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Possessing the noise-resilience feature, geometric phases have become important in robust quantum computation. Gates based on the Abelian and non-Abelian geometric phases have been experimentally demonstrated in different physical systems. However, previous proposals require cyclic evolution with a constant operation time even for small rotation angles, which set a limit to the gate operation time. Here, we experimentally realize noncyclic geometric gates, where the cyclic condition is removed and the operation time is proportional to the rotation angle. With the adiabatic process sped up by shortcut to adiabaticity, the fidelities of a noncyclic geometric gate characterized by randomized benchmarking are above 99.5%. Comparing with the dynamic scheme, we demonstrate the robustness of our gate against control instability in the experiment. Moreover, our results indicate that the noncyclic geometric gate with a smaller rotation angle corresponds to a shorter evolution time and higher fidelity. As small rotation angles are essential in the quantum algorithm, the superiority of noncyclic geometric gates makes them promising candidates in fast and robust quantum computation.

In superconducting quantum circuits, Josephson junctions are a key component to provide nonlinearity and enable superconducting qubits. Fabricating junctions with precise critical currents is crucial to defining qubit frequency. Here we suppress the critical current variation of Josephson junctions by varying the critical current density Jc and junction areas. The relative standard deviation of the critical current Ic is controlled to be below 0.8%. This uniform fabrication is promising for realizing scalable superconducting quantum computation.

Shortcuts to adiabaticity have been proved an effective routine for precise quantum state manipulation. Here, we experimentally demonstrate invariant-based shortcuts to adiabaticity to speed up the population transfer in a superconducting circuit. Through inverse engineering of the Hamiltonian, we realize this protocol in a single-qubit and a two-qubit system. The Lewis–Risenfeld phase is characterized experimentally. Furthermore, we investigate the robustness of the scheme against amplitude and frequency errors.

Coherent quantum state transfer is a vital step in quantum information processing. Based on the stimulated Raman adiabatic passage (STIRAP), we realize robust quantum state transfer between two superconducting qubits, mediated by a tunable coupler. Utilizing parametric coupling techniques, we construct the STIRAP Hamiltonian by modulating the coupler frequency. A population transfer fidelity of 95.1 ( ± 2.0 ) % is achieved and is consistent with the numerical simulation result of 95.4%. By preparing the initial state in the maximal superposition state of one qubit, we research how the phase of the transferred state is related to the modulation pulses. We also find that the transfer process is robust against the fluctuation of modulation frequency. Numerical simulation confirms that our state transfer scheme is more robust than non-adiabatic protocols.

Raman spectrum is a common method of evaluating the graphitization degree of carbon materials. However, there is still some controversy over its evaluation for coal graphitization, i.e., whether large ID/IG means a high graphitization degree of coal. This work uses an ultraviolet (UV) Raman spectrum to find a better index of graphitization degree. The T peak (sp3 sites) of coal was first directly detected. The IT/IG and ID/IG decrease after pyrolysis in UV Raman spectra at 266 nm, which shows that the sp3 site relative content decreases and the sp2 site relative content increases. Moreover, the absolute value of the D band dispersion slopes as the excitation wavelength increases and the D peak width decreases, which shows that the coal gets more orderly after pyrolysis. The position difference (G–D) decreases and the G peak width increases after pyrolysis in UV–Vis Raman spectra, indicating the decomposition of vitrinite in coal. The 2D′ peak decreased after pyrolysis. These parameters in multi-wavelength Raman spectra can be used to evaluate the structure of coal.

Owing to the attractive advantages of the simple preparation process, convenient frequency adjustment, and stable mechanical structure, magnetic flux modulation with electric controlled permeability exhibits a better performance in the reduction of 1/f noise for magnetoresistive (MR) sensors than other schemes of magnetic flux modulation. However, the magnetic flux electric modulation (MFEM) has not been experimentally verified. In this work, a prototype of the MFEM structure was established by preparing an FeGaB film on a Pb(Mg1/3Nb2/3)0.7O3–PbTi0.3O3 substrate, and the modulation structure was integrated into an MR sensor. A test system was built to evaluate the modulation efficiency of the MFEM structure, and the results showed that the modulation efficiency reached 9.8% with an applied electric field of 2 kV/cm at a frequency of 10 010 Hz. Meanwhile, experiments were carried out to study the effects of driving electric fields’ amplitude and frequency on modulation efficiency, and it was revealed that the modulation efficiency could be further improved by increasing the amplitude of driving voltage and reducing the thickness of the ferroelectric layer.

We demonstrate a compact in-fiber integrated microresonator based on a silica microsphere and microstructure fiber. Whispering-gallery-modes (WGMs) are effectively excited through evanescent field coupling between the silica microsphere and one of the input tube waveguides of negative curvature fiber. The WGM spectrum with the Q-factor of ∼2.56 × 103 and the extinction ratio of ∼15.2 dB is achieved. The transmission spectra evolution for 5 h reveals the long-term stability of WGM excitation. The experimental results indicate that the in-fiber integrated resonator has the advantages of high stability, high integration, robustness, alignment-free assembly structure, and low cost, motivating potential applications in the lab-in-fiber platform.

The magnetic anisotropy of bit-patterned media, such as a mesocrystal, is a key parameter in spintronics. Here, we utilize the high sensitivity of dynamic cantilever magnetometry to investigate the foundation of a mesocrystal, an individual CoFe 2 O 4 pyramid nanocrystal. The magnetic anisotropy of the nanosample can be inferred through quantitatively correlating the main features in the evolution of the magnetic energy with frequency shifts in dynamic cantilever magnetometry measurements. Magnetometry data taken at 280 K exhibit hybrid magnetic anisotropy, including uniaxial anisotropy and cubic anisotropy. Low-temperature measurements further confirm the previously reported single-domain state and indicate that the cubic anisotropy is mainly magnetocrystalline anisotropy, while uniaxial anisotropy is likely to be induced by the interface between the CoFe 2 O 4 pyramid and the BiFeO 3 layer. The analysis provides an alternative interpretation for dynamic cantilever magnetometry data, which may extend the application of magnetometry.

We propose and demonstrate experimentally the arbitrary state-transfer in a qubit by using a superadiabatic approach in a superconducting circuit. We encode the qubit in a time-dependent dark state generated by an applied microwave field, speeding up the adiabatic evolution by transitionless quantum driving algorithms. This approach is realized experimentally in a qutrit system, which consists of a qubit and an ancillary level. Furthermore, we analyze the robustness of the implementation and measure the fidelity of transfer operation by using randomized benchmarking technique.

Based on the Navier slip model, a slip boundary format for the lattice Boltzmann method is developed for curve walls of which the shape is well considered. The main idea of this method is to convert the slip length into the slip velocity with a simplified algorithm. With the Navier slip model, the slip velocities at the boundary are obtained through the interpolation of the fluid points near the boundary and are then substituted into the velocity boundary conditions to construct the relationship between the slip length and the macroscopic flow field. This format is free from the restriction of the previous combined boundary conditions which can only be applied to flat boundaries. It also overcomes the limitation that the slip boundary can only simulate flows with small slip length. The present slip boundary condition is implemented for the lattice Bhatnagar-Gross-Krook model, which is verified by several cases, including the cylindrical Couette flow and the irregular Poiseuille flow. The numerical results agree well with theoretical analysis. Furthermore, this boundary condition is applied to the hydrofoil to study the drag reduction effect of the boundary slip phenomenon. It is found that the slip boundary can effectively reduce the drag of the hydrofoil at low Reynolds numbers. Moreover, the position of the slip boundary on the hydrofoil also has significant effects on the lift-to-drag ratio.

High-precision temperature measurements could guarantee temperature difference control accuracy in research and industrial production. To flexibly achieve high precision and large operating temperature range is a crucial problem for temperature measurements. Here, we demonstrate a method for a high-precision temperature measurement based on a weak measurement done using nematic liquid crystals (NLCs). By performing an analysis in the frequency domain, the temperature variation of NLCs is measured using a Sagnac interferometer with appropriate preselection and postselection. In order to obtain a large operating temperature range, there is a relatively large time delay that resulted from NLCs, and an operational principle is deduced explicitly by Jones matrices. In the proposed method, the precision of 3 × 10−6 °C could be achieved by a currently available spectrometer and the operating temperature range can be modulated by the thickness of NLCs. Moreover, the temperature sensitivity of 13.5 nm/°C could be realized for NLCs with 100 μm thickness, which exhibits at least three orders of magnitude larger than the value for other frequency domain analyses.

Hopf-link semimetals exhibit exotic gapless band structures with fascinating topological properties, which have never been observed in nature. Here we demonstrate nodal lines with topological form of Hopf-link chains in artificial semimetal-bands. Driving superconducting quantum circuits with elaborately designed microwave fields, we mapped the momentum space of a lattice to a parameter space of the Hamiltonian for a Hopf-link semimetal. By measuring the energy spectrum, we directly imaged nodal lines in cubic lattices. By tuning the driving fields, we adjusted various parameters of Hamiltonian. Important topological features, such as link-unlink topological transitions and the robustness of the Hopf-link chain structure were investigated. Moreover, we extracted the linking number by detecting the Berry phase associated with different loops encircling nodal lines. This topological invariant clearly reveals the nontrivial topology of the Hopf-link semimetal. Our results provide knowledge for developing new materials and quantum devices., Comment: 6 pages, 4 figures. arXiv admin note: text overlap with arXiv:1702.01512

Srx(Na0.5Bi0.5)1−xTi0.99Mn0.01O3 (x = 0.2, 0.4, 0.6, and 0.8) relaxor ferroelectric thin films were grown on Pt/Ti/SiO2/Si substrates by the Sol-Gel method. The influence of the Sr content on the microstructures, ferroelectric properties, and energy-storage performances of the thin films were investigated in detail. The Sr0.6(Na0.5Bi0.5)0.4Ti0.99Mn0.01O3 thin film exhibits very slim hysteresis loops with the highest electric breakdown field strength due to reduced oxygen vacancies. Owing to the high breakdown field strength of 3134.3 kV/cm, the Sr0.6(Na0.5Bi0.5)0.4Ti0.99Mn0.01O3 thin film shows a giant recoverable energy-storage density of 33.58 J/cm3. These results indicate that the Sr0.6(Na0.5Bi0.5)0.4Ti0.99Mn0.01O3 thin film is promising for applications of advanced capacitors with high energy-storage density.

We propose and experimentally demonstrate a scheme to simulate the interaction between a two-level system and a classical light field. Under the transversal driving of two microwave tones, the effective Hamiltonian in an appropriate rotating frame is identical to that of the general semi-classical Rabi model. We experimentally realize this Hamiltonian with a superconducting transmon qubit. By tuning the strength, phase, and frequency of the two microwave driving fields, we simulate the quantum dynamics from the weak to extremely strong driving regime. Under these conditions, we observe that, as a function of increased Rabi drive strength, the qubit evolution gradually deviates from the normal sinusoidal Rabi oscillation, in accordance with the predictions of the general semi-classical Rabi model far beyond the weak driving limit. Our scheme provides an effective approach to investigate the extremely strong interaction between a two-level system and a classical light field. Such strong interactions are usually inaccessible in experiments.

The quaternary system of relaxor-ferroelectric based Pb(Ni1/3Nb2/3)O3-Pb(ZrxTi1−x)O3-Pb(In0.5Nb0.5)O3 (PNN-PZT-PIN) piezoelectric ceramic at the morphotropic phase boundary was investigated via the solid reaction method. The optimized ceramic with excellent electric properties of er = 8084, d33 = 977 pC/N, kp = 0.61, and Ec = 3.0 kV/cm was fabricated into d33-mode discs with separated surface electrodes, which were arranged in a series connection and, then as a piezo-stack, assembled into a barbell-shaped energy harvester that could bear a strong mechanical vibration. It is found that under a vibration mass-induced bending moment, the energy harvester produces an open circuit voltage of 26.4 Vp-p at the acceleration of 2.5 g at a load of 1.56 MΩ, which is two times higher in comparison to one without surface electrode separation. Its power output is 30 μW at the acceleration of 1 g and 104 μW at 2.5 g, which are even six times higher than that of a previously reported barbell-shaped energy harvester at ro...

The authors report significant tunability of the bandgap in very long-wave infrared (VLWIR) InAs/GaSb/InSb/GaSb superlattices. Calculations using the empirical tight binding method have shown the flexibility in tuning the energy levels of the valence band by inserting a thin InSb layer in the middle of the GaSb layer of a normal type-II binary InAs/GaSb superlattice. Through the experimental realization of several barrier structure photodiodes with 15 ML InAs/7 ML GaSb active region, the cutoff wavelength was extended from 14.5 μm to 18.2 μm by inserting 0.6 ML InSb at different locations in GaSb layer. The agreement between the theoretical predictions and the experimental measurement suggests a way to exploit this advantage for the realization of very long-wave infrared detection without increasing the thickness of InAs layer. At 77 K, the quantum efficiency of a very long-wave detector with the cutoff wavelength of 16.9 μm reached at a maximum value of 30%, and the R0A is kept at a stable value of 10 Ω ...

An interface is constructed based on a bismuth ferrite oxide (BFO) thin film and p-type silicon, and the temperature dependence of the interface properties has been studied systematically using terahertz time-domain spectroscopy. The BFO/Si interface exhibits quasi-two-dimension electron gas (2DEG) transport in the temperature range of 80 to 140 K: the electrons at the interface possess large electron mobility (∼106 cm2/V s) and long scattering time (∼100 ps). As the temperature is higher than 140 K, an abrupt decrease in THz interface conductivity is observed due to the breakdown of the 2DEG induced by the surface phase transition in the BFO thin film. Our result reveals that the interface formed between BFO and Si provides a special platform for designing and fabricating THz photonic devices.

The Halbach type hollow cylindrical permanent magnet array (HCPMA) is a volume compact and energy conserved field source, which have attracted intense interests in many practical applications. Here, using the complex variable integration method based on the Biot-Savart Law (including current distributions inside the body and on the surfaces of magnet), we derive analytical field solutions to an ideal multipole HCPMA in entire space including the interior of magnet. The analytic field expression inside the array material is used to construct an analytic demagnetization function, with which we can explain the origin of demagnetization phenomena in HCPMA by taking into account an ideal magnetic hysteresis loop with finite coercivity. These analytical field expressions and demagnetization functions provide deeper insight into the nature of such permanent magnet array systems and offer guidance in designing optimized array system.

We propose a scheme to perform two-qubit state tomography by independently measuring the ensemble average of quantum states of two coupled superconducting transmon qubits. Each qubit is capacitively coupled to its own readout cavity and can be measured separately. In order to obtain the density matrix of a two-qubit state, we apply four two-qubit unitary operations to the initial state and measure the corresponding qubit states, from which the elements of the two-qubit density matrix can be extracted. By using this scheme, we measure the entangled two qubits with high fidelity.

In semiconductor technology, In2O3 nanowire field effect transistor (FET) can serve as an important building block due to its admirable electrical switching properties. However, the relatively too large threshold voltages and threshold voltage fluctuations of the devices may hinder their extensive applications. In this report, N+ ion implantation of gate dielectric was conducted to modulate the threshold voltage of In2O3 nanowire FET. Electrical measurements reveal that the threshold voltage can be reduced to as low as −2.0 V from the initial −23.2 V after ion implantation. This can be attributed to the effects of implantation induced electron traps. Moreover, it is found that the stability of threshold voltage can be improved by ion implantation. This simple and convenient method indicates that gate dielectric ion implantation may be a potential way to realize the low voltage operation and uniform In2O3 nanowire FETs.

A method to measure the contact angle, which is indicative of wetting, using small liquid volumes dispensed directly on microplate wells is described and demonstrated. Experiments with enhanced green protein samples of volumes 4.4–6 μl showed no measured variance in the contact angle. Experiments with phosphate buffer solution with varied concentrations of a non-ionic detergent (Tween 20) dissolved, however, revealed smaller contact angles with increased detergent concentration. It is experimentally shown that drops can be located up to 7° from the lowest position of the well without affecting the accuracy of contact angle measurements. Numerical simulations confirm the ability of the drops to manifest the correct contact angle despite the lack of axis-symmetry in their shape while residing on a circular surface. This method offers a convenient means to determine the wetting characteristics of different liquid samples in different microplates.

In this paper, we report a barbell-shaped piezoelectric energy harvester (BSPEH) operating in a d33 mode and aiming for mechanical vibration energy harvesting in a high temperature (H-T) circumstance. BSPEH is composed of a ring-shaped multilayer piezo-stack, a tip mass, and an elastic shaft connecting them together. The piezo-stack is made of bismuth scandium lead titanate (BiScO3-PbTiO3) ceramic with a large piezoelectric coefficient of d33 = 450 pC/N and a high Curie temperature point Tc of around 450 °C. Experimental results show that the BSPEH works effectively and steadily in a wide temperature range from room temperature (R-T) till Tc/2. Furthermore, it is found that under a constant mechanical vibration excitation, the power output of the BSPEH at 200 °C is even two times higher than that at R-T. The proposed harvester shows a great potential for applications as a self-power source of wire-less sensor system in H-T circumstance.

In this letter, we propose an effective route to obtain large recoverable strain, purely electrostrictive effects and high energy-storage density by inducing defect dipoles into Na0.5Bi0.5TiO3 (NBT)-based relaxor ferroelectrics. It has been found that pinched and double polarization hysteresis loops with high maximum polarization (Pmax) and negligible remanent polarization (Pr) can be observed due to the presence of acceptor-induced defect dipoles. A large recoverable strain of 0.24% with very little hysteresis and high electrostriction coefficient of 0.022 m4 C2 with purely electrostrictive characteristics were acquired when 11 mol. ‰ Mn-doped. Meanwhile, a high recoverable energy density of 1.06 J/cm3 with excellent temperature stability was obtained at the same composition owing to the enlarged value of Pmax-Pr (36.8 μC/cm2) and relatively high electric field (95 kV/cm). Our achievement can open up the exciting opportunities for ferroelectric materials in high-precision positioning devices and high ele...

The enhancement of the electrocaloric effect (ECE) was achieved by the amplifying effect of applied electric field through devising the thin films' structure. The PbZr0.95Ti0.05O3/PbZr0.52Ti0.48O3 bilayer structured thin films were fabricated on a Pt(111)/Ti/SiO2/Si substrate using sol-gel method. The ΔS = 20.5 J K−1 kg−1 and ΔT = 24.8 K for bilayer thin films is achieved around 125 °C much below Tc, which is caused by the amplifying electric field induced phase transition of OAFE/RFE in PZr0.95Ti0.05O3 layer. It is also worth mentioning that the films exhibit outstanding ECE at room temperature; ΔS = 11.9 J K−1 kg−1 and ΔT = 10.7 K are observed, which are attributed to the effect of amplifying electric field in PbZr0.95Ti0.05O3 layer and RFE/TFE at morphotropic phase boundaries (MPB) in PbZr0.52Ti0.48O3 layer. This result indicates that to amplify the local electric field engineering and to maximize the number of coexisting phases in heterostructures or multilayer thin films may be an effective way for c...

By driving a 3D transmon with microwave fields, we generate an effective avoided energy-level crossing. Then we chirp microwave frequency, which is equivalent to driving the system through the avoided energy-level crossing by sweeping the avoided crossing. A double-passage chirp produces Landau-Zener-Stuckelberg-Majorana (LZSM) interference that agree well with the numerical results, especially with the initial state being an eigen-energy state in the center of an avoided level crossing. A time-resolved state tomography measurement is performed in the evolution of LZSM interference, showing an experimental evidence for the dynamical evolution of quantum state. Our method is fully applicable to other quantum systems that contain no intrinsic avoided level crossing, providing an alternative approach for quantum control and quantum simulation.