Reduced density matrix and entanglement in interacting quantum field theory with Hamiltonian truncation.

Entanglement is the fundamental difference between classical and quantum systems and has become one of the guiding principles in the exploration of high- and low-energy physics. The calculation of entanglement entropies in interacting quantum field theories, however, remains challenging. Here, we present the first method for the explicit computation of reduced density matrices of interacting quantum field theories using truncated Hamiltonian methods. The method is based on constructing an isomorphism between the Hilbert space of the full system and the tensor product of Hilbert spaces of sub-intervals. This naturally enables the computation of the von Neumann and arbitrary R\'enyi entanglement entropies as well as mutual information, logarithmic negativity and other measures of entanglement. Our method is applicable to equilibrium states and non-equilibrium evolution in real time. It is model independent and can be applied to any Hamiltonian truncation method that uses a free basis expansion. We benchmark the method on the free Klein-Gordon theory finding excellent agreement with the analytic results. We further demonstrate its potential on the interacting sine-Gordon model, studying the scaling of von Neumann entropy in ground states and real time dynamics following quenches of the model

Preprint arXiv: 2211.00023 Submitted on 31 Oct 2022

Tensor network states, and in particular Projected Entangled Pair States(PEPS) have been a strong ansatz for the variational study of complicatedquantum many-body systems, thanks to their built-in entanglement entropy arealaw. In this work, we use a special kind of PEPS - Gauged Gaussian FermionicPEPS (GGFPEPS) to find the ground state of $2+1d$ dimensional pure$\mathbb{Z}_2$ lattice gauge theories for a wide range of coupling constants.We do so by combining PEPS methods with Monte-Carlo computations, allowing forefficient contraction of the PEPS and computation of correlation functions.Previously, such numerical computations involved the calculation of thePfaffian of a matrix scaling with the system size, forming a severe bottleneck;in this work we show how to overcome this problem. This paves the way forapplying the method we propose and benchmark here to other gauge groups, higherdimensions, and models with fermionic matter, in an efficient,sign-problem-free way

Star-Formation in the Ultraluminous Infrared Galaxy F00183-7111

We report the detection of molecular CO(1-0) gas in F00183-7111, one of the most extreme Ultra-Luminous Infrared Galaxies known, with the Australia Telescope Compact Array. We measure a redshift of 0.3292 for F00183-7111 from the CO(1-0) line and estimate the mass of the molecular gas in 00183 to be 1 $\times$ 10$^{10}$ M$_{\odot}$. We find that F00183-7111 is predominately powered by the AGN and only $\sim$14 per cent of the total luminosity is contributed by star-formation (SFR $\sim$220 M$_{\odot}$ yr$^{-1}$). We also present an optical image of F00183-7111, which shows an extension to the East. We searched for star-formation in this extension using radio continuum observations but do not detect any. This suggests that the star-formation is likely to be predominately nuclear. These observations provide additional support for a model in which the radio emission from ULIRGs is powered by an intense burst of star-formation and by a radio-loud AGN embedded in its nucleus, both triggered by a merger of gas-rich galaxies.Comment: 5 pages, 2 figures, Accepted for publication in MNRAS Letters Accepted 2014 January 19. Received 2013 December 30; in original form 2013 November 2

The core fundamental plane of B2 radio galaxies

The photometric, structural and kinematical properties of the centers of elliptical galaxies, harbor important information of the formation history of the galaxies. In the case of non active elliptical galaxies these properties are linked in a way that surface brightness, break radius and velocity dispersion of the core lie on a fundamental plane similar to that found for their global properties. We construct the Core Fundamental Plane (CFP) for a sizeable sample of low redshift radio galaxies and compare it with that of non radio ellipticals. To pursue this aim we combine data obtained from high resolution HST images with medium resolution optical spectroscopy to derive the photometric and kinematic properties of ~40 low redshift radio galaxies. We find that the CFPs of radio galaxies is indistinguishable from that defined by non radio elliptical galaxies of similar luminosity. The characteristics of the CFP of radio galaxies are also consistent (same slope) with those of the Fundamental Plane (FP) derived from the global properties of radio (and non radio) elliptical galaxies. The similarity of CFP and FP for radio and non radio ellipticals suggests that the active phase of these galaxies has minimal effects for the structure of the galaxies.Comment: 8 pages, 4 figures, accepted for publication in Astronomy and Astrophysic

Velamentous cord insertion associated with vasa praevia.

editorial reviewedVelamentous cord insertion is a rare placental abnormality, that may be associated with vasa praevia, i.e. the presence of an umbilical vessel near the internal cervical orifice. In case of spontaneous rupture of the membranes, there is a major risk of fetal haemorrhage, which is often lethal for the unborn baby. The challenge of care is based on the prenatal diagnosis during the 2nd trimester ultrasound. In case a vasa praevia is confirmed during the 3rd trimester, elective caesarean section should be carried out prior to the onset of labour, between 34 and 36 weeks of pregnancy. Corticosteroid treatment for fetal lung maturation is recommended at 32 weeks of gestation because of the increased risk of preterm delivery. Velamentous cord insertion may be associated with other adverse pregnancy outcomes such as intrauterine growth restriction, death in utero, placental abnormalities.L’insertion vélamenteuse du cordon ombilical est une anomalie placentaire rare, pouvant être associée à un vasa praevia, c’est-à-dire la présence d’un vaisseau ombilical en regard de l’orifice interne du col utérin. En cas de rupture spontanée des membranes, le risque d’hémorragie fœtale est majeur et, le plus souvent, létal pour l’enfant à naître. Le défi de la prise en charge est le diagnostic anténatal à l’échographie du 2ème trimestre. En cas de vasa praevia confirmé lors du 3ème trimestre, une césarienne doit être programmée avant la mise en travail spontanée, aux alentours de 34-36 semaines d’aménorrhée. Une cure de maturation pulmonaire par corticostéroïdes est recommandée à 32 semaines d’aménorrhée en raison du risque accru de prématurité. L’insertion vélamenteuse du cordon peut être associée à d’autres complications périnatales telles qu’un retard de croissance intra-utérin, une mort fœtale in utero, des anomalies placentaires