Inversion of moments to retrieve joint probabilities in quantum sequential measurements

A sequence of moments encode the corresponding probability distribution. Probing if quantum joint probability distribution can be retrieved from the associated set of moments -- realized in the sequential measurement of a dichotomic observable at different time intervals -- reveals a negative answer i.e., the joint probabilities of sequential measurements do not agree with the ones obtained by inverting the moments. This is indeed a reflection of the non-existence of a bonafide grand joint probability distribution, consistent with all the physical marginal probability distributions. Here we explicitly demonstrate that given the set of moments, it is not possible to retrieve the three-time quantum joint probability distribution resulting from quantum sequential measurement of a single qubit dichotomic observable at three different times. Experimental results using a nuclear magnetic resonance (NMR) system are reported here to corroborate these theoretical observations viz., the incompatibility of the three-time joint probabilties with those extracted from the moment sequence.Comment: 7 pages, 5 figures, RevTe

Observation of Spin-glass-like Behavior in SrRuO3 Epitaxial Thin Films

We report the observation of spin-glass-like behavior and strong magnetic anisotropy in extremely smooth (~1-3 \AA) roughness) epitaxial (110) and (010) SrRuO3 thin films. The easy axis of magnetization is always perpendicular to the plane of the film (unidirectional) irrespective of crystallographic orientation. An attempt has been made to understand the nature and origin of spin-glass behavior, which fits well with Heisenberg model.Comment: 5 pages, 5 Figure

Ferroelectric photovoltaic properties in doubly substituted (Bi0.9La0.1)(Fe0.97Ta0.03)O3 thin films

This work was supported by the DOE-EPSCoR Grant No. DE-FG02-08ER46526. Acknowledgment is also due to NSF Grant No. #1002410 for providing fellowships to R.K.K., D.B., and J.S.Y.Doubly substituted [Bi0.9La0.1][Fe0.97Ta0.03]O3 (BLFTO) films were fabricated on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition. The ferroelectric photovoltaic properties of ZnO:Al/BLFTO/Pt thin film capacitor structures were evaluated under white light illumination. The open circuit voltage and short circuit current density were observed to be ∼0.20 V and ∼1.35 mA/cm2, respectively. The band gap of the films was determined to be ∼2.66 eV, slightly less than that of pure BiFeO3 (2.67 eV). The PVproperties of BLFTO thin films were also studied for various pairs of planar electrodes in different directions in polycrystalline thin films.Publisher PDFPeer reviewe

Unipolar resistive switching in cobalt titanate thin films

We report giant resistive switching of an order of 104, long-time charge retention characteristics up to 104 s, non-overlapping SET and RESET voltages, ohmic in low resistance state (LRS) and space charge limited current (SCLC) mechanism in high resistance state (HRS) properties in polycrystalline perovskite Cobalt Titanate (CoTiO3 ~ CTO) thin films. Impedance spectroscopy study was carried out for both LRS and HRS states which illustrates that only bulk resistance changes after resistance switching, however, there is a small change (<10% which is in pF range) in the bulk capacitance value in both states. These results suggest that in LRS state current filaments break the capacitor in many small capacitors in a parallel configuration which in turn provides the same capacitance in both states even there was 90 degree changes in phase-angle and an order of change in the tangent loss.Comment: 7 pages, 4 figure

Experimental verification of the ab initio phase transition sequence in SrZrO3 and comparisons with SrHfO3 and SrSnO3

AK acknowledges the CSIR-National Physical Laboratoryinternal net work project, INDIA. Hitesh Borkar would like to acknowledge the CSIR (SRF) to provide fellowship to carry out PhD program.We present detailed Raman studies of SrZrO3 (SZO) that show three anomalies in Raman modes:One has a small jump in frequency ω; one has its intensity vanish; and a third has a sharp change in temperature derivative dω(T)/dT from flat below T = 600 K to a Curie-Weiss dependence above 600 K with extrapolation to zero frequency at the known transition temperature T = 970K, thereby proving the latter to be displacive. In addition, the P4mm ferroelectric phase predicted at high stresses [Amisi et al., Phy. Rev. B 85, 064112 (2012)] has preliminary support from polarization-voltage experiments. The inference of a new transition in the temperature region 600-650 K is in disagreement with neutron studies. Comparisons are given for family member SrSnO3 and SrHfO3, and we discuss the different conclusions of Kennedy and Knight, J Phys.Condens. Mat. 27, 365401 (2015). We show that a known transition in SrHfO3 is also displacive with a well-behaved soft mode.Publisher PDFPeer reviewe