A. Mann

Thermal coherent states

Abstract The formalism of thermo field dynamics is used to define a thermal coherent state, and thus calculate some correlation functions. The relation of the thermal coherent state so defined to earlier definitions is briefly discussed.

Relation Between Quantum and Thermal Fluctuations

Abstract A relation between quantum and thermal fluctuations, called the generalized uncertainty relation, is derived and discussed. It is given in the terminology of thermo field dynamics. The relation enables us to separate the purely thermal fluctuation from the total fluctuation.

Temperature in a pure state

Abstract Given two independent systems A and A, let them interact briefly at t =0. With proper choice of interaction, the resultant correlation between the systems will cause measurements performed on system A to be indistinguishable from measurements of system A performed at finite temperature—provided the measurements are coupled to the system A only. This holds while the total system (A and A) is in a pure state.

High-accuracy Su(1,1) interferometers with minimum-uncertainty input states

Abstract We obtain an exact analytical expression for the phase sensitivity of an SU(1,1) interferometer fed with two-mode field states which are minimum-uncertainty states for the SU(1,1) generators. These states optimize the uncertainty relation which makes possible an essential improvement of the measurement accuracy of the interferometer.

Relative phase determination and clocks synchronization via shared entanglement

We present a protocol for determining the relative phase of nonoverlapping classical fields via shared atomic entangled pairs. The protocol is then generalized allowing the synchronization of spatially separated clocks. The analysis, more exact than published hitherto, stresses the advantage of entangling time reversed states. We show that interference between fields which do not coexist in time is possible.

Bell's inequality violation and symmetry

Abstract Bells inequality violation is related to the breakdown of symmetry of photonic field states. The states allowing the violation are characterized by a parameter γ associated with the interaction of the nonlinear medium and radiation. The violation is shown for small values of γ , where the particle aspect of light dominates. The degrading of the entanglement of the beam with increasing γ is discussed. The essential local noncommutativity of the operators involved is obvious.

ENTANGLEMENT, INFORMATION THEORY AND BELL'S INEQUALITY

Abstract Information theory is used to quantify entanglement of two spin - 1 2 particles or two photons. Noise contaminating a pure entangled (singlet) state is parametrized to allow convenient comparison with experimental studies of possible violation of Bells inequality for such states.

Simple non-hermitian choices for the standardization operator in projected perturbation theory

Abstract We suggest simple non-hermitian choices for the Peierls standardization operator and test them in a simplified one-dimensional model of H+2.

Symmetry and a similarity transformation for perturbation theory of short-range atomic interactions

Abstract Di-atomic molecules possess a peculiar symmetry. Considerations based on it are used in an attempt to extend Byers-Browns perturbation treatment of short range atomic interactions. Example of a soluble model is treated briefly.

Unusual Doppler shift of fourth sound in a 3He−4He mixture

Abstract Independent macroscopic motions and several sounds in a superfluid imply unusual Doppler shifts. There appears in particular a special outstripping effect as found by Nepomnyashchy and Revzen: the center of the spreading sound moves faster than the flowing superfluid part of the liquid itself. Here we show that with the admixture of 3 He this effect substantially increases , so that it becomes more accessible to experimental observation. We find here also the physical origin of the phenomenon: negative “effective compressibility” of the normal component.