Quantum Key Distribution using Continuous-variable non-Gaussian States

In this work we present a quantum key distribution protocol using continuous-variable non-Gaussian states, homodyne detection and post-selection. The employed signal states are the Photon Added then Subtracted Coherent States (PASCS) in which one photon is added and subsequently one photon is subtracted. We analyze the performance of our protocol, compared to a coherent state based protocol, for two different attacks that could be carried out by the eavesdropper (Eve). We calculate the secret key rate transmission in a lossy line for a superior channel (beam-splitter) attack, and we show that we may increase the secret key generation rate by using the non-Gaussian PASCS rather than coherent states. We also consider the simultaneous quadrature measurement (intercept-resend) attack and we show that the efficiency of Eve's attack is substantially reduced if PASCS are used as signal states.Comment: We have included an analysis of the simultaneous quadrature measurement attack plus 2 figures; we have also clarified some point

With phases: how two wrongs can sometimes make a right

Combining experimental phases and those from refinement of very incomplete models significantly improves electron-density maps

The Paradox of Tik Tok Anti-Pro-Anorexia Videos: How Social Media Can Promote Non-Suicidal Self-Injury and Anorexia

The literature shows that social pressure promotes non-suicidal self-injury (NSSI) eating disorders, along with self-injury, are also favored by underregulated social media. Tik tok is one of the most used social media platforms among adolescents. It has been shown that the time young children spend on this platform doubled during the lockdown. The theme of anorexia is very common on this platform. While most "pro-ana" (pro-anorexia) videos, where users exchanged advice on how to pathologically lose weight, have been censored by the application, other "anti-pro-ana" (anti-pro-anorexia) videos, officially aimed at raising awareness of the consequences of anorexia, have become increasingly popular. However, our case shows how even these safer videos paradoxically lead the users to emulate these "guilty" behaviors

Bipartite quantum channels using multipartite cluster-type entangled coherent states

We propose a particular encoding for bipartite entangled states derived from multipartite cluster-type entangled coherent states (CTECSs). We investigate the effects of amplitude damping on the entanglement content of this bipartite state, as well as its usefulness as a quantum channel for teleportation. We find interesting relationships among the amplitude of the coherent states constituting the CTECSs, the number of subsystems forming the logical qubits (redundancy), and the extent to which amplitude damping affects the entanglement of the channel. For instance, in the sense of sudden death of entanglement, given a fixed value of the initial coherent state amplitude, the entanglement life span is shortened if redundancy is increased.Comment: 6 pages, 3 figures, REVTeX 4.1, BibTe

Alice in wonderland: experimental jurisprudence on the internal point of view

Humans have this extraordinary cognitive ability: They imagine inexistent objects, they treat them as if they were real, and by doing so they make them real. They thus give rise to a shared institutional reality that enables them to cooperate in ways that would be impossible otherwise. In this paper, we would like to revisit the account that HLA Hart gives of the practice of collective acceptance that makes a legal system possible. We try to provide an explanation of what Hart calls the 'internal point of view', on the basis of experiments on institutional concepts, drawing on the paradigm known as 'embodied cognition'. Experts and non-experts in law rated the role of several cognitive dimensions for a list of words referring to two kinds of abstract concepts (institutional and theoretical/scientific) and two kinds of concrete ones (food and artifact). Institutional concepts were distinguished into pure-institutional (e.g., 'contract', 'state', 'property') and meta-institutional (e.g., 'norm', 'duty', 'justice'). The results provide an empirical account of how our way of thinking about institutions changes as we acquire expertise in the legal field, thus shading light on the cognitive underpinnings of the 'internal point of view'

Unitary transformation approach for the trapped ion dynamics

We present a way of treating the problem of the interaction of a single trapped ion with laser beams based on successive aplications of unitary transformations onto the Hamiltonian. This allows the diagonalization of the Hamiltonian, by means of recursive relations, without performing the Lamb-Dicke approximation.Comment: 8 page

Spontaneous emission and teleportation in cavity QED

In this work, we consider atomic spontaneous emission in a system consisting of two identical two-level atoms interacting dispersively with the quantized electromagnetic field in a high-Q cavity. We investigate the destructive effect of the atomic decay on the generation of maximally entangled states, following the proposal by Zheng S B and Guo G C (2000 Phys. Rev. Lett. 85 2392). In particular, we analyze the fidelity of teleportation performed using such a noisy channel and calculatethe maximum spontaneous decay rate we may have in order to realize teleportation.Comment: 11 pages, 6 figures, LaTe

A structural study of the interaction between the Dr haemagglutinin DraE and derivatives of chloramphenicol

The structures of two Dr adhesin (DraE) complexes with chloramphenicol derivatives, namely chloramphenicol succinate and bromamphenicol, have been solved. The structures reveal important functional groups for small-molecule binding and imply possible modifications to the molecule that would permit a more wide-ranging interaction without the toxic side effects associated with chloramphenicol