Optomechanical state reconstruction and nonclassicality verification beyond the resolved-sideband regime

Quantum optomechanics uses optical means to generate and manipulate quantum states of motion of mechanical resonators. This provides an intriguing platform for the study of fundamental physics and the development of novel quantum devices. Yet, the challenge of reconstructing and verifying the quantum state of mechanical systems has remained a major roadblock in the field. Here, we present a novel approach that allows for tomographic reconstruction of the quantum state of a mechanical system without the need for extremely high quality optical cavities. We show that, without relying on the usual state transfer presumption between light an mechanics, the full optomechanical Hamiltonian can be exploited to imprint mechanical tomograms on a strong optical coherent pulse, which can then be read out using well-established techniques. Furthermore, with only a small number of measurements, our method can be used to witness nonclassical features of mechanical systems without requiring full tomography. By relaxing the experimental requirements, our technique thus opens a feasible route towards verifying the quantum state of mechanical resonators and their nonclassical behaviour in a wide range of optomechanical systems.Comment: 12 pages + 9 pages of appendices, 4 figure

Structural Quantification of Entanglement

We introduce an approach which allows a detailed structural and quantitative analysis of multipartite entanglement. The sets of states with different structures are convex and nested. Hence, they can be distinguished from each other using appropriate measurable witnesses. We derive equations for the construction of optimal witnesses and discuss general properties arising from our approach. As an example, we formulate witnesses for a 4-cluster state and perform a full quantitative analysis of the entanglement structure in the presence of noise and losses. The strength of the method in multimode continuous variable systems is also demonstrated by considering a dephased GHZ-type state.Comment: 12 pages, 1 table and 3 figure

Operational Gaussian Schmidt-Number Witnesses

The general class of Gaussian Schmidt-number witness operators for bipartite systems is studied. It is shown that any member of this class is reducible to a convex combination of two types of Gaussian operators using local operations and classical communications. This gives rise to a simple operational method, which is solely based on measurable covariance matrices of quantum states. Our method bridges the gap between theory and experiment of entanglement quantification. In particular, we certify lower bounds of the Schmidt number of squeezed thermal and phase-randomized squeezed vacuum states, as examples of Gaussian and non-Gaussian quantum states, respectively.Comment: 9 pages, 4 figure

Effects Of Exposure To Violence On Health In Iraq Between 2006-2007

Iraq has experienced protracted years of war in last two decades. These prolonged years of war in Iraq manifested conflict and violence, degeneration of economic conditions and a serious breakdown of public health services. Deaths, injury and acts of violence such as kidnapping, threat and witnessing heavy casualties are only a few examples of events that Iraqi people experienced during war times. Conflict can result in lasting and profound consequences for the health of the Iraq population. The burden of the communicable, non-communicable disease and mental illnesses in war zone areas is rising rapidly and becoming a major challenge to global development. Using data from the 2006-2007 Iraq Household Socio-Economic Survey, I examine the association between violence exposure and morbidity for a sample of Iraqis individuals. We find that exposure to violence is associated with both increased incidence of chronic and acute illnesses, particularly respiratory and mental illness. Interestingly, the health of adolescents and adults appears to be most at risk to violence exposure while that of children is largely protected

Quantum Correlations in Nonlocal BosonSampling

Determination of the quantum nature of correlations between two spatially separated systems plays a crucial role in quantum information science. Of particular interest is the questions of if and how these correlations enable quantum information protocols to be more powerful. Here, we report on a distributed quantum computation protocol in which the input and output quantum states are considered to be classically correlated in quantum informatics. Nevertheless, we show that the correlations between the outcomes of the measurements on the output state cannot be efficiently simulated using classical algorithms. Crucially, at the same time, local measurement outcomes can be efficiently simulated on classical computers. We show that the only known classicality criterion violated by the input and output states in our protocol is the one used in quantum optics, namely, phase-space nonclassicality. As a result, we argue that the global phase-space nonclassicality inherent within the output state of our protocol represents true quantum correlations.Comment: 5 pages, 1 figure, comments are very welcome

Quantum Correlations and Global Coherence in Distributed Quantum Computing

Deviations from classical physics when distant quantum systems become correlated are interesting both fundamentally and operationally. There exist situations where the correlations enable collaborative tasks that are impossible within the classical formalism. Here, we consider the efficiency of quantum computation protocols compared to classical ones as a benchmark for separating quantum and classical resources and argue that the computational advantage of collaborative quantum protocols in the discrete variable domain implies the nonclassicality of correlations. By analysing a toy model, it turns out that this argument implies the existence of quantum correlations distinct from entanglement and discord. We characterize such quantum correlations in terms of the net global coherence resources inherent within quantum states and show that entanglement and discord can be understood as special cases of our general framework. Finally, we provide an operational interpretation of such correlations as those allowing two distant parties to increase their respective local quantum computational resources only using locally incoherent operations and classical communication.Comment: Minor modifications and correction

Effect of soybean planting patterns on some plant environmental measurements and yield

‘Essex\u27 soybeans (Glycine max (L.) Merr.) were used to investi-gate how the relationship between plant density and distribution and environmental weather factors such as radiation, temperature and soil moisture influences soybean yield. Field studies were conducted during the 1980 growing season on a Sequatchie loam soil at the Plant and Soil Science Field Laboratory near Knoxville, Tennessee. Soybean yields were measured at plant populations of 2, 4, 6, 8, 10, and 12 plants per 30 cm of row in 25 cm, 51 cm, 76 cm, and 102-cm rows. Soil moisture depletion was measured by neutron meter in the middle of the row and adjacent to the row to determine the pattern of soil moisture as affected by different plant populations and row spacings. Incoming radiation was measured at the top of the plant canopy and down vertically in the middle of the row and over the main axis of the plant. Vinyl tipped waterproof probes were used for soil tempera-ture measurements at 8 plants per 30 cm of the row for 25, 51, and 76- cm row spacings. As an average of all plant populations the highest yields were obtained from the 25-cm row spacing. Among plant populations, the yield for 2 plants per 30 cm of row was the lowest regardless of the row spacing. Interactions of the number of plants and row spacings showed that the 25-cm row spacing with 8 or 10 plants per 30 cm of row generally outyielded all other planting patterns. Percent surface soil moisture early in the season was very similar for all planting patterns. Later in the season the pattern of soil moisture was indicated that regardless of row spacing, moisture use in the row was higher than in the middle of the row. Moisture content in wider rows (76, 102 cm) was higher than in narrower rows probably because of less competition among plants to exploit surface moisture and larger area between rows. Yields were reduced in relation to the reduction in surface soil moisture. Soybeans which were grown in narrow rows had a significant effect on solar interception. Number of plants per 30 cm of the row was not as influential on light interception as row spacings. The percent of radiation reaching the soil surface in the middle of the row increased with row width. During the day early in the season at full canopy closure there was no significant difference between middle-of-the-row and in-the-row soil temperatures at 25-cm row spacing. The soil temperature reached its maximum value about 2 hours after the maximum air temperature. Soil temperature difference at time of canopy closure was not significant between the 25-cm and 76-cm row spacings

Entanglement and nonclassicality: a mutual impression

We find a sufficient condition to imprint the single-mode bosonic phase-space nonclassicality onto a bipartite state as modal entanglement and vice versa using an arbitrary beam splitter. Surprisingly, the entanglement produced or detected in this way depends only on the nonclassicality of the marginal input or output states, regardless of their purity and separability. In this way, our result provides a sufficient condition for generating entangled states of arbitrary high temperature and arbitrary large number of particles. We also study the evolution of the entanglement within a lossy Mach-Zehnder interferometer and show that unless both modes are totally lost, the entanglement does not diminish

Measurement-Device-Independent Approach to Entanglement Measures

Within the context of semiquantum nonlocal games, the trust can be removed from the measurement devices in an entanglement-detection procedure. Here we show that a similar approach can be taken to quantify the amount of entanglement. To be specific, first, we show that in this context a small subset of semiquantum nonlocal games is necessary and sufficient for entanglement detection in the LOCC paradigm. Second, we prove that the maximum pay-off for these games is a universal measure of entanglement which is convex and continuous. Third, we show that for the quantification of negative-partial-transpose entanglement, this subset can be further reduced down to a single arbitrary element. Importantly, our measure is operationally accessible in a measurement-device-independent way by construction. Finally, our approach is simply extended to quantify the entanglement within any partitioning of multipartite quantum states.Comment: 8 pages, 2 figures, the main result is split into two theorems with slight modifications, extended proof