Two-qubit quantum photonic processor manufactured by femtosecond laser writing

We present an experimental implementation of a two-qubit photonic quantum processor fabricated using femtosecond laser writing technology. We employ femtosecond laser writing to create a low-loss reconfigurable photonic chip implementing precise single-qubit and two-qubit operations. The performance of single-qubit and two-qubit gates is characterized by full process tomography. An exemplary application of the processor to determining the ground state energy of an H2 molecule using the variational quantum eigensolver algorithm is demonstrated. Our results highlight the potential of femtosecond laser writing technology to deliver high quality small-scale quantum photonic processors.Comment: 20 pages, 15 figure

The atmospheric role in the Arctic water cycle: A review on processes, past and future changes, and their impacts

This is the final version of the article. Available from the publisher via the DOI in this record.Atmospheric humidity, clouds, precipitation, and evapotranspiration are essential components of the Arctic climate system. During recent decades, specific humidity and precipitation have generally increased in the Arctic, but changes in evapotranspiration are poorly known. Trends in clouds vary depending on the region and season. Climate model experiments suggest that increases in precipitation are related to global warming. In turn, feedbacks associated with the increase in atmospheric moisture and decrease in sea ice and snow cover have contributed to the Arctic amplification of global warming. Climate models have captured the overall wetting trend but have limited success in reproducing regional details. For the rest of the 21st century, climate models project strong warming and increasing precipitation, but different models yield different results for changes in cloud cover. The model differences are largest in months of minimum sea ice cover. Evapotranspiration is projected to increase in winter but in summer to decrease over the oceans and increase over land. Increasing net precipitation increases river discharge to the Arctic Ocean. Over sea ice in summer, projected increase in rain and decrease in snowfall decrease the surface albedo and, hence, further amplify snow/ice surface melt. With reducing sea ice, wind forcing on the Arctic Ocean increases with impacts on ocean currents and freshwater transport out of the Arctic. Improvements in observations, process understanding, and modeling capabilities are needed to better quantify the atmospheric role in the Arctic water cycle and its changes.We thank all colleagues involved in the Arctic Freshwater Synthesis (AFS) for fruitful discussions. In particular, John Walsh is acknowledged for his constructive comments on the manuscript. AFS has been sponsored by the World Climate Research Programme’s Climate and the Cryosphere project (WCRP-CliC), the International Arctic Science Committee (IASC), and the Arctic Monitoring and Assessment Programme (AMAP). The work for this paper has been supported by the Academy of Finland (contracts 259537 and 283101), the UK Natural Environment Research Council (grant NE/J019585/1), the US National Science Foundation grant ARC-1023592 and the Program “Arctic” and the Basic Research Program of the Presidium Russian Academy of Sciences. NCAR is supported by the U.S. National Science Foundation. We gratefully acknowledge the project coordination and meeting support of Jenny Baeseman and Gwenaelle Hamon at the CliC International Project Office. No new data were applied in the manuscript. Data applied for Figures 2 and 3 are available from the JRA-55 archive at http://jra. kishou.go.jp/JRA-55/index_en. html#usage

Влияние снежного покрова на промерзание и протаивание грунта на Западном Шпицбергене

This paper presents the results of experimental research of snow cover influence on ground freezing/thawing in Svalbard. Observations show that even before the snow disappearance ground thaws for dozens of centimeters that increases the thaw depth later in the season. Under the snow cover of 40 cm the thaw depth can reach 35–50 cm. The thawing can be caused by melt water with slightly positive temperature, percolating under the snow cover near the ground surface. The data on ground temperature regime during a year under various snow depths are given. Under a shallow snow cover the ground cools significantly, and this process causes the slowing down subsequent thawing.Рассматриваются результаты натурных измерений и расчётов влияния снежного покрова на промерзание и протаивание грунта на Западном Шпицбергене. Установлено, что ещё до схода снежного покрова грунт протаивает на десятки сантиметров, в результате чего увеличивается толщина талого слоя. Так, под снегом, толщиной 40 см, глубина протаивания грунта составляет 35–50 см. По мнению авторов, это может быть вызвано талой водой с небольшой положительной температурой, фильтрующейся под снежным покровом в приповерхностной части грунта

Influence of snow cover on soil freezing and thawing in the West Spitsbergen

This paper presents the results of experimental research of snow cover influence on ground freezing/thawing in Svalbard. Observations show that even before the snow disappearance ground thaws for dozens of centimeters that increases the thaw depth later in the season. Under the snow cover of 40 cm the thaw depth can reach 35–50 cm. The thawing can be caused by melt water with slightly positive temperature, percolating under the snow cover near the ground surface. The data on ground temperature regime during a year under various snow depths are given. Under a shallow snow cover the ground cools significantly, and this process causes the slowing down subsequent thawing