Surface Ion Trap for Fast Microwave Gates

We theoretically investigate the use of fast pulsed two-qubit gates for trapped ion quantum computing in a two-dimensional microtrap architecture. In one dimension, such fast gates are optimal when employed between nearest neighbors, and we examine the generalization to a two-dimensional geometry. We demonstrate that fast pulsed gates are capable of implementing high-fidelity entangling operations between ions in neighboring traps faster than the trapping period, with experimentally demonstrated laser repetition rates. Notably, we find that without increasing the gate duration high-fidelity gates are achievable even in large arrays with hundreds of ions. To demonstrate the usefulness of this proposal, we investigate the application of these gates to the digital simulation of a 40-mode Fermi-Hubbard model. This also demonstrates why shorter chains of gates required to connect arbitrary pairs of ions make this geometry well suited for large-scale computation.

A nano-carbon and iron composite--carbon coated iron nanoparticles produced by carbon arc method can be used as a new kind of magnetic targeting and heating drug carrier for cancer therapy. It presents an special nanostructure of iron nanoparticles in inner core and nano-carbon shells outside. The nano-carbon shells have a high drug adsorption ability because of its high surface area and its inner core has great effect of targeting magnetic heating. Magnetic induction heating effect of pig liver injected mixed liquids with different concentration carbon coated iron particles in physiological saline indicates that the more quantity of nanoparticles used, the higher temperature it is. Magnetic induction heating effect of the pig liver was compared in the case of filling method and injection method (both were containing 0.3g carbon coated iron nanoparticles). The iron nanoparticle in its inner core has good effect of magnetic induction heating, the temperature can go up to 51 °C in the case that carbon coated iron nanoparticles mixed with physiological saline were distributed uniformly in pig liver. And the temperature can go up to 46°C in the case that carbon-coated iron nanoparticles was injected in a certain section of pig liver. It is obvious that injected one is much better than that of filled, but they are all enough to kill the cancer cells.

In this study we present a set of guidelines for the design of current carrying micro-conductors/micro-coils (MCs) for magnetic nanoparticles manipulation in biomedical applications. Precise spatial manipulation requires steep magnetic field gradients and due to the consequences of scaling laws, these gradients should be maximized as the size of the particle reduces. Conventional planar coils have many construction and functional limitations, such as generating only small magnetic field gradients, Joule heating, and limited ability to move particles with high spatial resolution. On the other hand, micro-coils can provide a satisfactory solution to all these problems. The geometrical and structural parameters play significant roles in determining the ability to move guide and transport nanoparticles. Design guidelines were generated from a detailed theoretical treatment and finite element analysis (FEA). The spatial distributions of magnetic fields, field gradients and magnetic forces on particles were simulated using FEA for different geometrical/structural parameters and wire arrangements. An array of wires create a chain of magnetic potential wells that are controllable in terms of magnitude and direction and therefore can be used to control the motion and position of magnetic nano-particles by tuning the current through the array.

Optimal design of bi-planar heater with magnetic field self-suppression configuration based on multi-objective optimization

Magnetic field heating study of Fe-doped Au nanoparticles

Ultracold trapped atomic ions excited into highly energetic Rydberg states constitute a promising platform for scalable quantum information processing. Elementary building blocks for such tasks are high-fidelity and sufficiently fast entangling two-qubit gates, which can be achieved via strong dipole–dipole interactions between microwave-dressed Rydberg ions, as recently demonstrated experimentally (Zhang et al 2020 Nature 580 345). We theoretically investigate the performance of three protocols leading to controlled-phase gate operations. Starting from a microscopic description of Rydberg ions in a linear Paul trap, we derive an effective Hamiltonian that faithfully captures the essential dynamics underlying the gate protocols. We then use an optimization scheme to fine-tune experimentally controllable parameters like laser detuning and Rabi frequency to yield maximal gate fidelity under each studied protocol. We show how non-adiabatic transitions resulting from fast laser driving relative to the characteristic time scales of the system detrimentally affect the fidelity. Despite this, we demonstrate that in the realistic scenario of Rydberg ions with finite radiative lifetimes, optimizing the best found gate protocol enables achievement of fidelities as high as 99.25 % for a gate time of 0.2 μ s . This considerably undercuts entangling gate durations between ground state ions, for which gate times are typically limited by the comparably slower time scales of vibrational modes. Overall, this places trapped Rydberg ions into the regime where fast high-accuracy quantum computing and eventually quantum error correction become possible.

Magnetic nanoparticles, especially superparamagnetic nanoparticles (SPIONs), have attracted tremendous attention for various biomedical applications. Facile synthesis and functionalization together with easy control of the size and shape of SPIONS to customize their unique properties, have made it possible to develop different types of SPIONs tailored for diverse functions/applications. More recently, considerable attention has been paid to the thermal effect of SPIONs for the treatment of diseases like cancer and for nanowarming of cryopreserved/banked cells, tissues, and organs. In this mini-review, recent advances on the magnetic heating effect of SPIONs for magnetothermal therapy and enhancement of cryopreservation of cells, tissues, and organs, are discussed, together with the non-magnetic heating effect (i.e., high Intensity focused ultrasound or HIFU-activated heating) of SPIONs for cancer therapy. Furthermore, challenges facing the use of magnetic nanoparticles in these biomedical applications are presented.

Closed form solutions are presented for the steady magnetohydrodynamic (MHD) buoyancydriven convection flow, heat and mass transfer from a semi-infinite vertical surface with wall transpiration, first order chemical reaction, viscous heating, Ohmic heating and magnetic induction effects. Magnetic Reynolds number is large enough to permit the inclusion of magnetic induction effects. The governing boundary layer equations with physically pertinent boundary conditions are normalized and solved using a power-series method. The effects of Eckert number (Ec), Hartmann number (M), magnetic Prandtl number (Prm), chemical reaction parameter (K), Schmidt number, thermal Grashof number and Prandtl number (Pr) on velocity, current density, magnetic induction field and temperature gradient are studied graphically and in tables. An increase in Eckert number is found to strongly enhance magnetic induction values. Current density is decreased with magnetic Prandtl number. Velocity is reduced with Hartmann number but enhanced with magnetic Prandtl number. Progressively weaker destructive chemical reaction (K) lowers wall temperature gradient. Applications of the study arise in thermal plasma reactor modelling, electromagnetic induction calorimetry of reactive metallic liquids, and magnetohydrodynamic transport phenomena in chromatographic systems and magnetic field control of materials processing.

The objective of our investigation was to evaluate safety during MR imaging (i.e., magnetic field interactions, heating, and artifacts) for metallic stents. Different types of metallic stents were tested for magnetic field interactions, heating, and artifacts using a 1.5-T MR system. Magnetic field-related translational attraction and torque were assessed using previously described techniques. Heating was evaluated using an infrared thermometer to record temperatures immediately before and after performing MR imaging using a whole-body-averaged specific absorption rate of 1.3 W/kg. Artifacts were assessed by placing the stents inside a fluid-filled phantom and performing MR imaging using fast spoiled gradient-echo and T1-weighted spin-echo pulse sequences. For the 10 different stents evaluated, we found no magnetic field interactions. the highest temperature change was < or = +0.3 degrees C, and the artifacts involved signal voids that would not create diagnostic problems as long as the area of interest was not positioned exactly where a particular stent was located. The findings of the safety tests indicated that the 10 different metallic stents would be safe for patients undergoing MR imaging procedures using MR systems with static magnetic fields of 1.5 T or less.

Effects of Ohmic heating, induced magnetic field and Newtonian heating on magnetohydrodynamic generalized Couette flow of Jeffrey nanofluid between two parallel horizontal plates with convective cooling

We probe electric-field noise near the metal surface of an ion-trap chip in the temperature range from 295 to 530 K. We observe a nontrivial temperature dependence with the noise amplitude at 1 MHz frequency saturating around 500 K. Measurements of the noise spectrum reveal a 1/&lt;em&gt;f&lt;/em&gt;&lt;sup&gt;α≈1&lt;/sup&gt; dependence and a small decrease in α between low and high temperatures. This behavior can be explained by considering noise from a distribution of thermally activated two-level fluctuators with activation energies between 0.35 and 0.65 eV. Processes in this energy range may be relevant to understanding electric-field noise in ion traps; for example, defect motion in the solid state and surface adsorbate binding energies. Lastly, the study of these processes may aid in identification of the origin of excess electric-field noise in ion traps—a major source of ion motional decoherence limiting the performance of surface traps as quantum devices.

Effect of Test Method and Needle Plane Configuration on Partial Discharge Inception Voltage Measurement of Mineral Oil based on Weibull Analysis

Magnetic properties and heating effect in bacterial magnetic nanoparticles

As one of the excellent piezoelectric materials, piezoelectric ceramic has been widely used to develop a highly precise displacement measurement system, which is the key part of the scanning probe system of the high-precision measuring instrument.Based on the high-precision scanning probe system, the micro/nano structures can be easily and accurately detected by the instrument system.However, due to the limitations caused by the character of hysteresis and nonlinearity, it is difficult to further improve the precision of highly precise displacement measurement system.In this work, we present a novel method to develop the highly precise displacement measurement system based on the quantum spin effect.The nitrogen vacancy (NV) color center of single crystal diamond as a sensitive element senses the change of the micro-displacement.Based on the electron spin magnetic resonance effect of diamond nitrogen vacancy color center, the variation of the magnetic field generated from the magnetic steel can be detected with high precision by the electron spin.The relative relation between the displacement and the magnetic gradient field can be used to establish the correlation model between the displacement and the electron spin resonance peak.In the experiment, a corresponding micro-displacement measurement system is established based on the cylindrical permanent magnet, according to the correlation model between the electron spin resonance effect and micro-displacement.The linear region of magnetic field gradient is designed to detect the micro-displacement.Firstly, the intensity distribution of magnetic field gradient is measured by the gauss meter.As the measurement results show, the gradient value is -7.77 Gauss/mm along the core axis of cylindrical permanent magnet, and the intensity of magnetic field gradient distribution region is linear in the millimeter range.Meanwhile, the electron spin magnetic resonance peak of diamond nitrogen vacancy color center is achieved by the optically detected magnetic resonance technology.The electron spin magnetic resonance peak is approximately 2.79 MHz/Gauss in the magnetic field achieved by the fluorescence spectrum of diamond nitrogen vacancy color center, attributed to the relation model between Zeeman splitting effect and magnetic field. In the experiment, the electron spin magnetic resonance signal of diamond nitrogen vacancy color center is lockedin by the demodulation method to achieve the change of micro-displacement.As the results show, the sensitivity is about 16.67 V/mm at the corresponding demodulation frequency of 3000.56 MHz.By the calculation, the resolution of micro-displacement measurement system is about 60 nm based on our method.It proves out a high precision and well reliability method to detect the micro-displacement.By the further theoretical calculation, based on the electron spin effect, the detection resolution of our method can be enhanced up to sub-nanometer scale by reducing the distance between the NV color center and the magnet.It presents a new research direction and field for the micro-displacement detection system.

Eutectic lead–lithium (PbLi) alloy is the most promising candidate for liquid tritium breeder material in the blanket of a fusion power reactor. Corrosion of structural blanket steels in the flowing PbLi in the presence of a strong plasma-confining magnetic field and volumetric heating is among the most serious limitations in the design of a robust breeding blanket system. Anew flowing PbLi corrosion loop called Corrosion Upgrade PbLi Experiment (CoUPLE) with a magnetic field and surface heating of the test-section is under development at Oak Ridge National Laboratory (ORNL). The proposed ORNL PbLi loop will reach prototypical blanket conditions (PbLi temperature up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$650~^{\circ }$</tex-math> </inline-formula>C, velocity up to 20cm/s, magnetic field up to 4 T) and be able to show the corrosion performance of candidate structural steels and functional electroinsulating materials and establish their corrosion mitigation. The developed computational model in COMSOL Multiphysics is used in this study as a design tool and also for the pre-experimental analysis to plan future experiments on corrosion/precipitation and help in the design and analysis of real blanket systems.