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Nanowire Quantum Dot Surface Engineering for High Temperature Single Photon Emission
摘要： Generating single photons at high temperature remains a major challenge, particularly for group III-As and III-P materials widely used in optical communication. Here, we report a high temperature single photon emitter based on a “surface-free” GaAs quantum dot in a GaAsP nanowire. By using self-catalyzed vapor-liquid-solid growth and simple surface engineering, we can significantly enhance the optical signal from the QDs with a highly polarized photoluminescence at 750 nm. The “surface-free” nanowire quantum dots show photon antibunching up to 160 K and well resolved exciton lines as high as 220 K.
关键词： surface engineering,photon antibunching,quantum dot,single photon source,nanowire
更新于2025-09-12 10:27:22
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GaAs Quantum Dot in a Parabolic Microcavity Tuned to <sup>87</sup> Rb D <sub/>1</sub>
摘要： We develop a structure to efficiently extract photons emitted by a GaAs quantum dot tuned to Rubidium. For this, we employ a broadband microcavity with a curved gold backside mirror which we fabricate by a combination of photoresist reflow, dry reactive ion etching in an inductively coupled plasma and selective wet chemical etching. Precise reflow and etching control allows us to achieve a parabolic backside mirror with a short focal distance of 265 nm. The fabricated structures yield a predicted (measured) collection efficiency of 63 % (12 %), an improvement by more than one order of magnitude compared to unprocessed samples. We then integrate our quantum dot parabolic microcavities onto a piezoelectric substrate capable of inducing a large in-plane biaxial strain. With this approach, we tune the emission wavelength by 0.5 nm/kV, in a dynamic, reversible and linear way, to the Rubidium D1 line (795 nm).
关键词： two-photon resonance fluorescence,strain tuning,microcavity,single-photon source,extraction efficiency,semiconductor quantum dots
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Towards Storage of Sub-Megahertz Single Photons in Gradient Echo Memory
摘要： Quantum repeaters are foundational to establishing the long distance quantum communication channels necessary to create a global communication network. A quantum memory capable of storing optical quantum states is an integral component of the quantum repeater. A wide variety of mechanisms for implementing an optical quantum memory have been investigated, ranging from simple optical delay lines to complicated photon echo schemes. The scheme of interest here is the gradient echo memory (GEM). GEM has been demonstrated to be one of the most efficient memory schemes to date, with up to 87% recall efficiency and up to 1ms coherence time when performed in a cold atomic ensemble of 87Rb atoms. Until now, GEM has only been investigated with weak coherent pulses as no single photon source met the demanding spectral requirements of the memory protocol. In particular, it requires sub-megahertz linewidth photons at the atomic transitions of 87Rb. A compatible source has been developed utilising cavity-enhanced spontaneous parametric downconversion (SPDC) generating photons with a bandwidth of 429 ± 10 kHz. This is, to our knowledge, the narrowest single photon bandwidth from SPDC to date. Integration with this source enables single photon storage for the first time using GEM and allows for its single photon level characteristics to finally be investigated. Single-photon quantum memory opens up the prospect of using the system as a quantum optical gate. Storing multiple single photon states simultaneously in the quantum memory can potentially give rise to photon-photon interactions due to cross phase modulation.
关键词： single photon source,gradient echo memory,quantum repeaters,sub-megahertz linewidth photons,quantum memory
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - Indistinguishable On-Chip Single-Photon Sources
摘要： Progress on integrating InGaAs quantum-dot single-photon sources within GaAs semiconductor photonic chips is reviewed. With resonant excitation, a radiative lifetime as short as 23 ps has been observed for a dot in a photonic-crystal nano-cavity, leading to single-photon emission with both high purity and indistinguishability.
关键词： Purcell effect,photonic nano-structure,single-photon source,integrated quantum photonics,quantum dot
更新于2025-09-11 14:15:04
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Efficient excitation of dye molecules for single photon generation
摘要： A reliable single photon source is required for many aspects of quantum technology. Organic molecules are attractive for this application because they can have high quantum yield and can be photostable, even at room temperature. To generate a photon with high probability, a laser must excite the molecule efficiently. We develop a simple model for that efficiency and discuss how to optimise it. We demonstrate the validity of our model through experiments on a single dibenzoterrylene (DBT) molecule in an anthracene crystal. We show that the excitation probability cannot exceed 75% at room temperature, but can increase to over 99% if the sample is cooled to liquid nitrogen temperature. The possibility of high photon generation efficiency with only modest cooling is a significant step towards a reliable photon source that is simple and practical.
关键词： single molecules,photon anti-bunching,single photon source,quantum optics,confocal microscopy
更新于2025-09-09 09:28:46
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Generation of narrow-band single-photon states via spontaneous parametric down-conversion for quantum memories in doped crystals
摘要： We present experimental results on the generation of narrow-band single-photon states via cavity-enhanced spontaneous parametric down-conversion in a PPLN crystal and demonstrate the feasibility of conditional preparation of single 867-nm photons with a 70-MHz linewidth, compatible with optical quantum memory devices based on Nd3+-doped isotopically pure Y7LiF4 crystals.
关键词： single-photon source,cavity,spontaneous parametric down-conversion
更新于2025-09-04 15:30:14
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Photon Noise Suppression by a Built-in Feedback Loop
摘要： Visionary quantum photonic networks need transform-limited single photons on demand. Resonance fluorescence on a quantum dot provides the access to a solid-state single photon source, where the environment is unfortunately the source of spin and charge noise that leads to fluctuations of the emission frequency and destroys the needed indistinguishability. We demonstrate a built-in stabilization approach for the photon stream, which relies solely on charge carrier dynamics of a two-dimensional hole gas inside a micropillar structure. The hole gas is fed by hole tunneling from field-ionized excitons and influences the energetic position of the excitonic transition by changing the local electric field at the position of the quantum dot. The standard deviation of the photon noise is suppressed by nearly 50% (noise power reduction of 6 dB) and it works in the developed micropillar structure for frequencies up to 1 kHz. This built-in feedback loop represents an easy way for photon noise suppression in large arrays of single photon emitters and promises to reach higher bandwidth by device optimization.
关键词： semiconductor heterostructure,single photon source,two-dimensional hole gas,Quantum dots,quantum optics,resonance fluorescence
更新于2025-09-04 15:30:14