Ghost factors in Gauss-sum factorization with transmon qubits

Robustness of a universal gate set implementation in transmon systems via Chopped Random Basis optimal control

We numerically study the implementation of a universal two-qubit gate set, composed of CNOT, Hadamard, phase and $π/8$ gates, for transmon-based systems. The control signals to implement such gates are obtained using the Chopped Random Basis optimal control technique, with a target gate infidelity of $10^{-2}$. During the optimization processes we account for the leakage toward non-computational states, an important non-ideality affecting transmon qubits. We also test and benchmark the optimal control solutions against the introduction of Gaussian white noise and spectral distortion, two key n…

Ghost imaging with non-Gaussian quantum light

Non-local point-to-point correlations between two photons have been used to produce "ghost" images without placing the camera towards the object. Here we theoretically demonstrated and analyzed the advantage of non-Gaussian quantum light in improving the image quality of ghost imaging system over traditional Gaussian light source. For any squeezing degree, the signal-to-noise ratio (SNR) of the ghost image can be enhanced by the non-Gaussian operations of photon addition and subtraction on the two-mode squeezed light source. We find striking evidence that using non-Gaussian coherent operations…

超导transmon量子比特在宽带一维腔体中的衰减

Decay of transmon qubit in a broadband one-dimensional cavity

研究超导transmon量子比特与宽带一维腔体模式的衰减动力学，通过解析方法推导共振频率偏移和宽度，揭示马尔可夫与非马尔可夫两种动态 regime 的区别及耦合对衰减的影响。

频率拥挤传输子系统中的单量子比特门

Single qubit gates in frequency-crowded transmon systems

最近在三维腔中超导transmon量子比特的实验工作表明，它们的相干时间比它们的二维腔对应物增加了一个数量级。然而，为了利用这些相干时间，同时按比例增加量子位的数量，有利的是寻址全部耦合到相同的3D腔场的各个量子位。控制这个系统的挑战来自光谱拥挤，其中量子位的泄漏跃迁接近于其他量子位的计算跃迁。在这里，它示出了快速脉冲是可能的，其使用脉冲包络的两个正交控制来寻址单个量子位，而单独的DRAG方法仅给出了比常规高斯脉冲形状的边际改进。另一方面，使用马格努斯展开的一阶结果给出了快速分析脉冲形状，其给出了特定选通时间的高保真度选通，直到第二量子位上的相位因子。进一步的数值分析证实了这些结果，并产生更快的门，表明泄漏态的非谐性不提供一个基本的量子速度限制。

利用$N$级强度关联实现热光鬼像的理论方案

A theoretical scheme of thermal-light ghost imaging by $N$th-order intensity correlation

本文提出了一种基于$N$阶相关热光的鬼像成像理论方案。我们得到高斯薄透镜方程的鬼成像协议。我们表明，它是可能的产生$N-1$鬼图像的对象在不同的地方在一个非本地的方式通过一个高阶相关的成像过程与$N$第阶相关的热源和相关测量。我们研究了该方案中鬼像的可见性，得到了$N$阶相关热光鬼像可见性的上界。研究发现，当相关阶数变大时，鬼像的可见性可以显著增强。

何时数值脉冲优化真的有所帮助？误差预算、鲁棒性权衡及transmon单量子比特门的校准指导

When does numerical pulse optimization actually help? Error budgets,robustness tradeoffs, and calibration guidance for transmon single-qubit gates

研究发现DRAG在退相干限制下性能接近最优，GRAPE在短门时间提供零相干误差，但DRAG在频率漂移鲁棒性上更优，为transmon单量子比特门校准提供指导。