Reaching the quantum limit of sensitivity in electron spin resonance

We report pulsed electron-spin resonance (ESR) measurements on an ensemble of Bismuth donors in Silicon cooled at 10mK in a dilution refrigerator. Using a Josephson parametric microwave amplifier combined with high-quality factor superconducting micro-resonators cooled at millikelvin temperatures, we improve the state-of-the-art sensitivity of inductive ESR detection by nearly 4 orders of magnitude. We demonstrate the detection of 1700 bismuth donor spins in silicon within a single Hahn echo with unit signal-to-noise (SNR) ratio, reduced to just 150 spins by averaging a single Carr-Purcell-Meiboom-Gill sequence. This unprecedented sensitivity reaches the limit set by quantum fluctuations of the electromagnetic field instead of thermal or technical noise, which constitutes a novel regime for magnetic resonance.Comment: Main text : 10 pages, 4 figures. Supplementary text : 16 pages, 8 figure

Storage and retrieval of microwave fields at the single-photon level in a spin ensemble

We report the storage of microwave pulses at the single-photon level in a spin-ensemble memory consisting of $10^{10}$ NV centers in a diamond crystal coupled to a superconducting LC resonator. The energy of the signal, retrieved $100\, \mu \mathrm{s}$ later by spin-echo techniques, reaches $0.3\%$ of the energy absorbed by the spins, and this storage efficiency is quantitatively accounted for by simulations. This figure of merit is sufficient to envision first implementations of a quantum memory for superconducting qubits.Comment: 6 page

Contributions of the Environmental Non Governmental Organisations and international law on climate change

This study aims at finding out how Non Governmental Organisations (NGOs) perceive this issue and what roles they play in the fight against this phenomenon and in its formation in order to contribute to this domain and analyse contributions of Non Governmental Organisations to the International law on climate change. Results show that consequences of climate changeare visible and real. Thus, NGOs such as Friends of the Earth, Greenpeace, World Wild Funds (WWF), World Watch Institute (WWI) and Sierra Club emerged in the mode of the International law, bringing an effective participation in International negotiations by cooperating with States and by sensitizing citizens and political decision-makers. For this purpose, the United Nations Framework Convention on Climate Change (UNFCCC) was adopted in 1992 and the Kyoto Protocol in 1997 as well as several other multilateral treaties during different Conventions of Parties (COP). However, this struggle is opposed by industrialists and other States that protect their short-term interests and support the idea that climate change mightnot exist or climatic change is not due to men, but rather to natural phenomena. That is why NGOs have to actively play their role of pressure to call out to decision makers and populations on consequences of the climate change so that we can attenuate this phenomenon because the more we are doing nothing today, the more difficult it will be to avoid the consequences tomorrow