论坛时间

北京时间2022年11月3日（周四）10:00-18:00

11月4日（周五）9:00-12:15

会议地点

量子院320报告厅（线下）

蔻享学术直播（线上）

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主办单位

北京海外学人中心

北京量子信息科学研究院

论坛简介

2022北京国际青年创新发展论坛量子信息科学平行论坛暨北京量子信息科学研究院“量子聚光”论坛旨在为海内外优秀青年学者搭建学术交流和学术成果展示平台。论坛以“慧聚量子，引才引智”为主题，将通过线上专题演讲、学术报告和人才洽谈等方式，围绕量子计算、量子通信、量子精密测量、量子物态科学等量子信息科学领域展开深入探讨。学术报告人包括来自普林斯顿大学、哈佛大学、耶鲁大学、加州大学洛杉矶分校、巴塞尔大学等的15名青年学者。

日程安排

报告人简介及报告摘要

1.万阳：针对等离子体尾波加速器的瞬态高清成像研究

【报告摘要】 近年来基于等离子体尾波的新型粒子加速器技术发展迅速，因其超高的加速梯度和优异的束流特性，有望在医学、工业及高能物理等领域的应用带来革命性变化。尾波加速器的电磁场结构会极大地影响被加速粒子束的品质，因此发展针对尾场直接定量的诊断技术，对于深入理解粒子注入及加速等重要物理过程进而优化束流品质具有重要意义。本报告将介绍利用超快相对论电子束对等离子体尾波电磁结构进行瞬态高分辨诊断的概念，以及威兹曼研究所在这方面的一系列最新实验成果。

2.邹奕权：Observation of a new type of ion-Rydberg molecule and its vibrational dynamics with an ion microscope

【报告摘要】 Rydberg atoms can form novel types of ultra long-range Rydberg molecules. These molecules exhibit extreme properties such as huge bond lengths and large electric dipole moments. Here we report the observation of a new type of Rydberg molecule formed by an ion and a Rydberg atom with a bond length of several micrometers. Using a high spatial resolution ion microscope, we directly resolved the bond length and the angular alignment of the molecule. Furthermore, by applying a weak electric field, we have studied the temporal vibrational dynamics of molecules in real space, which are slowed down by many orders of magnitude compared to conventional molecules.

3.翟亮：Identical photons from different quantum dots

【报告摘要】 Advances in photonic quantum technologies call for creation, manipulation and detection of a large number of identical single photons. Self-assembled quantum dots (QDs) represent a semiconductor platform that creates single photons in a near-deterministic manner. Benefited from established fabrication facilities, QDs can be integrated into various nanostructures. For applications, however, a significant roadblock is the poor quantum coherence upon interfering photons created by two or more independent QDs. In other words, the photons created by different QDs are not identical.

Here, we present two-photon interference from two QDs separated in remote cryostats with visibility of 93%. The key is the employment of gated GaAs QDs in a p-i-n diode. Exploiting the current photonic engineering technologies, our result presents a route to creating photons with >99% similarity in every aspect from separate QDs.

The identical photons allow a photon-photon entanglement to be created. We demonstrate a CNOT gate using photons from the remote QDs and standard linear optics. The average CNOT process fidelity is ~88% and the output entanglement fidelity is ~85%. Such an entanglement marks a first step towards involving multiple – not just one –quantum-dot-based single-photon sources for applications.

4.黄雨青：Spin amplification and quantum interference in semiconductor quantum dots structures

【报告摘要】 Semiconductor quantum dots structures are promising building blocks for quantum information and spintronic applications. The quasi-0D character of the materials not only inhibits dissipation of quantum information, e.g. spin, but also give rise to superior optical properties, e.g. single-photon emission, which may lead to the next-generation information processing, storage and transfer. In this talk, I will firstly introduce our recent efforts to achieve record-high spin polarization in InGaAs quantum dots at and above room temperature with an innovated approach of remote spin filtering. Next, I will discuss the effect of Fano interference in these semiconductor nanostructures with two examples. In the first example, I will showcase the quantum interference of spin wavefunction in InGaAs quantum dot structures, which can be tailored to control spin generation. In the second example, I will discuss the use of Fano interference to regulate the spectral diffusion of a perovskite single photon emitter in cavity.

5.段嘉华：Nano-optics on flatland: manipulate light-matter interactions at the nanoscale

【报告摘要】 To enhance light-matter interactions and manipulate photons at the nanoscale, scientists are exploring the fundamental optical phenomenon of polaritons, coupling photons with other particles (e.g. electrons, phonons, excitons), in the vast library of van der Waals (vdW) materials. In this talk, I will present our recent research on the manipulation of vdW polaritons, especially their dispersion, propagation and optical loss. Our work demonstrates that vdW materials with hyperbolic dispersion support polaritonic waves with unique properties, such as diffraction-free propagation, enhanced photonic density of states and reconfigurability. By stacking and twisting these hyperbolic vdW materials, we introduce the rise of twist-optics, where low-loss and highly collimated propagation of nanolight becomes possible.

6.柳叔毅：Light-matter interaction at (near) atomic scale

【报告摘要】 Recent state of-the-art experimental and theoretical studies showed that plasmonic fields can be confined to few nanometers and even down to atomic scale. Sophisticated experiments combining scanning tunneling microscopy with local optical detection and excitation (LT-photon-STM) now allow us to directly investigate microscopic mechanisms of plasmon-driven phenomena in plasmonic nano-gaps and also to perform optical spectromicroscopy at unprecedented spatial resolution.

In this talk, I will introduce the development of our home-built LT-photon-STM and discuss our recent studies on near-field physics in the plasmonic STM junction, as well as tip enhanced Raman spectroscopy and near atomic scale coherent phonon spectroscopy.

7.王积银：半导体-超导体复合超导器件的输运特性研究

【报告摘要】 马约拉纳费米子因为其遵循非阿贝尔统计特性可以用来构建拓扑量子比特以及拓扑量子计算。半导体—超导体复合体系是构建拓扑超导体以及马约拉纳费米子零能模的重要研究平台。其中，锑化铟(InSb)半导体纳米线具有非常强的自旋轨道耦合以及大的g因子等优异的性质,是构建复合体系的理想半导体材料。

我们以InSb半导体纳米线为基础，主要开展了两个方面的研究，包括如何构建马约拉纳费米子零能模和如何使用马约拉纳费米子零能模。第一方面的研究包括 (1)发展了可靠的寻找马约拉纳费米子零能模的实验方案; (2)采用掺杂铂(Pt)的方式提高了复合器件的超导临界磁场; (3) 开发了新型的隧穿结从而排除了大量的拓扑平庸的亚能隙能态;(4)研究了新型的高迁移率半导体—超导体复合体系。第二方面包括(1)实现了通过超流相位对半导体—超导体岛的奇偶性读取；(2)采用控制约瑟夫森结长度来增强超流的临界磁场。

8.邓鹏：Probing the mesoscopic size limit of quantum anomalous Hall Insulators

【报告摘要】 Quantum anomalous Hall (QAH) insulators host chiral edge states conducting dissipationless transport. To date, tremendous experimental efforts have been devoted to studying the transport behaviors of macroscopic QAH devices, while the transport in mesoscopic scaled QAH devices remained largely unexplored. The inelastic scattering length L_s is the fundamental mesoscopic length scale that governs the transport behaviors of QAH samples. Here, we examined L_s in three different regimes, namely the QAH, quantum critical, and insulating regimes, of the QAH system. Although the resistance changes by five orders of magnitude when tuning between these distinct electronic phases, scaling analysis indicates a universal L_s among all regimes. Furthermore, we fabricated mesoscopic scaled devices with sizes on the order of L_s. In these mesoscopic devices, transport behaviors distinct from those in their macroscopic counterpart are revealed, enabling the direct detection of the values of L_s in QAH.

9.林海城：探索和调控单层硒化物超导薄膜的物性

【报告摘要】 高温超导体多是层状材料，因而研究低维超导体的物性具有重要意义。我们利用分子束外延制备手段获得数个原子层的低维超导薄膜，并通过扫描隧道显微镜在原子尺度上表征它们的电子结构。我的报告内容分为两个方面：1、在单层铁硒/石墨烯异质结中，实空间中BCS-BEC过渡的证据；2、引入无序后，单层二硒化铌中出现超导多重分形的现象。

10.王鹏捷：One-Dimensional Luttinger Liquids in a Two-Dimensional Moiré Lattice

【报告摘要】 Electrons in one-dimensional (1D) electronic systems provides a powerful tool for understanding strongly correlated physics including the quasi-particle excitations, e.g., spin-charge separation. Substantial theoretical efforts have attempted to extend the LL phenomenology to two dimensions (2D), especially in models of closely packed perfect arrays of 1D quantum wires, each being described as a LL. However, despite exciting theoretical developments, an experimental demonstration of high-quality arrays of 1D LLs suitable for realizing these models remains absent. In this talk, I will mainly introduce our recent experimental realization of 2D arrays of 1D LLs in a moiré superlattice made of twisted bilayer tungsten ditelluride (tWTe2). The tWTe2 hosts identical, parallel 1D electronic channels, separated by a fixed nanoscale distance, tunable by the twist angle between layers. At a twist angle of ~ 5 degrees, we find that hole-doped tWTe2 exhibits exceptionally large transport anisotropy and a universal power-law scaling behavior, consistent with the formation of a 2D anisotropic phase that resembles an array of LLs. I will also discuss the opportunities toward correlated and topological quantum phases based on coupled-wire models and LL physics.

11.Jessie Zhang：Optical tweezer arrays of molecules for quantum science

【报告摘要】 Quantum computing and simulation platforms based on optical trapping of neutral particles have garnered great interest in recent years. Ultracold polar molecules, compared to their atom counterparts, possess rich internal structures and exhibit long-range dipole-dipole interactions that render them useful for many quantum science applications. At the heart of many of these proposals is the ability to trap and control ultracold molecules at the individual particle level. In this talk, I will discuss our demonstration of this capability, achieved by assembling single rovibrational ground state NaCs molecules (4.6 D) in optical tweezers starting from single ultracold atoms. This bottom-up approach utilizes laser cooling and trapping techniques of ultracold atoms and has enabled us to achieve full quantum state control, including all the internal and external degrees of freedom, on individually trapped molecules in an array. Furthermore, I will present characterization of the rotational transition and coherence of the ground state molecules, and an implementation of a magic trap using elliptically polarized trapping light, which is a crucial step towards generating dipolar interactions, and thus entanglement, between molecules. With these tools in hand, this platform provides new opportunities for quantum science applications harnessing the rich features of ultracold molecules.

12.钟长春：Quantum transduction is enhanced by single mode squeezing operators

【报告摘要】 Quantum transduction is an essential ingredient in scaling up distributed quantum architecture and is actively pursued based on various physical platforms. In this talk, I will first briefly introduce the concept of quantum transduction. Then I will discuss our recent approach for transduction, which relaxes the impedance matching condition to half impedance matching condition, and it can be achieved by introducing a two-photon drive in given transducers. We show the transduction channel capacity is enhanced and can be understood in a simple interference picture with the help of Bloch-Messiah decomposition. The parameter regimes with positive quantum capacity are identified and compared with and without the drive, indicating that the parametric drive-induced enhancement is promising in demonstrating quantum state conversion, and is expected to boost the performance of transduction with various physical platforms.

13.乌星：Where is All the Antimatter? Electron EDM Search in Cold Molecules Edges Closer

【报告摘要】 The Standard Model of particle physics accurately describes all fundamental particles discovered so far. However, it is unable to address two great mysteries in physics, the nature of dark matter and why matter dominates over antimatter throughout the Universe. Novel theories beyond the Standard Model, such as models that incorporate supersymmetry, may explain these phenomena. These models predict very massive particles whose interactions violate time-reversal (T) symmetry and would give rise to an electric dipole moment (EDM) along the electron’s spin. Thus, searching for EDM provides a powerful probe to these new physics and sheds light on the mystery of the matter-antimatter asymmetry of the Universe. 

Here, I share with you the exciting journey of the ACME electron EDM search that has set the current best limit on the value of electron EDM, measured by spin precession in a superposition of quantum states in cold molecules. This result severely constrains T-violating new physics in 3～30 TeV energy range, exceeding what can be reached at the Large Hadron Collider. New upgrades are now underway, projecting over an order of magnitude sensitivity enhancement for the next EDM search.

14.张树康：Anomalous Landau Quantization in Intrinsic Magnetic Topological Insulators

【报告摘要】 The intrinsic magnetic topological insulators, Mn(Bi_1-xSb_x)₂Te₄, in their spin-aligned strong field configuration have been identified as a Weyl semimetal with single pair of Weyl nodes. A direct consequence of the Weyl state is the layer-dependent Chern number (C) in thin film quantization. Previous reports in MnBi₂Te₄ thin films revealed the higher C states in the spin alignment by either increasing the film thickness or controlling chemical potential into electron doping. A clear picture of the higher Chern states is still missing as the situation is complicated by the emerging of surface band Landau levels (LLs) in magnetic field. Here, I report a tunable layer-dependent of C= 1 state with the Sb substitutions by performing a detailed analysis of the quantization states in Mn(Bi_1-xSb_x)₂Te₄ dualgated devices, consistent with the calculations of the bulk Weyl point separations in the compounds. The observed Hall quantization plateaus for our thicker Mn(Bi_1-xSb_x)₂Te₄ films under strong magnetic fields can be interpreted from a theory of surface and bulk spin-polarized Landau levels spectrum in thin film magnetic topological insulators. These results demonstrate that Mn(Bi_1-xSb_x)₂Te₄ thin films provide a highly tunable platform for probing the physics of the anomalous Landau quantization that is strongly sensitive to magnetic order. 

15.王利坤：Single Molecule Coherence with Femtosecond THz-STM

【报告摘要】 A scanning tunneling microscope (STM) combined with femtosecond terahertz (THz) laser pulses can enable coherence measurements of single molecules. We report THz pump-probe measurements that demonstrate quantum sensing based on a hydrogen (H2) molecule in the junction created with an STM tip near a surface. Atomic-scale spatial and femtosecond temporal resolutions were obtained from this quantum coherence. The H2 acts as a two-level system (TLS) in a double-well potential, with its coherent oscillatory superposition exhibiting extreme sensitivity to the applied electric field and the underlying atomic composition and electrostatics of the copper nitride (Cu2N) monolayer islands grown on a Cu(100) surface. We acquired a series of time-lapsed images of THz induced rectification current of H2 over Cu2N islands for variable pump-probe delay times to visualize the heterogeneity of the chemical environment at sub-angstrom scale.

论坛联系方式

联 系 人：王老师（北京量子院人力资源部）

联系电话：010-83057523

电子邮箱：wangjingyi@baqis.ac.cn