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We experimentally demonstrated V-groove-based self-aligned SiN edge coupler (EC) on a monolithic CMOS-SiPh platform. 520 mW power handling capability were achieved.

Photonic system component counts are increasing rapidly, particularly in CMOS-compatible silicon photonics processes. Large numbers of cascaded active photonic devices are difficult to implement when accounting for constraints on area, power dissipation, and response time. Plasma dispersion and the thermo-optic effect, both available in CMOS-compatible silicon processes, address a subset of these criteria. With the addition of a few back-end-of-line etch processing steps, silicon photonics platforms can support nano-opto-electro-mechanical (NOEM) phase shifters. Realizing NOEM phase shifters that operate at CMOS-compatible voltages (≤ 1.2 V) and with low insertion loss remains a challenge. Here, we introduce a novel NOEM phase shifter fabricated alongside 90 nanometer transistors that imparts 5.63 radians phase shift at 1.08 volts bias over an actuation length of 25μm with an insertion loss of less than 0.04 dB and 3 dB bandwidth of 0.26 MHz.

Controlling thermal transport is important for a range of devices and technologies, from phase change memories to next-generation electronics. This is especially true in nano-scale devices where thermal transport is altered by the influence of surfaces and changes in dimensionality. In superconducting nanowire single-photon detectors, the thermal boundary conductance between the nanowire and the substrate it is fabricated on influences all of the performance metrics that make these detectors attractive for applications. This includes the maximum count rate, latency, jitter, and quantum efficiency. Despite its importance, the study of thermal boundary conductance in superconducting nanowire devices has not been done systematically, primarily due to the lack of a straightforward characterization method. Here, we show that simple electrical measurements can be used to estimate the thermal boundary conductance between nanowires and substrates and that these measurements agree with acoustic mismatch theory across a variety of substrates. Numerical simulations allow us to refine our understanding, however, open questions remain. This work should enable thermal engineering in superconducting nanowire electronics and cryogenic detectors for improved device performance.

Current crowding at bends of superconducting nanowire single-photon detector (SNSPD) is one of the main factors limiting the performance of meander-style detectors with large filling factors. In this paper, we propose a new concept to reduce the influence of the current crowding effect, a so-called variable thickness SNSPD, which is composed of two regions with different thicknesses. A larger thickness of bends in comparison to the thickness of straight nanowire sections locally reduces the current density and reduces the suppression of the critical current caused by current crowding. This allows variable thickness SNSPD to have a higher critical current, an improved detection efficiency, and decreased dark count rate in comparison with a standard uniform thickness SNSPD with an identical geometry and film quality.

We demonstrate a multilayer nanoscale cryogenic heater-based switch (M-hTron) that uses a normal-metal heater overlapping a thin-film superconductor separated by a thin insulating layer. The M-hTron eliminates leakage current found in three-terminal superconducting switches and applies heat locally to the superconductor, reducing the energy required to switch the device. Modeling using the energy-balance equations and the acoustic mismatch model demonstrates reasonable agreement with experiment. The M-hTron is a promising device for digital superconducting electronics that require high fan-out and offers the possibility of enhancing readout for superconducting-nanowire single-photon detectors.

One of the most challenging obstacles to realizing exascale computing is minimizing the energy consumption of L2 cache, main memory, and interconnects to that memory. For promising cryogenic computing schemes utilizing Josephson junction superconducting logic, this obstacle is exacerbated by the cryogenic system requirements that expose the technology’s lack of high-density, high-speed and power-efficient memory. Here we demonstrate an array of cryogenic memory cells consisting of a non-volatile three-terminal magnetic tunnel junction element driven by the spin Hall effect, combined with a superconducting heater-cryotron bit-select element. The write energy of these memory elements is roughly 8 pJ with a bit-select element, designed to achieve a minimum overhead power consumption of about 30%. Individual magnetic memory cells measured at 4 K show reliable switching with write error rates below 10−6, and a 4 × 4 array can be fully addressed with bit select error rates of 10−6. This demonstration is a first step towards a full cryogenic memory architecture targeting energy and performance specifications appropriate for applications in superconducting high performance and quantum computing control systems, which require significant memory resources operating at 4 K.

Voltage noise measurements on close to optimally doped YBa2Cu3O7-δ nanostructures have been performed. The measured resistance noise at temperature T = 96 K (above critical temperature $T_{C}$ = 85 K) shows a quadratic dependence on the bias current, e.g., the voltage power spectral density $S_{V}\alpha$ V 2. Moreover, the normalized voltage noise $S_{V}$ / V 2 is inversely proportional to the device volume. This is a clear indication that the noise is the result of an ensemble of independent resistive fluctuators, evenly distributed within the sample volume. For our structures, we obtain a product $S_{V}$ / V 2 × Vol . = const . a 6 × 10−33 m3/Hz resulting in a Hooge's parameter 3.4 × 10−4, which is among the lowest reported in literature. At lower temperature, T = 2 K (well below $T_{C}$ ) the total voltage fluctuations are given by the combined effect of critical current fluctuations and resistance fluctuations. For the critical current noise, we obtain a product $S_{I}/I_{C}$ 2 × Vol . = const . a 6 × 10−32 m3 /Hz. The larger value of the relative critical current noise is most probably due to the fact that the critical current is determined by edge effects whereas the resistance is given by the total volume of the device.

There has been a demand for a scalable superconducting memory technology for cryogenic computing for some time. This demand has proven difficult to satisfy due to the simultaneous need for high speed operation, low power consumption, and high density, all while maintaining cryogenic and SFQ compatibility. In an effort to satisfy this demand, we have developed a simple memory cell based on our prior work with nanowire-based memories. Due to the memory cell’s reliance on kinetic inductance, the cell can be scaled to almost any size. The cell has been designed specifically such that it can easily form into an array simply by arranging in a 2D pattern. This design eliminated the need for external addressing circuitry. This new cell, when operated in isolation and without the heater, performs very well with predicted bit error rates around 10−17. However, preliminary array tests show that while the memory operates, the predicted error rates rise to 1.5 × 10−3. We believe that this issue is predominantly due to the hTron-channel kinetic inductance dramatically changing upon the application of the row-select heaters. This issue might be addressed by designing the cell to compensate for the change in kinetic inductance when the heater is activated. If this remedy proves to be effective, then this memory would enable the development of compact and scalable memory arrays.

Background Breast cancer is a common disorder in women, constituting one of the main causes of death all over the world. The purpose of this study was to determine the diagnostic value of the breast tissue diseases by the help of thermography. Materials and methods In this paper, we applied non-contact infrared camera, INFREC R500 for evaluating the capabilities of thermography. The study was conducted on 60 patients suspected of breast disease, who were referred to Imam Khomeini Imaging Center. Information obtained from the questionnaires and clinical examinations along with the obtained diagnostic results from ultrasound images, biopsies and thermography, were analyzed. The results indicated that the use of thermography as well as the asymmetry technique is useful in identifying hypoechoic as well as cystic masses. It should be noted that the patient should not suffer from breast discharge. Results The accuracy of asymmetry technique identification is respectively 91/89% and 92/30%. Also the accuracy of the exact location of identification is on the 61/53% and 75%. The approach also proved effective in identifying heterogeneous lesions, fibroadenomas, and intraductal masses, but not ISO-echoes and calcified masses. Conclusions According to the results of the investigation, thermography may be useful in the initial screening and supplementation of diagnostic procedures due to its safety (its non-radiation properties), low cost and the good recognition of breast tissue disease.

An ex situ ozone annealing has been applied both on YBa2Cu3O7-d (YBCO) films and nanowires. From the investigation on bare films, by measuring the superconducting resistive transition in temperature and the X-ray diffraction pattern, we have observed that the ozonation can be a powerful tool to oxygenate the YBCO structure. To probe the effective role of this reactive annealing on nanostructures, we have fabricated nanowires with widths down to 100 nm, covered by a 20-nm-thick Au layer. We have compared the critical current density and the broadening of the resistance transition measured before and after the ozone treatment, concluding that the ozone is instrumental in recovering very high quality superconducting properties inside the nanostructures, which were degraded by the oxygen out-diffusion occurring during the nanopatterning.

Topological superconductivity is central to a variety of novel phenomena involving the interplay between topologically ordered phases and broken-symmetry states. The key ingredient is an unconventional order parameter, with an orbital component containing a chiral $p_x$ + i$p_y$ wave term. Here we present phase-sensitive measurements, based on the quantum interference in nanoscale Josephson junctions, realized by using Bi$_2$Te$_3$ topological insulator. We demonstrate that the induced superconductivity is unconventional and consistent with a sign-changing order parameter, such as a chiral $p_x$ + i$p_y$ component. The magnetic field pattern of the junctions shows a dip at zero externally applied magnetic field, which is an incontrovertible signature of the simultaneous existence of 0 and $\pi$ coupling within the junction, inherent to a non trivial order parameter phase. The nano-textured morphology of the Bi$_2$Te$_3$ flakes, and the dramatic role played by thermal strain are the surprising key factors for the display of an unconventional induced order parameter., Comment: 47 pages, 7 figures in the main text and 12 figures in the supplementary material

Superconducting NbN nanonetworks with a very small number of interconnected nanowires, with diameter of the order of 4 nm, are fabricated combining a bottom-up (use of porous silicon nanotemplates) with a top-down technique (high-resolution electron beam lithography). The method is easy to control and allows the fabrication of devices, on a robust support, with electrical properties close to a one-dimensional superconductor that can be used fruitfully for novel applications.

We report on the growth and characterization of ultrathin YBa2Cu3O7-delta (YBCO) films on MgO (110) substrates, which exhibit superconducting properties at thicknesses down to 3 nm. YBCO nanowires, with thicknesses down to 10 nm and widths down to 65 nm, have also been successfully fabricated. The nanowires protected by a Au capping layer showsuperconducting properties close to the as-grown films and critical current densities, which are limited by only vortex dynamics. The 10-nm-thick YBCO nanowires without the Au capping present hysteretic current-voltage characteristics, characterized by a voltage switch which drives the nanowires directly from the superconducting to the normal state. We associate such bistability to the presence of localized normal domains within the superconductor. The presence of the voltage switch in ultrathin YBCO nanostructures, characterized by high sheet resistance values and high critical current values, makes our nanowires very attractive devices to engineer single-photon detectors.

We report on the growth and characterization of ultrathin YBa2Cu3O7-δ (YBCO) films on MgO (110) substrates, which exhibit superconducting properties at thicknesses down to 3 nm. YBCO nanowires, with thicknesses down to 10 nm and widths down to 65 nm, have also been successfully fabricated. The nanowires protected by a Au capping layer show superconducting properties close to the as-grown films and critical current densities, which are limited by only vortex dynamics. The 10-nm-thick YBCO nanowires without the Au capping present hysteretic current-voltage characteristics, characterized by a voltage switch which drives the nanowires directly from the superconducting to the normal state. We associate such bistability to the presence of localized normal domains within the superconductor. The presence of the voltage switch in ultrathin YBCO nanostructures, characterized by high sheet resistance values and high critical current values, makes our nanowires very attractive devices to engineer single-photon detectors.

We successfully fabricated and studied planar superconductor-normal-superconductor (SNS) Josephson junctions made of YBa2Cu3O7-? (YBCO) high-TC superconductor (S) and Au normal metal (N). The crucial step in fabrication was done by using a Pt/Au bilayer encapsulation of the patterned YBCO nanogap. This procedure preserves the YBCO nanogap from the degradation due to the contact with resists, water, and chemicals involved in further processing for hybrid devices. The junctions exhibit Fraunhofer-like modulation patterns and Shapiro steps when they are irradiated by a rf field. Furthermore, we analyzed the IC(T) characteristics of our hybrid junctions employing a SINI?S (superconductor-insulator-normal conductor-insulator-superconductor) model.

In the present work, we report the growth of fully untwinned high-quality a-axis-oriented YBa2Cu3O7-delta films on (100) SrLaGaO4 substrates by using PrBa2Cu3O7-delta as a buffer layer. We also fabricated nanowires at different angles gamma with respect to the [0,1,0] direction of the substrate and studied the in-plane anisotropy of the critical current density, which we explained by considering the anisotropy in the coherence length xi and London penetration depth lambda L. Finally, half-integer Shapiro-like steps measured in slightly underdoped c-axis oriented (gamma = 90 degrees) nanowires point towards a different transport regime, which could shed light on intriguing issues of high-critical-temperature superconductors.

We have realized YBa2Cu3O7-delta nanowires and nano Superconducting Quantum Interference Devices (nanoSQUID). The measured temperature dependence of the wire resistances below the superconducting transition temperature has been analyzed using a thermally activated vortex entry model valid for wires wider than the superconducting coherence length. The extracted zero temperature values of the London penetration depth, lambda(0) similar or equal to 270 +/- 15 nm, are in good agreement with the value obtained from critical current modulations as a function of an externally applied magnetic field in a nanoSQUID implementing two nanowires.

We have investigated the transport properties of optimally doped Pr2-xCexCuO4-δ (PCCO) nanobridges with width down to 100 nm. The critical current density of the nanobridges approaches the Ginzburg-Landau theoretical limit, which demonstrates nanostructures with properties close to the as-grown films. The current voltage characteristics are hysteretic with a sharp voltage switch, of the order of a few millivolts, that we interpret with the occurrence of a hot spot formation. The values of the retrapping current and the voltage switch obtained by modeling the heat transport in the nanobridges are very close to the experimental ones. This feature, together with the extremely short recombination times, make PCCO nanostructures attractive candidates for ultrafast single photon detectors.

The present work is an investigation on the effect of working gas composition as well as applied voltage and operating pressure on the behavior of SXR emitted from the APF device. Three volumetric ratios(90:10), (75:25), and (50:50) of nitrogen:neon (N2:Ne) admixture were used with operating conditions at applied voltages of 11, 12, and 13 kV and operating pressures of 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 torr. Using (N2:Ne) gas mixture ratios of (90:10) and (75:25) and at applied voltage of 11 kV, the optimum pressure for maximum intensity of SXR was 3.5 torr. However, for the percentage of (50:50), it shifts to higher pressure of 4 torr. At higher applied voltages of 12 and 13 kV, the optimum pressures shift to higher values, 4 torr for both volumetric ratios (90:10) and (75:25), and 4.5 torr for the ratio of (50:50). It was found that the intensity of SXR increases with the increase of neon (Ne) percentage in the admixture of (N2:Ne) and applied voltage. The highest intensity was for the volumetric ratio of (50:50) operating at the voltage of 13 kV. Our results illustrated that mixing neon (Ne) with nitrogen (N2) as the working gas in the PF is a power source of SXR emission.

Experimental results related to HXR and SXR properties of Neon plasma on the APF plasma focus device is presented. The experiments were carried on over a wide range of neon pressure and at voltages 11, 12 and 13 kV using plastic scintillator (NE102A) coupled with high gain PMT and six filtered photo PIN diodes. For the charging voltages of 11–13 kV with 2.17–3.04 kJ stored energy, the optimum operating pressure in neon is found to be in the range of 3.5–5 torr and the highest HXR emission was observed in the pressure of 5 torr at the voltage 13 kV and the maximum average HXR production is (9.84 ± 0.59) ×10–7 volt sec. The behavior of SXR intensities were registered by different filters and it was found out that Al-Mylar 6 μm and Cu 10 μm has the highest and lowest amount of X-ray transmission.

In the present work, the effect of applied voltage and operating pressure on behaviour of X-rays emitted from nitrogen gas (N2) used in APF plasma focus facility is investigated. It was found that the optimum conditions for high emissions of SXR and HXR from the plasma focus (PF) are different. At four applied voltages of 10, 11, 12, and 13 kV, the optimum pressures for SXR and HXR emissions of nitrogen gas (N2) were obtained. At lower voltages, 10, and 11 kV optimum pressure for SXR emission was 3.5 torr while for HXR emission was 2.5 torr. At higher voltages, 12, and 13 kV, the optimum pressures shift to higher values at 4 and 3 torr for SXR and HXR emissions, respectively. Among the applied voltages, the least intensity of both SXR and HXR was at voltage 10 kV and the most intensity was for 13 kV which confirm with increasing voltage, the intensity of X-ray emission increases. Also the results obtained by images of pin-hole camera were in compatible with the results of detected signals by different filtered Pin-diodes and Scintillation detector. Our results illustrate that the voltage and the pressure are effective parameters in X-ray emission from the PF.

An investigation on the HXR emitted from APF plasma focus device operated with different volumetric ratios of nitrogen-neon (N2:Ne) admixture working gas at different voltage-pressure limits is presented. The optimum pressures obtained at the applied voltages of 12, and 13 kV were 3.5 torr for percentage of (50:50) of (N2:Ne) admixture and 3 torr for percentages of (75:25) and (90:10) in admixture and also for pure N2, while at the voltage of 11 kV, the optimum pressures were 3 torr for percentage of (50:50) and 2.5 torr for percentages of (75:25), (90:10), and pure N2. At each applied voltages of 11, 12, and 13 kV, with increasing percentage of N2 in the (N2:Ne) admixture, the intensity of HXR was found to increase where the low intensity was for percentage of (50:50) of (N2:Ne) and the higher intensity was for pure N2. The results illustrate that the voltage and the composition of working gas are effective parameters in the HXR emission from a plasma focus device.

Experimental results related to soft X-ray (SXR) properties of Neon plasma on the APF plasma focus device is presented. The experiments were carried on over wide range of neon pressure and at voltages 11, 12 and 13 kV six filtered photo PIN diodes and pin-hole camera. For the charging voltages of 11–13 kV with 2.17–3.04 kJ stored energy, the optimum operating pressure in neon is found to be in the range of 3.5–5 torr. The behavior of SXR intensities was registered by different filters and found out that Al-Mylar 6 μm and Cu 10 μm has the highest and lowest amount of X-ray transmission, respectively.

Angular distribution of ion beam emission from an argon gas-filled plasma focus devices has been investigated using an array of five Faraday cups. The argon ion beam emission is found to be highly pressure-dependent and reaches its maximum at the pressure of 1 torr. The ions flux decreased as the working pressure increased; the maximum ion density at 1 torr was estimated to be around 9.24 × 1024 ions/steradian. Also, the study on the angular distribution of X-rays has been carried out using TLD-100 dosimeters. The intensity of ions reduced significantly at angles higher than ±11° but the X-ray distribution was bimodal, peaked approximately at ±15°.

This paper, presents the variation of hard X-ray (HXR) intensity in the APF plasma focus device for different insulator sleeves. For Pyrex and Quartz insulators, the lengths of 40 and 50 mm seems optimal to yield maximum HXR intensity, respectively. Also using the Pyrex insulator leads to production of higher HXR intensity than the Quartz insulator. The results illustrate that the length and the material of the insulator has a considerable effect on the HXR intensity.

This paper presents an experimental study of neutron yield as well as neutron angular distribution on the APF plasma focus device. The system operates with pure deuterium gas in varying the filling pressure and working voltages of 11.5 and 13.5 kV. The maximum average of neutron yield is (2.88 ± 0.29 × 108) neutrons per shot at the pressure of 7 torr. The neutron angular distribution is measured with housing an array of seven silver activation Geiger-Muller counters at the angles of 0°, ±30°, ±60°, and ±90° in a distance of 90 cm from the anode tip. The results of neutron angular distribution suggest that the neutron production mechanism may be predominantly beam target model.

In this paper, an investigation on the X-rays emitted in different pressures by APF plasma focus devices using filtered PIN-diodes and fast plastic scintillation detector is reported. The highest X-ray emission was observed in the pressure of 1.6 torr and the behavior of X-ray intensities registered by different filters versus applied pressure were seemed to be similar. The X-ray angular distribution was bimodal, peaked approximately at ±18°. The intensity of X-rays decreased abruptly along the central axis of the device where the cylindrical plasma pinch was formed.

Topological superconductivity is central to a variety of novel phenomena involving the interplay between topologically ordered phases and broken-symmetry states. The key ingredient is an unconventional order parameter, with an orbital component containing a chiral p x + ip y wave term. Here we present phase-sensitive measurements, based on the quantum interference in nanoscale Josephson junctions, realized by using Bi2Te3 topological insulator. We demonstrate that the induced superconductivity is unconventional and consistent with a sign-changing order parameter, such as a chiral p x + ip y component. The magnetic field pattern of the junctions shows a dip at zero externally applied magnetic field, which is an incontrovertible signature of the simultaneous existence of 0 and π coupling within the junction, inherent to a non trivial order parameter phase. The nano-textured morphology of the Bi2Te3 flakes, and the dramatic role played by thermal strain are the surprising key factors for the display of an unconventional induced order parameter., Proximity effect may induce unconventional superconductivity in the topologically protected surface states of a topological insulator, however experimental evidence remains rare. Here, Charpentier et al. report proximity effect induced superconductivity in nanoscale Josephson junctions and suggest an unconventional p-wave order parameter.

The advances of nanotechnologies applied to high-critical-temperature superconductors (HTSs) have recently given a huge boost to the field, opening new prospectives for their integration in hybrid devices. The feasibility of this research goes through the realization of HTS nanogaps with superconductive properties close to the as-grown bulk material at the nanoscale. Here we present a fabrication approach allowing the realization of YBa2Cu3O7-delta (YBCO) nanogaps with dimensions as small as 35 nm. To assess the quality of the nanogaps, we measure, before and after an ozone treatment, the current-voltage characteristics and the resistance versus temperature of YBCO nanowires with various widths and lengths, fabricated by using different lithographic processes. The analysis of the superconducting transition with a thermally activated vortex-entry model allows us to determine the maximum damage the nanowires undergo during the patterning which relates to the upper bound for the dimension of the nanogap. We find that the effective width of the nanogap is of the order of 100 nm at the superconducting transition temperature while retaining the geometrical value of about 35 nm at lower temperatures. The feasibility of the nanogaps for hybrid Josephson devices is demonstrated by bridging them with thin Au films. We detect a Josephson coupling up to 85 K with an almost ideal magnetic-field response of the Josephson current. These results pave the way for the realization of complex hybrid devices, where tiny HTS nanogaps can be instrumental to study the Josephson effect through barriers such as topological insulators or graphene.

We have fabricated YBa2Cu3O7-delta (YBCO) nano superconducting quantum interference devices (nanoSQUIDs), realized in Dayem bridge configuration, on films with thickness down to 10 nm. The devices, which have not been protected by a Au capping layer during the nanopatterning, show modulations of the critical current as a function of the externally applied magnetic field from 300 mK up to the critical temperature of the nanobridges. The absence of the Au shunting layer and the enhancement of the sheet resistance in ultrathin films lead to very large voltage modulations and transfer functions, which make these nanoSQUIDs highly sensitive devices. Indeed, by using bare YBCO nanostructures, we have revealed an upper limit for the intrinsic white flux noise level S-Phi,w(1/2) < 450 n Phi(0) Hz(-1/2).

We report on measurements of YBa2Cu3O7- ? nanowire based Superconducting QUantum Interference Devices (nanoSQUIDs) directly coupled to an in-plane pick-up loop. The pick-up loop, which is coupled predominantly via kinetic inductance to the SQUID loop, allows for a significant increase of the effective area of our devices. Its role is systematically investigated and the increase in the effective area is successfully compared with numerical simulations. Large effective areas, together with the ultra low white flux noise below 1 ? ? 0 / Hz, make our nanoSQUIDs very attractive as magnetic field sensors.