120468461
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 .
119995096
Coherent and thermal coherent state
The characterization of coherent states as the quantum states that split into two uncorrelated beams is considered. The characterization leads to the study of coherent states at finite temperature—thermal coherent states (TCS’s). These TCS’s are defined within the formalism of thermo field dynamics (TFD). TFD allows a generalization of the uncertainty relation that accounts for both thermal and quantum fluctuations. The TCS is shown to be a minimal state for the generalized uncertainty relation.
40587572
Inverted spectroscopy and interferometry for quantum-state reconstruction of systems with SU(2) symmetry
We consider how the conventional spectroscopic and interferometric schemes can be rearranged to serve for reconstructing quantum states of physical systems possessing SU(2) symmetry. The discussed systems include a collection of two-level atoms, a two-mode quantized radiation field with a fixed total number of photons, and a single laser-cooled ion in a two-dimensional harmonic trap with a fixed total number of vibrational quanta. In the proposed rearrangement, the standard spectroscopic and interferometric experiments are inverted. Usually one measures an unknown frequency or phase shift using a system prepared in a known quantum state. Our aim is just the inverse, i.e., to use a well-calibrated apparatus with known transformation parameters to measure unknown quantum states.
16820646
Analytic representations based on SU(1,1) coherent states and their applications
We consider two analytic representations of the SU(1,1) Lie group: the representation in the unit disc based on the SU(1,1) Perelomov coherent states and the Barut - Girardello representation based on the eigenstates of the SU(1,1) lowering generator. We show that these representations are related through a Laplace transform. A `weak' resolution of the identity in terms of the Perelomov SU(1,1) coherent states is presented which is valid even when the Bargmann index k is smaller than . Various applications of these results in the context of the two-photon realization of SU(1,1) in quantum optics are also discussed.
18649329
Generation of single-mode intelligent states and an analytic approach to their quantum statistical properties
We discuss a scheme for generation of single-mode photon states associated with the two-photon realization of the SU(1,1) algebra. This scheme is based on the process of non-degenerate down-conversion with the signal prepared initially in the squeezed vacuum state and with a measurement of the photon number in one of the output modes. We focus on the generation and properties of single-mode SU(1,1) intelligent states which minimize the uncertainty relations for Hermitian generators of the group. Properties of the intelligent states are studied by using a `weak' extension of the analytic representation in the unit disc. Then we are able to obtain exact analytical expressions for expectation values describing quantum statistical properties of the SU(1,1) intelligent states. Attention is mainly devoted to the study of photon statistics and linear and quadratic squeezing.
16492315
Empirical State Determination of Entangled Two-Level Systems and Its Relation to Information Theory
Theoretical methods for empirical state determination of entangled two-level systems are analyzed in relation to information theory. We show that hidden variable theories would lead to a Shannon index of correlation between the entangled subsystems which is larger than that predicted by quantum mechanics. Canonical representations which have maximal correlations are treated by the use of Schmidt and Hilbert-Schmidt decomposition of the entangled states, including especially the Bohm singlet state and the GHZ entangled states. We show that quantum mechanics does not violate locality, but does violate realism.
118024645
REQUEST FOR EXTENSION OF E-310
117834746
Proposal for a national underground science facility
The idea is explored of establishing a laboratory complex shielded from the cosmic ray flux at the earth’s surface for the purpose of housing and providing technical support for experiments in particle physics, astrophysics, and other scientific disciplines. The scientific motivation for such an underground science facility is described, and the questions of location and desired properties of the facility are discussed.
121590665
Limit on the production cross section for massive leptons
119389242
Derivation of the critical temperature for the superfluid phase of hadronic matter
Abstract We give a quantitative derivation of the temperature at which superfluidity of hadronic matter ends. Using considerations similar to those used by Landau for 4 He, we find T c ⩽ 190 MeV in close agreement with Hagedorn's “limiting” temperature.
123621331
APPROACH TO THE NUCLEAR MANY-BODY PROBLEM BY VARIATIONALLY DETERMINED TRANSFORMATION. II.
We present a generalization of the Hartree-Fock (HF) method incorporating two-body correlations. The correlations are introduced by means of a unitary operator ${e}^{\mathrm{iF}}$, where $F$ is a Hermitian one- and two-body operator to be determined by the variational principle. Assuming that the matrix elements of $F$ are small so that powers of $F$ higher than the second may be neglected, a set of linear equations determining $F$ is obtained. The relation between our method and methods used to treat singular interactions is discussed. The method is applied to two recently suggested models and is compared with the HF method, second-order perturbation theory, and with the random-phase approximation. It is found that our method yields very good results within the range of validity of our approximations, which seems to call forth applications to more realistic problems. Possible applications to the study of collective phenomena in nuclei are indicated.