Abstract Many quantum photonic technologies require the efficient generation of entangled pairs photons, but to date there have been few ways produce them reliably. Sources based on parametric down conversion operate at very low efficiency per pulse due probabilistic process. Semiconductor dots can emit single photons deterministically they fall short extremely low-extraction efficiency. Strategies for extracting from dots, such as embedding in narrowband optical cavities, are difficult...

Abstract Many of the quantum information applications rely on indistinguishable sources polarization-entangled photons. Semiconductor dots are among leading candidates for a deterministic entangled photon source; however, due to their random growth nature, it is impossible find different emitting photons with identical wavelengths. The wavelength tunability has therefore become fundamental requirement number envisioned applications, example, nesting via entanglement swapping and interfacing...

Abstract Semiconductor InAs/GaAs quantum dots grown by the Stranski–Krastanov method are among leading candidates for deterministic generation of polarization-entangled photon pairs. Despite remarkable progress in past 20 years, many challenges still remain this material, such as extremely low yield, degree entanglement and large wavelength distribution. Here, we show that with an emerging family GaAs/AlGaAs droplet etching nanohole infilling, it is possible to obtain a ensemble emitters on...

Abstract Single photon sources are key components for quantum technologies such as communication, computing and metrology. A challenge towards the realization of global networks transmission losses in optical fibers. Therefore, single required to emit at low-loss telecom wavelength bands. However, an ideal source has yet be discovered. Here, we review recent progress realizing sources. We start with emission based on atomic ensembles spontaneous parametric down conversion, then focus...

Abstract Quantum key distribution (QKD) enables the transmission of information that is secure against general attacks by eavesdroppers. The use on-demand quantum light sources in QKD protocols expected to help improve security and maximum tolerable loss. Semiconductor dots (QDs) are a promising building block for communication applications because deterministic emission single photons with high brightness low multiphoton contribution. Here we report on first intercity experiment using...

Transferring entangled states between photon pairs is essential in quantum communication. Semiconductor dots are the leading candidate for generating polarization-entangled photons deterministically. Here we show first time swapping of two emitted by a single dot. A joint Bell measurement heralds successful generation state Ψ^{+}, yielding fidelity 0.81±0.04 and violating CHSH inequalities. Our source matches atomic memory frequencies, facilitating implementation hybrid repeaters.

Efficient generation of entangled photon pairs at telecom wavelengths is a key ingredient for long-range quantum networks. While embedding semiconductor dots into hybrid circular Bragg gratings has proven effective, it conflicts with p - i n diode heterostructures which offer superior coherence. We propose and analyze photonic crystal gratings, incorporating air holes to facilitate charge carrier transport without compromising optical properties. Through numerical simulations, broad cavity...

We demonstrate for the first time on-demand and wavelength-tunable single-photon emission from light-hole (LH) excitons in strain engineered GaAs quantum dots (QDs). The LH photon tensile-strained QDs is systematically investigated with polarization-resolved, power-dependent photoluminescence spectroscopy, photon-correlation measurements. By integrating QD-containing nanomembranes onto a piezo-actuator driving single picosecond laser pulses, we achieve triggered emission. Fourier transform...

The electron-hole exchange interaction is a fundamental mechanism that drives valley depolarization via intervalley exciton hopping in semiconductor multi-valley systems. Here, we report polarization-resolved photoluminescence spectroscopy of neutral excitons and negatively charged trions monolayer MoSe$_2$ WSe$_2$ under biaxial strain. We observe marked enhancement(reduction) on the triplet trion polarization with compressive(tensile) strain while unaffected. origin this effect shown to be...

Solid-state quantum platforms have great potential as well-controllable, scalable devices for applications in communication. Semiconductor dots are a leading candidate the deterministic generation of high-quality single or entangled photons. Wavelength tunability is fundamental requirement interference large number local emitters, enhancing their scalability. Here, we explore strain tuning GaAs/AlGaAs emitting photons close to transitions negatively charged Si-vacancy centers diamonds, which...

Long-distance fiber-based quantum communication relies on efficient non-classical light sources operating at telecommunication wavelengths. Semiconductor dots are promising candidates for on-demand generation of single photons and entangled photon pairs such applications. However, their brightness is strongly limited due to total internal reflection the semiconductor/vacuum interface. Here we overcome this limitation using a dielectric antenna structure. The source consists gallium phosphide...

We employ active feedback to stabilize the frequency of single photons emitted by two separate quantum dots an atomic standard. The transmission a single, rubidium-based Faraday filter serves as error signal for stabilization less than 1.5% emission linewidth. Long-term stability is demonstrated Hong-Ou-Mandel interference between from dots. observed visibility $V_{\mathrm{lock}}=(41 \pm 5)$% limited only internal dephasing Our approach facilitates networks with indistinguishable distributed...

Strain-free GaAs/AlGaAs semiconductor quantum dots (QDs) grown by droplet etching and nanohole infilling (DENI) are highly promising candidates for the on-demand generation of indistinguishable entangled photon sources. The spectroscopic fingerprint optical properties QDs significantly influenced their morphology. effects geometry infilled material on exciton binding energies fine structure splitting well-understood. However, a comprehensive understanding QD morphology remains elusive. To...

Large-scale quantum networks require the implementation of long-lived memories as stationary nodes interacting with qubits light. Epitaxially grown dots hold great potential for on-demand generation single and entangled photons high purity indistinguishability. Coupling these emitters to long coherence times enables development hybrid nanophotonic devices that incorporate advantages both systems. Here we report first GaAs/AlGaAs by droplet etching nanohole infilling method, emitting a narrow...

Colloidal semiconductor nanocrystals are promising materials for classical and quantum light sources due to their efficient photoluminescence (PL) versatile chemistry. While visible emitters well-established, excellent (near-infrared) still being pursued. We present the first comprehensive analysis of low-temperature PL from two-dimensional (2D) PbS nanoplatelets (NPLs). Ultrathin 2D NPLs exhibit high crystallinity confirmed by scanning transmission electron microscopy, revealing Moiré...

Coercive fields of piezoelectric materials can be strongly influenced by environmental temperature. We investigate this influence using a heterostructure consisting single crystal film and quantum dots containing membrane. Applying electric field leads to physical deformation the film, thereby inducing strain in thus modifying their optical properties. The wavelength dot emission shows butterfly-like loops, from which coercive are directly derived. results suggest that at cryogenic...

The on-chip integration of single photon and entangled emitters such as epitaxially grown semiconductor quantum dots into photonic frameworks is a rapidly evolving research field. GaAs offer high purity degree entanglement due to, in part, exhibiting very small fine structure splitting along with short radiative lifetimes. Integrating strain-tunable nanostructures enhances the optical fingerprint, i.e., lifetimes coupling these sources, allows for manipulation routing generated states light....

GaAs quantum dots (QDs) grown by local droplet etching (LDE) have been studied extensively in recent years. The LDE method allows for high crystallinity, as well precise control of the density, morphology, and size QDs. These properties make QDs an ideal candidate single photon entangled sources at short wavelengths (<800 nm). For technologically important telecom wavelengths, however, it is still unclear whether can be realized. Controlling growth conditions does not enable shifting...

Quantum key distribution (QKD) enables the transmission of information that is secure against general attacks by eavesdroppers. The use on-demand quantum light sources in QKD protocols expected to help improve security and maximum tolerable loss. Semiconductor dots (QDs) are a promising building block for communication applications because deterministic emission single photons with high brightness low multiphoton contribution. Here we report on first intercity experiment using bright photon...

Abstract Semiconductor quantum dots are leading candidates for the on-demand generation of single photons and entangled photon pairs. High quality indistinguishability from different sources critical information applications. The inability to grow perfectly identical with ideal optical properties necessitates application post-growth tuning techniques via e.g. temperature, electric, magnetic or strain fields. In this review, we summarize state-of-the-art highlight advantages tunable...

Epitaxially grown semiconductor quantum dots are promising candidates for pure single photon and polarization-entangled pair emission. Excellent optical properties can typically be ensured only if these so-called “artificial atoms” buried deep inside the host material. Quantum close to surface prone charge carrier fluctuations trap states on surface, degrading brightness, coherence, stability of We report high-purity emission [g(2)(0) = 0.016 ± 0.015] GaAs/AlGaAs that were 20 nm below...

Semiconductor-based emitters of pairwise photonic entanglement are a promising constituent quantum technologies. They known for the ability to generate discrete states on-demand with low multiphoton emission, near-unity fidelity, and high single photon indistinguishability. However, dots typically suffer from luminescence blinking, lowering efficiency source hampering their scalable application in networks. In this paper, we investigate adjust intermittence neutral exciton emission...

Efficient generation of entangled photon pairs at telecom wavelengths is a key ingredient for long-range quantum networks. While embedding semiconductor dots into hybrid circular Bragg gratings has proven effective, it conflicts with $p$-$i$-$n$ diode heterostructures which offer superior coherence. We propose and analyze photonic crystal gratings, incorporating air holes to facilitate charge carrier transport without compromising optical properties. Through numerical simulations, broad...