Experimental test of a Bell inequality with nonmaximally entangled states

Eine den lokalen Realismus widerlegende schlupflochfreie Verletzung einer Bell-Ungleichung wurde bisher nicht erreicht. Eine Verletzung der Eberhard-Ungleichung mit nicht maximal verschränkten Zuständen ermöglicht das Schließen des Detektionsschlupflochs mit einer Detektionseffizienz von 2/3. In dieser Arbeit wurden Photonenpaare in nicht maximal verschränkten Zuständen mit Lawinenphotodioden und hocheffizienten supraleitenden Phasenübergangsthermistoren, sogenannten “transition-edge sensors” (TESs), für ihre Verwendung in einem endgültigen, auf der Eberhard-Ungleichung basierten Bell-Experiment untersucht. Polarisationsverschränkte Photonenpaare wurden in einer Sagnac-Quelle in nicht maximal verschränkten Zuständen hergestellt. Für jeden der erzeugten Zustände wurde aus Messungen mit Lawinenphotodioden eine Dichtematrix rekonstruiert. Eine durchschnittliche Reinheit von 99,26(2) Prozent und eine durchschnittliche Güte für einen idealen, nicht maximal verschränkten Zustand von 99,01(1) Prozent wurden aus diesen Dichtematrizen berechnet. Ein hocheffizientes Detektionssystem basierend auf supraleitenden Phasenübergangsthermistoren, die von supraleitenden Quanteninterferometern ausgelesen werden, wurde in einem adiabatischen Entmagnetisierungskryostat installiert. Eine beispiellos hohe Ankündigungseffizienz von 82,2(3) Prozent für einen Produktzustand und 79,7(2) Prozent für einen verschränkten Zustand wurde direkt beobachtet. Die Eberhard-Ungleichung wurde mit supraleitenden Phasenübergangsthermistoren gemessen, jedoch waren die Ergebnisse noch nicht ausreichend für eine Verletzung. Weitere Verbesserungen des Aufbaus sind erforderlich. Diese Arbeit demonstriert die Schlüsselkomponenten, die für die Verletzung der Eberhard-Ungleichung benötigt werden: ein hocheffizientes Detektionssystem einschließlich des Einkoppelns in Fasern und eine Quelle hochreiner, nicht maximal verschränkter Zustände. Zusammen mit einem Quantenzufallsgenerator und zusätzlicher räumlicher Trennung ebnet diese Arbeit den Weg für ein endgültiges, schlupflochfreies Bell-Experiment, das nicht nur als grundsätzliche Fragestellung wichtig ist, sondern auch für Anwendungen wie geräteunabhängige Quantenschlüsselverteilung und die Zertifizierung von geräteunabhängiger Zufälligkeit.A loophole-free violation of a Bell inequality, which would refute local realism, has not been achieved yet. A violation of the Eberhard inequality using nonmaximally entangled states allows closure of the detection loophole with a detection efficiency of 2/3. In this thesis, nonmaximally entangled photon pairs were investigated with avalanche photodiodes and highly-efficient transition-edge sensors for their implementation in a conclusive Bell experiment based on the Eberhard inequality. The polarization-entangled photon pairs were generated in nonmaximally entangled states using a Sagnac source. For each of the produced states, a density matrix was reconstructed from measurements performed with avalanche photodiodes. An average purity of 99.26(2) percent and an average fidelity with the ideal nonmaximally entangled state of 99.01(1) percent was calculated from these density matrices. A highly-efficient detection system based on superconducting transition-edge sensors read out by superconducting quantum interference devices was installed in an adiabatic demagnetization refrigerator. An unprecedentedly high heralding efficiency was directly observed: 82.2(3) percent for a product state and 79.7(2) percent for an entangled state. The Eberhard inequality was measured with transition-edge sensors, but the results were not yet adequate for a violation. Further improvements of the setup are required. This thesis demonstrates the key components needed for a violation of the Eberhard inequality: a highly-efficient detection system including fibre coupling and a high-purity source of nonmaximally entangled photon pairs. Together with a quantum random number generator and additional space-like separation, this work paves the way for a loophole-free Bell experiment, which is important not only to address a fundamental question but also for applications such as device-independent quantum key distribution and certification of device-independent randomness

Bell violation with entangled photons, free of the fair-sampling assumption

The violation of a Bell inequality is an experimental observation that forces one to abandon a local realistic worldview, namely, one in which physical properties are (probabilistically) defined prior to and independent of measurement and no physical influence can propagate faster than the speed of light. All such experimental violations require additional assumptions depending on their specific construction making them vulnerable to so-called "loopholes." Here, we use photons and high-efficiency superconducting detectors to violate a Bell inequality closing the fair-sampling loophole, i.e. without assuming that the sample of measured photons accurately represents the entire ensemble. Additionally, we demonstrate that our setup can realize one-sided device-independent quantum key distribution on both sides. This represents a significant advance relevant to both fundamental tests and promising quantum applications

Quantum teleportation using active feed-forward between two Canary Islands

Quantum teleportation [1] is a quintessential prerequisite of many quantum information processing protocols [2-4]. By using quantum teleportation, one can circumvent the no-cloning theorem [5] and faithfully transfer unknown quantum states to a party whose location is even unknown over arbitrary distances. Ever since the first experimental demonstrations of quantum teleportation of independent qubits [6] and of squeezed states [7], researchers have progressively extended the communication distance in teleportation, usually without active feed-forward of the classical Bell-state measurement result which is an essential ingredient in future applications such as communication between quantum computers. Here we report the first long-distance quantum teleportation experiment with active feed-forward in real time. The experiment employed two optical links, quantum and classical, over 143 km free space between the two Canary Islands of La Palma and Tenerife. To achieve this, the experiment had to employ novel techniques such as a frequency-uncorrelated polarization-entangled photon pair source, ultra-low-noise single-photon detectors, and entanglement-assisted clock synchronization. The average teleported state fidelity was well beyond the classical limit of 2/3. Furthermore, we confirmed the quality of the quantum teleportation procedure (without feed-forward) by complete quantum process tomography. Our experiment confirms the maturity and applicability of the involved technologies in real-world scenarios, and is a milestone towards future satellite-based quantum teleportation

Opinion on the re-evaluation of sodium carboxy methyl cellulose (E 466) as a food additive in foods for infants below 16 weeks of age and follow-up of its re-evaluation as food additive for uses in foods for all population groups

Sodium carboxy methyl cellulose (E 466) was re-evaluated in 2018 by the former EFSA Panel on Food Additives and Nutrient sources added to Food (ANS). As a follow-up to this assessment, the Panel on Food Additives and Flavourings (FAF) was requested to assess the safety of E 466 for its uses as a food additive in food for infants below 16 weeks of age belonging to food categories (FC) 13.1.5.1 (Dietary foods for infants for special medical purposes and special formulae for infants) in line with Regulation (EC) No 1333/2008. In addition, the FAF Panel was requested to address the issues already identified during the re-evaluation of the food additive when used in food for the general population, including the safety assessment for FC 13.1.5.1 and 13.1.5.2 (Dietary foods for babies and young children for special medical purposes as defined in directive 1999/21/EC). The process involved the publication of a call for data. Based on the received data, the Panel concluded that the technical data provided by the interested business operator support an amendment of the specifications for sodium carboxy methyl cellulose (E 466) laid down in Commission Regulation (EU) No 231/2012. The interested business operators declared that E 466 is not used in food for infants below 16 weeks of age and in FC 13.1.5.1. Due to the lack of data, an assessment has not been performed for this FC and age group. The interested business operators did not provide biological and toxicological data to support the uses of E 466 in FC 13.1.5.2. Due to the almost unchanged database compared to the situation before the call for data, the FAF Panel confirmed the previous EFSA ANS Panel conclusion according to which the available data did not allow for an adequate assessment of the safety of use of sodium carboxy methyl cellulose (E 466) in infants and young children consuming foods belonging to the FC 13.1.5.2. (c) 2022 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority

Re-evaluation of locust bean gum (E 410) as a food additive in foods for infants below 16 weeks of age and follow-up of its re-evaluation as a food additive for uses in foods for all population groups

Locust bean gum (E 410) was re-evaluated in 2017 by the former EFSA Panel on Food Additives and Nutrient sources added to Food (ANS). As a follow-up to that assessment, the Panel on Food Additives and Flavourings (FAF) was requested to assess the safety of locust bean gum (E 410) for its uses as a food additive in food for infants below 16 weeks of age belonging to food category 13.1.5.1 (Dietary foods for infants for special medical purposes and special formulae for infants). In addition, the FAF Panel was requested to address the issues already identified during the re-evaluation of the food additive when used in food for the general population, including the safety assessment for FC 13.1.5.1 and 13.1.5.2 (Dietary foods for babies and young children for special medical purposes as defined in directive 1999/21/EC). The process involved the publication of a call for data. Based on the received data, the Panel concluded that the technical data provided by the interested business operators support an amendment of the specifications for locust bean gum (E 410) laid down in Commission Regulation (EU) No 231/2012. The Panel identified a reference point of 1,400 mg/kg bw per day based on reduced blood zinc levels in a piglet study. It applied the margin of exposure (MoE) for the safety assessment of locust bean gum (E 410) when used as a food additive in FC 13.1.5.1 and 13.1.5.2. The Panel concluded that a MoE above 1 would not raise a safety concern. A MoE above 1 was obtained for some of the scenarios and exposure levels for infants. For toddlers (consumers only of food for special medical purposes), the MoE was above 1 for all exposure levels

Follow-up of the re-evaluation of sulfur dioxide (E 220), sodium sulfite (E 221), sodium bisulfite (E 222), sodium metabisulfite (E 223), potassium metabisulfite (E 224), calcium sulfite (E 226), calcium bisulfite (E 227) and potassium bisulfite (E 228)

Sulfur dioxide-sulfites (E 220-228) were re-evaluated in 2016, resulting in the setting of a temporary ADI of 0.7 mg SO2 equivalents/kg bw per day. Following a European Commission call for data, the present follow-up opinion assesses data provided by interested business operators (IBOs) and additional evidence identified in the publicly available literature. No new biological or toxicological data addressing the data gaps described in the re-evaluation were submitted by IBOs. Taking into account data identified from the literature search, the Panel concluded that there was no substantial reduction in the uncertainties previously identified in the re-evaluation. Therefore, the Panel considered that the available toxicity database was inadequate to derive an ADI and withdrew the current temporary group acceptable daily intake (ADI). A margin of exposure (MOE) approach was considered appropriate to assess the risk for these food additives. A lower confidence limit of the benchmark dose of 38 mg SO2 equivalents/kg bw per day, which is lower than the previous reference point of 70 mg SO2 equivalents/kg bw per day, was estimated based on prolonged visual evoked potential latency. An assessment factor of 80 was applied for the assessment of the MoE. At the estimated dietary exposures, when using a refined exposure scenario (Data set D), MOEs at the maximum of 95th percentile ranges were below 80 for all population groups except for adolescents. The dietary exposures estimated using the maximum permitted levels would result in MOEs below 80 in all population groups at the maximum of the ranges of the mean, and for most of the population groups at both minimum and maximum of the ranges at the 95th percentile. The Panel concluded that this raises a safety concern for both dietary exposure scenarios. The Panel also performed a risk assessment for toxic elements present in sulfur dioxide-sulfites (E 220-228), based on data submitted by IBOs, and concluded that the maximum limits in the EU specifications for arsenic, lead and mercury should be lowered and a maximum limit for cadmium should be introduced

When Does an Alien Become a Native Species? A Vulnerable Native Mammal Recognizes and Responds to Its Long-Term Alien Predator

The impact of alien predators on native prey populations is often attributed to prey naiveté towards a novel threat. Yet evolutionary theory predicts that alien predators cannot remain eternally novel; prey species must either become extinct or learn and adapt to the new threat. As local enemies lose their naiveté and coexistence becomes possible, an introduced species must eventually become ‘native’. But when exactly does an alien become a native species? The dingo (Canis lupus dingo) was introduced to Australia about 4000 years ago, yet its native status remains disputed. To determine whether a vulnerable native mammal (Perameles nasuta) recognizes the close relative of the dingo, the domestic dog (Canis lupus familiaris), we surveyed local residents to determine levels of bandicoot visitation to yards with and without resident dogs. Bandicoots in this area regularly emerge from bushland to forage in residential yards at night, leaving behind tell-tale deep, conical diggings in lawns and garden beds. These diggings were less likely to appear at all, and appeared less frequently and in smaller quantities in yards with dogs than in yards with either resident cats (Felis catus) or no pets. Most dogs were kept indoors at night, meaning that bandicoots were not simply chased out of the yards or killed before they could leave diggings, but rather they recognized the threat posed by dogs and avoided those yards. Native Australian mammals have had thousands of years experience with wild dingoes, which are very closely related to domestic dogs. Our study suggests that these bandicoots may no longer be naïve towards dogs. We argue that the logical criterion for determining native status of a long-term alien species must be once its native enemies are no longer naïve

Re-evaluation of neohesperidine dihydrochalcone (E 959) as a food additive

The present opinion deals with the re-evaluation of neohesperidine dihydrochalcone (E 959) when used as a food additive. It is obtained by catalytic hydrogenation of a flavanone - neohesperidine - which is naturally occurring and thus isolated by alcohol extraction in bitter oranges (Citrus aurantium). Based on in vivo data in rat, neohesperidine dihydrochalcone is likely to be absorbed, also in humans, and to become systemically available. It does not raise a concern regarding genotoxicity. The toxicity data set consisted of studies on subchronic and prenatal developmental toxicity. No human studies were available. The data set was considered sufficient to derive a new acceptable daily intake (ADI). Based on the weight of evidence (WoE) analysis, the Panel considered unlikely that neohesperidine dihydrochalcone would lead to adverse effects on health in animals in the dose ranges tested. The Panel also considered that a carcinogenicity study was not warranted and that the lack of human data did not affect the overall confidence in the body of evidence. The Panel derived an ADI of 20 mg/kg bodyweight (bw) per day based on a no observed adverse effect level (NOAEL) of 4,000 mg/kg bw per day from a 13-week study in rat, applying the standard default factors of 100 for inter- and intraspecies differences and of 2 for extrapolation from subchronic to chronic exposure. For the refined brand-loyal exposure assessment scenario, considered to be the most appropriate for the risk assessment, the exposure estimates at the mean ranged from < 0.01 to 0.09 mg/kg bw per day and at the 95th percentile (P95) from 0.01 to 0.24 mg/kg bw per day. Considering the derived ADI of 20 mg/kg bw per day, the exposure estimates were below the reference value in all age groups. Therefore, the Panel concluded that dietary exposure to the food additive neohesperidine dihydrochalcone (E 959) at the reported uses and use levels would not raise a safety concern

A high-resolution climatological snowfall map for Antarctica

status: Published onlin