The ideal wavelength for daylight free-space quantum key distribution

Deleted Journal, Год журнала: 2024, Номер 1(1)

Опубликована: Март 1, 2024

Quantum key distribution (QKD) has matured in recent years from laboratory proof-of-principle demonstrations to commercially available systems. One of the major bottlenecks is limited communication distance fiber networks due exponential signal damping. To bridge intercontinental distances, low Earth orbit satellites transmitting quantum signals over atmosphere can be used. These free-space links, however, only operate during night, as sunlight otherwise saturates detectors used measure states. For applying QKD a global internet with continuous availability and high data rates, operation daylight required. In this work, we model satellite-to-ground channel for different light sources identify optimal wavelength under ambient conditions. Daylight possible within Fraunhofer lines or near-infrared spectrum, where intrinsic background sun comparably low. The highest annual secret length considering finite effect achievable at Hα line. More importantly, provide fundamental that adapted, general, any other specific link scenario taking into account required modifications. We also propose true single-photon source based on color center hexagonal boron nitride coupled microresonator implement such scheme. Our results applied roof-to-roof scenarios are, therefore, relevant near-future networks.

Язык: Английский

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Selective Generation of Luminescent Defects in Hexagonal Boron Nitride

Laser & Photonics Review, Год журнала: 2024, Номер 18(6)

Опубликована: Фев. 11, 2024

Abstract Single photon emitters from atomic defects in crystals like hexagonal boron nitride (hBN) are vital for quantum technologies. Although various techniques devised to obtain emission hBN, simultaneous control over position, type, and spectrum has not been achieved yet. Here, ion implantation with 12 C, 20 Ne, 69 Ga used create a composite population ≈820 nm. The correlation of Raman photoluminescence (PL) spectroscopy helps identify the defects’ type. After selecting as species yielding maximum emitter brightness, strategy based on thermal annealing is developed modify composition induced defects. This results an ensemble selected spectral properties, even when starting different conditions. Specifically, induces defect transmutation one type another, shifting wavelength 820 625 Moreover, sample patterning combined focused beam subsequent efficient method deterministically set position well PL composition. These offer practical avenue achieve situ positioning tuning ensembles promising information sensing applications.

Язык: Английский

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First-principles theory of the nitrogen interstitial in hBN: a plausible model for the blue emitter

Nanoscale, Год журнала: 2024, Номер 16(8), С. 4125 - 4139

Опубликована: Янв. 1, 2024

We elaborate on the methodology of computing color centers in periodic and cluster models hBN. Using first-principles methods, we determined various optical properties nitrogen interstitial defect compared them to experimental results.

Язык: Английский

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Narrowband Quantum Light Emission from Oxygen-Related Color Centers in Hexagonal Boron Nitride

ACS Photonics, Год журнала: 2024, Номер 11(6), С. 2359 - 2367

Опубликована: Май 8, 2024

Hexagonal boron nitride (hBN) is attracting increasing attention for quantum information science due to its ability host carbon-related color centers that perform as robust, high-temperature light sources, well native defects such charged VB– with optically addressable spin states toward spin-based applications. So far, achieving isolation of individual out ensemble emission remains difficult their low yield, warranting the search other candidates. Here, we show oxygen annealing creates emitters characterized by a phonon-sideband-free in 800 nm band. The strongly linearly polarized (79%), characteristic dipole rotation 20° and saturation intensity around 1 MHz, comparable brightest hBN reported previously. Their time dynamics appear free spectral diffusion or blinking, implying excellent room-temperature photostability without additional passivation techniques. Detailed cryogenic studies estimate zero pump power line width down 87.5 μeV, which several orders magnitude narrower compared defect center under nonresonant excitation. demonstrated photophysical properties oxygen-related are promising advance free-space communication might enable indistinguishable single photons interfacing 87Rb vapor-based memory technologies future work.

Язык: Английский

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Optical lineshapes of the C center in silicon from ab initio calculations: Interplay of localized modes and bulk phonons

Physical review. B./Physical review. B, Год журнала: 2025, Номер 111(12)

Опубликована: Март 14, 2025

Язык: Английский

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Polarization-encoded quantum key distribution with a room-temperature telecom single-photon emitter

National Science Review, Год журнала: 2025, Номер unknown

Опубликована: Апрель 16, 2025

ABSTRACT Single-photon sources (SPSs) are directly applicable in quantum key distribution (QKD) because they allow the implementation of canonical BB84 protocol. To date, QKD implementations using SPSs not widespread need for cryogenic operation, or frequency conversion to a wavelength efficiently transmitted over telecommunication fibers. We report an observation polarization-encoded room-temperature telecom SPS based on GaN defect. A field test 3.5 km deployed fiber with 4.0-dB loss yielded bit error rate (QBER) 5.0% and secure 585.9 bps. Further testing 32.5-km spool (attenuation 11.2 dB), which exhibited substantially lower polarization mode dispersion, QBER 3.2% 50.4 These results illustrate potential defects supporting communication.

Язык: Английский

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Experimental Single-Photon Quantum Key Distribution Surpassing the Fundamental Weak Coherent-State Rate Limit

Physical Review Letters, Год журнала: 2025, Номер 134(21)

Опубликована: Май 29, 2025

Язык: Английский

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Finite key performance of satellite quantum key distribution under practical constraints

Communications Physics, Год журнала: 2023, Номер 6(1)

Опубликована: Авг. 10, 2023

Abstract Global-scale quantum communication networks will require efficient long-distance distribution of signals. While optical fibre communications are range-limited due to exponential losses in the absence memories and repeaters, satellites enable intercontinental communications. However, design satellite key (SatQKD) systems has unique challenges over terrestrial networks. The typical approach modelling SatQKD been estimate performances with a fully optimised protocol parameter space few payload platform resource limitations. Here, we analyse how practical constraints affect performance for Bennett-Brassard 1984 (BB84) weak coherent pulse decoy state finite size effects. We consider engineering limitations trade-offs mission including limited in-orbit tunability, random number generation rates storage, source intensity uncertainty. quantify limits determine long-term capacity provide benchmarks support upcoming missions.

Язык: Английский

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Combining experiments on luminescent centres in hexagonal boron nitride with the polaron model and ab initio methods towards the identification of their microscopic origin

Nanoscale, Год журнала: 2023, Номер 15(34), С. 14215 - 14226

Опубликована: Янв. 1, 2023

We narrow down the microscopic origin to 3 out of 26 defect transitions by comparing experiments with ab initio methods and polaron model. show excellent agreement between theory experimental photoluminescence excitation spectroscopy.

Язык: Английский

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Fundamentals and emerging optical applications of hexagonal boron nitride: a tutorial

Advances in Optics and Photonics, Год журнала: 2024, Номер 16(2), С. 229 - 229

Опубликована: Март 19, 2024

Hexagonal boron nitride (hBN), also known as white graphite, is a transparent layered crystal with wide bandgap. Its structure resembles featuring layers composed of honeycomb lattices held together through van der Waals forces. The hBN facilitates exfoliation into thinner flakes and makes it highly anisotropic in in-plane out-of-plane directions. Unlike both insulating transparent, making an ideal material for isolating devices from the environment acting waveguide. As result, has found extensive applications optical devices, electronic quantum photonic devices. This comprehensive tutorial aims to provide readers thorough understanding hBN, covering its synthesis, lattice spectroscopic characterization, various optoelectronic designed without prior experience those expertise specific fields seeking understand relevance connections others.

Язык: Английский

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