Experimental demonstration of a fast calibration method for integrated photonic circuits with cascaded phase shifters

With the development of research on integrated photonic quantum information processing, the integration level of the integrated quantum photonic circuits has been increasing continuously, which makes the calibration of the phase shifters on the chip increasingly difficult. For the calibration of multiple cascaded phase shifters that is not easy to be decoupled, the resources consumed by conventional brute force methods increase exponentially with the number of phase shifters, making it impossible to calibrate a relatively large number of cascaded phase shifters. In this work, we experimentally validate an efficient method for calibrating cascaded phase shifters that achieves an exponential increase in calibration efficiency compared to the conventional method, thus solving the calibration problem for multiple cascaded phase shifters. Specifically, we experimentally calibrate an integrated quantum photonic circuit with nine cascaded phase shifters and achieve a high-precision calibration with an average fidelity of 99.26%.     

A scheme for demonstration of four-photon de Broglie wavelength

We propose a scheme to effectively generate a four-photon path-entangled number state [the NOON state i.e. 1/√2（｜N,0〉 ＋ ｜0, N〉）] for the demonstration of four-photon de Broglie wavelength. Our scheme rcquires only linear optical elements, photon detectors and post-selections which are all within the reach of current technology.     

Feasible schemes for preparing all five-photon graph states

We propose feasible experimental schemes for preparing all five-photon graph states. Our schemes require only linear optical elements, photon detectors and post-selection, which are available in current experiment so that these schemes are within the reach of the current technology.     

基于冗余图态的多人协作量子计算

量子计算是一种基于量子力学基本原理设计的新型计算模型,在某些特定问题上表现出了远超经典计算机的处理能力.随着量子计算任务复杂度的提高,如何分配量子计算资源,实现多方协作的量子计算,将成为量子计算领域待解决的一个重要问题.本文在一次性量子计算的基础上,提出了基于冗余图态的多人协作量子计算方案.不同于传统图态中每个节点仅对应一个粒子,冗余图态中每个节点都对应若干粒子.参与量子计算的每一方都将分配到一组完整涵盖各节点的粒子,各方将自行协商完成图态的分割以及后续的测量,从而实现多人协作的量子计算.在本方案中,参与量子计算的各方可以根据自身任务的需要来确定量子计算的合作方式并进行资源分配,使量子计算具备更高的灵活性与开放性.此外,本文还提出了一个两方协作制备任意单比特量子态的光学实验方案.