We report on a series of experiments on the dynamics of spontaneous emission controlled nanolasers. The laser cavity is a photonic crystal slab cavity, embedding self-assembled quantum dots as gain material. The implementation of cavity electrodynamics effects increases significantly the large signal modulation bandwidth, with measured modulation speeds of the order of 10 GHz while keeping an extinction ratio of 19 dB. A linear transient wavelength shift is reported, corresponding to a chirp of less than 100 pm for a 35-ps laser pulse. We observe that the chirp characteristics are independent of the repetition rate of the laser up to 10 GHz.
For a scalable photonic device producing entangled photons, it is desirable to have multiple quantum emitters in an ensemble that can be collectively excited, despite their spectral variability. For quantum dots, Rabi rotation, the most popular method for resonant excitation, cannot assure a universal, highly efficient excited state preparation, because of its sensitivity to the excitation parameters. In contrast, Adiabatic Rapid Passage (ARP), relying on chirped optical pulses, is immune to quantum dot spectral inhomogeneity. Here, we advocate the robustness of ARP for simultaneous excitation…
We study the quantum correlations induced by spontaneous parametric down-conversion (SPDC) of a frequency comb. We derive a theoretical method to find the output state corresponding to a pump with an arbitrary spectral profile. After applying it to the relevant example of a spectrally chirped pump, we run an optimization algorithm to numerically find the pump profiles maximizing some target functions. These include the number of independently squeezed modes and the variances of nullifiers defining cluster states used in many continuous-variable quantum information protocols. To assess the adva…
Quantum Dots as Solid-State Sources of Entangled Photon Pairs
Beijing Institute of Technology（北京理工大学）；Singapore University of Technology and Design（新加坡科技设计大学）；Agency for Science Technology and Research (A*STAR)（科学技术研究局）；Eastern Institute of Technology（东方理工学院）；University of Southern Denmark（南丹麦大学）；Nanyang Technological University（南洋理工大学）
A heterogeneous III-V/silicon integration platform for on-chip quantum photonic circuits with single quantum dot devices
光子集成是光子量子科学的一项使能技术，提供比传统体光学更大的可扩展性、稳定性和功能性。在这里，我们描述了一个可扩展的，异构的III-V/硅集成平台，以生产硅$_3$ N $_4$光子电路，将GaAs基纳米光子器件含有自组装的InAs/GaAs量子点。我们证明了纯单光子发射从GaAs波导和腔中的单个量子点-其中观察到自发发射率的强控制-直接发射到Si $_3$ N $_4$波导中，通过倏逝波耦合效率> 90%。迄今为止，InAs/GaAs量子点构成了最有前途的固态触发单光子源，提供明亮、纯净且难以区分的发射，并且可以通过电学和光学控制。Si $_3$ N $_4$波导提供低损耗传播、可定制的色散和高克尔非线性，这对于线性和非线性光信号处理到量子水平是理想的。我们将这两者结合在一个集成平台中，这将使一类新的可扩展，高效和通用的集成量子光子器件成为可能。
Spontaneous emission from excitonic transitions in InAs/GaAs quantum dots embedded in photonic crystal waveguides at 5K into non-guided and guided modes is determined by direct hyperspectral imaging. This enables measurement of the absolute coupling efficiency into the guided modes, the beta-factor, directly, without assumptions on decay rates used previously. Notably, we found beta-factors above 90% over a wide spectral range of 40meV in the fast light regime, reaching a maximum of (99 $\pm$ 1)%. We measure the directional emission of the circularly polarized transitions in a magnetic field i…
Integrated photonic circuits provide a versatile toolbox of functionalities for advanced quantum optics applications. Here, we demonstrate an essential component of such a system in the form of a Purcell enhanced single-photon source based on a quantum dot coupled to a robust on-chip integrated resonator. For that, we develop GaAs monolithic ring cavities based on distributed Bragg reflector ridge waveguides. Under resonant excitation conditions, we observe an over twofold spontaneous emission rate enhancement using Purcell effect and gain a full coherent optical control of a QD-two-level syst…
