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The problem of detecting communities in real-world networks has been extensively studied in the past, but most of the existing approaches work on single-domain networks , i.e. they consider only one type of relationship between nodes. Single-domain networks may contain noisy edges and they may lack some important information. Thus, some authors have proposed to consider the multiple relationships that connect the nodes of a network, thus obtaining multi-domain networks. However, most community detection approaches are limited to multi-layer networks , i.e. networks generated from the superposition of several single-domain networks (called layers) that are regarded as independent of each other. In addition to being computationally expensive, multi-layer approaches might yield inaccurate results because they ignore potential dependencies between layers. This paper proposes a multi-domain discrete-time quantum walks (MDQW) model for multi-domain networks. First, the walking space of network nodes in multi-domain network is constructed. Second, the quantum permutation circuit of the coin state is designed based on the coded particle state. Then, using different coin states, the shift operator performs several quantum walks on the particles. Finally, the corresponding update rule is selected to move the node according to the measurement result of the quantum state. With continuous update iteration, the shift operator automatically optimizes the discovered community structure. We experimentally compared our MDQW method with four state-of-the-art competitors on five real datasets. We used the normalized mutual information (NMI) to compare clustering quality, and we report an increase in NMI of up to 3.51 of our MDQW method in comparison with the second-best performing competitor. The MDQW method is much faster than its competitors, allowing us to conclude that MDQW is a useful tool in the analysis of large real-life multi-domain networks. Finally, we illustrate the usefulness of our approach on two real-world case studies. [ABSTRACT FROM AUTHOR]

We report the fabrication and testing of arrays of nanoscale superconducting quantum interference devices (SQUIDs) directly written into a thin film of the high-transition temperature superconductor YBa2Cu-3O7−δ with a focused helium ion beam. We compare three array configurations with 400 nm by 400 nm nanoSQUIDs connected in series and parallel and a two-dimensional (2D) combination of both. Our electrical transport measurements show that series arrays of three nanoSQUIDs exhibit modulation voltages greater than 1 mV and that combining the devices in parallel greatly enhances the slope of the voltage–magnetic field characteristic. A 2D array with 3 SQUIDS in series and 7 in parallel exhibited a transfer function of 5.51 mV/mT. [ABSTRACT FROM AUTHOR]

This work focuses on the characterization of five palygorskite clays from the Brazilian state of Piaui and their feasibility as eco-friendly adsorbents for the removal of Fe3+ ions from aqueous solutions. For characterization, we applied the techniques of X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), size distribution measurements, density measurement by He pycnometry, superconducting quantum interference device (SQUID) magnetometry, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTA), zeta potential measurement, hydrophobicity determination by contact angle, Brunauer–Emmett–Teller surface area analysis (BET technique) and atomic force microscopy (AFM). Batch experiments were performed in function of process parameters such as contact time and initial concentration of Fe3+. The natural palygorskites (Palys) had excellent performance for the removal of Fe3+ from aqueous solutions by adsorption (around 60 mg/g), and the Langmuir is supposedly the best model fitted the experimental data. [ABSTRACT FROM AUTHOR]

We present two variants of a magnetic microcalorimeter with paramagnetic temperature sensors and integrated dc-superconducting quantum interference device readout for high-resolution x-ray emission spectroscopy. Each variant employs two overhanging gold absorbers with a sensitive area of 150 × 150 μm2 and a thickness of 3 μm, thus providing a thickness related quantum efficiency of >98% for photons up to 5 keV and >50% for photons up to 10 keV. The first variant operated nominally but suffered from Joule power dissipation of the Josephson junction shunt resistors, athermal phonon loss, and slew rate limitations of the overall setup. Overall, it only achieved an energy resolution of Δ E FWHM = 8.9 eV for 5.9 keV photons. In the second variant, we introduced an innovative tetrapod absorber geometry as well as a membrane technique for diverting dissipated heat away from the temperature sensors. When all mitigations are applied optimally, the second variant achieves an energy resolution of Δ E FWHM = 1.25 (18) eV for 5.9 keV photons and hence provides the present best energy resolving power E / Δ E FWHM among all existing energy-dispersive detectors for soft and tender x-rays. [ABSTRACT FROM AUTHOR]

Emerging non-superconductor quantum magnetic sensors, such as optically pumped magnetometer, fluxgate, magnetic tunnel junction, and diamond nitrogen-vacancy center, are approaching the performance of superconductor quantum interference devices (SQUIDs). These sensors are enabling magnetography for human bodies and brain–computer interface. Will they completely replace the SQUID magnetography in the near future? [ABSTRACT FROM AUTHOR]

Superconductors are materials with zero electrical resistivity and the ability to expel magnetic fields, which is known as the Meissner effect. Their dissipationless diamagnetic response is central to magnetic levitation and circuits such as quantum interference devices. In this work, we used superconducting diamagnetism to shape the magnetic environment governing the transport of spin waves—collective spin excitations in magnets that are promising on-chip signal carriers—in a thin-film magnet. Using diamond-based magnetic imaging, we observed hybridized spin-wave– Meissner-current transport modes with strongly altered, temperature-tunable wavelengths and then demonstrated local control of spin-wave refraction using a focused laser. Our results demonstrate the versatility of superconductor-manipulated spin-wave transport and have potential applications in spin-wave gratings, filters, crystals, and cavities. [ABSTRACT FROM AUTHOR]

Granular aluminum (grAl) is an applied quantum material. We present nano-superconducting quantum interference devices (nanoSQUIDs) based on grAl thin films. These devices exhibit non-hysteretic behavior, allowing conventional SQUID readout down to temperatures well below the critical temperature as well as detection properties comparable to those of Dayem bridge-based devices of greater complexity. Despite being much longer than the coherence length, the current–phase relation of these grAl constrictions appears to be single valued at least down to half their critical temperature. This suggests that grAl thin films should be described as a network of inter-grain Josephson junctions. [ABSTRACT FROM AUTHOR]

We demonstrate a 3-port Josephson parametric circulator matched to 50 Ω using second order Chebyshev networks. The device notably operates with two of its signal ports at the same frequency and uses only two out-of-phase pumps at a single frequency. As a consequence, when operated as an isolator, it does not require phase coherence between the pumps and the signal, thus simplifying the requirements for its integration into standard dispersive qubit readout setups. The device utilizes parametric couplers based on a balanced bridge of rf-superconducting quantum interference device arrays, which offer purely parametric coupling and high dynamic range. We characterize the device by measuring its full 3 × 3 S-matrix as a function of frequency and the relative phase between the two pumps. We find up to 15 dB nonreciprocity over a 200 MHz signal band, port match better than 10 dB, low insertion loss of 0.6 dB, and saturation power exceeding −80 dBm. [ABSTRACT FROM AUTHOR]

A novel one-dimensional malleable spin-crossover (SCO) complex {[Fe(MPEG-trz)3](BF4)2} has been successfully synthesized by molecular self-assembly between 4-amino-1,2,4-triazoles (MPEG-trz) grafted with a long flexible chain methoxy polyethylene glycol (MPEG) and metallic complex Fe(BF4)2•6H2O. The detailed structure information was illustrated by using FT-IR and 1H NMR measurements, while the physical behaviors of the malleable SCO complexes were systematically investigated by using magnetic susceptibility measurements using superconductivity quantum interference device (SQUID) and differential scanning calorimetry (DSC). This new metallopolymer exhibits a remarkable spin crossover transition behavior, between two spin quantum states (Fe2+ ions): high spin (HS) state (quintet state) and low spin (LS) state (singlet state), at a specific critical temperature with a slender hysteresis loop of 1 K. DFT computations revealed the partial rules of HOMO-LUMO energy levels and spin density distributions of different four-position substituted [Fe(1,2,4-triazole)3]2+ derivatives with different length of repeat units in polymer complexes. This can go a step further to depict the spin and magnetic transition behaviors of SCO polymer complexes. Furthermore, the coordination polymers possess an excellent processability due to an outstanding malleability, which can be easily shaped into a polymer film with spin magnetic switching properties. [ABSTRACT FROM AUTHOR]

Lead halide perovskites are new key materials in various application areas such as high efficiency photovoltaics, lighting, and photodetectors. Doping with Mn, which is known to enhance the stability, has recently been reported to lead to ferromagnetism below 25 K in methylammonium lead iodide (MAPbI3) mediated by superexchange. Two most recent reports confirm ferromagnetism up to room temperature but mediated by double exchange between Mn2+ and Mn3+ ions. Here we investigate a wide concentration range of MAMnxPb1−xI3 and Mn-doped triple-cation thin films by soft X-ray absorption, X-ray magnetic circular dichroism, and quantum interference device magnetometry. The X-ray absorption lineshape shows clearly an almost pure Mn2+ configuration, confirmed by a sum-rule analysis of the dichroism spectra. A remanent magnetization is not observed down to 2 K. Curie-Weiss fits to the magnetization yield negative Curie temperatures. All data show consistently that significant double exchange and ferromagnetism do not occur. Our results show that Mn is not suitable for creating ferromagnetism in lead halide perovskites. There have been recent studies reporting that Mn-doped MAPBI3 houses a ferromagnetic phase mediated by a double exchange mechanism. Here, however, using X-ray magnetic circular dichroism and magnetic susceptibility measurements, the authors uncover contradicting experimental evidence to indicate an absence of magnetic ordering in this material, suggesting that our understanding of Mn-doped lead halide perovskites may need reassessing. [ABSTRACT FROM AUTHOR]

Topological materials are promising candidates in fault-tolerant quantum information processing architectures, making it essential to understand the dephasing mechanisms in these materials. Here, we investigate gated, nanoscale mesas fabricated on thin films of cadmium arsenide (Cd3As2), a three-dimensional Dirac semimetal that can be tuned into different topological phases. We observe two independent types of conductance oscillations, one as a function of the applied magnetic field and the other as a function of the gate voltage. Varying the dimensions of the nanostructures allows the discrimination of a variety of scenarios for similar oscillations previously reported in the literature. We conclude that the conductance oscillations are not a signature of topological boundary states per se, but rather are universal conductance fluctuations. These results broadly inform future interpretations of electronic quantum interference in mesoscopic devices made from topological materials. [ABSTRACT FROM AUTHOR]

We show that in quantum waveguides, the Fano resonance profile associated with propagating modes has its analogs with evanescent modes as well. This is found to be an unusual and a universal effect for any attractive potential. Further, we show that quantum dots or attractive impurity potentials embedded in the interior of a quantum waveguide yield significantly large Seebeck coefficient (thermopower) and power factor. Hence, they are good candidates for enhancing the thermoelectric energy conversion efficiency. We study the effect of a waveguide tapering on transport properties for the first time and the effect of curvature on the transmission coefficients. We propose a nanoscale current rectification device in two dimensions using tapered quantum waveguides. [ABSTRACT FROM AUTHOR]

We develop a novel method based on sources and absorbers to examine quantum scattering in finite, nanoscale systems. We show that the Cauchy (mixed) boundary conditions (BCs) are required to put the scattering theory into an action integral formulation. These complex BCs are reduced to simpler Dirichlet BCs by introducing totally absorbing "stealth regions." Material properties of these enclosing regions are optimized to give decaying solutions so that the scattering amplitudes vanish at the finite boundaries. With the active scattering region now surrounded by absorbers, we construct an "electron antenna" to provide incident waves. The method retains all the physical aspects of the conventional theory while providing new insights into "near-field" scattering effects. The action integral is discretized and evaluated to derive the local wavefunction everywhere. In two-dimensional quantum waveguides, we obtain the scattered wavefunction for geometrically complex scattering centers, showing the flexibility of our method. The modal decomposition of reflected and transmitted waves allows us to obtain transmission coefficients for both propagating and evanescent modes. Using group theory, we develop selection rules for the scattered modes depending on the symmetry of the potential. Our method outperforms the limitations of traditional perturbative estimates, transfer-matrix, S-matrix discretizations, and other schemes to provide a complete nonasymptotic variational description for electron transport in quantum waveguides. [ABSTRACT FROM AUTHOR]

The photodetachment of the F−(HOCH3) anion, which sheds light on the post-transition-state dynamics of the F + CH3OH → HF + CH3O reaction, is investigated using a reduced-dimensional quantum wave packet method on ab initio based potential energy surfaces for both the neutral and anionic species. The detachment of an electron in the anion precursor produces both bound and resonance species in a hydrogen-bonded potential well in the product channel, in qualitative agreement with the photoelectron-photofragment coincidence (PPC) spectrum. The measured photoelectron-photofragment coincidence spectroscopy is reproduced by the quantum calculations. Our results indicated that the HF product is vibrationally excited, while the OCH3 product is internally cold, thus providing unambiguous assignments of the experimental spectrum. [ABSTRACT FROM AUTHOR]

The mining town of Aggeneys is situated in a world-class polymetallic base metal district. The Black Mountain Mining Complex (BMC), located in the Northern Cape, South Africa, contains six known orebodies with more than 25.5 Mt contained metal in resources and reserves. Currently, three of the six known orebodies are actively mined. The Big Syncline East prospect is situated directly east of the massive Big Syncline mineral resource of > 150 Mt of open pit and underground resources. Big Syncline is one of the six declared resources at BMC. Recent high-power super conducting quantum interference device transient EM identified a large 3500-Siemens conductor at depths greater than 400 m. Initial follow-up drilling confirmed the presence of mineralized sulfides. A follow-up drone-based magnetic survey was flown, primarily to improve on the poor-quality, high-ground clearance magnetic data recorded with a fixed-wing aeromagnetic system, but also to trial a novel hybrid ground and drone total-field transient EM survey over the extreme topography encountered in the area. Results are very encouraging and now pave the way for more routine implementation of hybrid ground-drone total-field transient EM applications, where a large transmitting loop on the surface is surveyed by a relative fast-moving drone-carried fast-sampling total-field magnetometer. [ABSTRACT FROM AUTHOR]

Hexagonal Y1 - x Hox Mn0.8 Fe0.2O3 polycrystalline samples were synthesized by high-temperature solid-state reaction method. The effects of Ho3+ doping on microstructure and magnetic properties of YMn0.8 Fe0.2O3 were investigated in this paper. X-ray diffraction (XRD) and Raman spectra (RS) show that all samples are of single-phase hexagonal structure without another impurity phase. When the doping concentration (x) of Ho3+ is lower than 0.15, the lattice constants, unit cell volume and bond length between the Mn--O of the samples decrease with x increasing. The decrease of the lattice constants may be related to the interaction between the Mn3+ / Fe3+ 3d orbital and the Ho3+ 4f orbital, resulting in lattice distortion and electron loss. The displacements of the rare-earth atoms at the A-site relative to the plane and the inclination of the MnO5 bipyramids are suppressed with increasing doping concentration, which is demonstrated by the shift deviations of the rare-earth atoms and the variations of the Raman phonon modes. At the same time, the trimerization of Mn3+ at the B-site is weakened. The magnetic properties of the samples were measured using the superconductor quantum interference device (SQUID). Results show that the antiferromagnetic (AFM) order decreases upon Ho3 + doping, consistent with the reduced superexchange interaction between Mn3+ --O2- --Mn3+. The AFM transition temperature TN decreases. Besides, the magnetization of the samples and the weak ferromagnetic (WFM) order at low temperature are significantly enhanced, which is attributed to the suppressed magnetic resistance behavior of the system and the ferromagnetic order generated by the spin exchange interaction between Ho3+ --O2- --Mn3+. These provide an idea for us to further explore room temperature multiferroic materials. [ABSTRACT FROM AUTHOR]

The Baiyun gold deposits in the Qingchengzi ore concentration area have significant deep exploration potential. Transient electromagnetic (TEM) exploration is conducted to identify ore-bearing strata and ore-controlling structures in the mining area's periphery. Previous tests have revealed that it is challenging to penetrate the conductive layer to obtain deep information using a conventional in-loop TEM method with an induction coil. Field data are acquired using a high-temperature superconductor (HTS) superconductive quantum interference device (SQUID) magnetometer with a fixed-loop configuration. The exploration results indicate that the SQUID TEM system can detect the distribution of ore-bearing strata, and the ore-control structures within deep formations. The paper explores two extension areas in the east and west of the Baiyun thrust nappe structural belt. The inversion results reveal that the Baiyun gold deposit is significantly compressed, with noticeable thrusts and faults. Since the thrust fault zone extends to the south stably, the lower section has a gentle dip angle favorable area for deep prospecting. [ABSTRACT FROM AUTHOR]

Hexagonal Y1 - x Hox Mn0.8 Fe0.2O3 polycrystalline samples were synthesized by high-temperature solid-state reaction method. The effects of Ho3+ doping on microstructure and magnetic properties of YMn0.8 Fe0.2O3 were investigated in this paper. X-ray diffraction (XRD) and Raman spectra (RS) show that all samples are of single-phase hexagonal structure without another impurity phase. When the doping concentration (x) of Ho3+ is lower than 0.15, the lattice constants, unit cell volume and bond length between the Mn--O of the samples decrease with x increasing. The decrease of the lattice constants may be related to the interaction between the Mn3+ / Fe3+ 3d orbital and the Ho3+ 4f orbital, resulting in lattice distortion and electron loss. The displacements of the rare-earth atoms at the A-site relative to the plane and the inclination of the MnO5 bipyramids are suppressed with increasing doping concentration, which is demonstrated by the shift deviations of the rare-earth atoms and the variations of the Raman phonon modes. At the same time, the trimerization of Mn3+ at the B-site is weakened. The magnetic properties of the samples were measured using the superconductor quantum interference device (SQUID). Results show that the antiferromagnetic (AFM) order decreases upon Ho3 + doping, consistent with the reduced superexchange interaction between Mn3+ --O2- --Mn3+. The AFM transition temperature TN decreases. Besides, the magnetization of the samples and the weak ferromagnetic (WFM) order at low temperature are significantly enhanced, which is attributed to the suppressed magnetic resistance behavior of the system and the ferromagnetic order generated by the spin exchange interaction between Ho3+ --O2- --Mn3+. These provide an idea for us to further explore room temperature multiferroic materials. [ABSTRACT FROM AUTHOR]

In this paper, we present the development and characterization of a fully differential SiGe BiCMOS low noise amplifier (LNA) with active impedance matching for the readout of superconducting, quantum interference devices (SQUIDs). Impedance matching is particularly important when using the LNA over a broad frequency range and it is achieved using the Miller effect by adding a negative feedback loop. This approach avoids the degradation of the noise performance that is generated by simply using a parallel resistor at the LNA input. Furthermore, this impedance matching implementation preserves the signal to noise ratio (SNR) because both the signal and the noise are divided by 2 due to the negative feedback loop. This was verified by measuring a lower input voltage noise with the LNA input loaded with a 100 Ω resistor at 77 K compared to a short-circuit. In addition, we present simulations and measurements of the LNA frequency response, input impedance and input voltage noise. The obtained performances for the LNA show a flat gain of 173 V/V with a cut-off frequency of 26MHz and a referred input voltage white noise spectral density level of 0.34 nV/ Hz with a corner frequency of 72 Hz in input matching condition. These values are in good agreement with the simulations. Finally, a discussion about the impact of the impedance matching on the SQUID biasing is also presented. [ABSTRACT FROM AUTHOR]

The properties of the bound states of two quantum waveguides coupled via the window of the width s in their common boundary are calculated under the assumption that the transverse electric field E is applied to the structure. It is shown that the increase in the electric intensity brings closer to each other fundamental propagation thresholds of the opening and the arms. As a result, the ground state, which in the absence of the field exists at any nonzero s, exhibits the energy E0 decrease for the growing E and in the high-field regime E0 stays practically the same regardless of the size of the connecting region. It is predicted that the critical window widths s c r n , n = 1 , 2 , … , at which new excited localized orbitals emerge, strongly depend on the transverse voltage; in particular, the field leads to the increase in s c r n , and, for quite strong electric intensities, the critical width unrestrictedly diverges. This remarkable feature of the electric-field-induced switching of the bound states can be checked, for example, by the change of the optical properties of the structure when the gate voltage is applied; namely, both the oscillator strength and absorption spectrum exhibit a conspicuous maximum on their E dependence and turn to zero when the electric intensity reaches its critical value. Comparative analysis of the two-dimensional (2D) and 3D geometries reveals their qualitative similarity and quantitative differences. [ABSTRACT FROM AUTHOR]

Zigzag-edged graphene nanoribbon (ZGNR) has great potential in designing quantum waveguide devices to conduct electric currents metallically. Using non-equilibrium Green's function (NEGF) method, we theoretically study geometry dependent transport properties and current–voltage (I–V) characteristics of T-stub ZGNR quantum waveguides sized in tens of nanometers. Instead of the perfect transmission in straight ZGNR, anti-resonance effects appear in transmission spectrum due to strong electronic reflection depending on the size of central region in T-stub ZGNR. In addition, the I–V characteristics of T-stub ZGNR quantum waveguides are mainly influenced by the transverse width of the central region. Meanwhile, the current flowing over the T-stub ZGNR quantum waveguides gradually converges as the longitudinal length of the central region increases. We also find that a single edge-defect at certain positions of the central region may slightly suppress the transmission and reduce the current. Our findings provide a viable design option for adjusting current response in graphene-based quantum devices. [ABSTRACT FROM AUTHOR]

• The biomagnetic field around the current flowing in the thoracic spinal cord was measured by a magnetoneurograph system. • Our novel method for synchronized bilateral sciatic nerve stimulation obtained an adequate magnetic signal for assessment. • This is the first report to achieve noninvasive and detailed visualization of thoracic electrophysiological activity. Noninvasive and detailed visualization of electrophysiological activity in the thoracic spinal cord through magnetoneurography. In five healthy volunteers, magnetic fields around current flowing in the thoracic spinal cord after alternating unilateral and synchronized bilateral sciatic nerve stimulation were measured using a magnetoneurograph system with superconductive quantum interference device biomagnetometers. The current distribution was obtained from the magnetic data by spatial filtering and visualized by superimposing it on the X-ray image. Conduction velocity was calculated using the peak latency of the current waveforms. A sufficiently high magnetic signal intensity and signal-to-noise ratio were obtained in all participants after synchronized bilateral sciatic nerve stimulation. Leading and trailing components along the spinal canal and inward components flowing into the depolarization site ascended to the upper thoracic spine. Conduction velocity of the inward current in the whole thoracic spine was 42.4 m/s. Visualization of electrophysiological activity in the thoracic spinal cord was achieved through magnetoneurography and a new method for synchronized bilateral sciatic nerve stimulation. Magnetoneurography is expected to be a useful modality in functional assessment of thoracic myelopathy. This is the first report to use magnetoneurography to noninvasively visualize electrophysiological activity in the thoracic spinal cord in detail. [ABSTRACT FROM AUTHOR]

Superconductivity serves as a unique solid-state platform for electron interference at a device-relevant lengthscale, which is essential for quantum information and sensing technologies. As opposed to semiconducting transistors that are operated by voltage biasing at the nanometer scale, superconductive quantum devices cannot sustain voltage and are operated with magnetic fields, which impose a large device footprint, hindering miniaturization and scalability. Here, we introduce a system of superconducting materials and devices that have a common interface with a ferroelectric layer. An amorphous superconductor was chosen for reducing substrate-induced misfit strain and for allowing low-temperature growth. The common quantum pseudowavefunction of the superconducting electrons was controlled by the nonvolatile switchable polarization of the ferroelectric by means of voltage biasing. A controllable change of 21% in the critical temperature was demonstrated for a continuous film geometry. Moreover, a controllable change of 54% in the switching current of a superconducting quantum interference device was demonstrated. The ability to voltage bias superconducting devices together with the nonvolatile nature of this system paves the way to quantum-based memory devices. [ABSTRACT FROM AUTHOR]

The quantum dynamics calculations of the H + HS (v = 0, j = 0) reaction on the ³A' and ³A'' potential energy surfaces (PESs) are performed using the reactant coordinate based time-dependent wave packet method. State-averaged and state-resolved results for both channels of the title reaction are presented in the 0.02-1.0 eV collision energy range and compared with those carried out with quasi-classical trajectory (QCT) method. Total integral cross sections (ICSs) for both channels are in excellent agreement with previous quantum mechanical (QM)-Coriolis coupling results while poorly agree with the QCT ICSs of the exchange channel, particularly near the threshold energy region. The product rotational distributions show that for the abstraction channel, the agreement between our QM and the QCT results improves with increasing collision energy. For the exchange channel, our calculations predict colder rotational distributions as compared to those obtained by QCT calculations. Although the QM total differential cross sections (DCSs) are in qualitatively good agreement with the QCT results, the two sets of the state-to-state DCSs with several peaks exhibit great divergences. The origin of the divergences are traced by analyzing the QM DCS for the H + HS (v = 0, j = 0) → H2 (v ' = 0, j' = 0) + S reaction on the ³A'' PES at Ec = 1.0 eV. It is discovered that several groups of J partial waves are involved in the reaction and the shape of the DCS is greatly altered by quantum interferences between them. [ABSTRACT FROM AUTHOR]

We report on measurements of YBa2Cu3O7-δ nanowire based Superconducting QUantum Interference Devices (nanoSQUIDs) directly coupled to an in-plane pick-up loop. The pick-up loop, which is coupled predominantly via kinetic inductance to the SQUID loop, allows for a significant increase of the effective area of our devices. Its role is systematically investigated and the increase in the effective area is successfully compared with numerical simulations. Large effective areas, together with the ultra low white flux noise below 1 μΦ0√Hz, make our nanoSQUIDs very attractive as magnetic field sensors. [ABSTRACT FROM AUTHOR]

We theoretically investigate the influence of the phonon bath on photon blockade in a simultaneously driven dot-cavity system. An optimal condition for avoiding two-photon excitation of a cavity field is put forward which can be achieved by modulating the phase difference and the strengths of the driving fields. The second-order correlation function and the mean photon number of the cavity field are discussed. In the absence of phonon effect, the strong photon blockade in a moderate quantum dot (QD)-cavity coupling regime occurs, which can be attributed to the destructive quantum interference arisen from different transition paths induced by simultaneously driving the dressed QD-cavity system. The participation of acoustic-phonon reservoir produces new transition channels for the QD-cavity system, which leads to the damage of destructive interference. As a result, the photon blockade effect is hindered when taking the electron-phonon interaction into account. It is also found that the temperature of the phonon reservoir is disadvantageous for the generation of photon blockade. [ABSTRACT FROM AUTHOR]

The photoassociation processes via the pump-dump scheme for the heternuclear (Na + H → NaH) and the homonuclear (Na + Na → Na2) molecular systems are studied, respectively, using the timedependent quantum wavepacket method. For both systems, the initial atom pair in the continuum of the ground electronic state (X¹Σ+) is associated into the molecule in the bound states of the excited state (A¹Σ+) by the pump pulse. Then driven by a time-delayed dumping pulse, the prepared excited-state molecule can be transferred to the bound states of the ground electronic state. It is found that the pump process can induce a superposition of the rovibrational levels |v, j〉 on the excited state, which can lead to the field-free alignment of the excited-state molecule. The molecular alignment can affect the dumping process by varying the effective coupling intensity between the two electronic states or by varying the population transfer pathways. As a result, the final population transferred to the bound states of the ground electronic state varies periodically with the delay time of the dumping pulse. [ABSTRACT FROM AUTHOR]

We present accurate state-to-state quantum wave packet calculations of integral cross sections and rate constants for the title reaction. Calculations are carried out on the best available ground 12A' global adiabatic potential energy surface of Deskevich et al. [J. Chem. Phys. 124, 224303 (2006)]. Converged state-to-state reaction cross sections have been calculated for collision energies up to 0.5 eV and different initial rotational and vibrational excitations, DCl(v = 0, j = 0 - 1; v = 1, j = 0). Also, initial-state resolved rate constants of the title reaction have been calculated in a temperature range of 100-400 K. It is found that the initial rotational excitation of the DCl molecule does not enhance reactivity, in contract to the reaction with the isotopologue HCl in which initial rotational excitation produces an important enhancement. These differences between the isotopologue reactions are analyzed in detail and attributed to the presence of resonances for HCl(v = 0, j), absent in the case of DCl(v = 0, j). For vibrational excited DCl(v = 1, j), however, the reaction cross section increases noticeably, what is also explained by another resonance. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) superconductors are important both for the basic understanding of pairing mechanism and potential applications in nanosuperconducting quantum interference devices. In this work, we explore the phonon-mediated superconductivity of hole-doped and lithium-deposited monolayer BC2N by first-principles calculations. Our results reveal that the hole-doped planar BC2N cannot superconduct due to weak electron–phonon coupling (EPC) with λ = 0.07. When lithium is deposited on the monolayer, the EPC constant is enhanced significantly to 0.52 and the superconducting transition temperature Tc is determined to be 3.58 K. Because more phonons, in particular the out-of-plane modes, are triggered to participate in the EPC process, the Tc is higher than 1.4 K of Ca-deposited graphene, 1.3 K of Li-deposited stanene, and 3 K of doped WS2 and NbSe2. It is also found that tensile biaxial strain weakens the EPC and leads to a decreased superconducting transition temperature. Our findings will provide a new guideline for designing novel 2D superconductors and enrich the potential application of 2D BC2N. [ABSTRACT FROM AUTHOR]

Nano-superconducting quantum interference devices (nano-SQUIDs) with high energy sensitivity and spatial resolution are essential in many applications such as single spin detection, nano-electromechanical vibration detection and microscale magnetic imaging. This paper studies a Dayem-type niobium nano-SQUID using focus ion beam milling technology. The device has two 42 nm × 60 nm nano-bridges and an integrated on-chip Nb modulation flux line located beside the SQUID loop with a 100 nm nanogap. The non-hysteretic temperature range of the nano-SQUID is about 1.4 K from 4.6 K to 6.0 K, which could broaden the operation temperature range of the device. The maximal transfer coefficient VΦ and peak-to-peak voltage ΔV are 8.53 mV/Φ0 and 430 μV at 4.8 K, respectively. [ABSTRACT FROM AUTHOR]

Ballistic thermal conductances (BTCs) by phonons through superlattice quantum-waveguides are investigated by using the scattering-matrix method and the elastic continuum theory. A comparison for the cylindrical model (CM) and the rectangular model (RM) is addressed. We find that for these two models, the quantum thermal conductance can be observed even when the superlattices exist in quantum-waveguides. At low temperature, BTCs for the CM and the RM present almost the same behaviors regardless of the periodic length of superlattices. However, at higher temperature, BTCs for the RM are larger than those for the CM stemming from lower cutoff frequencies of high order modes for the RM. We also find that BTCs undergo a noticeable transformation from the monotonic decrease to constant with increasing the periodic number of superlattices. A brief analysis of these results is given. [ABSTRACT FROM AUTHOR]

Superconducting quantum interference devices (SQUIDs) incorporating thin film nanobridges as weak links have sensitivities approaching that required for single spin detection at 4.2 K. However, due to thermal hysteresis they are difficult to operate at much lower temperatures which hinder their application to many quantum measurements. To overcome this, we have developed nanoscale SQUIDs made from titanium-gold proximity bilayers. We show that their electrical properties are consistent with a theoretical model developed for heat flow in bilayers and demonstrate that they enable magnetic measurements to be made on a sample at system temperatures down to 60 mK. [ABSTRACT FROM AUTHOR]

The ability to control the degree of spin in molecular junctions (MJs) is attractive for their applications in spintronics. Here, it is demonstrated that spin‐resolved quantum interference (SQI) can effectively improve spin‐filtering behavior of MJs. By first‐principle calculations in combination with nonequilibrium Green's function investigations, spin‐resolved charge transport in graphene/Cr‐porphyrin/graphene MJs shows that, due to the SQI, the tunable spin filtering behaviors can be achieved by changing the length of molecule. The SQI related phase coherence/decoherence in these MJs is revealed by considering the effects of temperature and electron–phonon interactions. Furthermore, a higher spin filtering efficiency in low bias region can be obtained by Cr‐doped in single‐porphyrin junction, due to the Cr‐enhanced SQI. These results show great potential for the application of MJs with SQI in the molecular intergrated circuit and provide a promising way for designing spin molecular devices by using quantum interference. [ABSTRACT FROM AUTHOR]

The use of a high-Tc (HTS) rf-superconducting quantum interference device (SQUID) for inspecting the liquid component of lithium-ion (Li-ion) batteries is proposed. It is possible that a small amount of metal can become mixed in with components of Li-ion batteries during the manufacturing process and contaminate them, with a resultant fire risk, Thus, the development of a highly sensitive inspection system is required. In this article we describe a test system, we developed using a single channel HTS rf-SQUID consisting of a cryostat, a polyethylene tube, and a permanent magnet. The SQUID needs to be installed as close to the battery liquid as possible to obtain more sensitive readings. Therefore, we designed a microscope-type SQUID cryostat in which the SQUID can approach the target as close as 1 mm. In the system, the liquid was not flowed through the polyethylene tube, but a small metallic sample stack on a fishing line was moved by a motor. A stainless steel cut wire with a nominal size of φ 50 μm was prepared. After magnetizing the sample, the stray magnetic field of the sample was measured by the SQUID. The peak-to-peak signal scaled inversely with the cube of the stand-off distance. It was found that a signal of the sample with φ 50 μm at a distance of 26 mm could be detected if the signal-to-noise ratio (SNR) > 3 was supposed as the threshold of the inspection. The dependence on the sample size was also investigated, using stainless steel samples with different sizes (φ 50–φ 160 μm). The peak-to-peak signal scaled with the cube of the diameter. [ABSTRACT FROM AUTHOR]

A simple tabletop setup based on a superconductor quantum interference device is proposed to test the gravitational interaction. A D-shaped superconducting loop has the straight segment immersed inside a massive sphere while the half-circle segment is wrapped around the sphere. The superconducting condensate within the straight arm of the loop thus bathes inside a gravitational simple harmonic oscillator potential while the condensate in the half-circle arm bathes in the constant gravitational potential around the sphere. The resulting phase difference at the Josephson junctions on both sides of the straight arm induces a sinusoidal electric current that has a frequency determined by the precise gravitational potential due to the massive sphere. [ABSTRACT FROM AUTHOR]

We report on electron spin resonance spectroscopy measurements using a superconducting flux qubit with a sensing volume of 6 fl. The qubit is read out using a frequency-tunable Josephson bifurcation amplifier, which leads to an inferred measurement sensitivity of about 20 spins in a 1 s measurement. This sensitivity represents an order of magnitude improvement when compared to flux-qubit schemes using a direct current-superconducting quantum interference device switching readout. Furthermore, noise spectroscopy reveals that the sensitivity is limited by flicker (1 / f) flux noise. [ABSTRACT FROM AUTHOR]

At low energies, the quantum wave–like nature of molecular interactions results in distinctive scattering behavior, ranging from the universal Wigner laws near 0 kelvin to the occurrence of scattering resonances at higher energies. It has proven challenging to experimentally probe the individual waves underlying these phenomena. We report measurements of state-to-state integral and differential cross sections for inelastic NO-He collisions in the 0.2 to 8.5 centimeter–1 range with 0.02 centimeter–1 resolution. We studied the onset of the resonance regime by probing the lowest-lying resonance dominated by s and p waves only. The highly structured differential cross sections directly reflect the increasing number of contributing waves as the energy is increased. Only with CCSDT(Q) level of theory was it possible to reproduce our measurements. [ABSTRACT FROM AUTHOR]

It is difficult to investigate the behavior of solitons in realistic inhomogeneity media in experiment due to inhomogeneity of the media and noise from the unwanted coupling. We propose to use a waveguide-like transmission line which is based on direct-current super-conducting quantum interference devices to simulate behavior of solitons because we find that the behavior of the node flux in this transmission is similar to that of solitons with variable mass. [ABSTRACT FROM AUTHOR]

It is difficult to investigate the behavior of solitons in realistic inhomogeneity media in experiment due to inhomogeneity of the media and noise from the unwanted coupling. We propose to use a waveguide-like transmission line which is based on direct-current super-conducting quantum interference devices to simulate behavior of solitons because we find that the behavior of the node flux in this transmission is similar to that of solitons with variable mass. [ABSTRACT FROM AUTHOR]

Quantum control of complex objects in the regime of large size and mass provides opportunities for sensing applications and tests of fundamental physics. The realization of such extreme quantum states of matter remains a major challenge. We demonstrate a quantum interface that combines optical trapping of solids with cavity-mediated light-matter interaction. Precise control over the frequency and position of the trap laser with respect to the optical cavity allowed us to laser-cool an optically trapped nanoparticle into its quantum ground state of motion from room temperature. The particle comprises 108 atoms, similar to current Bose-Einstein condensates, with the density of a solid object. Our cooling technique, in combination with optical trap manipulation, may enable otherwise unachievable superposition states involving large masses. [ABSTRACT FROM AUTHOR]

The ability to inject dopant atoms with high spatial resolution, flexibility in dopant species, and high single ion detection fidelity opens opportunities for the study of dopant fluctuation effects and the development of devices in which function is based on the manipulation of quantum states in single atoms, such as proposed quantum computers. The authors describe a single atom injector, in which the imaging and alignment capabilities of a scanning force microscope (SFM) are integrated with ion beams from a series of ion sources and with sensitive detection of current transients induced by incident ions. Ion beams are collimated by a small hole in the SFM tip and current changes induced by single ion impacts in transistor channels enable reliable detection of single ion hits. They discuss resolution limiting factors in ion placement and processing and paths to single atom (and color center) array formation for systematic testing of quantum computer architectures in silicon and diamond. © 2008 American Vacuum Society.

Beating of ependymal cilia in the mammalian brain ventricle causes cerebrospinal fluid circulation. Beating of ependymal cilia is studied in vitro in many laboratories but has not been monitored non-invasively in live animals. We have developed a new method for remote sensing of the magnetic flux density changes associated with the reciprocal movement of a magnetic particle bound to cilia in the lateral ventricle of a newborn rat brain with superconducting quantum interference device (SQUID). We detected an oscillatory signal (10–20 Hz and ca. 10 pT amplitude) from a small neodymium magnetic particle attached to cilia with the SQUID above the specimen; the distance between the cilia to the SQUID sensor was 12 mm. This successful detection provides a new sensing platform that enables the non-invasive measurement of beating of ependymal cilia from a live animal. [ABSTRACT FROM AUTHOR]

Effective operators for the Laplacian in surfaces of three-dimensional waveguides are investigated as their diameters vanish. [ABSTRACT FROM AUTHOR]

We present the design and implementation of a mechanical low-pass filter vibration isolation used to reduce the vibrational noise in a cryogen-free dilution refrigerator operated at 10 mK, intended for scanning probe techniques. We discuss the design guidelines necessary to meet the competing requirements of having a low mechanical stiffness in combination with a high thermal conductance. We demonstrate the effectiveness of our approach by measuring the vibrational noise levels of an ultrasoft mechanical resonator positioned above a superconducting quantum interference device. Starting from a cryostat base temperature of 8 mK, the vibration isolation can be cooled to 10.5 mK, with a cooling power of 113 µW at 100 mK. We use the low vibrations and low temperature to demonstrate an effective cantilever temperature of less than 20 mK. This results in a force sensitivity of less than 500 zN/ Hz and an integrated frequency noise as low as 0.4 mHz in a 1 Hz measurement bandwidth. [ABSTRACT FROM AUTHOR]

Abstract We propose extending Bohmian mechanics (BM) with the moving particle semi-implicit method, a particle method for uncompressed fluids. The application of this method prevents the node of the Bohm quantum potential from breaking numerical calculations while maintaining a low calculation cost. We validated our extended method by comparing our results with those from the conventional method for a one-dimensional harmonic oscillator, Gaussian barrier and rectangular barrier. The proposed method was found to simulate the temporal changes in the probability density for a rectangular barrier. In addition, the relational equation obtained by this method reveals an interesting correspondence between the pressure of a classical fluid and the Bohm quantum potential. Highlights • Bohmian mechanics is extended using moving particle semi-implicit method. • The interesting relation between the pressure of a classical fluid and the Bohm quantum potential is obtained. • The calculation cost is reduced more than the conventional method. • The temporal changes in the probability density for a rectangular barrier is simulated using the proposed method. [ABSTRACT FROM AUTHOR]

Abstract This paper systematically develops the Schrödinger formalism that is valid also for gyrotropic media where the material weights W = ε χ χ ∗ μ ≠ W ¯ are complex. This is a non-trivial extension of the Schrödinger formalism for non- gyrotropic media (where W = W ¯) that has been known since at least the 1960s (Wilcox, 1966; Kato, 1967). Here, Maxwell’s equations are rewritten in the form i ∂ t Ψ = M Ψ where the selfadjoint (hermitian) Maxwell operator M = W − 1 Rot | ω ≥ 0 = M ∗ takes the place of the Hamiltonian and Ψ is a complex wave representing the physical field (E , H) = 2 Re Ψ. Writing Maxwell’s equations in Schrödinger form gives us access to the rich toolbox of techniques initially developed for quantum mechanics and allows us to apply them to classical waves. To show its utility, we explain how to identify conserved quantities in this formalism. Moreover, we sketch how to extend our ideas to other classical waves. [ABSTRACT FROM AUTHOR]

We report on the experimental observation of period multiplication in parametrically driven tunable superconducting resonators. We modulate the magnetic flux through a superconducting quantum interference device, attached to a quarter-wavelength resonator, with frequencies nω close to multiples, n =2, 3, 4, and 5, of the resonator fundamental mode and observe intense output radiation at ω. The output field manifests n-fold degeneracy with respect to the phase, and the n states are phase shifted by 2π/n with respect to each other. Our demonstration verifies the theoretical prediction by Guo et al. [Phys. Rev. Lett. 111, 205303 (2013)] and paves the way for engineering complex macroscopic quantum cat states with microwave photons. [ABSTRACT FROM AUTHOR]

We experimentally study electron transport between two superconducting indium leads, coupled to the WTe2 crystal surface. WTe2 is characterized by presence of Fermi arc surface states, as a predicted type-II Weyl semimetal candidate. We demonstrate Josephson current in unprecedentedly long 5 µm In-WTe2-In junctions, which is confirmed by I-V curves evolution with temperature and magnetic field. The Josephson current is mostly carried by the topological surface states, which we demonstrate in a double-slit superconducting quantum interference device geometry, realized by coupling the opposite WTe2 crystal surfaces. [ABSTRACT FROM AUTHOR]

We developed a novel magnetic coupling module, formed of a monolayer superconducting flux concentrator that is integrated with a coplanar resonator, strongly coupled to hightemperature superconducting radio frequency superconducting quantum interference device (SQUID). Three types of resonators, including a long stripline resonator between the input loop and the pick-up loop of the flux concentrator, a complementary split ring resonator, and a spiral shape inside the input loop, are explored. The resonance quality factor of different patterns of these three types of the resonators, as well as their coupling to the SQUID, is evaluated using finite-element-method simulations. Several readout methods are tested to couple the electronic system to the resonators by inductive (coil) or capacitive (transmission line) methods, and the optimum readout is reported for each of the resonators. Among the evaluated resonator types, a spiral shape with an optimal behavior at the resonance frequency of 836 MHz, showing the highest quality factor together with the strongest coupling to the SQUID, compared to other types of the resonators, is fabricated using a 200-nm-thick YBCO film on a 1-mm-thick crystalline LaAlO3 substrate. The flux concentrator of the module is optimized by the variation of the linewidth of its different parts and also its input loop radius to obtain the maximum flux transformation efficiency. [ABSTRACT FROM AUTHOR]