Cross-verification of independent quantum devices

Quantum computers are on the brink of surpassing the capabilities of even the most powerful classical computers. This naturally raises the question of how one can trust the results of a quantum computer when they cannot be compared to classical simulation. Here we present a verification technique that exploits the principles of measurement-based quantum computation to link quantum circuits of different input size, depth, and structure. Our approach enables consistency checks of quantum computations within a device, as well as between independent devices. We showcase our protocol by applying it to five state-of-the-art quantum processors, based on four distinct physical architectures: nuclear magnetic resonance, superconducting circuits, trapped ions, and photonics, with up to 6 qubits and 200 distinct circuits

Disappeared persons and homicide in El Salvador

During 2012–2013, the homicide rate in El Salvador came down from 69.9 to 42.2 per 100,000 population following a government brokered truce between the leaders of the two major gangs, Mara Salvatrucha and Barrio 18. But despite the apparent successes of the truce, it was speculated that the drop in murders could have been due to the killers simply hid the bodies of their victims. This paper aims at determining whether gangs effectively disappeared their victims to cut down the official counts of murders, or they committed these crimes for other reasons. The results from this study suggest that Salvadoran gangs had been using disappearance as a method to gain sustained social control among residents of already gang-dominated areas, that together with homicide, disappearance is part of a process of territorial spread and strategic strengthening by which these groups are enhancing their capabilities to interfere in the alliances of Mexican drug trafficking organizations with Central American criminal organizations specializing in the trans-shipment of drugs and in providing access to local markets to distribute and sell drugs. Our findings show that the risk for disappearance has been large even before the truce was in place and that actually, it continues as such and going through a process of geographic expansion

Interdisciplinary collaboration in the treatment of alcohol use disorders in a general hospital department:A mixed-method study

Background !nterdisciplinary collaborations (i.e., where various disciplines work coordinated and interdependently toward shared goals) are stated to yield higher team effectiveness than multidisciplinary approaches (i.e., where various disciplines work in parallel within their professional boundaries) in somatic health care settings. Nevertheless, research is lacking on interdisciplinary approaches for alcohol use disorder (AUD) treatment of hospitalized patients as these types of approaches are still uncommon. This study aims to evaluate an innovative interdisciplinary AUD treatment initiative at a general hospital department by 1) identifying which and to what extent network partners are involved and 2) to explore how network partners experienced the interdisciplinary collaboration. Methods A mixed-method study was conducted, using 1) measures of contact frequency and closeness in a social network analysis and 2) semi-structured interviews, which were analyzed thematically. Respondents were network partners of an interdisciplinary collaboration in a general hospital department, initially recruited by the collaborations' project leader. Results The social network analysis identified 16 network partners, including a 'core' network with five central network partners from both inside and outside the hospital. The project leader played an important central role in the network and the resident gastroenterologist seemed to have a vulnerable connection within the network. Closeness between network partners was experienced regardless of frequency of contact, although this was especially true for the 'core' group that (almost) always consisted of the same network partners that were present at biweekly meetings. Interview data showed that presence of the 'core' network partners was reported crucial for an efficient collaboration. Respondents desired knowledge about the collaborations' effectiveness, and one structured protocol with working procedures, division of responsibilities and agreements on information sharing and feedback. Conclusions The design of this interdisciplinary collaboration has potential in improving the treatment of hospital patients with AUD and was evaluated positively by the involved network partners. Interdisciplinary collaborations may offer a critical solution to increase treatment rates of patients with AUD and should be adopted in hospitals on a larger scale. Research towards the effectiveness of interdisciplinary collaborations in the treatment of hospitalized patients with AUD is needed. A correction to this paper has been published: https://doi.org/10.1186/s13011-022-00492-

Genuine Counterfactual Communication with a Nanophotonic Processor

In standard communication information is carried by particles or waves. Counterintuitively, in counterfactual communication particles and information can travel in opposite directions. The quantum Zeno effect allows Bob to transmit a message to Alice by encoding information in particles he never interacts with. The first suggested protocol not only required thousands of ideal optical components, but also resulted in a so-called "weak trace" of the particles having travelled from Bob to Alice, calling the scalability and counterfactuality of previous proposals and experiments into question. Here we overcome these challenges, implementing a new protocol in a programmable nanophotonic processor, based on reconfigurable silicon-on-insulator waveguides that operate at telecom wavelengths. This, together with our telecom single-photon source and highly-efficient superconducting nanowire single-photon detectors, provides a versatile and stable platform for a high-fidelity implementation of genuinely trace-free counterfactual communication, allowing us to actively tune the number of steps in the Zeno measurement, and achieve a bit error probability below 1%, with neither post-selection nor a weak trace. Our demonstration shows how our programmable nanophotonic processor could be applied to more complex counterfactual tasks and quantum information protocols.Comment: 6 pages, 4 figure

Barriers and facilitators for treatment-seeking for mental health conditions and substance misuse:Multi-perspective focus group study within the military

Background Globally, millions are exposed to stressors at work that increase their vulnerability to develop mental health conditions and substance misuse (such as soldiers, policemen, doctors). However, these types of professionals especially are expected to be strong and healthy, and this contrast may worsen their treatment gap. Although the treatment gap in the military has been studied before, perspectives of different stakeholders involved have largely been ignored, even though they play an important role. Aims To study the barriers and facilitators for treatment-seeking in the military, from three different perspectives. Method In total, 46 people participated, divided into eight homogeneous focus groups, including three perspectives: soldiers with mental health conditions and substance misuse (n = 20), soldiers without mental health conditions and substance misuse (n = 10) and mental health professionals (n = 16). Sessions were audio-taped and transcribed verbatim. Content analysis was done by applying a general inductive approach using ATLAS.ti-8.4.4 software. Results Five barriers for treatment-seeking were identified: fear of negative career consequences, fear of social rejection, confidentiality concerns, the ‘strong worker’ workplace culture and practical barriers. Three facilitators were identified: social support, accessibility and knowledge, and healthcare within the military. The views of the different stakeholder groups were highly congruent. Conclusions Barriers for treatment-seeking were mostly stigma related (fear of career consequences, fear of social rejection and the ‘strong worker’ workplace culture) and this was widely recognised by all groups. Social support from family, peers, supervisors and professionals were identified as important facilitators. A decrease in the treatment gap for mental health conditions and substance misuse is needed and these findings provide direction for future research and destigmatising interventions

Accounting for photodegradation dramatically improves prediction of carbon losses in dryland systems

Traditional models of decomposition fail to capture litter mass loss patterns in dryland systems. This shortcoming has stimulated research into alternative drivers of decomposition, including photodegradation. Here, we use aboveground litter decomposition data for dryland (arid) sites from the Long-term Intersite Decomposition Experiment Team data set to test hypotheses (models) about the mechanisms and impacts of photodegradation. Incorporating photodegradation into a traditional biotic decomposition model substantially improved model predictions for mass loss at these dryland sites, especially after four years. The best model accounted for the effects of solar radiation via photodegradation loss from the intermediate cellulosic and lignin pools and direct inhibition of microbial decomposition. Despite the concurrent impacts of photodegradation and inhibition on mass loss, the best photodegradation model increased mass loss by an average of 12% per year compared to the biotic-only decomposition model. The best model also allowed soil infiltration into litterbags to reduce photodegradation and inhibition of microbial decomposition by shading litter from solar radiation. Our modeling results did not entirely support the popular hypothesis that initial lignin content increases the effects of photodegradation on litter mass loss; surprisingly, higher initial lignin content decreased the rate of cellulosic photodegradation. Importantly, our results suggest that mass loss rates due to photodegradation may be comparable to biotic decomposition rates: Mass loss due to photodegradation alone resulted in litter mass losses of 6–15% per year, while mass loss due to biotic decomposition ranged from 20% per year during early-stage decomposition to 3% per year during late-stage decomposition. Overall, failing to account for the impacts of solar radiation on litter mass loss under-predicted long-term litter mass loss by approximately 26%. Thus, not including photodegradation in dryland decomposition models likely results in large underestimations of carbon loss from dryland systems

Belemmerende en bevorderende factoren voor hulp zoeken bij psychische klachten of verslaving:Focusgroepstudie vanuit meerdere perspectieven binnen de Nederlandse krijgsmacht

Achtergrond Wereldwijd worden miljoenen mensen op het werk blootgesteld aan stressvolle factoren die de kans op het ontwikkelen van psychische klachten en/of verslaving (PK/V) verhogen (bijvoorbeeld militairen, politie, artsen). Maar het zijn ook juist deze beroepen waar men geacht wordt sterk en gezond te zijn. Hierdoor is het soms moeilijker om hulp te zoeken voor PK/V. Zo laat Engels onderzoek zien dat 60% van de militairen met PK/V hier geen professionele hulp voor zoekt. Eerder onderzoek naar hulp zoeken voor PK/V richtte zich met name op het perspectief van militairen met PK/V, waarbij andere belangrijke perspectieven niet meegenomen werden. Daarnaast is dit probleem niet eerder onderzocht binnen de Nederlandse krijgsmacht. Doel Het doel van de huidige studie was de belemmerende en bevorderende factoren voor het zoeken van hulp voor PK/V in kaart te brengen binnen de Nederlandse krijgsmacht vanuit verschillende perspectieven. Methode In totaal hebben 46 mensen deelgenomen aan de studie verdeeld over acht focusgroepen, met drie verschillende perspectieven: vier groepen militairen met PK/V (totaal 20 deelnemers), twee groepen militairen zonder PK/V (totaal 10 deelnemers) en twee groepen zorgprofessionals (totaal 16 deelnemers). De focusgroepen zijn opgenomen en letterlijk uitgeschreven. Vervolgens is met behulp van kwalitatieve data-analysesoftware contentanalyse uitgevoerd vanuit een inductieve benadering. Resultaten Er zijn vijf belemmerende factoren voor het zoeken van hulp gevonden: (1) angst voor negatieve carrièregevolgen, (2) angst voor sociale afwijzing, (3) zorgen rond de vertrouwelijkheid, (4) de militaire werkcultuur en (5) praktische barrières. Ook zijn drie bevorderende factoren gevonden: (1) sociale steun, (2) toegankelijkheid zorgverlening en kennis over waar hulp te verkrijgen en (3) militaire zorgverlening. Ondanks dat het onderzoek zich expliciet richtte op verschillende perspectieven kwamen de visies van de deelnemers sterk overeen. Conclusie De meeste belemmerende factoren voor het zoeken van hulp waren gerelateerd aan stigma (angst voor carrièregevolgen, sociale afwijzing en militaire werkcultuur) en dit werd benoemd door alle drie de verschillende perspectieven. Sociale steun vanuit het thuisfront, collega’s, leidinggevende en zorgprofessionals werd gezien als bevorderend voor het zoeken van hulp. De resultaten van de huidige studie geven richting voor zowel toekomstig (interventie)onderzoek als beleid, om ervoor te zorgen dat meer militairen hulp zoeken voor PK/V

Trace-free counterfactual communication with a nanophotonic processor

Abstract: In standard communication information is carried by particles or waves. Counterintuitively, in counterfactual communication particles and information can travel in opposite directions. The quantum Zeno effect allows Bob to transmit a message to Alice by encoding information in particles he never interacts with. A first remarkable protocol for counterfactual communication relied on thousands of ideal optical operations for high success rate performance. Experimental realizations of that protocol have thus employed post-selection to demonstrate counterfactuality. This post-selection, together with arguments concerning a so-called “weak trace” of the particles traveling from Bob to Alice, have led to a discussion regarding the counterfactual nature of the protocol. Here we circumvent these controversies, implementing a new, and fundamentally different, protocol in a programmable nanophotonic processor, based on reconfigurable silicon-on-insulator waveguides that operate at telecom wavelengths. This, together with our telecom single-photon source and highly efficient superconducting nanowire single-photon detectors, provides a versatile and stable platform for a high-fidelity implementation of counterfactual communication with single photons, allowing us to actively tune the number of steps in the Zeno measurement, and achieve a bit error probability below 1%, without post-selection and with a vanishing weak trace. Our demonstration shows how our programmable nanophotonic processor could be applied to more complex counterfactual tasks and quantum information protocols

Variability and Change in the West Antarctic Peninsula Marine System: Research Priorities and Opportunities

The west Antarctic Peninsula (WAP) region has undergone significant changes in temperature and seasonal ice dynamics since the mid-twentieth century, with strong impacts on the regional ecosystem, ocean chemistry and hydrographic properties. Changes to these long-term trends of warming and sea ice decline have been observed in the 21st century, but their consequences for ocean physics, chemistry and the ecology of the high-productivity shelf ecosystem are yet to be fully established. The WAP shelf is important for regional krill stocks and higher trophic levels, whilst the degree of variability and change in the physical environment and documented biological and biogeochemical responses make this a model system for how climate and sea ice changes might restructure high-latitude ecosystems. Although this region is arguably the best-measured and best-understood shelf region around Antarctica, significant gaps remain in spatial and temporal data capable of resolving the atmosphere-ice-ocean-ecosystem feedbacks that control the dynamics and evolution of this complex polar system. Here we summarise the current state of knowledge regarding the key mechanisms and interactions regulating the physical, biogeochemical and biological processes at work, the ways in which the shelf environment is changing, and the ecosystem response to the changes underway. We outline the overarching cross-disciplinary priorities for future research, as well as the most important discipline-specific objectives. Underpinning these priorities and objectives is the need to better define the causes, magnitude and timescales of variability and change at all levels of the system. A combination of traditional and innovative approaches will be critical to addressing these priorities and developing a co-ordinated observing system for the WAP shelf, which is required to detect and elucidate change into the future