Exotic States in the Dynamical Casimir Effect

We consider the interaction of a qubit with a single mode of the quantized electromagnetic field and show that, in the ultrastrong coupling regime and when the qubit-field interaction is switched on abruptly, the dynamical Casimir effect leads to the generation of a variety of exotic states of the field, which cannot be simply described as squeezed states. Such effect also appears when initially both the qubit and the field are in their ground state. The non-classicality of the obtained exotic states is characterized by means of a parameter based on the volume of the negative part of the Wigner function. A transition to non-classical states is observed by changing either the interaction strength or the interaction time. The observed phenomena appear as a general feature of nonadiabatic quantum gates, so that the dynamical Casimir effect can be the origin of a fundamental upper limit to the maximum speed of quantum computation and communication protocols.Comment: 5 pages, 4 figure

Non-perturbative interpretation of the Bloch vector's path beyond rotating wave approximation

The Bloch vector's path of a two-level system exposed to a monochromatic field exhibits, in the regime of strong coupling, complex corkscrew trajectories. By considering the infinitesimal evolution of the two-level system when the field is treated as a classical object, we show that the Bloch vector's rotation speed oscillates between zero and twice the rotation speed predicted by the rotating wave approximation. Cusps appear when the rotation speed vanishes. We prove analytically that in correspondence to cusps the curvature of the Bloch vector's path diverges. On the other hand, numerical data show that the curvature is very large even for a quantum field in the deep quantum regime with mean number of photons $\bar{n}\lesssim 1$. We finally compute numerically the typical error size in a quantum gate when the terms beyond rotating wave approximation are neglected.Comment: 9 pages, 8 figure

Matter-wave interferometry: towards antimatter interferometers

Starting from an elementary model and refining it to take into account more realistic effects, we discuss the limitations and advantages of matter-wave interferometry in different configurations. We focus on the possibility to apply this approach to scenarios involving antimatter, such as positrons and positronium atoms. In particular, we investigate the Talbot-Lau interferometer with material gratings and discuss in details the results in view of the possible experimental verification.Comment: 18 pages; 8 figure

Dynamical Casimir Effect in Quantum Information Processing

We demonstrate, in the regime of ultrastrong matter-field coupling, the strong connection between the dynamical Casimir effect (DCE) and the performance of quantum information protocols. Our results are illustrated by means of a realistic quantum communication channel and show that the DCE is a fundamental limit for quantum computation and communication and that novel schemes are required to implement ultrafast and reliable quantum gates. Strategies to partially counteract the DCE are also discussed.Comment: 7 pages, 5 figure

Plasma concentrations of boosted and unboosted atazanavir are predicted by 63396C>T SNP in the PXR gene

Purpose of the study Atazanavir (ATV) is administered at the usual adult dose of 300 mg with 100 mg of ritonavir (RTV) once a day (boosted). However, 400 mg once a day (unboosted) is also used in some settings. ATV plasma concentrations are influenced by efflux transporters, influx transporters and metabolism enzymes. The expression of many of these proteins is regulated by nuclear receptors such as PXR. Recently polymorphisms in the regulatory region of the PXR gene have been reported to influence its expression and the activity of downstream genes, such as CYP3A4 and ABCB1. The aim of this study was to investigate whether polymorphisms in PXR influence trough concentrations (Ctrough) of boosted or unboosted ATV