Tunable superconducting resonators via on-chip control of local magnetic field

Superconducting microwave resonators play a pivotal role in superconducting quantum circuits.The ability to finetune their resonant frequencies provides enhanced control and flexibility.Here,we introduce a frequency-tunable superconducting coplanar waveguide resonator.By applying electrical currents through specifically designed ground wires,we achieve the generation and control of a localized magnetic field on the central line of the resonator,enabling continuous tuning of its resonant frequency.We demonstrate a frequency tuning range of 54.85 MHz in a 6.21-GHz resonator.This integrated and tunable resonator holds great potential as a dynamically tunable filter and as a key component of communication buses and memory elements in superconducting quantum computing.

Magnetic Nonreciprocity in a Hybrid Device of Asymmetric Artificial Spin-Ice-Superconductors

Controlling the size and distribution of potential barriers within a medium of interacting particles can unveil unique collective behaviors and innovative functionalities.We introduce a unique superconducting hybrid device using a novel artificial spin ice structure composed of asymmetric nanomagnets.This structure forms a distinctive superconducting pinning potential that steers unconventional motion of superconducting vortices,thereby inducing a magnetic nonreciprocal effect,in contrast to the electric nonreciprocal effect commonly observed in superconducting diodes.Furthermore,the polarity of the magnetic nonreciprocity is in situ reversible through the tunable magnetic patterns of artificial spin ice.Our findings demonstrate that artificial spin ice not only precisely modulates superconducting characteristics but also opens the door to novel functionalities,offering a groundbreaking paradigm for superconducting electronics.

二维层状NiO/g-C_(3)N_(4)复合材料在无铁光电类芬顿体系中有效去除环丙沙星的研究

环丙沙星(CIP)的过量使用已经对生态环境造成了很大的威胁。本文设计了一种新型无铁的光电类芬顿体系用于降解水中的CIP。采用溶剂热法合成了NiO/g-C_(3)N_(4)复合材料。通过XRD分析,确定了不同催化剂的晶相和化学组成;红外光谱进一步证实了NiO/g-C_(3)N_(4)复合材料的分子结构,结果表明,成功地合成了NiO/g-C_(3)N_(4)复合材料。利用SEM观察了材料的形貌,结果表明性能最佳的NiO/g-C_(3)N_(4)-60%为二维花状结构。TEM进一步证明NiO/g-C_(3)N_(4)-60%具有片层状结构。由于层状结构,NiO/g-C_(3)N_(4)-60%具有较大的比表面积和丰富的活性位点,有利于电子的传输。XPS分析表明Ni^(2+)和Ni^(3+)共存于NiO/g-C_(3)N_(4)-60%复合材料中并且NiO/g-C_(3)N_(4)-60%具有低配位氧缺陷。EPR谱也证实了氧空位的存在,氧空位不仅促进了H_(2)O_(2)的活化,而且有利于金属离子形成稳定的混合价态。UV-Vis-DRS、PL和电化学测试表明NiO/g-C_(3)N_(4)-60%具有最强的光吸收能力、最低的电荷转移电阻和最快的电荷分离效率,有利于活性物质的生成和CIP的快速降解。因此,花状NiO/g-C_(3)N_(4)-60%在光电类芬顿体系中表现出光电协同作用,不仅可以通过Ni^(3+)/Ni^(2+)之间的转化将电芬顿过程中产生的H_(2)O_(2)有效分解为·OH,同时也能够产生光生电子和空穴,促进光照下·OH、·O_(2)^(−)和h^(+)的生成,从而提高环丙沙星的降解效率。以催化性能最佳的NiO/g-C_(3)N_(4)-60%为催化剂时,在90 min内CIP的降解率达到将近100%,120 min时矿化效率达到82.0%,与传统芬顿体系(最佳pH值为2.8–3.5)相比,新型光电类芬顿体系具有较宽的pH范围,当pH值为6时,降解率仍可达78.8%。NiO/g-C_(3)N_(4)-60%在光电类芬顿体系中也表现出良好的结构稳定性,连续5次循环后,降解效率仍保持在96.3%。根据HPLC-MS的结果,提出了CIP降解的两种可能途径。本研究为废水中抗生素的快速降解提供了理论依据。

Isomerization of Hydrofluorocyclopentenes Promoted by Fluoride Anion

The isomerization of hydrofluorocyclopentenes promoted by fluoride anion was investigated. It was found that two processes were responsible for interconversion of the isomers: an allylic syn-addition/elimination of fluoride anion that does not change the mutual positions of hydrogen atoms but is responsible for transfers of fluorine atoms, and a fluoride anion-assisted deprotonation/protonation which does not change the mutual positions of fluorine atoms but is responsible for transfers of hydrogen atoms. In the deprotonation, HF can easily capture excess fluoride anion to form HF2- anion which can probably inhibit the protonation.

Mid-infrared superconducting nanowire single photon detector enhanced by overcoupled metasurfaces

Superconducting nanowire single-photon detectors(SNSPDs)with low energy gaps exhibit superior single-photon sensitivity at infrared wavelengths[1],and state-of-the-art SNSPDs have the potential to meet the stringent demands of mid-IR(MIR)detection[2].However,the nanowire thickness(~λ/1000-λ/600)and width(~λ/166-λ/60)are much smaller than those at MIR wavelengths,which results in weak absorption with a low detection efficiency[3].

基于智能手机的实时远程快速现场评估在超声内镜引导细针穿刺抽吸中的价值

目的探讨联合智能手机实时图片交流进行远程快速现场评估(rapid on-site evaluation,ROSE)的可行性,以及远程ROSE在提高超声内镜医师诊断效率中的作用。方法回顾性分析2020年4月—2021年5月于山东大学齐鲁医院接受超声内镜引导细针穿刺抽吸术(endoscopic ultrasound-guided fine needle aspiration,EUS-FNA)诊断的188例患者资料。其中2020年4—10月未行ROSE的为非ROSE组(91例),2020年11月—2021年5月引入了ROSE的为ROSE组(97例),ROSE组中2020年11月—2021年3月为手机组(52例),即内镜医师通过智能手机微信发送ROSE图像给细胞病理医师;2021年4—5月为self-ROSE组(45例),由经过细胞病理培训的超声内镜医师独立判断ROSE结果。比较患者基本信息、ROSE结果、术后病理及术后随访情况,分析远程ROSE的诊断效能。结果188例患者中179例(95.2%)为胰腺实性病变,9例(4.8%)为腹腔病变。非ROSE组、手机组、self-ROSE组穿刺次数差异无统计学意义[3(3,4)比3(3,4)比3(2,4),H=1.320,P=0.517]。以最终诊断为金标准,非ROSE组诊断的敏感度、特异度、准确率、阳性预测值、阴性预测值、Kappa值分别为80.6%(58/72)、89.5%(17/19)、82.4%(75/91)、96.7%(58/60)、54.8%(17/31)、0.6,ROSE组相应指标为97.4%(74/76)、100.0%(21/21)、97.9%(95/97)、100.0%(74/74)、91.3%(21/23)、0.9,手机组为95.2%(40/42)、100.0%(10/10)、96.2%(50/52)、100.0%(40/40)、83.3%(10/12)、0.9,self-ROSE组为100.0%(34/34)、100.0%(11/11)、100.0%(45/45)、100.0%(34/34)、100.0%(11/11)、1.0。ROSE组的敏感度(P=0.002)、准确率(P=0.001)和阴性预测值(P=0.009)高于非ROSE组,其余诊断效能指标差异无统计学意义(P>0.05)。手机组和self-ROSE组上述诊断效能指标差异无统计学意义(P>0.05)。结论智能手机微信辅助下实时远程ROSE能很好地适应病理科及超声内镜医师需求,远程ROSE应用后内镜医师诊断准确率与细胞病理医师相当,有助于内镜下获得更充分的标本,提高EUS-FNA诊断准确性。

Simulation for embedded-defects foam terahertz images of active bifocal terahertz imaging system at 0.22 THz based on geometric optics

We simulate the measurements of an active bifocal terahertz imaging system to reproduce the ability of the system to detect the internal structure of foams having embedded defects.Angular spectrum theory and geometric optics tracing are used to calculate the incident and received electric fields of the system and the scattered light distribution of the measured object.The finite-element method is also used to calculate the scattering light distribution of the measured object for comparison with the geometric optics model.The simulations are consistent with the measurements at the central axis of the horizontal stripe defects.

Clonal evolution analyses of a chronic myeloid leukemia patient with hematopoietic stem cell transplantation based on deep sequencing

Background The Philadelphia(Ph)chromosome is the hallmark chromosome aberration in chronic myeloid leukemia(CML),which confers the cancer phenotype of the disease.However,how the Ph chromosome forms and the genetic clonal evolution structure after targeted Ph treatment are still unclear.Methods In this study,we performed genome sequencing and clonal evolution analyses in a series of bone marrow specimens and skin biopsy from a CML patient who had received hematopoietic stem cell transplantation from her sister,then relapsed(lymphoid blast crisis),and received Ph-targeted therapy.Results The Ph chromosome was the“driver”clonal change in the original CML and the relapse.Both the patient and her sister had micro-deletions in the BCR gene region;however,the patient had a frameshift BRIP1 mutation that may account for the malfunctioning homologous recombination DNA repair of the BCR gene region and formation of the Ph chromosome.Conclusion We found that the BCR-ABL1 translocation was the driving force of the patient’s CML and relapse.The malfunctioning double-strand DNA break repair caused by the BRIP1 mutation could be the cause of Ph chromosome formation in the patient.

Mid-infrared single photon detector with superconductor Mo_(0.8)Si_(0.2) nanowire

Mid-infrared(mid-IR)single photon detectors have broad applications in science and technology,such as biomolecular spectrum analysis[1]and astronomical observations[2].Unfortunately,it is much more difficult than detecting near-infrared photons due to the significantly reduced energy of mid-IR single photon.

Temperature dependence of niobium superconducting nanowire single-photon detectors in He-3 cryocooler

Performances of superconducting nanowire single-photon detectors(SNSPDs) based on low TCmaterials strongly depend on the operating temperatures. We have fabricated infrared-sensitive niobium SNSPDs based on doped niobium(Nb*) films and measured them in He-3cryocooler. The critical current approaches to the de-pairing current at 0.3 K. Therefore, with the decrease in temperatures, we have observed a monotonous increase of count rate at the wavelength of 1,521 nm and exponential decrease of dark count rate at all bias currents. The possible origin of dark counts for doped Nb devices is also discussed.

Wideband cryogenic amplifier for a superconducting nanowire single-photon detector

We present a low-power inductorless wideband differential cryogenic amplifier using a 0.13-μm Si Ge Bi CMOS process for a superconducting nanowire single-photon detector(SNSPD).With a shunt-shunt feedback and capacitive coupling structure,theoretical analysis and simulations were undertaken,highlighting the relationship of the amplifier gain with the tunable design parameters of the circuit.In this way,the design and optimization flexibility can be increased,and a required gain can be achieved even without an accurate cryogenic device model.To realize a flat terminal impedance over the frequency of interest,an RC shunt compensation structure was employed,improving the amplifier’s closed-loop stability and suppressing the amplifier overshoot.The S-parameters and transient performance were measured at room temperature(300 K)and cryogenic temperature(4.2 K).With good input and output matching,the measurement results showed that the amplifier achieved a 21-d B gain with a 3-d B bandwidth of 1.13 GHz at 300 K.At 4.2 K,the gain of the amplifier can be tuned from 15 to 24 d B,achieving a 3-d B bandwidth spanning from 120 k Hz to 1.3 GHz and consuming only 3.1 m W.Excluding the chip pads,the amplifier chip core area was only about 0.073 mm^(2).

Enhanced photon communication through Bayesian estimation with an SNSPD array

Laser communication using photons should consider not only the transmission environment’s effects,but also the performance of the single-photon detector used and the photon number distribution.Photon communication based on the superconducting nanowire single-photon detector(SNSPD)is a new technology that addresses the current sensitivity limitations at the level of single photons in deep space communication.The communication’s bit error rate(BER)is limited by dark noise in the space environment and the photon number distribution with a traditional single-pixel SNSPD,which is unable to resolve the photon number distribution.In this work,an enhanced photon communication method was proposed based on the photon number resolving function of four-pixel array SNSPDs.A simulated picture transmission was carried out,and the error rate in this counting mode can be reduced by 2 orders of magnitude when compared with classical optical communication.However,in the communication mode using photon-enhanced counting,the four-pixel response amplitude for counting was found to restrain the communication rate,and this counting mode is extremely dependent on the incident light intensity through experiments,which limits the sensitivity and speed of the SNSPD array’s performance advantage.Therefore,a BER theoretical calculation model for laser communication was presented using the Bayesian estimation algorithm in order to analyze the selection of counting methods for information acquisition under different light intensities and to make better use of the SNSPD array’s high sensitivity and speed and thus to obtain a lower BER.The counting method and theoretical model proposed in this work refer to array SNSPDs in the deep space field.

Saturation efficiency for detecting 1550 nm photons with a 2×2 array of Mo0.8Si0.2 nanowires at 2.2 K

Amorphous materials are attractive candidates for fabricating the superconducting nanowire single-photon detectors(SNSPDs) due to their superior tolerance and scalability over crystalline niobium nitride. However, the reduced superconducting transition temperature degenerates both operating temperature and saturation efficiency. Herein, the SNSPD(6.5 nm thickness and 50 nm width) based on the amorphous Mo0.8Si0.2 film with a high optical absorption coefficient demonstrates close-to-unity intrinsic detection efficiency for 1550 nm photons from 75 m K to 2.2 K. Further, a high-performance array SNSPD with optimized 90 nm-width wires is also demonstrated. As-fabricated uniform 4-pixel SNSPD exhibits a saturation plateau for the photon counts at 2.2 K,which overcomes the limitation of operation at low temperature(< 1 K) for traditional amorphous SNSPDs.Coupled with superior intrinsic quantum efficiency, highly efficient photon counts, and low dark count ratio, this detector paves a way for achieving high efficiency and superior yield for large array systems.