examine social entrepreneurship in wider contexts including Asia, Latin America, and Africa, to address ‘marginalisation’ of studies in the field
Nuclear Dynamics at the Balance Energy
We study the mass dependence of various quantities (like the average and
maximum density, collision rate, participant-spectator matter, temperature as
well as time zones for higher density) by simulating the reactions at the
energy of vanishing flow. This study is carried out within the framework of
Quantum Molecular Dynamics model. Our findings clearly indicate an existence of
a power law in all the above quantities calculated at the balance energy. The
only significant mass dependence was obtained for the temperature reached in
the central sphere. All other quantities are rather either insensitive or
depend weakly on the system size at balance energy. The time zone for higher
density as well as the time of maximal density and collision rate follow a
power law inverse to the energy of vanishing flow.Comment: 9 figures, Submitted to Phys. Rev.
Approximate analytical results on the cavity dynamical Casimir effect in the presence of a two-level atom
We study analytically the photon generation from vacuum due to the Dynamical
Casimir effect in a cavity with a two-level atom, prepared initially in an
arbitrary pure state. Performing small unitary transformations we obtain closed
analytical expressions for the probability amplitudes and other important
quantities in the resonant/dispersive regimes.Comment: 5 pages, 2 figure
Nakajima-Zwanzig versus time-convolutionless master equation for the non-Markovian dynamics of a two-level system
We consider the exact reduced dynamics of a two-level system coupled to a
bosonic reservoir, further obtaining the exact time-convolutionless and
Nakajima-Zwanzig non-Markovian equations of motion. The considered system
includes the damped and undamped Jaynes-Cummings model. The result is obtained
by exploiting an expression of quantum maps in terms of matrices and a simple
relation between the time evolution map and time-convolutionless generator as
well as Nakajima-Zwanzig memory kernel. This non-perturbative treatment shows
that each operator contribution in Lindblad form appearing in the exact
time-convolutionless master equation is multiplied by a different time
dependent function. Similarly, in the Nakajima-Zwanzig master equation each
such contribution is convoluted with a different memory kernel. It appears that
depending on the state of the environment the operator structures of the two
set of equations of motion can exhibit important differences.Comment: 12 pages, no figure
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