On the heating of source of the Orion KL hot core

We present images of the J=10-9 rotational lines of HC3N in the vibrationally excited levels 1v7, 1v6 and 1v5 of the hot core (HC) in Orion KL. The images show that the spatial distribution and the size emission from the 1v7 and 1v5 levels are different. While the J=10-9 1v7 line has a size of 4''x 6'' and peaks 1.1'' NE of the 3 mm continuum peak, the J=10--9 1v5 line emission is unresolved (<3'') and peaks 1.3'' south of the 3 mm peak. This is a clear indication that the HC is composed of condensations with very different temperatures (170 K for the 1v7 peak and $>230$ K for the 1v5 peak). The temperature derived from the 1v7 and 1v5 lines increases with the projected distance to the suspected main heating source I. Projection effects along the line of sight could explain the temperature gradient as produced by source I. However, the large luminosity required for source I, >5 10^5 Lsolar, to explain the 1v5 line suggests that external heating by this source may not dominate the heating of the HC. Simple model calculations of the vibrationally excited emission indicate that the HC can be internally heated by a source with a luminosity of 10^5 Lsolar, located 1.2'' SW of the 1v5 line peak (1.8'' south of source I). We also report the first detection of high-velocity gas from vibrationally excited HC3N emission. Based on excitation arguments we conclude that the main heating source is also driving the molecular outflow. We speculate that all the data presented in this letter and the IR images are consistent with a young massive protostar embedded in an edge-on disk.Comment: 13 pages, 3 figures, To be published in Ap.J. Letter

Speed limits for quantum gates in multi-qubit systems

We use analytical and numerical calculations to obtain speed limits for various unitary quantum operations in multiqubit systems under typical experimental conditions. The operations that we consider include single-, two-, and three-qubit gates, as well as quantum-state transfer in a chain of qubits. We find in particular that simple methods for implementing two-qubit gates generally provide the fastest possible implementations of these gates. We also find that the three-qubit Toffoli gate time varies greatly depending on the type of interactions and the system's geometry, taking only slightly longer than a two-qubit controlled-NOT (CNOT) gate for a triangle geometry. The speed limit for quantum-state transfer across a qubit chain is set by the maximum spin-wave speed in the chain.Comment: 7 pages (two-column), 2 figures, 2 table

The space of rules and rules of space: reflecting on local ordinances during the Covid-19 pandemic

This article investigates the role of the spatial dimension in the formulation of pandemic rules in Italy, with a specific focus on the municipal ordinances enacted in Milan. The study conducts a critical review of multidisciplinary literature, which often marginalises the significance of spatial dynamics in the development of (pandemic) regulatory frameworks, relegating “space” to a peripheral rather than central concern. This research proposes an analytical framework to evaluate spatial rules based on key thematic categories, with reference to the application and structural attributes of pandemic regulations. The article also discusses the practical integration of spatial dimensions into regulatory design, emphasising the imperative of acknowledging and engaging with unique spatial characteristics in order to enhance the efficacy of legal and policy interventions

Selective darkening of degenerate transitions for implementing quantum controlled-NOT gates

We present a theoretical analysis of the selective darkening method for implementing quantum controlled-NOT (CNOT) gates. This method, which we recently proposed and demonstrated, consists of driving two transversely-coupled quantum bits (qubits) with a driving field that is resonant with one of the two qubits. For specific relative amplitudes and phases of the driving field felt by the two qubits, one of the two transitions in the degenerate pair is darkened, or in other words, becomes forbidden by effective selection rules. At these driving conditions, the evolution of the two-qubit state realizes a CNOT gate. The gate speed is found to be limited only by the coupling energy J, which is the fundamental speed limit for any entangling gate. Numerical simulations show that at gate speeds corresponding to 0.48J and 0.07J, the gate fidelity is 99% and 99.99%, respectively, and increases further for lower gate speeds. In addition, the effect of higher-lying energy levels and weak anharmonicity is studied, as well as the scalability of the method to systems of multiple qubits. We conclude that in all these respects this method is competitive with existing schemes for creating entanglement, with the added advantages of being applicable for qubits operating at fixed frequencies (either by design or for exploitation of coherence sweet-spots) and having the simplicity of microwave-only operation.Comment: 25 pages, 5 figure

Quantum limit of photothermal cooling

We study the problem of cooling a mechanical oscillator using the photothermal (bolometric) force. Contrary to previous attempts to model this system, we take into account the noise effects due to the granular nature of photon absorption. This allows us to tackle the cooling problem down to the noise dominated regime and to find reasonable estimates for the lowest achievable phonon occupation in the cantilever

Comportamento agronômico de uvas de mesa no Vale do São Francisco.

O presente trabalho tem como objetivo avaliar 122 genótipos de uvas de mesa, visando selecionar aqueles com características superiores para serem recomendados para cultivo comercial ou para serem utilizados em programas de melhoramento genético

Comportamento agronômico de genótipos de videira para produção de vinhos finos no Vale do São Francisco.

Este trabalho tem como objetivo avaliar o comportamento agronômico de 58 genótipos de videira com aptidão para produção de vinhos finos no Vale do São Francisco