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Addressable quantum circuits with array of Josephson field effect transistors Kaveh Delfanazari, University of Cambridge In this talk, we will first review our progress on the proximitized superconducting two-dimensional (2D) electron gases in InGaAs heterostructures, such as the observation of coherent quantum transport, Aharonov-Bohm type effect and topological suppression of magneto-conductance oscillations in 2D Josephson junctions (JJs). Then, we will demonstrate a novel hybrid superconducting-semiconducting (S-Sm) quantum integrated circuit (QIC) on a chip of semiconducting InGaAs that contains one-dimensional arrays of Josephson Field Effect Transistors (JoFETs). All JoFETs embedded into the QICs are addressed and controlled by only two universal split-gates. The device advantages include: switching between individual devices and studying the statistics, quantum yields and reproducibility of many devices (S-Sm contacts, S-Sm-S JJs, and JoFETs) in one fridge cooldown. We discuss the device design, fabrication, characterization and measurements in sub-Kelvin temperature ranges. Our systematic studies could be very important for the optimisation of hybrid qubits and the realisation of the scalable topological quantum processors. Identifying and Eliminating Interference in Josephson Digital Electronics Aaron Lee, Northrop Grumman A new technique was developed to measure noise and interference in a test stand for Josephson digital circuits. A spectrum analyzer measured the spectrum of the Josephson output amplifier and found the frequency characteristics of noise currents as amplitude modulation sidebands of the data pattern. Noise on the output amplifier bias current appeared as AM sidebands of the data pattern 1010 at one half of the clock frequency. Noise on logic gate bias current also appeared as AM sidebands when the digital circuit was biased at the threshold between correct and incorrect operation. Calibration tones were injected and AM sidebands showed a linear response over 5 decades of calibration tone power. Instrumentation noise floor was low enough to sense 1 nA of 60 Hz current on chip. Observation of AM sidebands was used to optimize filtering and identify defective cabling to eliminate noise and interference in the cryocooled test stand. High-Tc SQUID magnetometers for multi-channel on-scalp MEG Silvia Ruffieux, Chalmers University of Technology In the growing field of on-scalp magnetoencephalography (MEG), brain activity is studied by non-invasively mapping the magnetic fields generated by neuronal currents with sensors that can be placed flexibly in close proximity to the subject's head. We have built a densely-packed 7-channel on-scalp MEG system based on high critical temperature (high-Tc) superconducting quantum interference device (SQUID) magnetometers, which can be placed as close as 1 mm from the head[1]. Here we present single-layer YBa2Cu3O7-x (YBCO) SQUID magnetometers with a directly coupled pickup loop on (10 mm)2 SrTiO3 (STO) bicrystal substrates which achieve a magnetic field noise level of 44 fT/√Hz down to a few Hz. We further present magnetometers with inductively coupled flux transformers achieving 11 fT/√Hz white noise level and 60 fT/√Hz at 10 Hz. We compare the suitability of the two magnetometer types for our on-scalp MEG system in terms of noise performance, crosstalk, and sensor fabrication and operation. Fast, Ultrasensitive Differential Magnetic DNA Assay Using HTS SQUID Gradiometer Sobhan Sepehri, Chalmers University of Technology We have developed a femtomolar sensitivity homogeneous DNA assay using magnetic nanoparticle (MNP) probes. The binding of the MNP labels with the target DNA molecules induces a change in the hydrodynamic volume of the MNPs and can be measured using ac susceptibility measurements [1,2]. Two identical microfluidic channels embedded in a single polydimethylsiloxane device is aligned parallel to the

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baseline and along the pickup loops of a planar HTS SQUID gradiometer. The control sample (no target) and the test sample (with target) are filled in each individual channel and their differential ac susceptibility is measured simultaneously. The measured signal is thus a result of relative differences in particle size distributions in the two channels. The elimination of the background signal from the unbound MNP in the differential readout allows measurements of small concentrations of target molecules without affecting the binding kinetics. We demonstrated experimental limit of detection of 45 fM. Effect of SQUID loop coupling on SQIF array sensitivity Emma Mitchell, CSIRO Manufacturing Series arrays of identical SQUIDs were developed to improve their periodic voltage-field response and noise performance compared to that of single dc-SQUIDs1. When an aperiodic magnetic response is preferred e.g. in absolute magnetic field detection2, an array of unequal loop areas (SQIFs) is used and the array sensitivity is expected to scale3 with the total junction number N. However recent results4 from large two dimensional SQIF arrays with N ~ 20,000 YBCO junctions show sub-linear scaling with N.The sensitivity of small SQUID/SQIF arrays fabricated using YBCO Josephson junctions show a dependence on the array geometry. Theoretical simulations of high-Tc SQUID array performance, using both analytical and numerical methods, are presented for a range of geometries (with loops in parallel and/or series), bias currents and junction parameter regimes for small arrays. The experimentally feasible regime of non-zero inductances is modelled, including nearest neighbour inductances and experimentally realised junction parameters spreads. High Tc SQIF for highly-sensitive microwave magnetometry Francois Couedo, ESPCI Paris, PSL, UPMC, CNRS Superconducting Quantum Interference Filters (SQIFs) are promising devices for detection [1] and amplification of radio frequency (RF) signals. Here, we report on GHz magnetometry using high Tc SQIFs made by the ion-irradiation technique on YBa2Cu3O7 thin films. A modulation of the output RF signal amplitude VRF with the DC magnetic field is observed at a frequency f = 1.125 GHz, which is a clear signature of a SQIF behavior. From this measurement, we extracted the RF magnetic field bRF detected by the SQIF. The lowest value that we measured is bRF = 9.5 pT, corresponding to a sensitivity of \(300 fT/ \sqrtHz\) [2]. The magnetometer response is linear over 7 decades in RF input power. This work demonstrates a promising approach for the realization of low dissipative sub-wavelength GHz magnetometers. Highly scalable readout electronics for large multi-channel dc-SQUID systems Sylke Bechstein, Physikalisch-Technische Bundesanstalt SQUID instruments for biomagnetic diagnostics, radiometry and astrophysics are often equipped with a large number of devices. For systems with more than a few tens of sensors, read-out with an equivalent number of independent components is not an appropriate solution to meet both, technical and financial requirements. In such cases, specifically tailored readout electronics are typically used. In this presentation, the general concept of a new highly scalable and flexible electronics is presented which is intended for operation of up to about 1000 SQUID channels in the linearizing flux locked loop mode. A prototype version for the readout of a low-noise biomagnetic system involving 72 SQUID sensors is demonstrated. Measurement results regarding gain, bandwidth, noise, and power consumption will be presented. Finally, we discuss other potential applications in magnetometry and radiation detection with transition edge sensors or metallic magnetic calorimeters.

YBCO nanowires for fundamental studies and single photon detector applications Floriana Lombardi, Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.

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The phase diagram of the cuprates superconductors is dominated by various nanoscale symmetry breaking orders, such as Charge Density Waves, that are strongly intertwined with superconductivity. Here we present our recent experiments where we use newly engineered YBa2Cu3O7-x nanowires, as a function of the doping, to disclose the effects of local orders on the normal and superconducting properties of nanodevices. We have found that untwinned and underdoped YBa2Cu3O7-xnanowires, with thicknesses below 10 nm, show a strong normal state anisotropy already at room temperature and the disappearance of the pseudogap feature, in the R(T) transition, in the b-axis direction. Analogously the nanowire superconducting properties are also affected. The amplitude of the switching voltage, in the current voltage characteristic, is anisotropic and strongly depend on the doping, reaching the maximum value close to optimal doping. We discuss these findings in view of applications of YBCO nanowires as single photon detectors. Demonstration of NbTiN SNSPD array with reduced readout lines Shigehito Miki, National Institute of Information and Communications Technology Two-dimensionally arranged SNSPD array would be a novel single photon imaging system, leading an innovation for various kinds of applications due to attractive features of SNSPD. A critical issue in a development of SNSPD array with large number of pixels is to reduce the number of readout lines which lead to a heat inflow from the room temperature. To reduce the number of readout cables, we have been developing SNSPD array with single-flux-quantum (SFQ) circuit. Furthermore, SNSPD array with row-column readout architecture can reduce the number of readout lines for the N x N pixel array to 2N from N2[1]. In this work, we report the demonstration of NbTiN-SNSPD array with row-column readout architecture and SFQ encoder circuit installed into a 0.1 W GM cryocooler system and confirmed the output signals from all of the pixels through the SFQ circuit with maintaining the temporal resolution of SNSPD. Hot-spot correlation length for SNSPDs with near-unity detection efficiency Gregory Goltsman, Moscow State Pedagogical University The hot spot (HS), produced by photon absorption, is the key player in the operation of superconducting nanowire single photon detectors (SNSPDs). Its properties and their dependence on material parameters and temperature, are widely discussed in the literature, but it is hard to measure these properties in a direct way – HS is too small and too short-living. We present a simple quantum detector tomography protocol, which allows, for an SNSPD with unity intrinsic detection efficiency, to measure two-spot detection efficiency and extract the hot-spot interaction length without ambiguity. We identify a significant parasitic contribution to the measured two-spot efficiency in waveguide-integrated SNSPD, related to an effect of bias circuit, and find a way to rule out this contribution at the stage of data processing or directly in the experiment. We find signatures of saturation of the two-spot efficiency, indicating hot spot interaction length of order of 100 nm. Supercontinuum single photon detector using multilayer superconducting nanowires Hao Li, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences In this work, we propose a supercontinuum SNSPD that can efficiently detect single photons in an ultrabroad spectral range by fabricating multilayer superconducting nanowires atop metallic mirror with silica acting as spacer layers. The multiple layer nanowires along with the mirror behaving as multiple cavities with well-separated absorbed resonances result in an extended absorption bandwidth while maintaining a considerable efficiency as opposed to conventional single layer nanowire detector. The calculation of the detector structure with single layer, bilayer and three layer nanowires is performed, which shows an extended absorption bandwidth with increased layers. Experimentally, we fabricate detectors with single layer and bilayer nanowires, which achieve detection efficiency over 50% from 950 to 1600 nm and over 60% from 950 to 1650 nm respectively, verifying the broaden detection bandwidth with increased layers. Finally, we present a detector design using three layer nanowires with absorption greater than 80% from 500 to 2800 nm.

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Statistics of dark and photon counts in current-carrying superconducting strips Alexej Semenov, DLR Institute of optical systems Timing jitter in photon detection restricts the accuracy in defining flight-times of photons referenced to the time of their emission while intrinsic statistics of photon counts may disguise the statistics of photon arrivals from the light source. Here we show that timing statistics of dark counts in straight current-carrying superconducting strips differs from the statistics of photon counts induced by coherent light. While light counts obey poissonian probability density in a fixed time window, dark counts demonstrate superpoissonian statistics. We compare different statistical models of dark counts e.g. vortex-assisted dark counts or internally correlated stochastic process governing local fluctuations in the free energy and show that internal fluctuations are likely to describe transition from saturated detection efficiency at large photon energies to quickly decreasing detection efficiency at small photon energies. We further estimate the effect of intrinsic fluctuations on timing jitter. Superconducting detectors fabricated using precision dislocation engineering Ilya Charaev, Massachusetts Institute of Technology We present an alternative approach to creating nanowires through local damage by a focused He ion beam (HIM). Motivated by the successful realization of Josephson junctions (JJ) after the introduction of dislocations into an otherwise orderly atomic arrangement [1], we have fabricated nanoscale detectors on superconducting films using He+ ion beam irradiation + beam technique allows for control of the atomic layer in three dimensions due to low dose and high collimation. We have performed an analysis of critical dose for different materials and have characterized patterned nanostructures. Our results suggest HIM may have advantages over e-beam lithography for some applications. NbN and MgB2 SNSPDs: a comparative study Sergey Cherednichenko, Chalmers University of Technology A number of superconductors have been studied for Superconducting Nanowire Single Photon Detectors (SNSPD): Nb, NbN, NbTiN, NbC, TaN, MoN, WSi. Whereas a high detection efficiency could be observed in most of the devices, all of them suffered from a large kinetic inductance, resulting in a rather long reset time,τ. This is particularly critical for large area detectors, where τ is 5-10ns even in the fastest NbN SNSPDs. Recently, we demonstrated that using very 5-8nm thick and clean MgB2 films, single photon detection could be observed at λ=1550 nm, with a reset time of ~70ps for a 100nm nanowire 120μm long. The excellent timing properties are due to much lower kinetic inductance. Here, we offer a comparative study of NbN and MgB2 SNSPDs conducted in a single set-up, where the detection efficiency, the reset time, and the jitter have been investigated, vs. nanowire width, length, operation temperature.

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Transition-Edge Sensor Development at NIST Joel Ullom, NIST and the University of Colorado Transition-Edge Sensors (TESs) are now finding applications across the electromagnetic spectrum. These versatile devices consist of thin superconducting films that are electrically biased in the resistive transition. Their temperature, resistance, and current respond to absorbed photons. In this talk, we report on work at NIST and the University of Colorado to improve and apply TES technology. For example, applications in soft x-ray spectroscopy are motivating the development of large-area TESs with sub-eV energy resolution that may supplant diffraction gratings in many photon-starved measurements at synchrotrons and free-electron lasers. Other recent applications of x-ray TESs include spectroscopy of highly charged ions and the determination of x-ray reference data used in industrial materials analysis. We also discuss a movement towards GHz frequency-domain multiplexing techniques for TES arrays and efforts to combine this readout with multichroic TES polarimeters for measurements of the cosmic microwave background that require very large numbers of sensors. Practical Superconducting Single-Photon Detector with Micron-Wide Strip Alexander Korneev, Moscow State Pedagogical University Superconducting single-photon detector (SSPD) is a device of choice for advanced applications in quantum optics, quantum computing, and quantum cryptography. We present a further evolution of SSPD based on the recently observed single-photon detection in micron-wide superconducting strips [1]. For efficient free-space and multi-mode-fibre coupling, we make these detectors as 20-µm-diameter double Archimedean spiral with the strip width of 1 µm. Spiral configuration reduces the current-crowding effect in the curved strip, and enables higher critical current. Further improvement of detection efficiency is achieved by integration into optical cavity. Such SSPDs exhibit 40-50 ps timing jitter, high detection efficiency and dark counts rate below 0.1 counts per second. We shall present experimental study of the detection mechanism in micron-wide strip and characterization of the detector performance. Graphene-based Josephson junction single photon detector Kin Chung Fong, Raytheon BBN Technologies Single photon detector is a key enabling technology in quantum information processing, future space missions of measuring the cosmic infrared background, and searching of dark matter. However, detecting low frequency photons is challenging because of their vanishingly small energy. Here we present how to use a superconductor-graphene-superconductor proximity junction to detect a single photon from a wide electromagnetic spectrum by sensing its thermal energy. This is possible because the Dirac fermions are in extreme thermal isolation with a minute specific heat that can be exploited for ultra-sensitive calorimetry. Specifically in this talk, we will discuss (1) the concept and modeling of single-photon detector performance, (2) a high sensitivity microwave bolometer reaching ~1e-19 W/Hz-1/2 at 0.2 K, and (3) the single-photon response from infra-red photons. Neutron imaging by using current-biased Nb nanowire detector with 10B converter Takekazu Ishida, Osaka Prefecture University We are developing a neutron transmission imager based on a superconducting current-biased kinetic inductance detector (CB-KID). The CB-KID comprises the X and Y meanderlines and a 10B conversion layer of neutron. The 4He or 7Li ion from the 10B(n, α)7Li reaction creates two hot spots in both the X and Y meanders. A pair of electromagnetic-wave pulses of opposite polarities propagate toward the ends of meanderlines [1]. The position of the nuclear reaction point can be evaluated from a difference in arrival timestamps of the two pulses at the two ends. We used a set of analog signal discriminators with fixed

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threshold levels and a time-to-digital converter (TDC) with 1-ns time resolution to recover the signals from 25-Hz pulsed neutrons of J-PARC. The energy-integrated spatial resolution reached 22 μm [2]. Further improvements in spatial resolution can be achieved by enhancing a temporal-resolution of readout circuit in future work. TES microcalorimeter detectors suitable for neutrino mass measurement Andrea Giachero, University of Milano - Bicocca HOLMES will perform a precise calorimetric measurement of the end point of the Electron Capture (EC) decay spectrum of 163 Ho in order to extract information on neutrino mass with a sensitivity below 2 eV. In its final configuration, HOLMES will deploy 1000 detectors of low temperature microcalorimeters with implanted 163 Ho nuclei. The baseline sensors for HOLMES are Mo/Cu TESs (Transition Edge Sensors) on SiNx membrane with gold absorbers. Considering the large number of pixels and an event rate of about 300 Hz/pixel, a large multiplexing factor and a large bandwidth are needed. To fulfill this requirement, HOLMES will exploit recent advances on microwave multiplexing. In this contribution we present the status of the activities in development, the performances of the developed microwave-multiplexed readout system, and the results obtained with the detectors specifically designed for HOLMES in terms of noise, time and energy resolutions. Nanosecond thermometry with Josephson junction Maciej Zgirski, Institute of Physics, Polish Academy of Sciences In our pioneering experiments we employ a superconducting weak link to measure rapidly changing electron temperature in a long superconducting nanowire with nanosecond resolution [1]. Investigation of thermal properties in nanoscale suffers from lack of fast thermometers that would be able to trace thermal transients appearing when electrical circuit is driven out of equilibrium due to, say, rapidly changing current responsible for Joule heating or photons absorbed in the bolometer. Proper understanding of thermal processes is essential for failure-free functioning of quantum circuits, involving design of nanoscale calorimeters and bolometers. In our quest to measure temperature even faster we utilized the ability of current-carrying superconducting weak link to instantaneously switch from superconducting to normal state. This switching depends on temperature, thus providing a feature required for a temperature sensor. The ease of integration, true nanometer size and simplicity make our thermometer a good candidate for exploring thermodynamics of low temperature quantum circuits. Hafnium MEGA array detector Sergey Shitov, National University of Science and Technology MISIS We present a new THz-range array detector using frequency division multiplexing at microwaves. The sensor exploits a non-equilibrium Microwave Electron Gas Absorber (MEGA) made from hafnium (Tc ≈ 375 mK, RN ≈ 30 Ω) read at probing frequency of 1.35-1.6 GHz. The microbridge sized 2.5 µm by 2.5 µm by 50 nm is integrated with a planar 600-700 GHz antenna near open end of a Nb resonator (Q-factor ~104) weakly coupled to a throughput line exhibiting variation of S21 at the resonant frequency. The circuit was tested at 50-350 mK confirming the model of hot electron gas absorption in the bridge, P~Te6‑Tph6. The idle NEP down to 10-18 W/√Hz and corresponding cross-over temperature for photon background 5 K are estimated for a practicable bolometer operating at bath temperature about 200 mK. The readout frequency at the resonance is suppressing a phase instability. The photon-energy limit is below the readout frequency.

Recent progress of adiabatic-quantum-flux-parametron circuit technologies Nobuyuki Yoshikawa, Yokohama National University

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Adiabatic quantum-flux-parametron (AQFP) is an extremely energy-efficient logic, whose switching energy can be reduced to the order of the thermodynamic limit around kBT due to the adiabatic switching of a superconducting logic gate. We are developing fundamental technologies for high-performance computing based on AQFP logic circuits to overcome the explosive increase of power consumption. We will review our latest research activities about AQFP integrated circuits. After introducing the operation principles of the AQFP logic, we will show the recent progress in AQFP cell libraries, clocking schemes, EDA tools, and a three-dimensional Josephson fabrication process. Based on these developments, the operation of large-scale AQFP integrated circuits, such as adders, register files, and microprocessors have been demonstrated. High-speed measurements of an AQFP adder exhibit the energy consumption of an AQFP gate is the order of a few tens of kBT. We will discuss a perspective of AQFP integrated circuit technologies toward energy-efficient computing. A novel stochastic number generator using adiabatic superconducting technology Olivia Chen, Yokohama National University Stochastic circuits (SC) are known for the small hardware footprint and high energy efficiency. A stochastic number generator (SNG) is a key part in the SC scheme, which converts a binary number to its corresponding stochastic format. Often the SNGs required for an SC take up about 40%-60% of the circuit area, which would eliminate the area benefits offered by SC. In this paper, we propose a true random number generator (TRNG) based stochastic number generation scheme, using adiabatic quantum-flux-parametron (AQFP) technology. With the proposed AQFP SNG, the overhead in SC using CMOS logics can be largely mitigated in AQFP. This is because of the extremely high efficiency in true RNG implementation (instead of pseudo-RNG) in AQFP, thanks to its unique operating nature. We further demonstrate a 32-bit AQFP SNG fabricated by using the AIST 10kA/cm2Nb high-speed standard process (HSTP). Independent Test and Evaluation of C3 Circuits Adam Sirois, NIST-Boulder NIST-Boulder led the independent test and evaluation effort for IARPA’s Cryogenic Computing Complexity (C3) program over the past five years, with the goal of verifying the components necessary to build a prototype superconducting computer. We have worked closely with C3 performers to verify performance and other critical parameters of ERSFQ and RQL based circuit prototypes from DC to 20 gigahertz frequencies. We summarize the accomplishments of the program and the remaining challenges for implementing large-scale single-flux-quantum (SFQ) based computing. Specifically, we discuss the evaluation of the performance of 16-bit Arithmetic Logic Units and other CPU components/designs. Finally, as the initial ‘end user’ of these prototypes, we discuss a ‘wish list’ focused on future research efforts to accommodate larger-scale circuits and better ways to quantify energy usage. RF Waveform Synthesizer Using RSFQ Circuits Manuel Castellanos-Beltran, NIST NIST’s Superconductive Electronics Group is developing Josephson-based synthesizers at gigahertz frequencies for rf metrology and control of superconducting qubits. In this presentation, I will show gigahertz waveforms including single tone, multi-tone, and gaussian waveforms produced from a prototype SFQ-based circuit operating at 4 K. Our prototype circuit consists of an RSFQ driver which generates SFQ pulses that are distributed with a network of splitters and Josephson transmission lines to a serially connected voltage multiplier (VM) comprised of SQUID stacks. This VM increases the amplitude of the pulse-encoded synthesized waveform by adding all the pulses generated in the RSFQ circuitry. A maximum amplitude of ≈130 µV and signal frequency generated of 4 GHz was achieved, consistent with the operating clock, as well as a signal-to-quantization-noise-error of 70 dB over the band of the delta-sigma modulation code. I will also discuss our plans to incorporate similar synthesizers in the operation of qubits. Design of a 16-bit bit-slice RSFQ multiplier for 64-bit microprocessors Jia-Hong Yang, State Key Laboratory of Computer Architecture, Institute of Computing Technology, Chinese Academy of Sciences

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Rapid single-flux-quantum (RSFQ) circuit technology is presented to be the next generation of integrated circuit for its ultra-high speed and ultra-low power consumption. Several bit-serial RSFQ Multipliers have been developed. Bit-slice multiplier is required for 64-bit microprocessors.We proposed a 16-bit bit-slice multiplier based on RSFQ circuit technology. Concurrent flow clocking is adopted for presented fully pipelined RSFQ multiplier. The systolic-like algorithm is used in the multiplier. The proposed multiplier consists of four systolic cells, sixteen 3:2 compressors and one 16-bit bit-slice adder, which is based on Ladner-Fischer adder.We design and simulate the proposed multiplier with the cell library based on AIST ADP2 process. The multiplier has 51 stages. The results show the proposed multiplier has higher throughput than bit-serial multipliers.

tbc Maja Cassidy, Microsoft Multilayer coaxial superconducting circuits with integrated 3D wiring Peter Leek, University of Oxford Superconducting circuits are a leading candidate for the realization of quantum computers, in particular for near-term applications which may be reached with circuits consisting of a few hundred qubits operated at high fidelity. Superconducting circuit topologies have so far typically been constrained to two dimensions, making them difficult to scale to large qubit numbers since control and measurement wiring is needed in the middle of large arrays. New circuit topologies that incorporate wiring in the third dimension can solve this problem. In this talk I will present an approach that builds on a coaxially-symmetric circuit QED unit cell with out-of-plane wiring [1] that provides a simple route to scaling to grids of many qubits. Arrays of qubits and resonators are fabricated on opposing sides of a substrate and capacitively coupled, while control and readout are achieved via off-chip coaxial wires running perpendicular to the chip plane and built into a precision micro-machined enclosure, providing a high-quality microwave environment for the circuit. Surface spins as a source 1/f charge noise in superconducting devices Tobias Lindstrom, National Physical Laboratory Noise and decoherence due to spurious two-level systems (TLS) located at or near material interfaces have long been identified as an important problems for superconducting devices such as SQUIDs, superconducting detectors and more recently qubits. Efforts to mitigate the effects of these TLS have historically been hampered by a lack of knowledge about their origin.Here, we combine measurements of dielectric loss, frequency noise and on-chip electron spin resonance using superconducting resonators. We show that desorption of surface spins by annealing sample at moderate temperatures is accompanied by an almost tenfold reduction in the charge-induced 1/f frequency noise.Our measurements reveal both the chemical signatures of adsorbed magnetic moments and highlights their role as an indirect source of charge noise in superconducting devices. Simulation of a dynamic quantum phase transition using a superconducting qubit

Dongning Zheng, Beijing National Laboratory for Condensed Matter Physics，Institute of Physics, Chinese Academy of Sciences We have prepared superconducting circuits containing multiple Xmon qubits. The energy relaxation time of single qubit can reach 60 ms. Quantum simulations of several many-body phenomena have been carried out using the devices. Here, we report observation of a dynamical quantum phase transition by a superconducting qubit simulation of quantum quench dynamics of many-body systems. We take the Ising model with a transverse field as an example. In experiment, the spin state initially polarized longitudinally evolves based on Hamiltonian with adjustable parameters depending on momentum and strength of the transverse magnetic field. The time evolving quantum state is read out by state tomography. Evidence of dynamical quantum phase transition such as paths of time evolution states on the Bloch sphere, the

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nonanalytic behavior in the dynamical free energy and the emergence of Skyrmion lattice in momentum-time space are provided. The experiment data agrees well with theoretical and numerical calculations. Tavis-Cummings level splitting with intermediate-scale superconducting circuits Martin Weides, University of Glasgow Applications such as analog quantum simulation have been proposed involving more than one controllable two-level system coupled to a single resonator. In this work, the circuit complexity is increased to study the Tavis-Cummings circuit consisting of a superconducting resonator interacting with up to eight individually frequency-controllable transmon qubits. It is a well-suited platform to study desired and parasitic effects occurring in scaled-up quantum circuits. We demonstrate the local control of the two-level systems interacting strongly with a microwave cavity. The local control circuitry causes a bypass shunting the resonator, and a Fano interference in the microwave readout, whose contribution can be calibrated away to recover the pure cavity spectrum. The simulator's attainable size of dressed states is limited by reduced signal visibility, and -if uncalibrated- by off-resonance shifts of sub-components. Our work proves control and readout of quantum coherent mesoscopic multi-qubit system of intermediate scale under conditions of noise. Tuning of dissipation in magnetic Josephson junctions towards quantum devices Davide Massarotti, University of Naples Federico II, CNR-SPIN UOS Napoli Josephson coupling between superconducting (S) and ferromagnetic (F) layers is driving new fundamental physics and innovative applications for superconducting electronics and quantum circuits [1]. Examples are the possibility to switch the ground state of a Josephson junction (JJ) from a 0 to a π phase state and to carry spin-triplet supercurrent in presence of magnetic inhomogeneities.We will report on transport measurements, as a function of temperature down to 20 mK, providing clear fingerprints of different dissipation sources in JJs composed by pure metallic ferromagnetic layers (SFS) [2], by an insulating barrier and a ferromagnetic layer (SIFS) [3], and by a ferromagnetic-insulator barrier (SIFS) [4,5], respectively. These fingerprints and the self-consistent reconstruction of the electrodynamics [2,5,6], give strong indications on the presence of triplet correlations, show the capability to tune the scaling energies through different means and point out new routes for superconducting qubits with ferromagnetic JJs.

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Fast thermometry and ultrasensitive calorimetry for microwave photons Jukka Pekola, Aalto University We describe our recent work on calorimetry based on on-chip thermometry with microsecond time resolution. Recent experimental results on fundamental temperature fluctuation limited detection of heat currents will be presented. Wednesday 4 September 2019 Field-effect metallic superconducting electronics Federico Paolucci, INFN Sezione di Pisa Despite electric-field-effect was believed to be ineffective on conventional BCS superconducting metals, a set of gating experiments performed on Titanium and Aluminum mesoscopic devices demonstrated the possibility to electrostatically suppress their critical super-current down to its full quenching. While the grounding mechanism of this phenomenon is not yet understood and requires for deep -both theoretical and experimental- reinvestigations of the intimate nature of the superconducting state, the technological exploitation of such phenomenon is at hand, promising a deep impact on superconducting energy-efficient classical and quantum computation architectures. In this talk I will go through the main findings on superconducting wires and Josephson Dayem-bridge devices highlighting both the basic physics discoveries and the application that this new technology provides. Cryogenic Calibration of the RF Josephson Arbitrary Waveform Synthesizer Justus Brevik, National Institute of Standards and Technology Boulder We report on efforts to extend the synthesis frequency capability of the Josephson arbitrary waveform synthesizer (JAWS) from the audio to gigahertz range. A loss of quantum-based accuracy of the output voltage pulses of the Josephson junction (JJ) array in the transmission from 4 K to room temperature limits the ability of the JAWS system to synthesize waveforms with accurate amplitude above audio frequencies. We have used cryogenic on-wafer calibration techniques to correct various error sources and transfer the quantum-accurate JJ signal to room temperature. We present traceable calibration measurements of the magnitude and phase of JAWS-synthesized waveforms. This is a critical first step in the progress toward the development of the first RF primary reference standard operating up to 1 GHz with a minimum of -30 dBm output power. These techniques will be extended to 40 GHz to provide quantum-based signal sources for the calibration of 5G telecommunication devices. Increasing Integration of Superconductor Electronics Beyond One Million Devices Sergey Tolpygo, MIT Lincoln Laboratory Superconductor electronics could become a technology of choice for energy efficient computing, quantum information processing, advanced sensing and imaging, etc., if a very large scale of integration (VLSI) is achieved. Recent progress in fabrication technology at MIT Lincoln Laboratory enabled circuits with ~ 1 million Josephson junctions (JJs), a device count usually viewed as VLSI threshold. I will review fabrication processes that we are developing in order to increase the scale of integration toward 10 million JJs per chip: a) the PSE2 process with two layers of Nb/Al/AlOx/Nb junctions and two layers of resistors, a layer of Mo2N kinetic inductors, and six planarized Nb wiring layers; b) a PSE2 node integrating magnetic π-junctions on one JJ layer with Nb/Al/AlOx/Nb JJs on another layer; c) a process with self-shunted high-Jc Nb/Al/AlOx/Nb JJs and 250-nm minimum linewdith. As an example, we demonstrated random access memory circuits with device density about 4∙106 JJs/cm2.

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Josephson Junction based Single Photon Counter at 14 GHz for searching Axions Leonid Kuzmin, Chalmers University of Technology Axions appear in extensions of the Standard Model and may be the solution of the Dark Matter in our Universe. In the mass region from few to several tens of microelectronvolt, detector sensitivity will be limited by the Standard Quantum Limit of linear amplifiers and single photon detectors are needed. We have developed a single photon counter based on a Josephson junction coupled to a coplanar waveguide for QUAX project. By measuring the switching voltage, we can register single photons at 14GHz with the rate of less than 1 photon per 3000 sec.We fabricated Al-AlOx-Al Josephson junctions and measured switching rate at different temperatures and for different positions of bias current relative to critical current. Measurements have shown a lifetime over 6000sec at 100mK, limited by external interferences. RF test shows that the detection probability decreases linearly with the decrease of the power, demonstrating the single-photon detection mechanism. Neon focussed-ion-beams for nanofabrication of superconducting nanowires Paul Warburton, University College London The leading fabrication tools for superconducting nanowires are electron-beam lithography (EBL) and focussed-ion-beam (FIB). Here I will present our work on Nb and NbN nanowires created using neon FIB and compare this with EBL. We show that by using neon FIB we can achieve NbN wires with width less than 20nm [1]. These are embedded into waveguide resonators which maintain high single-photon Q, showing that the neon-FIB technique does not significantly add to losses. We have also used neon FIB to fabricate Dayem-bridge Nb weak-link SQUIDs which present a flux-tunable inductive load to a coplanar waveguide resonator [2]. The resonator frequency may be tuned by approximately 1% while maintaining a quality factor of 10k-100k. We also report progress towards neon-FIB-patterned NbN nanowires for coherent quantum phase-slip devices [3]. Superspintronics – towards ultra-low dissipation spin-electronics Niladri Banerjee, Loughborough University The fundamental antagonism between superconductivity and ferromagnetism arises from the nature of electron pairing in these materials: parallel for ferromagnetism and antiparallel (singlet) for superconductivity. However, recent theoretical and experimental evidences [1] suggest a unique form of odd-frequency equal-spin (triplet) superconductivity that arises at carefully engineered interfaces between ferromagnets and superconductors. These equal-spin Cooper pairs are immune to the pair breaking exchange field in a ferromagnet and can propagate over length scales which are significantly longer than the singlet pair coherence lengths. These dissipationless triplet currents carry a net spin which raises the intriguing possibility of ultralow-dissipation superconducting spin-electronics (superspintronics).In this talk, following a brief introduction, I will discuss our work [2,3] in this area, specifically focussing on two recent results: spin-orbit coupling-driven superspintronics [4] and magnetisation reorientation due to superconducting transition [5].

NanoSQUID-on-tip thermal imaging: glimpse into dissipation in quantum systems Eli Zeldov, Weizmann Institute of Science Direct imaging and microscopy of dissipation in quantum systems is currently inaccessible because the existing thermal imaging methods lack the necessary sensitivity and are unsuitable for low temperature operation. We developed a scanning nanoSQUID with sub 50 nm diameter that resides at the apex of a sharp pipette [1] acting simultaneously as nanomagnetometer with single spin sensitivity and as nanothermometer providing cryogenic thermal imaging with four orders of magnitude improved thermal sensitivity of below 1 µK [2]. The non-contact non-invasive thermometry allows thermal imaging of minute energy dissipation down to the level equivalent to the fundamental Landauer limit for continuous readout

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of a single qubit. These advances enable observation of changes in dissipation due to single electron charging of a quantum dot, visualization and control of heat generated by electrons scattering off a single atomic defect in graphene [3], and direct imaging of dissipation mechanisms in the quantum Hall state. Tuning superconducting-resonator-frequency with SQUIDs and global fields Oscar Kennedy, UCL In a hybrid quantum system, distinct quantum systems are coupled. These hybrid systems can be operated to take advantage of the best properties of each of the distinct systems. Superconducting qubits strongly coupled to an ensemble of donor spins, can be used as a hybrid quantum memory. The donor spins have coherence times [1] four orders of magnitude longer than typical superconducting qubit coherence times.Storing quantum information from the qubit in the donor spin ensemble and returning it to the qubit requires the use of an intermediate system which can be realised by frequency-tunable superconducting micro-resonators interacting strongly with the qubit and the spin ensemble.We explore two techniques for frequency tuning; embedding SQUIDs and applying a global magnetic field. We demonstrate high quality factors, discuss field resilience and show coupling to spin ensembles. These devices will also have applications in high-sensitivity mK ESR and for their parametric effects. Y-Ba-Cu-O nano SQUIDs fabricated with a focused helium ion beam Shane Cybart, UC Riverside, UC San Diego Direct write patterning of high-transition temperature (high-TC) superconducting oxide thin films with a focused helium ion beam is a formidable approach for the scaling of high-TC circuit feature sizes down to the nano-scale [1]. Here we present the use of this technique to create nano-scale superconducting quantum interference devices (SQUID) with pick-up loops as small as 10 × 10 nm. The SQUID is defined entirely by helium ion irradiation from a gas field ion source focused to a sub-nm diameter. The irradiation converts the superconductor to an insulator, and no material is milled away or etched. In this manner, the device is created entirely within the plane of the film. SQUID properties such as critical current, dynamic resistance and inductance can be precisely controlled to optimize performance. Electrical measurements reveal large (0.8mV) modulation voltages with applied magnetic field. We measure a white noise level below 1 μΦ0/Hz1∕2. The development of 3D nano-SQUID at SIMIT Lei Chen, Shanghai Institute of Microsystem and Information Technology , Chinese Academy of Sciences The SQUID miniaturized into nanoscale is promising in the detection of single electron spin. A nano-SQUID with a strong spin coupling coefficient, a low flux noise, and a wide working field range is highly desired in a single spin resonance measurement. Nano-SQUIDs with nano-bridge junctions excel in a high working field range and a direct coupling from spins to the bridge. However, the common planar structure is known for problems such as a shallow flux modulation depth. Here, we developed a fabrication process for 3D Nb nano-SQUIDs. The characterization of the device shows an up to 71% modulation depth with a reversible current-voltage curve. Owing to the large modulation depth, the measured flux noise is as low as 0.34 μΦ0/Hz1/2. The working field range of the SQUID is more than 0.5 T. We believe that the 3D Nb nano-SQUIDs provides a promising step towards the single-spin inductive detection. Grooved Dayem Nanobridges as Building Blocks of YBCO SQUID Magnetometers Thilo Bauch, Dept. Microtechnology and Nanoscience, Chalmers University of Technology We present noise measurements performed on a YBa2Cu3O7-x nanoscale weak-link-based magnetometer consisting of a superconducting quantum interference device (SQUID) galvanically coupled to a 3.5 × 3.5 mm2 pick-up loop, reaching white flux noise levels and magnetic noise levels as low as \(6~\mu\Phi_0/\sqrt\mboxHz\) and \(100~\mboxfT/\sqrt\mboxHz\) at \(T=77~\mboxK\), respectively [1]. The low noise is achieved by introducing grooved Dayem bridges (GDBs), a new concept of a weak link. A fabrication technique has been developed for the realization of nanoscale grooved bridges, which substitutes standard Dayem bridge weak links. The introduction of these novel key blocks reduces

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the parasitic inductance of the weak links and increases the differential resistance of the SQUIDs. This greatly improves the device performance, thus resulting in a reduction of the white noise. SQUID readout with high dynamic range and intrinsic multiplexing capability Sebastian Kempf, Kirchhoff-Institute for Physics, Heidelberg University Due to their periodic flux-to-voltage characteristics, superconducting quantum interference devices (SQUIDs) are intrinsically non-linear devices and possess only a rather small linear flux range. For this reason, feedback circuits are often employed to linearize the SQUID transfer function. However, feedback circuits impose stringent performance requirements on the room-temperature SQUID electronics. The limited voltage range and the finite resolution of the digitizer, for example, limit the dynamic range of the SQUID system.Within this context, we have developed a flux ramp modulation based SQUID readout scheme that provides linearization of the SQUID transfer function without using a feedback circuit. At the same time, it significantly increases the dynamic range of the SQUID system and intrinsically allows to implement a MHz frequency-division SQUID multiplexer. We discuss the basics as well as a comprehensive suitability study of our readout approach and demonstrate its intrinsic multiplexing capability. Fine tuning and optimization of SQUID devices parameters by a thermal annealing Carmine Granata, Institute of Appied Sciences and Intelligent Systems - National Research Council Superconducting Quantum Interferences Device (SQUID) are among the most sensitive sensors of magnetic field and flux. One of the most important applications of SQUIDs is the large multichannel systems for magnetoencephalography. This application requires a large number of SQUID sensors showing an ultra high sensitivity and a good working stability. So, even a small change in the critical current from the design value can cause a noticeable increase of magnetic field noise and instability working conditions. In this presentation, we present experimental results concerning fine tuning and optimization of SQUID devices parameters by a thermal annealing technique. In particular we report the critical current sensor, voltage-flux (V-F) characteristics and the spectral density of the magnetic field of SQUID magnetometers for different annealing temperatures. The measurements demonstrate that is possible to reduce the SQUID noise by more than a factor of 5 and to make the V-F characteristics very stable.

Integrated superconducting circuits for THz imaging spectroscopy Jochem Baselmans, Delft University of Technology Superconducting circuits based upon thin NbTiN films, with a critical temperature of 15 K, allow the construction of lossless circuits for frequencies up to approximately 1.1 THz. Combining these with aluminum detectors, with a critical temperature of 1.2 K, and an associated gap frequency of 90 GHz, allows the construction of on-chip spectrometers operating in the 90 GHz – 1.1 THz frequency range. I will discuss the design and testing of the 320-380 GHz on-chip spectrometer, called Deshima, and its broad band, 240-480 GHz, successor. These devices combine a broad-band antenna, spectral filters and several hundreds of aluminum based kinetic Inductance Detectors to create a spectrometer with a resolution R ~ 500, that reads-out all spectral channels simultaneously on a footprint of a few cm2. The prime application for these devices is for sub-mm astronomy. Non-linear superconducting silicon resonators Francesca Chiodi, Centre de Nanosciences et de Nanotechnologies - CNRS Silicon is one of the most well-known materials, and the main actor in today electronics.Despite this, silicon superconductivity was only discovered in 2006 [1] in laser doped Si:B samples. Laser annealing is instrumental to cross the superconductivity threshold, as the required doping is above the solubility limit, and cannot be reached using conventional micro-electronic techniques. Laser doping allows the realisation of epitaxial, homogeneous, thin silicon layers (5-300 nm) with extreme active doping values as high as 11

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at. %, and without the formation of B aggregates.After demonstrating all-silicon SQUIDs and Josephson junctions [2,3], we have realised microwave silicon resonators, working in the 1-10 GHz range. We have investigated their dynamics following a light pulse or an RF pulse excitations. Moreover, we have shown a strong non-linear response with power, which, coupled to a high kinetic inductance, suggests that silicon resonators may be promising candidates for Kinetic Inductance Detectors. Titanium Nitride Microwave Kinetic Inductance Detectors for passive THz cameras Dmitry V. Morozov, University of Glasgow Microwave Kinetic Inductance Detectors (MKIDs) are a promising technology for passive terahertz sensing for security [1]. A 350GHz demonstration camera achieved a noise equivalent differential temperature of 0.1K in images acquired at 2Hz. Recently, a 350-pixel aluminium MKID array operating at ~300mK was demonstrated at Cardiff Airport generating images at 5Hz with very promising results. Future generations of such passive cameras would benefit from higher detector operating temperatures, not least from a simpler and less expensive cryogenics. Disordered superconductors with high resistivity, kinetic inductance and tunable transition temperature, such as TiN are ideal materials for the next generation of MKIDs. Here we present the design and characterization of MKID array based on atomic layer deposited TiN films [2]. MKIDs made with 30nm thick film have optical noise equivalent power limited by the source noise (~20-40aW/Hz0.5) and a time constant of ~15–20 microseconds. Operation at >1K is feasible after optimisation of TiN growth. Compact superconducting terahertz emitters up to 2 THz Huabing Wang, Nanjing University High-Tc superconducting terahertz emitters, which are made of Bi2Sr2CaCu2O8+δ (BSCCO) intrinsic Josephson junctions, perform fascinating potentials as THz generators, especially in sub-millimeter wave range. With only two BSCCO intrinsic Josephson junction stacks, we achieved a tunable frequency range from 0.108 to 2.095 THz. Thanks to the high critical current and high critical temperature, we obtained a record high frequency of 0.576 THz at 80 K, which is important for operation in liquid nitrogen temperatures. Recently, the power from a single disk type emitter was as high as 0.78 mW at 450 GHz and 54 K, showing a very high dc-to-THz conversion efficiency. Although more efforts should be made for understanding the mechanism, THz emitters of BSCCO intrinsic Josephson junctions can find already themselves many applications based on the above-mentioned performance. High-Q superconducting microwave resonators using a single-crystal Nb film Takashi Noguchi, RIKEN, NAOJ We have made superconducting microwave resonators using a high-quality Nb thin film with RRR ≈ 50 and studied their resonance characteristics in detail. It was observed that the measured internal quality factor Qi reached as high as 4×107 which might be the highest value obtained among the Nb thin-film superconducting microwave resonators ever reported.It was found that Qi of the Nb thin-film resonator decreases as temperature is lowered at the temperature below 0.9 K. We think that such a reduction of Qi at low temperature might be attributed to the increase of the residual resistance mainly due to the Kondo effect of the residual quasiparticles in the superconductor.In addition, the resonance frequency shift δfr/fr increases in proportion to log(T) at temperature T Design and characterization of Josephson Travelling-Wave Parametric Amplifiers Erik Jellyman, Lancaster University, University of Glasgow We are developing a Josephson traveling-wave parametric amplifier (JTWPA) using all-aluminium technology. The device is a superconducting coplanar transmission line with an array of 100-1000 non-hysteretic RF-SQUIDs. The Josephson inductance (LJ) exceed the geometric inductance and is in parallel to the latter; its modulation does not affect the device impedance. Modulation of LJ is achieved by the strong pump signal applied to the input port or by external magnetic flux. The SQUID array is analogous to a one-dimensional artificial medium with well-controlled quadratic and cubic non-linearities generating 2nd and 3rd harmonics of the signal. Device operation in the four- and three-wave mixing regimes is possible.We

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are characterizing JTWPAs in a dilution refrigerator down to 8 mK. In the three-wave-mixing regime, the device can yield 20 dB gain for GHz range signals with large frequency separation between the signal and the pump, making it an ideal amplifier for weak signals.

Coherent Semiconductor-Based Superconducting Quantum Circuits Karl Petersson, Microsoft Quantum Lab - Copenhagen, Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Denmark The recent development of semiconductors with epitaxial superconducting Al contacts offers new approaches to realizing coherent superconducting quantum devices. In particular, we have demonstrated superconducting transmon qubits with Josephson junctions based on hybrid superconductor-semiconductor nanowire materials [1-2]. These gate tunable transmons (gatemons) have the potential advantage that they can be readily controlled through local electrostatic gating of the junction element. I will discuss progress in improving coherence times and scalability of gatemon qubits. I will also discuss how these hybrid materials might be used to realize novel qubits that are intrinsically protected against sources of decoherence. Bi based topological Josephson junctions Alexander Brinkman, University of Twente Bi1-xSbx is an accidental three-dimensional Dirac semimetal at a doping level of x = 3% for which band inversion occurs. When a magnetic field is applied parallel to the current in Hall bar devices the degenerate Dirac cone splits into two Weyl cones and we observe a negative magnetoresistance as an indication of the chiral anomaly. The accidental three-dimensional Dirac semimetal is ideally suited for realizing Majorana bound states in superconducting hybrids since chirality prevents the 4pi-periodic current-phase relation from opening a gap at zero energy for Andreev bound states at perpendicular incidence. We observe a strong contribution of 4pi-periodic Majorana bound states to the supercurrent in Nb-Bi1-xSbx-Nb devices. The 4pi-modes are revealed by studying the junction under GHz microwave irradiation. The large g-factor of the Zeeman effect from a magnetic field applied in the plane of the junction, allows tuning of the junctions from 0 to pi regimes. MoRe/YBa2Cu3O7-x Josephson junctions and pi-loops M. I. Faley, Peter Grünberg Institute 5 We have developed Josephson junctions (ds-JJs) between the d-wave superconductor YBa2Cu3O7 (YBCO) and the s-wave MoRe alloy superconductor, using a Au film as a normal conducting barrier and a barrier for oxygen diffusion. The MoRe alloy has a superconducting transition temperature Tc of up to 15 K and is corrosion-resistant. I(V)-characteristics of the ds-JJs demonstrate a twice larger critical current along the [100] axis of the YBCO film compared to similarly-oriented ds-JJs made with a Nb top electrode. The characteristic voltage IcRn of the YBCO-Au-MoRe ds-JJs is 750 µV at 4.2 K. YBCO-Au-MoRe ds-JJs that are oriented along the [100] axis of the YBCO film exhibit a 200-times higher critical current than similar ds-JJs oriented along the [110] axis of the same YBCO film. Different layouts of pi-loops based on the novel ds-JJs were arranged in various mutual coupling configurations and the spontaneously-induced currents were investigated using a scanning SQUID microscope. Low temperature characterization of spin filter Josephson junctions Roberta Caruso, Università degli Studi di Napoli Federico II Ferromagnetic JJs present a rich emerging physics due to the coupling between ferromagnetism and superconductivity, they are sought to have applications in the emerging field of superconducting spintronics and in quantum and digital superconducting computation as phase shifters or as auxiliary circuit elements for error correction, readout and memory elements. Currently, their use is limited by their

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metallic, highly dissipative nature. In this work we will review the properties of low dissipation spin-filter junctions featuring a GdN barrier. In particular, we will present the first complete low temperature characterization of junctions with spin-filter efficiency as high as 98%. We also measured the junction parameters in a wide range of spin-filter efficiencies, and we found an unconventional temperature dependence of the critical current for high spin-polarized junctions, indicating the presence of unconventional transport mechanisms and of a strong magnetic activity compatible with spin-triplet coupling of the Cooper pairs. Superconducting heterostructure with barrier with strong spin-orbit interaction Karen Constantinian, Kotel’nikov IRE RAS We report on observation of superconducting current in a mesa-heterostructure with an interlayer with strong spin-orbit interaction. The superconducting current has been observed in mesa-heterostructures Nb/Au/Sr2IrO4/YBa2Cu3Ox with a 7 nm thick interlayer of strontium iridate barrier Sr2IrO4, which is known as a canted antiferromagnetic insulator with a strong spin-orbit interaction. The superconducting critical current density was jC ≈ 0.3 A/cm2 at T=4.2 K. The zero-bias conductance peak also took place. Under influence of weak magnetic field the critical current IC(H) dependence showed a sharp central peak and minor oscillating behaviour for side lobs, which along with the oscillating with microwave power Shapiro steps indicate the absence of pinholes. Integer and non-integer Shapiro step amplitudes were registered under microwave irradiation at frequencies fe=38 GHz and fe=50 GHz. The contribution of the second harmonic in superconducting current-phase relation was estimated to be no less than 0.3 relative to the first harmonic. Dissipative Effects on Step-edge junction arrays of various sizes Marcio de Andrade, Naval Information Warfare Center Pacific We studied the DC electrical performance of arrays of Yttrium Barium Copper Oxide (YBCO) Superconducting Quantum Interference Devices (SQUIDs). Magnetoresistive measurements are used to probe dissipative effects in these high-temperature superconducting (HTS) devices, potentially including the effects of large anisotropy, high operating temperature, and short coherence lengths. Step-edge junction arrays of various sizes containing between 30 and 4080 SQUID loops were characterized as a function of temperature (2 K < T < 90 K) and applied magnetic fields up to 9 T, normal to these planar devices. The field and temperature dependence of the superconducting parameters were evaluated in relation to array size and geometry. Furthermore, taking advantage of a transmission-line understanding of these arrays, we discuss how parameters extracted by these essentially DC measurements should affect the performance of these devices when operated as Superconducting Quantum Interference Filters (SQIFs), for use at microwave frequencies.