Gatemon Qubit Based on a Thin InAs-Al Hybrid Nanowire

We study a gate-tunable superconducting qubit(gatemon) based on a thin InAs-Al hybrid nanowire.Using a gate voltage to control its Josephson energy,the gatemon can reach the strong coupling regime to a microwave cavity.In the dispersive regime,we extract the energy relaxation time T_(1)~0.56 μs and the dephasing time T_(2)^(*)~0.38 μs.Since thin In As-Al nanowires can have fewer or single sub-band occupation and recent transport experiment shows the existence of nearly quantized zero-bias conductance peaks,our result holds relevancy for detecting Majorana zero modes in thin InAs-Al nanowires using circuit quantum electrodynamics.

Vacuum-gap-based lumped element Josephson parametric amplifier

We propose a lumped element Josephson parametric amplifier with vacuum-gap-based capacitor.The capacitor is made of quasi-floating aluminum pad and on-chip ground.We take a fabrication process compatible with air-bridge technology,which makes our design adaptable for future on-chip integrated quantum computing system.Further engineering the input impedance,we obtain a gain above 20 dB over 162-MHz bandwidth,along with a quasi quantum-limit noise performance.This work should facilitate the development of quantum information processing and integrated superconducting circuit design.

Parity-dependent unidirectional and chiral photon transfer in reversed-dissipation cavity optomechanics

Nonreciprocal elements,such as isolators and circulators,play an important role in classical and quantum information processing.Recently,strong nonreciprocal effects have been experimentally demonstrated in cavity optomechanical systems.In these approaches,the bandwidth of the nonreciprocal photon transmission is limited by the mechanical resonator linewidth,which is arguably much smaller than the linewidths of the cavity modes in most electromechanical or optomechanical devices.In this work,we demonstrate broadband nonreciprocal photon transmission in the reversed-dissipation regime,where the mechanical mode with a large decay rate can be adiabatically eliminated while mediating anti-PT-symmetric dissipative coupling with two kinds of phase factors.Adjusting the relative phases allows the observation of periodic Riemann-sheet structures with distributed exceptional points(Eps).At the Eps,destructive quantum interference breaks both theT-andP-inversion symmetry,resulting in unidirectional and chiral photon transmissions.In the reversed-dissipation regime,the nonreciprocal bandwidth is no longer limited by the mechanical mode linewidth but is improved to the linewidth of the cavity resonance.Furthermore,we find that the direction of the unidirectional and chiral energy transfer could be reversed by changing the parity of the Eps.Extending non-Hermitian couplings to a three-cavity model,the broken anti-PT-symmetry allows us to observe high-order Eps,at which a parity-dependent chiral circulator is demonstrated.The driving-phase controlled periodical Riemann sheets allow observation of the parity-dependent unidirectional and chiral energy transfer and thus provide a useful cell for building up nonreciprocal array and realizing topological,e.g.,isolators,circulators,or amplifiers.

比较两种丝素膜的结构、热分解机理与热力学参数

本文利用氯化钙-甲酸体系制备了来源于中国和泰国家蚕的两种丝素膜。通过扫描电子显微镜、傅里叶红外光谱和X射线衍射以及热重分析技术,分别表征了膜材料的形貌、分子构象、热稳定性以及热分解机理,获得了动力学参数(活化能E和指前因子A)和热力学参数(ΔH~≠、ΔG~≠和ΔS~≠),并对其进行了比较研究。结果表明,1.5 wt%浓度体系下的丝素膜结构主要呈现β-折叠, 3.0 wt%浓度体系下的膜结构以无规线团或α-螺旋为主;3.0 wt%浓度下的膜在不同升温速率下的分解温度、活化能和活化焓均低于1.5 wt%浓度下的,后者的热稳定性优于前者;相同浓度体系下,泰国丝素膜的β-折叠含量略高于中国丝素膜,具有更好的热稳定性;通过Achar微分法和Coats-Redfern积分法计算发现,两种丝素膜在464~594 K的热分解过程都遵循二维扩散机理。