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Background: Cryo-electron tomography (cryo-ET) enables the 3D visualization of cellular organization in near-native state which plays important roles in the field of structural cell biology. However, due to the low signal-to-noise ratio (SNR), large volume and high content complexity within cells, it remains difficult and time-consuming to localize and identify different components in cellular cryo-ET. To automatically localize and recognize in situ cellular structures of interest captured by cryo-ET, we proposed a simple yet effective automatic image analysis approach based on Faster-RCNN. Results: Our experimental results were validated using in situ cyro-ET-imaged mitochondria data. Our experimental results show that our algorithm can accurately localize and identify important cellular structures on both the 2D tilt images and the reconstructed 2D slices of cryo-ET. When ran on the mitochondria cryo-ET dataset, our algorithm achieved Average Precision >0.95. Moreover, our study demonstrated that our customized pre-processing steps can further improve the robustness of our model performance. Conclusions: In this paper, we proposed an automatic Cryo-ET image analysis algorithm for localization and identification of different structure of interest in cells, which is the first Faster-RCNN based method for localizing an cellular organelle in Cryo-ET images and demonstrated the high accuracy and robustness of detection and classification tasks of intracellular mitochondria. Furthermore, our approach can be easily applied to detection tasks of other cellular structures as well. [ABSTRACT FROM AUTHOR]

A current bottleneck in structure determination of macromolecular complexes by cryo electron microscopy (cryo-EM) is the large amount of data needed to obtain high-resolution 3D reconstructions, including through sorting into different conformations and compositions with advanced image processing. Additionally, it may be difficult to visualize small ligands that bind in sub-stoichiometric levels. Volta phase plates (VPP) introduce a phase shift in the contrast transfer and drastically increase the contrast of the recorded low-dose cryo-EM images while preserving high frequency information. Here we present a comparative study to address the behavior of different data sets during image processing and quantify important parameters during structure refinement. The automated data collection was done from the same human ribosome sample either as a conventional defocus range dataset or with a Volta phase plate close to focus (cfVPP) or with a small defocus (dfVPP). The analysis of image processing parameters shows that dfVPP data behave more robustly during cryo-EM structure refinement because particle alignments, Euler angle assignments and 2D & 3D classifications behave more stably and converge faster. In particular, less particle images are required to reach the same resolution in the 3D reconstructions. Finally, we find that defocus range data collection is also applicable to VPP. This study shows that data processing and cryo-EM map interpretation, including atomic model refinement, are facilitated significantly by performing VPP cryo-EM, which will have an important impact on structural biology. [ABSTRACT FROM AUTHOR]

We present hybridization of Josephson, CMOS, and nanocryotron (nTron) devices for a large-scale cryogenic memory application. The memory system proposed here is dynamic random access memory composed of address decoders based on an energy-efficient rapid single-flux-quantum logic, nTron line drivers, a CMOS memory cell array, and Josephson current sensors. Because drivers with voltage amplification and decoders are the major causes of power dissipation in the conventional Josephson-CMOS hybrid memory, drastic reduction in power consumption is expected. We show estimates that the power consumption of a 16-Mb memory is reduced to 1.36–2.77 mW, approximately 1/12 of the conventional Josephson-CMOS hybrid memory, and the access time is 0.78 ns for a read operation, when we assume a 65-nm CMOS process and a 1.0-$\mu$m Nb/AlO $_x$/Nb process. In the preliminary experiment, we fabricated nTrons using NbTiN thin film that are suitable for hybrid memory implementation, and measured with eight-transistor static random access memory cells fabricated using the Rohm 0.18-$\mu$ m CMOS process. We successfully triggered the nTron into the normal state, and observed output voltage of $\sim$0.1 V at 13.5 K. The experimental results support the potential of the hybrid memory using NbTiN nTrons. [ABSTRACT FROM PUBLISHER]

Low-temperature superconducting circuits have become important for many scientific applications. However, there are presently no high current-capacity switches (~1 mA) with low power dissipation for sub-Kelvin operation. One candidate for a sub-Kelvin switch is the cryotron, a device in which the superconductivity of a wire is suppressed with a magnetic field. Here, we demonstrate a cryotron switch suitable for sub-Kelvin temperatures. In the closed state, the maximum device current is about 900 μA. The device is switched to its open state with 2mA of control current and has a leakage of approximately 500 nA. The transition between the closed and open states of the device is faster than 200 ns, where the measurement is limited by the speed of our measurement apparatus. We also discuss low-temperature applications for our cryotron such as a single-pole, double-throw switch. [ABSTRACT FROM AUTHOR]

In February 2009 a new permafrost borehole was installed close to the British Antarctic Survey Station at Rothera Point, Adelaide Island (67.57195°S 68.12068°W). The borehole is situated at 31 m asl on a granodiorite knob with scattered lichen cover. The spatial variability of snow cover and of ground surface temperature (GST) is characterised through the monitoring of snow depth on 5 stakes positioned around the borehole and with thermistors placed at three different rock surfaces (A, B and C). The borehole temperature is measured by 18 thermistors placed at different depths between 0.3 and 30 m. Snow persistence is very variable both spatially and temporally with snow free days per year ranging from 13 and more than 300, and maximum snow depths varying between 0.03 and 1.42 m. This variability is the main cause of high variability in GST, that ranged between − 3.7 and − 1.5 °C. The net effect of the snow cover is a cooling of the surface. Mean annual GST, mean summer GST, and the degree days of thawing and the n-factor of thawing were always much lower at sensor A where snow persistence and depth were greater than in the other sensor locations. At sensor A the potential freeze–thaw events were negligible (0–3) and the thermal stress was at least 40% less than in the other sensor locations. The zero curtain effect at the rock surface occurred only at surface A, favouring chemical weathering over mechanical action. The active layer thickness (ALT) ranged between 0.76 and 1.40 m. ALT was directly proportional to the mean air temperature in summer, and inversely proportional to the maximum snow depth in autumn. ALT temporal variability was greater than reported at other sites at similar latitude in the Northern Hemisphere, or with the similar mean annual air temperature in Maritime Antarctica, because vegetation and a soil organic horizon are absent at the study site. Zero annual amplitude in temperature was observed at about 16 m depth, where the mean annual temperature is − 3 °C. Permafrost thickness was calculated to range between 112 and 157 m, depending on the heat flow values adopted. The presence of sub-sea permafrost cannot be excluded considering the depth of the shelf around Rothera Point and its glacial history. [ABSTRACT FROM AUTHOR]

Superconducting electronics basedon Josephson junctions are usedto sense and process electronic signals with minimal loss; however,they are ultrasensitive to magnetic fields, limited in their amplificationcapabilities, and difficult to manufacture. We have developed a 3-terminal,nanowire-based superconducting electrothermal device which has noJosephson junctions. This device, which we call the nanocryotron,can be patterned from a single thin film of superconducting materialwith conventional electron-beam lithography. The nanocryotron hasa demonstrated gain of >20, can drive impedances of 100 kΩ,and operates in typical ambient magnetic fields. We have additionallyapplied it both as a digital logic element in a half-adder circuit,and as a digital amplifier for superconducting nanowire single-photondetectors pulses. The nanocryotron has immediate applications in classicaland quantum communications, photon sensing, and astronomy, and itsinput characteristics are suitable for integration with existing superconductingtechnologies. [ABSTRACT FROM AUTHOR]

Highlights: [•] Describe a workflow for correlative fluorescent microscopy and cryo-electron tomography. [•] Highlight technical advances in cryo-correlative microscopy (cryo-CLEM). [•] Correlate structure, function and dynamics of cellular processes with cryo-CLEM. [Copyright &y& Elsevier]

Thin-wall YBa2Cu3O7-δ bulk single domains were grown from drilled preforms with a holes network in the aim of increasing the specific areas and diminishing the oxygen diffusion paths. By applying a progressive annealing at high temperature under oxygen pressure (10 MPa), crack-free superconductors were obtained in a very short time (less than 3 days). A crack-free microstructure fostered large size persistent current loops, which boosted the trapped field performances. A trapped field Bmax = 5.2 T at 17 K was achieved on a 16 mm-diameter thin-wall pellet (disk surface s = 1.987 cm2), which led to a striking trapped field density BmaxS=2.617 T cm-2. [ABSTRACT FROM AUTHOR]

We propose a design principle of digital logic gates based on Josephson cryotrons. The operation mode of digital logic gates AND and OR based on tunnel junctions 'superconductor-insulator-superconductor' was described. Mathematical models of the switching processes in the logic elements were developed, the transient characteristics during the logic state change were calculated, and the basic parameters of these models were determined. It was shown that digital logic gates 'AND' and 'OR' can be realized based on individual Josephson cryotrons and their logic state can be controlled by using current pulses as control inputs. Such logic gates satisfy all the requirements for digital logic elements and have switching time of about 2-3 ps. [ABSTRACT FROM AUTHOR]

Using the Ginzburg-Landau (GL) theory, we calculate the stability of sample symmetry-induced vortex-antivortex molecules in a mesoscopic superconducting bilayer exposed to a homogeneous magnetic field. We demonstrate the conditions under which the two condensates cooperatively broaden the field-temperature stability range of the composite (joint) vortex-antivortex state. In cases when such broadening is not achieved, a reentrance of the vortex-antivortex state is found at lower temperatures. In a large portion of the phase diagram noncomposite states are possible, in which the antivortex is present in only one of the layers. In this case, we demonstrate that the vortex-antivortex molecule in one of the layers can be pinned and enlarged by interaction with a vortex molecule in the other. Using analogies in the respective GL formalisms, we map our findings for the bilayer onto mesoscopic two-band superconductors. [ABSTRACT FROM AUTHOR]

Abstract: We investigate numerically the formation of vortex–antivortex pairs in thin-film superconducting strip in the presence of a straight current-carrying wire, oriented perpendicular to this strip. We demonstrate that the change in the number of the trapped vortices/antivortices inside the strip near the current-carrying wire results in a oscillatory dependence of the critical current I c on the magnitude of the control current I w in the wire. We consider the effect of the width of the superconducting strip and the width of the control wire on the period and the amplitude of the dc-Josephson-like oscillations of the critical current. [Copyright &y& Elsevier]

In this work, we consider controlling of logical states of Josephson memory cells (cryotrons) based on superconductor-insulator-superconductor (SIS) Josephson tunnel junctions by external current impulses. A mathematical model for the transitional processes that take place during direct logical transitions '0' → '1' and inverse logical transitions '1' → '0' is proposed. By means of mathematical modeling, we investigate transitional processes in cryotrons during the change of their logical state and obtain their transitional characteristics for operational temperatures T=11.6 K and T=81.2 K, close to the boiling temperatures of helium and nitrogen, respectively. It is shown that such memory cells can efficiently operate under the temperature T=81.2 K. The behavior of the Josephson cryotrons as well as their operational stability is explored. [ABSTRACT FROM AUTHOR]

We investigate theoretically and experimentally the transport properties of a plain Al superconducting strip in the presence of a single straight current-carrying wire, oriented perpendicular to the superconducting strip. It is well known that the critical current of the superconducting strip, Ic, in such a cryotron-like system can be tuned by changing the current in the control wire, Iw. We demonstrated that the discrete change in the number of the pinned vortices/antivortices inside the narrow and long strip nearby the current-carrying wire results in a peculiar oscillatory dependence of Ic on Iw. [ABSTRACT FROM AUTHOR]

In order to investigate the quench behavior of conduction cooled MgB2 magnets, a 100 mm inner bore diameter, 0.84 T at 20 K magnet has been built and tested. The test magnet consists of 4 double pancakes wound with the MgB2/Ni-Cu-Fe tape produced by Columbus. Each coil is cooled by means of a 2 mm thick copper disk placed during winding at the middle of the double pancake; after winding the double pancakes have been separately epoxy impregnated. Several experiments have been performed inducing a local transition in the coil by means of a controlled heater placed on the double pancake surface. The propagation of the normal zone has been monitored by means of 8 voltage probes positioned along the tape during coil manufacturing. Each voltage probe detects the voltage drop across a tape length of 30 mm. The experiments have been performed at different temperatures while keeping the magnet current constant during quench. In the paper we report an analysis of the quench propagation velocity measurements and a numerical investigation of the thermal and electrical behavior of the magnet. [ABSTRACT FROM AUTHOR]

A neuroscience research center with very high field MRI equipments has been opened in November 2006 by the CEA life science division. One of the imaging systems requires a highly homogeneous 11.75T magnet with a 900 mm warm bore. We describe the principle of calculation of the main coil deformations in order to perform field homogeneity loss assessment and mechanical dimensioning. This coil is wounded as double pancakes laterally wetted by Hell. As preliminary calculation runs led to high hoop stress levels, and due to the composite nature of this winding pack, a detailed finite element model of the coil structure is needed to obtain accurate computation of the displacement and stresses. Also, this finite element model serves as reference solution to validate a homogenized model. Then, a mixed full resolution/homogenized model is constructed in order to reduce the mesh size. A good correlation between this mixed model and full resolution one is observed. These three kinds of models will be exploited during the development phase of the magnet, to conduct mechanical design and estimation of field homogeneity losses. [ABSTRACT FROM AUTHOR]

A 700-mm bore superconducting magnet was built and operated in our laboratory to demonstrate the feasibility of newly developed MgB2 superconductor wire for fabricating MRI magnets. The magnet, an assembly of 10 coils each wound with a reacted and s-glass insulated wire ~1-km long, was immersed in solid nitrogen rather than in a bath of liquid cryogen. This MgB2 magnet was designed to operate in the temperature range 10-15 K, maintained by a cryocooler. A combination of this "wide" temperature range and immersion of the winding in solid nitrogen enables this magnet to operate under conditions not possible with a low temperature superconductor (LTS) counterpart. Tested individually at 13 K, each coil could carry current up to 100 A. When assembled into the magnet, some coils, however, became resistive, causing the magnet to prematurely quench at currents ranging from 79 A to 88 A, at which point the magnet generated a center field of 0.54 T. Despite the presence of a large volume (50 liters) of solid nitrogen in the cold body, cooldown from 77 K to 10 K went smoothly. [ABSTRACT FROM AUTHOR]

The toroidal magnetic field of ITER is provided by 18 Nb3 Sn superconducting coils that provide 5.3 Tin the Tokamak magnetic centre thanks to a nominal current of 68 kA. Two major procurement packages will be integrated to accomplish the final assembly of the coils: 1) the winding pack which houses the double pancakes in 7 stacked radial plates (RP) and 2) the TF coil case which houses the winding pack (WP) and is the main structural component of the ITER machine. 19 TF coil cases (18+1 spare) will be entirely procured by Japan, whereas the WP and the TF coil assembly will be shared between Japan (9) and Europe (10). The insertion process of the WP inside the coil case, VPI and final closure welding is presented with an emphasis on the R&D still remaining. An appropriate metrology strategy and correct benchmarking of the WP current center line (CCL) in the coil case external walls is essential to allow the correction of the error fields during operation. The TF coils will be assembled and pre-aligned in pairs together with their corresponding VV sector and craned to the Tokamak hall hanging from 2 independent hooks. The integration of the IF coils in the Tokamak primary datum system will have to bc accomplished within the maximum tolerances defined by the error field analysis. As-built 3D data collected during manufacture will be used to ensure the correct positioning of the CCL against the Tokamak datum system and ease the alignment process. Shimming will be used in the gravity support for vertical alignment and in the upper and lower OIS for toroidal alignment. A subsequent survey of the `as-installed' TF coils will determine the final Tokamak Datum System. [ABSTRACT FROM AUTHOR]

A new plasma fusion experiment, Wendelstein 7-X (W7-X), is built in the Max-Planck Institute for Plasma Physics in Greifswald (IPP), Germany. This experiment employs superconducting coils, allowing for plasma discharges up to 30 minutes duration. W7-X will be an "optimized" stellarator with respect to plasma transport and stability. The W7-X magnet consists of 70 individual coils in a toroidal arrangement. Each coil of W7-X is thoroughly tested before installation in a cryogenic test facility at the Commissariat a l'Energie Atomique (CEA) in Saclay, France. The tests are essential, because no access is foreseen to the magnetic system during the entire operation period of W7-X. The test procedure will be described briefly, and some test results will be presented. [ABSTRACT FROM AUTHOR]

The Broader Approach agreement between Europe and Japan includes the construction of a fully superconducting tokamak, the JT-60 Super Advanced (JT-60SA), as a satellite experiment to ITER. In particular, the whole Toroidal Field magnet system, described in this paper, will be provided to Japan by the EU. All the TF coil main constituents, i.e. conductor, winding pack, joints, casing, current leads, are here presented and discussed as well as the design criteria adopted to fulfil the machine requirements. The results of the analyses performed by the EU and JA to define and assess the TF magnet system conceptual design are reported and commented. Future work plan is also discussed. [ABSTRACT FROM AUTHOR]

CRPP has been selected to host the EDIPO test facility for the quality control tests of the ITER conductors. The new facility will be erected next to the existing SULTAN test facility at CRPP (Villigen) in Switzerland and will share the same cryo-plant. Operation of the two facilities is planned in parallel starting 2009. The new facility is designed to test short length samples built to the same specification as for SULTAN. EFDA procures 17 tons superconducting winding under industrial contract that will be delivered to CRPP in late 2008. The preparatory work at CRPP includes the design and procurement of several items as well as the final assembly and commissioning of the facility. An overview and the progress are reported, with focus on the main components: the vacuum vessel, the superconducting transformer and sample holder unit, the cryogenic cooling loop, the power supply and quench protection system, the HTS current leads and the magnetic screen. [ABSTRACT FROM AUTHOR]

Recently proposed synchrotrons, SF-SPS (Super-Ferric SPS) at CERN and DSF-MR (Dual Super-Ferric Main Ring) at Fermilab, would operate with a 0.5 Hz cycle (or 2 second time period) while accelerating protons to 480 GeV. We examine possibilities of superconducting magnet technology that would allow for an accelerator quality magnetic field sweep of 2 T/s. For superconducting magnets the AC losses in the coil compromise magnetic field quality and require high level of cryogenic cooling power. We outline a novel magnet technology based on HTS superconductors that may allow reduction of AC losses in the coil possibly up to an order of magnitude as compared to similar applications with LTS type conductors. [ABSTRACT FROM AUTHOR]

The BigRIPS fragment separator in the RIKEN RI beam factory has an air-core type superconducting quadrupole triplet as the first focusing element. The quadrupole triplet consists of three air-core superconducting coils having effective lengths of 500 mm, 800 mm, and 500 mm, and the maximum field gradients of 24 T/m, 20 T/m, and 20 T/m. All three quadrupoles are assembled into a single cryostat and cooled by liquid-helium bath cooling using a cryogenic plant. The coils have a flat racetrack shape and their warm bore radii are 90mm, 120 mm, and 120 mm. Its cryostat characterized by gas-cooled current leads with multiple electrodes is also discussed. [ABSTRACT FROM AUTHOR]

In 1986 Ansaldo Magnet Dept. (now ASG Superconductors) started, in cooperation with CERN, the design activities of the first 1 m-8 T LHC prototype dipoles. After several design steps and the manufacturing of 1+3 prototype dipoles 10 m long, the final design configuration 15 m long was defined by CERN. During the following years, a very close collaboration with CERN engineers and technicians lead to define the parameters about the most critical manufacturing processes, in particular winding of s.c. cable, collaring of coils, cold mass welding and test procedures. In the meantime, installation and commissioning of all the manufacturing plants followed: winding machines, curing presses, collaring press and welding press were installed, as well as geometrical measurements stations and vacuum chamber for leak test. Finally two manufacturing halls were fully dedicated to LHC dipoles production. At the beginning of year 2002, all the manufacturing plants were coming to be operational, ready to start the large scale production of LHC cold masses: 30 pre-series, 386 series and 30 spare cold masses have been produced till May 2007, to get a total number of 446 cold masses. In this paper we summarize all the data collected during a five years production: main manufacturing data, test results and production rate are presented. Final results about tests performed at CERN in superfluid He at 1.9 K are also included as well as correlation between test result and manufacturing rate. [ABSTRACT FROM AUTHOR]

Three terminal charges and nine intrinsic capacitances associated to the gate, source, and drain terminals of long-channel undoped surrounding-gate (SRG) MOSFETs are derived physically from an exact analytical solution of the channel current-continuity principle and channel charge-partition scheme in this paper. Although requiring lengthy and complex mathematical expressions, all explicit solutions for the capacitances can be obtained analytically. The validity of the analytical solutions is confirmed by comparing model predictions with simulation data obtained using the 3-D numerical solvers. The explicit expressions to the terminal charges and transcapacitance not only lead to a clearer understanding of SRG MOSFET device physics but also provide a better infrastructure to develop a complete carrier-based model for the SRG-MOSFET-based circuit simulation. [ABSTRACT FROM AUTHOR]

Adaptive-mesh-refinement hydrodynamic simulations have been performed of cross sections of fibrous foams saturated with cryogenic deuterium and tritium (DT). Material tracking indicates that the fibers and DT mix rapidly behind the shock. In addition, fluctuation decay lengths are on the order of a micron even in the absence of radiative and thermal energy transport. Outside the mix region, the Rankine–Hugoniot equations are satisfied to the degree to which the turbulence and transverse motion decay, a few percent or less. Simulations also show that the shock-front perturbations decay rapidly after the shock leaves the foam and enters a layer of DT ice, suggesting that the foam microstructure will not contribute to feedthrough. [ABSTRACT FROM AUTHOR]

This paper describes a novel µ-flux (micro flux) pump using a cryotron-like switch that may be coupled to a high-temperature superconductor (HTS) insert coil of a high-field nuclear magnetic resonance (NMR) magnet. The flux pump is essentially comprised of a single superconducting cryotron-like switch loop that is intermittently open and closed by magnetic field. There is inherently only small energy dissipation in the switching action because the triggering action of the switch is made magnetically not thermally. The micro flux pump can supply precisely a small amount of current into a superconducting load magnet. The switching is stable and fast because the thermal inertia and the temperature sensitivity of the flux pump are not relevant to the operation. The µ-flux pump can be designed to generate minimum total heat input to liquid helium bath of HTS insert coil of NMR magnet. [ABSTRACT FROM AUTHOR]

Accurate maps of large macromolecular complexes can be calculated from cryo-electron micrographs of non-crystalline specimens to resolutions of about 10 Å. A method to dock the atomic structures of domains solved by X-ray crystallography or nuclear magnetic resonance into cryo-EM maps is presented. Domains can be docked independently into large complexes without prior definition of the boundaries. No special symmetry is assumed and the procedure is suitable for general application to almost any system where a cryo-EM map (at 15 Å resolution or better) of a complex has been obtained and the atomic structures of the components are available. This is achieved through use of a real-space density matching procedure based on local correlation. A complete asymmetric unit search correlating a density object derived from the atomic coordinates and the density of the EM map is performed. The correlation coefficient is calculated locally in real space using only values of the search object and corresponding samples extracted from the EM map which are under the `footprint' of the positioned search object. The procedure has been demonstrated by docking the domains of GroEL from the crystal structure into a cryo-EM map Fourier filtered to 12 or 15 Å resolution. The correct positions were found without applying any additional constraints. A model of the oligomer built from the docked domains compared favourably with the known crystal structure, confirming the validity of the approach. The procedure is designed to facilitate the incorporation of additional constraints on the docking solutions, which could help to dock using lower resolution maps. [ABSTRACT FROM AUTHOR]

Amyloid fibrils are assemblies of misfolded proteins and are associated with pathological conditions such as Alzheimer's disease and the spongiform encephalopathies. In the amyloid diseases, a diverse group of normally soluble proteins self-assemble to form insoluble fibrils. X-ray fibre diffraction studies have shown that the protofilament cores of fibrils formed from the various proteins all contain a cross-β-scaffold, with β-strands perpendicular and β-sheets parallel to the fibre axis. We have determined the three-dimensional structure of an amyloid fibril, formed by the SH3 domain of phosphatidylinositol-3′-kinase, using cryo-electron microscopy and image processing at 25 Å resolution. The structure is a double helix of two protofilament pairs wound around a hollow core, with a helical crossover repeat of ∼600 Å and an axial subunit repeat of ∼27 Å. The native SH3 domain is too compact to fit into the fibril density, and must unfold to adopt a longer, thinner shape in the amyloid form. The 20 × 40-Å protofilaments can only accommodate one pair of flat β-sheets stacked against each other, with very little inter-strand twist. We propose a model for the polypeptide packing as a basis for understanding the structure of amyloid fibrils in general. [ABSTRACT FROM AUTHOR]

A cryofracture device has been developed for freeze-cleaving cultured cells grown on a polished substrate wafer. The fracture is made under liquid nitrogen and results in specimens suitable for ion microscopic analysis to reveal the intracellular elemental distribution. In performing this operation the nutrient media is also removed, precluding any need of prewashing the specimen and introducing any contamination or loss in subcellular ion concentrations. The design and performance of this device are described. [ABSTRACT FROM AUTHOR]

A superconducting loop stores persistent current without any ohmic loss, making it an ideal platform for energy efficient memories. Conventional superconducting memories use an architecture based on Josephson junctions (JJs) and have demonstrated access times less than 10 ps and power dissipation as low as 10−19 J. However, their scalability has been slow to develop due to the challenges in reducing the dimensions of JJs and minimizing the area of the superconducting loops. In addition to the memory itself, complex readout circuits require additional JJs and inductors for coupling signals, increasing the overall area. Here, we have demonstrated a superconducting memory based solely on lithographic nanowires. The small dimensions of the nanowire ensure that the device can be fabricated in a dense area in multiple layers, while the high kinetic inductance makes the loop essentially independent of geometric inductance, allowing it to be scaled down without sacrificing performance. The memory is operated by a group of nanowire cryotrons patterned alongside the storage loop, enabling us to reduce the entire memory cell to 3 μm × 7 μm in our proof-of-concept device. In this work we present the operation principles of a superconducting nanowire memory (nMem) and characterize its bit error rate, speed, and power dissipation. [ABSTRACT FROM AUTHOR]