Ultrafast geometric manipulation of electron spin and detection of the geometric phase via Faraday rotation spectroscopy

利用交叉相位调制实现单光子宽带光谱操控

Broadband spectral manipulation of single photons using cross-phase modulation

本文实验演示了利用短单模光纤中的交叉相位调制对电信波段单光子进行确定性宽带频率和带宽操控，实现了THz级频移和最高8.4倍带宽调控，为量子网络光谱路由提供紧凑可扩展方案。

Predicted Ultrafast Single Qubit Operations in Semiconductor Quantum Dots

Several recently proposed implementations of scalable quantum computation rely on the ability to manipulate the spin polarization of individual electrons in semiconductors. The most rapid single-spin-manipulation technique to date relies on the generation of an effective magnetic field via a spin-sensitive optical Stark effect. This approach has been used to split spin states in colloidal CdSe quantum dots and to manipulate ensembles of spins in ZnMnSe quantum wells with femtosecond optical pulses. Here we report that the process will produce a coherent rotation of spin in quantum dots contain…

用于电子束的超快等离子体转子

Ultrafast Plasmonic Rotors for Electron Beams

本研究通过在激发金纳米棒的正交偏振激光脉冲间引入相位偏移生成旋转等离子体近场偶极子，探究其与慢电子束的相互作用，揭示了等离子体场循环方向的调控作用及同步共振的角动量传递效果，为电子波包整形及相关领域应用提供了新途径。

Ultrafast Hole Spin Qubit with Gate-Tunable Spin-Orbit Switch

A key challenge in quantum computation is the implementation of fast and local qubit control while simultaneously maintaining coherence. Qubits based on hole spins offer, through their strong spin-orbit interaction, a way to implement fast quantum gates. Strikingly, for hole spins in one-dimensional germanium and silicon devices, the spin-orbit interaction has been predicted to be exceptionally strong yet highly tunable with gate voltages. Such electrical control would make it possible to switch on demand between qubit idling and manipulation modes. Here, we demonstrate ultrafast and universal…

Quantum Information Processing in Nanostructures

Semiconductor quantum dots integrated with ultrafast spectroscopy technology are prime candidates for building scalable architectures for Quantum Information Processing. In this review paper we survey the current state of theoretical proposals concerning all-optical control of nanostructure qubits and their interactions. These schemes offer potential for ultrafast optical manipulation of quantum information in time scales within the coherence time.

Ultrafast coherent control of a hole spin qubit in a germanium quantum dot

Operation speed and coherence time are two core measures for the viability of a qubit. Strong spin-orbit interaction (SOI) and relatively weak hyperfine interaction make holes in germanium (Ge) intriguing candidates for spin qubits with rapid, all-electrical coherent control. Here we report ultrafast single-spin manipulation in a hole-based double quantum dot in a germanium hut wire (GHW). Mediated by the strong SOI, a Rabi frequency exceeding 540 MHz is observed at a magnetic field of 100 mT, setting a record for ultrafast spin qubit control in semiconductor systems. We demonstrate that the s…

Ultrafast Generation and Control of an Electron Vortex Beam via Chiral Plasmonic Near Fields

Vortex-carrying matter waves, such as chiral electron beams, are of significant interest in both applied and fundamental science. Continuous wave electron vortex beams are commonly prepared via passive phase masks imprinting a transverse phase modulation on the electron's wave function. Here, we show that femtosecond chiral plasmonic near fields enable the generation and dynamic control on the ultrafast timescale of an electron vortex beam. The vortex structure of the resulting electron wavepacket is probed in both real and reciprocal space using ultrafast transmission electron microscopy. Thi…

超高通量超纠缠贝尔态的产生与探测

Ultrafast Processing of Hyper-Entangled Bell States at the Optical Bandwidth Limit

利用双偏振SU1,1非线性干涉仪物理探测超纠缠双光子，实现每秒5×10^11通量的偏振贝尔态产生与测量，速度提升超5个数量级。

TMDC异质结构中Rashba相互作用的超快光学调控

Ultrafast Optical Control of Rashba Interactions in a TMDC Heterostructure

本文通过理论计算与时间分辨克尔旋转测量，揭示了MoSe2/MoS2异质结构中Rashba效应诱导的谷内自旋弛豫机制，并发现其在50 K以上成为主导通道，为超快自旋操控提供了新途径。

Femtosecond Transfer and Manipulation of Persistent Hot-Trion Coherence in a Single CdSe/ZnSe Quantum Dot

Ultrafast transmission changes around the fundamental trion resonance are studied after exciting a p-shell exciton in a negatively charged II-VI quantum dot. The biexcitonic induced absorption reveals quantum beats between hot trion states at 133 GHz. While interband dephasing is dominated by relaxation of the P-shell hole within 390 fs, trionic coherence remains stored in the spin system for 85 ps due to Pauli blocking of the triplet electron. The complex spectro-temporal evolution of transmission is explained analytically by solving the Maxwell-Liouville equations. Pump and probe polarizatio…

Resonant and phonon-assisted ultrafast coherent control of a single hBN color center

Single-photon emitters in solid-state systems are important building blocks for scalable quantum technologies. Recently, quantum light emitters have been discovered in the wide-gap van der Waals insulator hBN. These color centers have attracted considerable attention due to their quantum performance at elevated temperatures and wide range of transition energies. Here, we demonstrate coherent state manipulation of a single hBN color center with ultrafast laser pulses and investigate in our joint experiment-theory study the coupling between the electronic system and phonons. We demonstrate that …