Weak force detection with superposed coherent states

We investigate the utility of non classical states of simple harmonic oscillators, particularly a superposition of coherent states, for sensitive force detection. We find that like squeezed states a superposition of coherent states allows displacement measurements at the Heisenberg limit. Entangling many superpositions of coherent states offers a significant advantage over a single mode superposition states with the same mean photon number.Comment: 6 pages, no figures: New section added on entangled resources. Changes to discussions and conclusio

Determinisitic Optical Fock State Generation

We present a scheme for the deterministic generation of N-photon Fock states from N three-level atoms in a high-finesse optical cavity. The method applies an external laser pulsethat generates an $N$-photon output state while adiabatically keeping the atom-cavity system within a subspace of optically dark states. We present analytical estimates of the error due to amplitude leakage from these dark states for general N, and compare it with explicit results of numerical simulations for N \leq 5. The method is shown to provide a robust source of N-photon states under a variety of experimental conditions and is suitable for experimental implementation using a cloud of cold atoms magnetically trapped in a cavity. The resulting N-photon states have potential applications in fundamental studies of non-classical states and in quantum information processing.Comment: 25 pages, 9 figure

Generation of arbitrary two dimensional motional state of a trapped ion

We present a scheme to generate an arbitrary two-dimensional quantum state of motion of a trapped ion. This proposal is based on a sequence of laser pulses, which are tuned appropriately to control transitions on the sidebands of two modes of vibration. Not more than $(M+1)(N+1)$ laser pulses are needed to generate a pure state with upper phonon number $M$ and $N$ in the $x$ and $y$ direction respectively.Comment: to appear in PR

Resonant Generation of Topological Modes in Trapped Bose Gases

Trapped Bose atoms cooled down to temperatures below the Bose-Einstein condensation temperature are considered. Stationary solutions to the Gross-Pitaevskii equation (GPE) define the topological coherent modes, representing nonground-state Bose-Einstein condensates. These modes can be generated by means of alternating fields whose frequencies are in resonance with the transition frequencies between two collective energy levels corresponding to two different topological modes. The theory of resonant generation of these modes is generalized in several aspects: Multiple-mode formation is described; a shape-conservation criterion is derived, imposing restrictions on the admissible spatial dependence of resonant fields; evolution equations for the case of three coherent modes are investigated; the complete stability analysis is accomplished; the effects of harmonic generation and parametric conversion for the topological coherent modes are predicted. All considerations are realized both by employing approximate analytical methods as well as by numerically solving the GPE. Numerical solutions confirm all conclusions following from analytical methods.Comment: One reference modifie

The effect of zinc oxide and elemental zinc boluses on the concentrations of Zn in serum and faeces, and on providing protection from natural Pithomyces chartarum challenge in calves

AIM: To investigate the efficacy of intra-ruminal Zn boluses as aids in providing protection from natural Pithomyces chartarum challenge in calves. METHODS: Sixty-two calves (mean weight 187 (SEM 3.25) kg) were divided into three groups. Commencing on Day 0, they received either a proprietary bolus containing 83% ZnO (ZnO group), a prototype Zn bolus containing 88% elemental Zn (Zn group), or remained untreated (Control group). Concentrations of Zn in serum and faeces were measured weekly between Days 6 and 34, activities of gamma-glutamyl transferase (GGT) in serum on Days -8, 20, 34 and 41, and faecal spore counts between Days 13 and 41. RESULTS: Between Days 6 and 34, mean concentrations of Zn in serum increased in both Zn treatment groups compared with Controls (p<0.001), but were lower in Zn than ZnO animals between Days 6 and 28 (p=0.05). Concentrations of Zn in faeces were increased in both groups following treatment with Zn. Mean concentrations of Zn in faeces in ZnO animals was higher than Zn animals on Days 13 and 20 (p<0.001), but decreased by Day 34, whereas for Zn animals they were still elevated on Day 34. Faecal spore counts were 354,000 and 183,000 on Days 13 and 20, respectively, 610,500 on Day 28, and 115,500 spores/g on Day 34. There were no clinical signs of facial eczema, but based on the activities of GGT on Day 41, 17/20 (85%) Controls were moderately or severely affected (GGT >250 IU/L) compared with 1/21 (5%) ZnO and 3/21 (14%) Zn animals. Mean activities of GGT on Day 41 for ZnO and Zn animals were not different (35 (95% CI= 23-54) and 54 (95% CI= 32-92) IU/L, respectively; p=0.18), but were below those of the Controls (502 (95% CI 296, 850) IU/L), confirming efficacy of both bolus treatments. In both ZnO and Zn animals, there was no significant relationship between concentration of Zn in serum and activity of GGT, but in Zn animals there was a significant relationship between the concentration of Zn in faeces and activity of GGT 21 days later. The regression equation y=2.136-0.002197x (where y is log(10)GGT activity, and x the concentration of Zn in faeces) provided an estimate of the threshold level of concentration of Zn in faeces. CONCLUSION: The study confirmed efficacy of elemental Zn boluses in providing protection from natural P. chartarum challenge in young cattle

The effect of zinc oxide and elemental zinc boluses on the concentrations of Zn in serum and faeces, and on providing protection from natural Pithomyces chartarum challenge in calves

AIM: To investigate the efficacy of intra-ruminal Zn boluses as aids in providing protection from natural Pithomyces chartarum challenge in calves. METHODS: Sixty-two calves (mean weight 187 (SEM 3.25) kg) were divided into three groups. Commencing on Day 0, they received either a proprietary bolus containing 83% ZnO (ZnO group), a prototype Zn bolus containing 88% elemental Zn (Zn group), or remained untreated (Control group). Concentrations of Zn in serum and faeces were measured weekly between Days 6 and 34, activities of gamma-glutamyl transferase (GGT) in serum on Days -8, 20, 34 and 41, and faecal spore counts between Days 13 and 41. RESULTS: Between Days 6 and 34, mean concentrations of Zn in serum increased in both Zn treatment groups compared with Controls (p<0.001), but were lower in Zn than ZnO animals between Days 6 and 28 (p=0.05). Concentrations of Zn in faeces were increased in both groups following treatment with Zn. Mean concentrations of Zn in faeces in ZnO animals was higher than Zn animals on Days 13 and 20 (p<0.001), but decreased by Day 34, whereas for Zn animals they were still elevated on Day 34. Faecal spore counts were 354,000 and 183,000 on Days 13 and 20, respectively, 610,500 on Day 28, and 115,500 spores/g on Day 34. There were no clinical signs of facial eczema, but based on the activities of GGT on Day 41, 17/20 (85%) Controls were moderately or severely affected (GGT >250 IU/L) compared with 1/21 (5%) ZnO and 3/21 (14%) Zn animals. Mean activities of GGT on Day 41 for ZnO and Zn animals were not different (35 (95% CI= 23-54) and 54 (95% CI= 32-92) IU/L, respectively; p=0.18), but were below those of the Controls (502 (95% CI 296, 850) IU/L), confirming efficacy of both bolus treatments. In both ZnO and Zn animals, there was no significant relationship between concentration of Zn in serum and activity of GGT, but in Zn animals there was a significant relationship between the concentration of Zn in faeces and activity of GGT 21 days later. The regression equation y=2.136-0.002197x (where y is log(10)GGT activity, and x the concentration of Zn in faeces) provided an estimate of the threshold level of concentration of Zn in faeces. CONCLUSION: The study confirmed efficacy of elemental Zn boluses in providing protection from natural P. chartarum challenge in young cattle