6,735 research outputs found
Detection of entanglement in ultracold lattice gases
We propose the use of quantum polarization spectroscopy for detecting
multi-particle entanglement of ultracold atoms in optical lattices. This
method, based on a light-matter interface employing the quantum Farady effect,
allows for the non destructive measurement of spin-spin correlations. We apply
it to the specific example of a one dimensional spin chain and reconstruct its
phase diagram using the light signal, readily measurable in experiments with
ultracold atoms. Interestingly, the same technique can be extended to detect
quantum many-body entanglement in such systems.Comment: Submitted to the Special Issue: "Strong correlations in Quantum
Gases" in The Journal of Low Temperature Physic
Genuine quantum correlations in quantum many-body systems: a review of recent progress
Quantum information theory has considerably helped in the understanding of
quantum many-body systems. The role of quantum correlations and in particular,
bipartite entanglement, has become crucial to characterise, classify and
simulate quantum many body systems. Furthermore, the scaling of entanglement
has inspired modifications to numerical techniques for the simulation of
many-body systems leading to the, now established, area of tensor networks.
However, the notions and methods brought by quantum information do not end with
bipartite entanglement. There are other forms of correlations embedded in the
ground, excited and thermal states of quantum many-body systems that also need
to be explored and might be utilised as potential resources for quantum
technologies. The aim of this work is to review the most recent developments
regarding correlations in quantum many-body systems focussing on multipartite
entanglement, quantum nonlocality, quantum discord, mutual information but also
other non classical measures of correlations based on quantum coherence.
Moreover, we also discuss applications of quantum metrology in quantum
many-body systems.Comment: Review. Close to published version. Comments are welcome! Please
write an email to g.dechiara[(at)]qub.ac.u
Thermometry Precision in Strongly Correlated Ultracold Lattice Gases
The precise knowledge of the temperature of an ultracold lattice gas
simulating a strongly correlated system is a question of both, fundamental and
technological importance. Here, we address such question by combining tools
from quantum metrology together with the study of the quantum correlations
embedded in the system at finite temperatures. Within this frame we examine the
spin- XY chain, first estimating, by means of the quantum Fisher
information, the lowest attainable bound on the temperature precision. We then
address the estimation of the temperature of the sample from the analysis of
correlations using a quantum non demolishing Faraday spectroscopy method.
Finally, we demonstrate that for sufficiently low temperatures the proposed
measurements are optimal to estimate accurately the temperature of the sample.Comment: 16 pages, 5 figure
Optical eigenmode imaging
We present an indirect imaging method that measures both amplitude and phase
information from a transmissive target. Our method is based on an optical
eigenmode decomposition of the light intensity and the first-order cross
correlation between a target field and these eigenmodes. We demonstrate that
such optical eigenmode imaging does not need any a priori knowledge of the
imaging system and corresponds to a compressive full-field sampling leading to
high image extraction efficiencies. Finally, we discuss the implications with
respect to second-order correlation imaging
Herpes simplex virus-type1 (HSV-1) impairs DNA repair in cortical neurons
Several findings suggest that Herpes simplex virus-1 (HSV-1) infection plays a role in the neurodegenerative processes that characterize Alzheimer's disease (AD), but the underlying mechanisms have yet to be fully elucidated. Here we show that HSV-1 productive infection in cortical neurons causes the accumulation of DNA lesions that include both single (SSBs) and double strand breaks (DSBs), which are reported to be implicated in the neuronal loss observed in neurodegenerative diseases. We demonstrate that HSV-1 downregulates the expression level of Ku80, one of the main components of non-homologous end joining (NHEJ), a major pathway for the repair of DSBs. We also provide data suggesting that HSV-1 drives Ku80 for proteasomal degradation and impairs NHEJ activity, leading to DSB accumulation. Since HSV-1 usually causes life-long recurrent infections, it is possible to speculate that cumulating damages, including those occurring on DNA, may contribute to virus induced neurotoxicity and neurodegeneration, further suggesting HSV-1 as a risk factor for neurodegenerative conditions
Long-range multipartite entanglement close to a first order quantum phase transition
We provide insight in the quantum correlations structure present in strongly
correlated systems beyond the standard framework of bipartite entanglement. To
this aim we first exploit rotationally invariant states as a test bed to detect
genuine tripartite entanglement beyond the nearest-neighbor in spin-1/2 models.
Then we construct in a closed analytical form a family of entanglement
witnesses which provides a sufficient condition to determine if a state of a
many-body system formed by an arbitrary number of spin-1/2 particles possesses
genuine tripartite entanglement, independently of the details of the model. We
illustrate our method by analyzing in detail the anisotropic XXZ spin chain
close to its phase transitions, where we demonstrate the presence of long range
multipartite entanglement near the critical point and the breaking of the
symmetries associated to the quantum phase transition.Comment: 6 pages, 3 figures, RevTeX 4, the abstract was changed and the
manuscript was extended including the contents of the previous appendix
A novel method to titrate Herpes simplex virus-1 (HSV-1) using laser-based scanning of near-infrared fluorophores conjugated antibodies
Among several strategies used for Herpes simplex virus (HSV) detection in biological specimens, standard plaque assay (SPA) remains the most reliable method to evaluate virus infectivity and quantify viral replication. However, it is a manual procedure, thereby affected by operator subjectivity, and it may be particularly laborious for multiple sample analysis. Here we describe an innovative method to perform the titration of HSV type 1 (HSV-1) in different samples, using the “In-Cell WesternTM” Assay (ICW) from LI-COR, a quantitative immunofluorescence assay that exploits laser-based scanning of near infrared (NIR). In particular, we employed NIR-immunodetection of viral proteins to monitor foci of HSV-1 infection in cell monolayers, and exploited an automated detection of their fluorescence intensity to evaluate virus titre. This innovative method produced similar and superimposable values compared to SPA, but it is faster and can be performed in 96 well plate, thus allowing to easily and quickly analyze and quantify many samples in parallel. These features make our method particularly suitable for the screening and characterization of antiviral compounds, as we demonstrated by testing acyclovir (ACV), the main anti-HSV-1 drug. Moreover, we developed a new data analysis system that allowed to overcome potential bias due to unspecific florescence signals, thus improving data reproducibility. Overall, our method may represents a useful tool for both clinical and research purposes
Intragenic transcriptional cis-activation of the human immunodeficiency virus 1 does not result in allele-specific inhibition of the endogenous gene
<p>Abstract</p> <p>Background</p> <p>The human immunodeficiency virus type 1 (HIV-1) favors integration in active genes of host chromatin. It is believed that transcriptional interference of the viral promoter over the endogenous gene or vice versa might occur with implications in HIV-1 post-integrative transcriptional latency.</p> <p>Results</p> <p>In this work a cell line has been transduced with a HIV-based vector and selected for Tat-inducible expression. These cells were found to carry a single silent integration in sense orientation within the second intron of the <it>HMBOX1 </it>gene. The HIV-1 Tat transactivator induced the viral LTR and repressed <it>HMBOX1 </it>expression independently of vector integration. Instead, single-cell quantitative <it>in situ </it>hybridization revealed that allele-specific transcription of <it>HMBOX1 </it>carrying the integrated provirus was not affected by the transactivation of the viral LTR in <it>cis</it>.</p> <p>Conclusion</p> <p>A major observation of the work is that the HIV-1 genome has inserted in genes that are also repressed by Tat and this could be an advantage for the virus during transcriptional reactivation. In addition, it has also been observed that transcription of the provirus and of the endogenous gene in which it is integrated may coexist at the same time in the same genomic location.</p
Advanced Label-Free Optical Methods for Spermatozoa Quality Assessment and Selection
Current in vitro fertilization (IVF) techniques require a severe selection of sperm, generally based on concentration, morphology, motility, and DNA integrity. Since routinely separation methods may damage the viability of the sperm cell, there is a growing interest in providing a method for noninvasively analyzing spermatozoa taking into account all those parameters. This chapter first reviews the state-of-the-art of label-free sperm cell imaging for IVF, highlighting the limitations of the used techniques. Then, our innovative approach combining Raman spectroscopy and digital holography will be described and its advantages detailed. These include the ability to perform a simultaneous and correlative morphological and biochemical analysis of sperm cells, without labeling, in a fast and reliable way. Finally, the difficulty in reaching clinical use will be discussed, as well as the possible solutions offered by new technological improvements
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