| 1. |
- Wengerowsky, Soeren, et al.
(författare)
-
Entanglement distribution over a 96-km-long submarine optical fiber
- 2019
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 116:14, s. 6684-6688
-
Tidskriftsartikel (refereegranskat)abstract
- Quantum entanglement is one of the most extraordinary effects in quantum physics, with many applications in the emerging field of quantum information science. In particular, it provides the foundation for quantum key distribution (QKD), which promises a conceptual leap in information security. Entanglement-based QKD holds great promise for future applications owing to the possibility of device-independent security and the potential of establishing global-scale quantum repeater networks. While other approaches to QKD have already reached the level of maturity required for operation in absence of typical laboratory infrastructure, comparable field demonstrations of entanglement-based QKD have not been performed so far. Here, we report on the successful distribution of polarization-entangled photon pairs between Malta and Sicily over 96 km of submarine optical telecommunications fiber. We observe around 257 photon pairs per second, with a polarization visibility above 90%. Our results show that QKD based on polarization entanglement is now indeed viable in long-distance fiber links. This field demonstration marks the longest-distance distribution of entanglement in a deployed telecommunications network and demonstrates an international submarine quantum communication channel. This opens up myriad possibilities for future experiments and technological applications using existing infrastructure.
|
|
| 2. |
- Wengerowsky, Soeren, et al.
(författare)
-
Passively stable distribution of polarisation entanglement over 192 km of deployed optical fibre
- 2020
-
Ingår i: NPJ QUANTUM INFORMATION. - : NATURE PUBLISHING GROUP. - 2056-6387. ; 6:1
-
Tidskriftsartikel (refereegranskat)abstract
- Quantum key distribution (QKD) based on entangled photon pairs holds the potential for repeater-based quantum networks connecting clients over long distance. We demonstrate long-distance entanglement distribution by means of polarisation-entangled photon pairs through two successive deployed 96 km-long telecommunications fibres in the same submarine cable. One photon of each pair was detected directly after the source, while the other travelled the fibre cable in both directions for a total distance of 192 km and attenuation of 48 dB. The observed two-photon Bell state exhibited a fidelity 85 +/- 2% and was stable over several hours. We employed neither active stabilisation of the quantum state nor chromatic dispersion compensation for the fibre.
|
|
| 3. |
- Zadeh, Iman Esmaeil, et al.
(författare)
-
Single-photon detectors combining high efficiency, high detection rates, and ultra-high timing resolution
- 2017
-
Ingår i: APL PHOTONICS. - : AIP Publishing. - 2378-0967. ; 2:11
-
Tidskriftsartikel (refereegranskat)abstract
- Single-photon detection with high efficiency, high time resolution, low dark counts, and high photon detection rates is crucial for a wide range of optical measurements. Although efficient detectors have been reported before, combining all performance parameters in a single device remains a challenge. Here, we show a broadband NbTiN superconducting nanowire detector with an efficiency exceeding 92%, over 150 MHz photon detection rate, and a dark count rate below 130 Hz operated in a Gifford-McMahon cryostat. Furthermore, with careful optimization of the detector design and readout electronics, we reach an ultra-low system timing jitter of 14.80 ps (13.95 ps decoupled) while maintaining high detection efficiencies (>75%).
|
|
| 4. |
- Gemmell, Nathan R., et al.
(författare)
-
A miniaturized 4K platform for superconducting infrared photon counting detectors
- 2017
-
Ingår i: Superconductors Science and Technology. - : Institute of Physics Publishing (IOPP). - 0953-2048 .- 1361-6668. ; 30:11
-
Tidskriftsartikel (refereegranskat)abstract
- We report on a miniaturized platform for superconducting infrared photon counting detectors. We have implemented a fibre-coupled superconducting nanowire single photon detector in a Stirling/Joule-Thomson platform with a base temperature of 4.2 K. We have verified a cooling power of 4 mW at 4.7 K. We report 20% system detection efficiency at 1310 nm wavelength at a dark count rate of 1 kHz. We have carried out compelling application demonstrations in single photon depth metrology and singlet oxygen luminescence detection.
|
|
| 5. |
- Zadeh, Iman Esmaeil, et al.
(författare)
-
Efficient Single-Photon Detection with 7.7 ps Time Resolution for Photon-Correlation Measurements
- 2020
-
Ingår i: ACS Photonics. - : AMER CHEMICAL SOC. - 2330-4022. ; 7:7, s. 1780-1787
-
Tidskriftsartikel (refereegranskat)abstract
- A broad range of scientific and industrial disciplines require precise optical measurements at very low light levels. Single-photon detectors combining high efficiency and high time resolution are pivotal in such experiments. By using relatively thick films of NbTiN (8-11 nm) and improving the pattern fidelity of the nanostructure of the superconducting nanowire single-photon detectors (SNSPD), we fabricated devices demonstrating superior performance over all previously reported detectors in the combination of efficiency and time resolution. Our findings prove that small variations in the nanowire width, in the order of a few nanometers, can lead to a significant penalty on their temporal response. Addressing these issues, we consistently achieved high time resolution (best device 7.7 ps, other devices similar to 10-16 ps) simultaneously with high system detection efficiencies (80-90%) in the wavelength range of 780-1000 nm, as well as in the telecom bands (1310-1550 nm). The use of thicker films allowed us to fabricate large-area multipixel devices with homogeneous pixel performance. We first fabricated and characterized a 100 x 100 mu m(2) 16-pixel detector and showed there was little variation among individual pixels. Additionally, to showcase the power of our platform, we fabricated and characterized 4-pixel multimode fiber-coupled detectors and carried out photon-correlation experiments on a nanowire quantum dot resulting in g(2) (0) values lower than 0.04. The multipixel detectors alleviate the need for beamsplitters and can be used for higher order correlations with promising prospects not only in the field of quantum optics, but also in bioimaging applications, such as fluorescence microscopy and positron emission tomography.
|
|
