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Alqedra, M., Huang, C. T., Yeung, E., Chang, W. H., Haffouz, S., Poole, P. J., . . . Zwiller, V. (2025). Entangled Photon Pair Generation in the Telecom O-Band from Nanowire Quantum Dots [Letter to the editor]. Nano Letters
Open this publication in new window or tab >>Entangled Photon Pair Generation in the Telecom O-Band from Nanowire Quantum Dots
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2025 (English)In: Nano Letters, ISSN 1530-6984, E-ISSN 1530-6992Article in journal, Letter (Refereed) Epub ahead of print
Abstract [en]

Entangled photon pairs at telecom wavelengths are essential for quantum communication, distributed computing, and quantum-enhanced sensing. The telecom O-band offers low chromatic dispersion and fiber loss, which is ideal for long-distance networks. Site-controlled nanowire quantum dots have emerged as a promising platform for generating single and entangled photons, offering high extraction efficiency and scalability. However, their operation has largely been restricted to the visible and first near-infrared (NIR-I) windows. Here, we demonstrate a bright source of entangled photon pairs in the telecom O-band based on site-controlled nanowire quantum dots. We measure a fine-structure splitting of 4.6 μeV, confirming suitability for high-fidelity polarization entanglement. Quantum-state tomography of the biexciton-exciton cascade reveals a maximum fidelity of 85.8 ± 1.1% to the Φ<sup>+</sup> Bell state and a maximum concurrence of 75.1 ± 2.1%. This work establishes nanowire quantum dots as viable entangled photon sources at telecom, advancing scalable quantum technologies for fiber-based networks.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2025
Keywords
entangled photons, nanowire quantum dots, quantum-state tomography, single-photon sources, telecom wavelength
National Category
Condensed Matter Physics Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-364430 (URN)10.1021/acs.nanolett.5c01130 (DOI)001500091700001 ()40452647 (PubMedID)2-s2.0-105007320573 (Scopus ID)
Note

QC 20250613

Available from: 2025-06-12 Created: 2025-06-12 Last updated: 2025-06-13Bibliographically approved
Staffas, T., Wollter, J., Elshaari, A. W. & Zwiller, V. (2025). Measuring vibrations using Doppler shifted frequency modulated continuous-wave LIDAR with single photons. Optics Letters, 50(2), 523-526
Open this publication in new window or tab >>Measuring vibrations using Doppler shifted frequency modulated continuous-wave LIDAR with single photons
2025 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 50, no 2, p. 523-526Article in journal (Refereed) Published
Abstract [en]

We demonstrate a frequency modulated continuous-wave (FMCW) light detection and ranging (LIDAR) system utilizing a superconducting nanowire single-photon detector (SNSPD) to measure vibrational spectra using reflected signals at the single-photon level. By determining the time-variant Doppler shift of the reflected probe signal, this system successfully reconstructs various audio signals, including pure sinusoidal, multi-tonal, and musical signals, up to 200 Hz, limited by the laser frequency modulation rate and the Nyquist sampling theorem. Additionally, we employ scanning galvo mirrors to perform 3D measurements and map audio signals from different regions in the scanned field of view. The integration of an SNSPD provides significant advantages such as near-unity detection efficiency, low dark count rates, and picosecond timing jitter, enabling measurements of vibrational spectra with as few as 100 detected reflected photons per laser sweep.

Place, publisher, year, edition, pages
Optica Publishing Group, 2025
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-359281 (URN)10.1364/OL.544481 (DOI)39815552 (PubMedID)2-s2.0-85215756753 (Scopus ID)
Note

QC 20250203

Available from: 2025-01-29 Created: 2025-01-29 Last updated: 2025-05-06Bibliographically approved
Gao, J., Khaymovich, I. M., Wang, X.-W., Xu, Z.-S., Iovan, A., Krishna, G., . . . Elshaari, A. W. (2025). Probing multi-mobility edges in quasiperiodic mosaic lattices. Science Bulletin, 70(1), 58-63
Open this publication in new window or tab >>Probing multi-mobility edges in quasiperiodic mosaic lattices
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2025 (English)In: Science Bulletin, ISSN 2095-9273, Vol. 70, no 1, p. 58-63Article in journal (Refereed) Published
Abstract [en]

The mobility edge (ME) is a crucial concept in understanding localization physics, marking the critical transition between extended and localized states in the energy spectrum. Anderson localization scaling theory predicts the absence of ME in lower dimensional systems. Hence, the search for exact MEs, particularly for single particles in lower dimensions, has recently garnered significant interest in both theoretical and experimental studies, resulting in notable progress. However, several open questions remain, including the possibility of a single system exhibiting multiple MEs and the continual existence of extended states, even within the strong disorder domain. Here, we provide experimental evidence to address these questions by utilizing a quasiperiodic mosaic lattice with meticulously designed nanophotonic circuits. Our observations demonstrate the coexistence of both extended and localized states in lattices with broken duality symmetry and varying modulation periods. By single-site injection and scanning the disorder level, we could approximately probe the ME of the modulated lattice. These results corroborate recent theoretical predictions, introduce a new avenue for investigating ME physics, and offer inspiration for further exploration of ME physics in the quantum regime using hybrid integrated photonic devices.

Place, publisher, year, edition, pages
Elsevier BV, 2025
Keywords
Mobility edge, Localization physics, Mosaic lattice, Nanophotonics
National Category
Atom and Molecular Physics and Optics Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-359941 (URN)10.1016/j.scib.2024.09.030 (DOI)001407032800001 ()39414538 (PubMedID)2-s2.0-85206438420 (Scopus ID)
Note

QC 20250212

Available from: 2025-02-12 Created: 2025-02-12 Last updated: 2025-02-12Bibliographically approved
Tao, M., Larocque, H., Gyger, S., Colangelo, M., Medeiros, O., Christen, I., . . . Errando-Herranz, C. (2025). Single-Photon Detectors on Arbitrary Photonic Substrates. ACS Photonics
Open this publication in new window or tab >>Single-Photon Detectors on Arbitrary Photonic Substrates
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2025 (English)In: ACS Photonics, E-ISSN 2330-4022Article in journal (Refereed) Epub ahead of print
Abstract [en]

Detecting nonclassical light is a central requirement for photonics-based quantum technologies. Unrivaled high efficiencies and low dark counts have positioned superconducting nanowire single-photon detectors (SNSPDs) as the leading detector technology for integrated photonic applications. However, a central challenge lies in their integration within photonic integrated circuits, regardless of material platform or surface topography. Here, we introduce a method based on transfer printing that overcomes these constraints and allows for the integration of SNSPDs onto arbitrary photonic substrates. With a kinetically controlled elastomer stamp, we transfer suspended SNSPDs onto commercially manufactured silicon and lithium niobate on insulator integrated photonic circuits. Focused ion beam metal deposition then wires the detectors to the circuits, thereby allowing us to monitor photon counts with >7% detection efficiencies. Our method eliminates detector integration bottlenecks and provides new venues for versatile, accessible, and scalable quantum information processors.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2025
Keywords
quantum photonics, single-photon detectors, optical quantum technologies, photonic integrated circuits, superconducting nanowire single-photon detectors
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-364260 (URN)10.1021/acsphotonics.5c00345 (DOI)001472919500001 ()40416322 (PubMedID)2-s2.0-105003173992 (Scopus ID)
Note

QC 20250609

Available from: 2025-06-09 Created: 2025-06-09 Last updated: 2025-06-09Bibliographically approved
Descamps, T., Schetelat, T., Gao, J., Poole, P. J., Dalacu, D., Elshaari, A. W. & Zwiller, V. (2024). Acoustic Modulation of Individual Nanowire Quantum Dots Integrated into a Hybrid Thin-Film Lithium Niobate Photonic Platform. Nano Letters, 24(40), 12493-12500
Open this publication in new window or tab >>Acoustic Modulation of Individual Nanowire Quantum Dots Integrated into a Hybrid Thin-Film Lithium Niobate Photonic Platform
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2024 (English)In: Nano Letters, ISSN 1530-6984, E-ISSN 1530-6992, Vol. 24, no 40, p. 12493-12500Article in journal (Refereed) Published
Abstract [en]

Surface acoustic waves are a powerful tool for controlling quantum systems, including quantum dots (QDs), where the oscillating strain field can modulate the emission wavelengths. We integrate InAsP/InP nanowire QDs onto a thin-film lithium niobate platform and embed them within Si3N4-loaded waveguides. We achieve a 0.70 nm peak-to-peak wavelength modulation at 13 dBm using a single focused interdigital transducer (FIDT) operating at 400 MHz, and we double this amplitude to 1.4 nm by using two FIDTs as an acoustic cavity. Additionally, we independently modulate two QDs with an initial wavelength difference of 0.5 nm, both integrated on the same chip. We show that their modulated emissions overlap, demonstrating the potential to bring them to a common emission wavelength after spectral filtering. This local strain-tuning represents a significant step toward generating indistinguishable single photons from remote emitters heterogeneously integrated on a single chip, advancing on-chip quantum information processing with multiple QDs.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2024
Keywords
integrated photonics, quantum dots, single-photon source, surface acoustic waves, thin-film lithium niobate
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-366717 (URN)10.1021/acs.nanolett.4c03402 (DOI)001324201300001 ()39324539 (PubMedID)2-s2.0-85205903445 (Scopus ID)
Note

QC 20250709

Available from: 2025-07-09 Created: 2025-07-09 Last updated: 2025-07-09Bibliographically approved
Tsintzos, S. I., Tsimvrakidis, K., Gates, J. C., Elshaari, A. W., Smith, P. G. .., Zwiller, V. & Riziotis, C. (2024). Coupling Nanowire Quantum Dots to Optical Waveguides by Microsphere-Induced Photonic Nanojet. Photonics, 11(4), Article ID 343.
Open this publication in new window or tab >>Coupling Nanowire Quantum Dots to Optical Waveguides by Microsphere-Induced Photonic Nanojet
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2024 (English)In: Photonics, ISSN 2304-6732, Vol. 11, no 4, article id 343Article in journal (Refereed) Published
Abstract [en]

Silica-on-silicon is a major optical integration platform, while the emergent class of the integrated laser-written circuits’ platform offers additionally high customizability and flexibility for rapid prototyping. However, the inherent waveguides’ low core/cladding refractive index contrast characteristic, compared to other photonic platforms in silicon or silicon nitride, sets serious limitations for on-chip efficient coupling with single photon emitters, like semiconductor nanowires with quantum dots, limiting the applications in quantum computing. A new light coupling scheme proposed here overcomes this limitation, providing means for light coupling >50%. The scheme is based on the incorporation of an optical microsphere between the nanowire and the waveguide, which is properly optimized and arranged in terms of size, refractive index, and the distance of the microsphere between the nanowire and waveguide. Upon suitable design of the optical arrangement, the photonic nanojet emitted by the illuminated microsphere excites efficiently the guided eigenmodes of the input channel waveguide, thus launching light with high-coupling efficiency. The method is tolerant in displacements, misalignments, and imperfections and is fabricationally feasible by the current state of art techniques. The proposed method enables the on-chip multiple single photon emitters’ integration, thus allowing for the development of highly customizable and scalable quantum photonic-integrated circuits for quantum computing and communications.

Place, publisher, year, edition, pages
Multidisciplinary Digital Publishing Institute (MDPI), 2024
Keywords
microspheres, nanowires, photonic nanojet, quantum circuits, quantum computing, quantum dots, quantum emitters, silica, waveguides
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-346383 (URN)10.3390/photonics11040343 (DOI)001211139000001 ()2-s2.0-85191610940 (Scopus ID)
Note

QC 20240516

Available from: 2024-05-14 Created: 2024-05-14 Last updated: 2024-05-16Bibliographically approved
Tsintzos, S. I., Tsimvrakidis, K., Sinani, A., Gates, J. C., Elshaari, A. W., Smith, P., . . . Riziotis, C. (2024). Enabling light coupling between nanowires and low refractive index contrast optical waveguides towards scalable quantum circuits. In: Integrated Optics: Devices, Materials, and Technologies XXVIII: . Paper presented at Integrated Optics: Devices, Materials, and Technologies XXVIII 2024, San Francisco, United States of America, Jan 29 2024 - Feb 1 2024. SPIE-Intl Soc Optical Eng, Article ID 1288913.
Open this publication in new window or tab >>Enabling light coupling between nanowires and low refractive index contrast optical waveguides towards scalable quantum circuits
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2024 (English)In: Integrated Optics: Devices, Materials, and Technologies XXVIII, SPIE-Intl Soc Optical Eng , 2024, article id 1288913Conference paper, Published paper (Refereed)
Abstract [en]

A primary constraint in the major photonic integration platform of Silica-on-Silicon, especially when combined with fabrication approaches like Direct Laser Writing is the optical waveguides' low refractive index contrast, leading thus to limitations for efficient coupling with currently available state-of-the-art single photon emitters such as semiconductor nanowires with quantum dots (NWQD). We propose and demonstrate a novel approach to drastically enhance the light coupling between silica based Laser-written channel waveguides and NWQDs, by incorporating an optical microsphere in their intermediate space. It is demonstrated that the induced photonic nanojet action of a suitably designed microsphere illuminated by the NWQD, excites efficiently the channel waveguide's modes and can enable light coupling to a degree even above 50%. The proposed method is reasonably robust to imperfections and misalignments and could be implemented by current state-of-the-art micro/nano patterning techniques. It is anticipated that the practical implementation of the method will allow the integration of multiple quantum emitters in silica based hybrid integrated circuits thus enabling their scalability towards for quantum computing and sensing applications.

Place, publisher, year, edition, pages
SPIE-Intl Soc Optical Eng, 2024
Keywords
Microspheres, Nanowires, Photonic Nanojet, Quantum Circuits, Quantum Computing, Quantum Dots, Silica, Waveguides
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-346410 (URN)10.1117/12.3003074 (DOI)2-s2.0-85191515752 (Scopus ID)
Conference
Integrated Optics: Devices, Materials, and Technologies XXVIII 2024, San Francisco, United States of America, Jan 29 2024 - Feb 1 2024
Note

QC 20240530

Available from: 2024-05-14 Created: 2024-05-14 Last updated: 2025-07-02Bibliographically approved
Zou, K., Meng, Y., Hao, Z., Li, J., Iovan, A., Descamps, T., . . . Hu, X. (2024). Fractal superconducting nanowire single-photon detector coupled with multi-mode optical fiber. In: CLEO: Science and Innovations, CLEO: S and I 2024 in Proceedings CLEO 2024, Part of Conference on Lasers and Electro-Optics: . Paper presented at CLEO: Science and Innovations in CLEO 2024, CLEO: S and I 2024 - Part of Conference on Lasers and Electro-Optics, Charlotte, United States of America, May 5 2024 - May 10 2024. Optical Society of America
Open this publication in new window or tab >>Fractal superconducting nanowire single-photon detector coupled with multi-mode optical fiber
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2024 (English)In: CLEO: Science and Innovations, CLEO: S and I 2024 in Proceedings CLEO 2024, Part of Conference on Lasers and Electro-Optics, Optical Society of America, 2024Conference paper, Published paper (Refereed)
Abstract [en]

Optical absorptance of fractal SNSPDs is insensitive to the speckles in multi-mode fiber (MMF). We demonstrate 73% system detection efficiency at 1540 nm and 69 ps timing jitter with a MMF-coupled fractal SNSPD.

Place, publisher, year, edition, pages
Optical Society of America, 2024
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-354672 (URN)2-s2.0-85205105179 (Scopus ID)
Conference
CLEO: Science and Innovations in CLEO 2024, CLEO: S and I 2024 - Part of Conference on Lasers and Electro-Optics, Charlotte, United States of America, May 5 2024 - May 10 2024
Note

QC 20241011

Available from: 2024-10-09 Created: 2024-10-09 Last updated: 2024-10-11Bibliographically approved
Zou, K., Meng, Y., Hao, Z., Li, J., Iovan, A., Descamps, T., . . . Hu, X. (2024). Fractal superconducting nanowire single-photon detector coupled with multi-mode optical fiber. In: 2024 Conference on Lasers and Electro-Optics, CLEO 2024: . Paper presented at 2024 Conference on Lasers and Electro-Optics, CLEO 2024, Charlotte, United States of America, May 7 2024 - May 10 2024. Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>Fractal superconducting nanowire single-photon detector coupled with multi-mode optical fiber
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2024 (English)In: 2024 Conference on Lasers and Electro-Optics, CLEO 2024, Institute of Electrical and Electronics Engineers Inc. , 2024Conference paper, Published paper (Refereed)
Abstract [en]

Optical absorptance of fractal SNSPDs is insensitive to the speckles in multi-mode fiber (MMF). We demonstrate 73% system detection efficiency at 1540 nm and 69 ps timing jitter with a MMF-coupled fractal SNSPD.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2024
Keywords
Adaptive optics, Detectors, Electro-optical waveguides, Fiber lasers, Fractals, Lasers and electrooptics, Optical coupling, Optical detectors, Optical fibers, Timing jitter
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-357706 (URN)2-s2.0-85210487346 (Scopus ID)
Conference
2024 Conference on Lasers and Electro-Optics, CLEO 2024, Charlotte, United States of America, May 7 2024 - May 10 2024
Note

 Part of ISBN 978-195717139-5

QC 20241213

Available from: 2024-12-12 Created: 2024-12-12 Last updated: 2024-12-13Bibliographically approved
Zou, K., Meng, Y., Hao, Z., Li, J., Iovan, A., Descamps, T., . . . Hu, X. (2024). Fractal superconducting nanowire single-photon detector coupled with multi-mode optical fiber. In: 2024 Conference on Lasers and Electro-Optics, CLEO 2024: . Paper presented at 2024 Conference on Lasers and Electro-Optics, CLEO 2024, Charlotte, United States of America, May 7 2024 - May 10 2024. Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>Fractal superconducting nanowire single-photon detector coupled with multi-mode optical fiber
Show others...
2024 (English)In: 2024 Conference on Lasers and Electro-Optics, CLEO 2024, Institute of Electrical and Electronics Engineers Inc. , 2024Conference paper, Published paper (Refereed)
Abstract [en]

Optical absorptance of fractal SNSPDs is insensitive to the speckles in multi-mode fiber (MMF). We demonstrate 73% system detection efficiency at 1540 nm and 69 ps timing jitter with a MMF-coupled fractal SNSPD.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2024
Keywords
Adaptive optics, Detectors, Electro-optical waveguides, Fiber lasers, Fractals, Lasers and electrooptics, Optical coupling, Optical detectors, Optical fibers, Timing jitter
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-359270 (URN)10.1364/cleo_at.2024.jw2a.95 (DOI)2-s2.0-85215296382 (Scopus ID)
Conference
2024 Conference on Lasers and Electro-Optics, CLEO 2024, Charlotte, United States of America, May 7 2024 - May 10 2024
Note

QC 20250131

Available from: 2025-01-29 Created: 2025-01-29 Last updated: 2025-01-31Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5726-1063

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