806 research outputs found
Dispersion spreading of biphotons in optical fibres and two-photon interference
We present the first observation of two-photon polarization interference
structure in the second-order Glauber's correlation function of two-photon
light generated via type-II spontaneous parametric down-conversion. In order to
obtain this result, two-photon light is transmitted through an optical fibre
and the coincidence distribution is analyzed by means of the START-STOP method.
Beyond the experimental demonstration of an interesting effect in quantum
optics, these results also have considerable relevance for quantum
communications.Comment: Accepted for publication in Phys.Rev.Let
The time as an emergent property of quantum mechanics, a synthetic description of a first experimental approach
The "problem of time" in present physics substantially consists in the fact
that a straightforward quantization of the general relativistic evolution
equation and constraints generates for the Universe wave function the
Wheeler-De Witt equation, which describes a static Universe. Page and Wootters
considered the fact that there exist states of a system composed by entangled
subsystems that are stationary, but one can interpret the component subsystems
as evolving: this leads them to suppose that the global state of the universe
can be envisaged as one of this static entangled state, whereas the state of
the subsystems can evolve. Here we synthetically present an experiment, based
on PDC polarization entangled photons, that allows showing with a practical
example a situation where this idea works, i.e. a subsystem of an entangled
state works as a "clock" of another subsystem
Recent experiments performed at "Carlo Novero" lab at INRIM on Quantum Information and Foundations of Quantum Mechanics
In this paper we present some recent work performed at "Carlo Novero" lab on
Quantum Information and Foundations of Quantum Mechanics.Comment: Contribution to III international workshop "Recent advances in
Foundations of Quantum Mechanics and Quantum Information. In memory of Carlo
Novero
Experimental realization of a measurement conditional unitary operation at single photon level and application to detector characterization
Our last experimental results on the realization of a measurement-conditional
unitary operation at single photon level are presented. This gate operates by
rotating by the polarization of a photon produced by means of Type-II
Parametric Down Conversion conditional to a polarization measurement on the
correlated photon. We then propose a new scheme for measuring the quantum
efficiency of a single photon detection apparatus by using this set-up. We
present experimental results obtained with this scheme compared with {\it
traditional} biphoton calibration. Our results show the interesting
potentiality of the suggested scheme.Comment: to appear in Proc. of SPIE meeting, Denver august 200
Experimental quantum cryptography scheme based on orthogonal states
Since, in general, non-orthogonal states cannot be cloned, any eavesdropping
attempt in a Quantum Communication scheme using non-orthogonal states as
carriers of information introduces some errors in the transmission, leading to
the possibility of detecting the spy. Usually, orthogonal states are not used
in Quantum Cryptography schemes since they can be faithfully cloned without
altering the transmitted data. Nevertheless, L. Goldberg and L. Vaidman [\prl
75 (1995) 1239] proposed a protocol in which, even if the data exchange is
realized using two orthogonal states, any attempt to eavesdrop is detectable by
the legal users. In this scheme the orthogonal states are superpositions of two
localized wave packets travelling along separate channels. Here we present an
experiment realizing this scheme
The PreAmplifier ShAper for the ALICE TPC-Detector
In this paper the PreAmplifier ShAper (PASA) for the Time Projection Chamber
(TPC) of the ALICE experiment at LHC is presented. The ALICE TPC PASA is an
ASIC that integrates 16 identical channels, each consisting of Charge Sensitive
Amplifiers (CSA) followed by a Pole-Zero network, self-adaptive bias network,
two second-order bridged-T filters, two non-inverting level shifters and a
start-up circuit. The circuit is optimized for a detector capacitance of 18-25
pF. For an input capacitance of 25 pF, the PASA features a conversion gain of
12.74 mV/fC, a peaking time of 160 ns, a FWHM of 190 ns, a power consumption of
11.65 mW/ch and an equivalent noise charge of 244e + 17e/pF. The circuit
recovers smoothly to the baseline in about 600 ns. An integral non-linearity of
0.19% with an output swing of about 2.1 V is also achieved. The total area of
the chip is 18 mm and is implemented in AMS's C35B3C1 0.35 micron CMOS
technology. Detailed characterization test were performed on about 48000 PASA
circuits before mounting them on the ALICE TPC front-end cards. After more than
two years of operation of the ALICE TPC with p-p and Pb-Pb collisions, the PASA
has demonstrated to fulfill all requirements
Self consistent, absolute calibration technique for photon number resolving detectors
Well characterized photon number resolving detectors are a requirement for
many applications ranging from quantum information and quantum metrology to the
foundations of quantum mechanics. This prompts the necessity for reliable
calibration techniques at the single photon level. In this paper we propose an
innovative absolute calibration technique for photon number resolving
detectors, using a pulsed heralded photon source based on parametric down
conversion. The technique, being absolute, does not require reference standards
and is independent upon the performances of the heralding detector. The method
provides the results of quantum efficiency for the heralded detector as a
function of detected photon numbers. Furthermore, we prove its validity by
performing the calibration of a Transition Edge Sensor based detector, a real
photon number resolving detector that has recently demonstrated its
effectiveness in various quantum information protocols.Comment: 9 pages, 2 figure
Covid-19 vaccine: A survey of hesitancy in patients with celiac disease
(1) Background: COVID-19 vaccination campaigns offer the best hope of controlling the pandemic. However, the fast production of COVID-19 vaccines has caused concern among the general public regarding their safety and efficacy. In particular, patients with chronic illnesses, such as celiac disease (CD), may be more fearful. Information on vaccine hesitancy plays a pivotal role in the development of an efficient vaccination campaign. In our study, we aimed to evaluate COVID-19 vaccine hesitancy among Italian CD patients. (2) Methods: an anonymous questionnaire was sent to CD patients followed at our tertiary referral center for CD in Milan, Italy. Patients were defined as willing, hesitant and refusing. We evaluated the reasons for hesitancy/refusal and the possible determinants, calculating crude and adjusted odds ratios [AdjORs] with 95% confidence intervals [CIs]. (3) Results: the questionnaire was sent to 346 patients with a response rate of 29.8%. Twenty-six (25.2%) of the 103 respondents were hesitant, with a total refusal rate of 4.8%. The main reason was fear of adverse events related to vaccination (68.2%). Among hesitant patients, 23% declared that their opinion was influenced by their CD. The determinants positively influencing willingness to be vaccinated against COVID-19 were adherence to a GFD, perception of good knowledge about COVID-19 and its vaccines, and a positive attitude to previous vaccines (AdjOR 12.71, 95% CI 1.82–88.58, AdjOR 6.50, 95% CI 1.44–29.22, AdjOR 0.70, 95% CI 0.11–4.34, respectively). (4) Conclusions: CD patients should be vaccinated against COVID-19 and a specific campaign to address the determinants of hesitancy should be developed
Quantum and classical characterization of single/few photon detectors
This paper's purpose is to review the results recently obtained in the
Quantum Optics labs of the National Institute of Metrological Research (INRIM)
in the field of single- and few-photon detectors calibration, from both the
classical and quantum viewpoint. In the first part of the paper is presented
the calibration of a single-photon detector with absolute methods, while in the
second part we focus on photon-number-resolving detectors, discussing both the
classical and quantum characterization of such devices.Comment: Quantum Matter in pres
Emotion dysregulation, impulsivity and anger rumination in borderline personality disorder: the role of amygdala and insula
© 2023 The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Borderline Personality Disorder (BPD) is a severe mental disorder, characterized by deficits in emotion regulation, interpersonal dysfunctions, dissociation and impulsivity. Brain abnormalities have been generally explored; however, the specific contribution of different limbic structures to BPD symptomatology is not described. The aim of this study is to cover this gap, exploring functional and structural alterations of amygdala and insula and to highlight their contribution to neuropsychiatric symptoms. Twenty-eight BPD patients (23.7 ± 3.42 years; 6 M/22F) and twenty-eight matched healthy controls underwent a brain MR protocol (1.5 T, including a 3D T1-weighted sequence and resting-state fMRI) and a complete neuropsychiatric assessment. Volumetry, cortical thickness and functional connectivity of amygdala and insula were evaluated, along with correlations with the neuropsychiatric scales. BPD patients showed a lower cortical thickness of the left insula (p = 0.027) that negatively correlated with the Anger Rumination Scale (p = 0.019; r = − 0.450). A focused analysis on female patients showed a significant reduction of right amygdala volumes in BPD (p = 0.037), that correlate with Difficulties in Emotion Regulation Scale (p = 0.031; r = − 0.415), Beck Depression Inventory (p = 0.009; r = − 0.50) and Ruminative Response Scale (p = 0.045; r = − 0.389). Reduced functional connectivity was found in BPD between amygdala and frontal pole, precuneus and temporal pole. This functional connectivity alterations correlated with Anger Rumination Scale (p = .009; r = − 0.491) and Barratt Impulsiveness Scale (p = 0.020; r = − 0.447). Amygdala and insula are altered in BPD patients, and these two limbic structures are implicated in specific neuropsychiatric symptoms, such as difficulty in emotion regulation, depression, anger and depressive rumination.Peer reviewe
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