12,954 research outputs found
Quantum Binary Decision for Driven Harmonic Oscillator
We address the problem of determining whether or not a harmonic oscillator
has been perturbed by an external force. Quantum detection and estimation
theory has been used in devising optimum measurement schemes. Detection
probability has been evaluated for different initial state preparations of
oscillator. The corresponding lower bounds on minimum detectable perturbation
intensity has been evaluated and a general bound for random phase perturbation
has been also induced.Comment: Latex 5 figs -- More info at http://enterprise.pv.infn.it/~pari
Unitary local invariance
We address unitary local (UL) invariance of bipartite pure states. Given a
bipartite state the complete
characterization of the class of local unitaries for which
is obtained.The two relevant parameters are
the rank of the matrix , , and the number of its
equal singular values, {\em i.e.} the degeneracy of the eigenvalues of the
partial traces of .Comment: Revised version. Accepted for publication Int. J. Quant. In
Polyphase thrust tectonic in the Barberton greenstone belt
In the circa 3.5 by-old Barberton greenstone belt, the supracrustal rocks form a thick and strongly deformed thrust complex. Structural studies in the southern part of the belt have shown that 2 separate phases of over-thrusting (D sub 1 and D sub 2) successively dismembered the original stratigraphy. Thrust nappes were subsequently refolded during later deformations (D sub 3 and D sub 4). This report deals with the second thrusting event which, in the study region appears to be dominant, and (unlike the earlier thrusting), affects the entire supracrustal pile. The supracrustal rocks form a predominantly NE/SW oriented, SE dipping tectonic fan (the D sub 2 fan) in which tectonic slices of ophiolitic-like rocks are interleaved with younger sedimentary sequences of the Diepgezet and malalotcha groups. Structural and sedimentological data indicate that the D sub 2 tectonic fan was formed during a prolonged, multi-stage regional horizontal shortening event during which several types of internal deformation mechanisms were successively and/or simultaneously active. Movement appears to have been predominantly to the NW and to the N. During D sub 2, periods of quiescence and sedimentation followed periods of thrust propagation. Although the exact kinematics which led to the formation of this fan is not yet known, paleoenvironmental interpretations together with structural data suggest that D sub 2 was probably related to (an) Archean collision(s)
- …