Correlated two-photon scattering in cavity optomechanics

We present an exact analytical solution of the two-photon scattering in a cavity optomechanical system. This is achieved by solving the quantum dynamics of the total system, including the optomechanical cavity and the cavity-field environment, with the Laplace transform method. The long-time solution reveals detailed physical processes involved as well as the corresponding resonant photon frequencies. We characterize the photon correlation induced in the scattering process by calculating the two-photon joint spectrum of the long-time state. Clear evidence for photon frequency anti-correlation can be observed in the joint spectrum. In addition, we calculate the equal-time second-order correlation function of the cavity photons. The results show that the radiation pressure coupling can induce photon blockade effect, which is strongly modulated by the phonon sideband resonance. In particular, we obtain an explicit expression of optomechanical coupling strength determining these sideband modulation peaks based on the two-photon resonance condition.Comment: 10 pages, 6 figure

Proposal for entangling remote micromechanical oscillators via optical measurements

We propose an experiment to create and verify entanglement between remote mechanical objects by use of an optomechanical interferometer. Two optical cavities, each coupled to a separate mechanical oscillator, are coherently driven such that the oscillators are laser cooled to the quantum regime. The entanglement is induced by optical measurement and comes about by combining the output from the two cavities to erase which-path information. It can be verified through measurements of degrees of second-order coherence of the optical output field. The experiment is feasible in the regime of weak optomechanical coupling. Realistic parameters for the membrane-in-the-middle geometry suggest entangled state lifetimes on the order of milliseconds.Comment: 4 pages, 2 figures + supplementary material (7 pages, 2 figs). Updates in v2: New Eq. (7) and Fig. 1 - results unchanged. Added supplementary material with various details. Updates in v3: Minor changes, journal ref. adde

Influence of temperature on the life history of turtles : an exploration of the embryonic and maternal adaptations to incubation temperature

This study explores the role of temperature on the early life history traits of Murray River short-necked turtles, Emydura macquarii. Firstly, I investigate the role of incubation temperature in inducing adaptive behavioural and physiological strategies within the nest. Secondly, I explore the interaction between genes, developmental conditions and the post-hatching environment to determine long-term effects on growth and survival of turtles. Lastly, I review the impact of climate change and habitat modifications on Murray River turtles. Investigation of heart rates of embryonic turtles incubated at constant temperatures (26oC and 30oC) revealed that heart rates experience circadian rhythms independent to time of day and the peak heart rate varies throughout the day between individuals. Heart rate patterns were consistent throughout the individuals monitored in that the peak heart rate and the minimal heart rate were observed 12 h apart, and intermediate heart rates occurred 6 h before and after these extremes. Heart beats per minute varied between individuals, but embryos showed 15-20% difference in heart rate throughout at 24 h period. This provides evidence of flexibility in metabolic activity independent of temperature. Examination of the differences in heart rates of embryonic turtles incubated in either a group environment or individually, at a constant 30oC, and in darkness, showed that mortality rates were not affected but embryos incubated in the group environment had significantly shorter incubation duration. Heart rates were significantly higher in the embryos incubated individually during the middle of incubation, but were similar for the final two weeks of incubation. The mean heart rate variability was significantly higher in embryos incubated individually during the final two weeks of incubation. There was no significant difference between the two treatments in either neuromuscular ability or morphology. Changes in heart rates within a nest environment may be important for coordinating development and hatching between individuals in a nest. Analysing the order of oviposition in relation to incubation temperature in embryonic turtles incubated in fluctuating regimes indicated that eggs may be differentially suited for a particular temperature environment. Control eggs had shorter incubation duration when incubated with respect to oviposition order under two fluctuating temperature regimes (both equivalent to a constant 26 oC) reflecting temperatures experiences at the top and at the bottom of a nest. Bottom nest incubation temperatures fluctuated between 23oC and 29 oC and top of nest incubation temperatures fluctuated between 19 oC and 33 oC over a 24 h period. That is, if an embryo was oviposited early, it would incubate at the bottom of the nest and be exposed to slight fluctuations in temperature, and if an embryo was oviposited late it would be exposed to high fluctuation in temperature at the top of a nest. Order of oviposition also affected egg mass, with eggs oviposited early being heavier than those oviposited last, but this was not reflected in hatchling mass. There was no significant difference in neuromuscular ability between the treatment groups. Embryonic heart rates in the high fluctuating treatment group maintained significantly higher heart rates at the intermediate temperature of 26oC in the second last week of incubation, but in the final week of incubation the embryos in the control group had significantly higher heart rates at both an intermediate temperature (26oC) and a low temperature (19oC). In the slight fluctuating temperature regime, the embryos in the control group had significantly higher heart rates in the final week of incubation during the hotter temperature period (29oC). This study indicates turtle embryos are optimised for an incubation environment that their oviposition order, and subsequent position within a nest, would dictate. Studying the interaction between genotype, incubation temperature, and post-hatching environment (population density or temperature) on growth in hatchling turtles indicated effects of genotype and incubation temperature was still evident 11 months after hatching. Hotter post-hatching environments encouraged higher feeding rates in turtles and had significant effects on growth 11 months after hatching. The effect of higher population densities on growth was evident one month after hatching but not at 5 or 11 months after hatching. Oviposition order also affected growth, whereby late oviposited hatchings incubated at a hotter temperature (30oC) and reared in a warmer post-hatching environment, grew faster than turtles from the same clutch oviposited earlier. Long-term effects of genotype, oviposition order, incubation temperature, and post-hatching environment are evident in turtles. The results from this thesis identify areas of plasticity in embryonic and hatchling turtles at different life stages. Long-lasting environmental effects exist and a narrow range of thermal optima has been identified as being advantageous to hatchling turtles when they are at their most vulnerable

Modulational instability of partially coherent signals in electrical transmission lines

We present an investigation of the modulational instability of partially coherent signals in electrical transmission lines. Starting from the modified Ginzburg-Landau equations and the Wigner-Moyal representation, we derive a nonlinear dispersion relation for the modulational instability. It is found that the effect of signal broadbandness reduces the growth rate of the modulational instability.Comment: 5 pages, 1 figure, to appear in Physical Review

Theoretical study of angle-resolved two-photon photoemission in two-dimensional insulating cuprates

We propose angle-resolved two-photon photoemission spectroscopy (AR-2PPES) as a technique to detect the location of the bottom of the upper Hubbard band (UHB) in two-dimensional insulating cuprates. The AR-2PPES spectra are numerically calculated for small Hubbard clusters. When the pump photon excites an electron from the lower Hubbard band, the bottom of the UHB is less clear, but when an electron in the nonbonding oxygen band is excited, the bottom of the UHB can be identified clearly, accompanied with additional spectra originated from the spin-wave excitation at half filling.Comment: 5 pages, 4 figure

Canonical, squeezed and fermionic coherent states in a right quaternionic Hilbert space with a left multiplication on it

Using a left multiplication defined on a right quaternionic Hilbert space, we shall demonstrate that various classes of coherent states such as the canonical coherent states, pure squeezed states, fermionic coherent states can be defined with all the desired properties on a right quaternionic Hilbert space. Further, we shall also demonstrate squeezed states can be defined on the same Hilbert space, but the noncommutativity of quaternions prevents us in getting the desired results.Comment: Conference paper. arXiv admin note: text overlap with arXiv:1704.02946; substantial text overlap with arXiv:1706.0068

Fidelity for imperfect postselection

We describe a simple measure of fidelity for mixed state postselecting devices. The measure is most appropriate for postselection where the task performed by the output is only effected by a specific state.Comment: 8 Pages, 8 Figure

Testing quantum nonlocality by generalized quasiprobability functions

We derive a Bell inequality based on a generalized quasiprobability function which is parameterized by one non-positive real value. Two types of known Bell inequalities formulated in terms of the Wigner and Q functions are included as limiting cases. We investigate violations of our Bell inequalities for single photon entangled states and two-mode squeezed vacuum states when varying the detector efficiency. We show that the Bell inequality for the Q function allows the lowest detection efficiency for violations of local realism.Comment: 6 pages, 3 figure

Measurement of dynamic Stark polarizabilities by analyzing spectral lineshapes of forbidden transitions

We present a measurement of the dynamic scalar and tensor polarizabilities of the excited state 3D1 in atomic ytterbium. The polarizabilities were measured by analyzing the spectral lineshape of the 408-nm 1S0->3D1 transition driven by a standing wave of resonant light in the presence of static electric and magnetic fields. Due to the interaction of atoms with the standing wave, the lineshape has a characteristic polarizability-dependent distortion. A theoretical model was used to simulate the lineshape and determine a combination of the polarizabilities of the ground and excited states by fitting the model to experimental data. This combination was measured with a 13% uncertainty, only 3% of which is due to uncertainty in the simulation and fitting procedure. The scalar and tensor polarizabilities of the state 3D1 were measured for the first time by comparing two different combinations of polarizabilities. We show that this technique can be applied to similar atomic systems.Comment: 13 pages, 7 figures, submitted to PR

Lateral Effects in Fermion Antibunching

Lateral effects are analyzed in the antibunching of a beam of free non-interacting fermions. The emission of particles from a source is dynamically described in a 3D full quantum field-theoretical framework. The size of the source and the detectors, as well as the temperature of the source are taken into account and the behavior of the visibility is scrutinized as a function of these parameters.Comment: 22 pages, 4 figure