Detection of zeptojoule microwave pulses using electrothermal feedback in proximity-induced Josephson junctions

We experimentally investigate and utilize electrothermal feedback in a microwave nanobolometer based on a normal-metal (\mbox{Au}_{x}\mbox{Pd}_{1-x}) nanowire with proximity-induced superconductivity. The feedback couples the temperature and the electrical degrees of freedom in the nanowire, which both absorbs the incoming microwave radiation, and transduces the temperature change into a radio-frequency electrical signal. We tune the feedback in situ and access both positive and negative feedback regimes with rich nonlinear dynamics. In particular, strong positive feedback leads to the emergence of two metastable electron temperature states in the millikelvin range. We use these states for efficient threshold detection of coherent 8.4 GHz microwave pulses containing approximately 200 photons on average, corresponding to 1.1 \mbox{ zJ} \approx 7.0 \mbox{ meV} of energy

Noisy pre-processing facilitating a photonic realisation of device-independent quantum key distribution

Device-independent quantum key distribution provides security even when the equipment used to communicate over the quantum channel is largely uncharacterized. An experimental demonstration of device-independent quantum key distribution is however challenging. A central obstacle in photonic implementations is that the global detection efficiency, i.e., the probability that the signals sent over the quantum channel are successfully received, must be above a certain threshold. We here propose a method to significantly relax this threshold, while maintaining provable device-independent security. This is achieved with a protocol that adds artificial noise, which cannot be known or controlled by an adversary, to the initial measurement data (the raw key). Focusing on a realistic photonic setup using a source based on spontaneous parametric down conversion, we give explicit bounds on the minimal required global detection efficiency.Comment: 5+16 pages, 4 figure

Bond-Propagation Algorithm for Thermodynamic Functions in General 2D Ising Models

Recently, we developed and implemented the bond propagation algorithm for calculating the partition function and correlation functions of random bond Ising models in two dimensions. The algorithm is the fastest available for calculating these quantities near the percolation threshold. In this paper, we show how to extend the bond propagation algorithm to directly calculate thermodynamic functions by applying the algorithm to derivatives of the partition function, and we derive explicit expressions for this transformation. We also discuss variations of the original bond propagation procedure within the larger context of Y-Delta-Y-reducibility and discuss the relation of this class of algorithm to other algorithms developed for Ising systems. We conclude with a discussion on the outlook for applying similar algorithms to other models.Comment: 12 pages, 10 figures; submitte

The conceptual design of a 36 GHz RF undulator

The CompactLight project supported by European H₂020 is to design a hard X-ray FEL facility beyond today’s state of the art. The project integrates photo injector, X-band acceleration and innovative compact short-period undulators together to make the machine more compact. RF undulator has an extraordinary advantage of working at very short undulator period. A conceptual design for a RF undulator at 36 GHz using a corrugated cylindrical waveguide operating in the HE11 mode is presented in this paper. Based on beam dynamics simulation and photon beam radiation simulations, the possibility of RF undulator to be used in CompactLight project is evaluated

Overall Evolution of Realistic Gamma-ray Burst Remnant and Its Afterglow

Conventional dynamic model of gamma-ray burst remnants is found to be incorrect for adiabatic blastwaves during the non-relativistic phase. A new model is derived, which is shown to be correct for both radiative and adiabatic blastwaves during both ultra-relativistic and non-relativistic phase. Our model also takes the evolution of the radiative efficiency into account. The importance of the transition from the ultra-relativistic phase to the non-relativistic phase is stressed.Comment: 9 pages, aasms4 style, 3 ps figures, minor changes, will be published in Chin. Phys. Let

Identification of α°-thalassaemia (–SEA) using an enzyme-linked immunosorbent assay (ELISA) for embryonic zeta-globin chain detection – a preliminary study

Objectives: This study aimed to evaluate the UBI MAGIWELTM ζ-GLOBIN ELISA Kit for the presumptive diagnosis of αo-thalassaemia. The ELISA results obtained were confirmed by molecular characterisation of αo-thalassaemia using a Duplex-PCR. Methods: Routine peripheral blood counts and red cell indices were determined in 94 blood samples sent for Hb analysis. Hb subtypes were quantified by high performance liquid chromatography (HPLC) and Hb electrophoresis conducted on agarose gel at pH 8.5. Zeta-globin chain levels were determined using the UBI MAGIWELTM ζ-GLOBIN ELISA Kit. Molecular analysis was performed using a duplex-PCR which simultaneously amplifies a normal 136 bp sequence between the ψα−α2-globin genes and a 730 bp Southeast Asian deletion-specific sequence (–SEA) between the ψα2−θ1-globin genes. Results: Using the ELISA assay kit, 20 blood samples were presumptively identified as α-thalassaemia carriers from elevated ζ-globin chains (OD>0.3) while the remaining 74 blood samples showed OD<0.3. Molecular characterisation confirmed amplification of the 136 bp normal fragment in all the blood samples. Seventeen of the 20 DNA samples from the α-thalassaemia carriers amplified the SEA-deletion specific fragment. The remaining three DNA samples did not amplify the SEA-deletion specific fragment but amplified the normal α-globin gene sequence, indicating the presence of amplifiable DNA in these samples. Further molecular characterisation of the α-3.7 and -α4.2 deletions and Hb Constant Spring (CS) mutation showed the absence of these defects in these 3 DNA samples. Conclusion: This preliminary investigation showed the sensitivity and specificity of the UBI MAGIWEL ζ-globin ELISA kit as 100 % and 96.1 % respectively in the detection of α-thalassaemia-1 carriers (–SEA)