Thomas K. Bracht, Moritz Cygorek, Tim Seidelmann, Vollrath Martin Axt, and Doris E. Reiter
Entangled photon pairs are essential for quantum communication technology. They can be generated on-demand by semiconductor quantum dots, but several mechanisms are known to reduce the degree of entanglement. While some obstacles like the finite fine-structure splitting of the exciton states can currently be overcome, the excitation scheme itself can impair the entanglement fidelity. Here, we demonstrate that the swing-up of quantum emitter population (SUPER) scheme, using two red-detuned laser pulses applied to a quantum dot in a cavity, yields almost perfectly entangled photons. The entanglement remains robust against phonon influences even at elevated temperatures, due to decoupling of the excitation and emission process. With this achievement, quantum dots are ready to be used as entangled photon pair sources in applications requiring high degrees of entanglement up to temperatures of approximately 80 K.
{"title":"Temperature-independent almost perfect photon entanglement from quantum dots via the SUPER scheme","authors":"Thomas K. Bracht, Moritz Cygorek, Tim Seidelmann, Vollrath Martin Axt, and Doris E. Reiter","doi":"10.1364/opticaq.498559","DOIUrl":"https://doi.org/10.1364/opticaq.498559","url":null,"abstract":"Entangled photon pairs are essential for quantum communication technology. They can be generated on-demand by semiconductor quantum dots, but several mechanisms are known to reduce the degree of entanglement. While some obstacles like the finite fine-structure splitting of the exciton states can currently be overcome, the excitation scheme itself can impair the entanglement fidelity. Here, we demonstrate that the swing-up of quantum emitter population (SUPER) scheme, using two red-detuned laser pulses applied to a quantum dot in a cavity, yields almost perfectly entangled photons. The entanglement remains robust against phonon influences even at elevated temperatures, due to decoupling of the excitation and emission process. With this achievement, quantum dots are ready to be used as entangled photon pair sources in applications requiring high degrees of entanglement up to temperatures of approximately 80 K.","PeriodicalId":501828,"journal":{"name":"Optica Quantum","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138817166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We introduce a framework for simulating quantum optics by decomposing the system into a finite rank (number of terms) superposition of coherent states. This allows us to define a resource theory, where linear optical operations are “free” (i.e., do not increase the rank), and the simulation complexity for an m-mode system scales quadratically in m, in stark contrast to the Hilbert space dimension. We outline this approach explicitly in the Fock basis, relevant in particular for Boson sampling, where the simulation time (space) complexity for computing output amplitudes, to arbitrary accuracy, scales as O(m2 2n) [O(m2n)] for n photons distributed among m modes. We additionally demonstrate that linear optical simulations with the n photons initially in the same mode scales efficiently, as O(m2n). This paradigm provides a practical notion of “non-classicality,” i.e., the classical resources required for simulation. Moreover, by making connections to the stellar rank formalism, we show this comes from two independent contributions, the number of single-photon additions and the amount of squeezing.
我们引入了一个模拟量子光学的框架，将系统分解为有限阶（项数）的相干态叠加。这样，我们就能定义一种资源理论，其中的线性光学操作是 "免费 "的（即不增加阶数），而 m 模式系统的模拟复杂度以 m 为单位呈二次方扩展，这与希尔伯特空间维度形成了鲜明对比。我们在福克基础上明确概述了这种方法，尤其与玻色子采样相关，对于分布在 m 个模式中的 n 个光子，计算任意精度输出振幅的模拟时间（空间）复杂度为 O(m2 2n) [O(m2n)]。此外，我们还证明，对于最初处于同一模式的 n 个光子的线性光学模拟，其复杂度也能高效地缩放为 O(m2 n)。这一范式提供了 "非经典性 "的实用概念，即模拟所需的经典资源。此外，通过与恒星秩形式主义的联系，我们表明这来自两个独立的贡献，即单光子添加的数量和挤压的数量。
{"title":"Simulation of quantum optics by coherent state decomposition","authors":"Jeffrey Marshall and Namit Anand","doi":"10.1364/opticaq.504311","DOIUrl":"https://doi.org/10.1364/opticaq.504311","url":null,"abstract":"We introduce a framework for simulating quantum optics by decomposing the system into a finite rank (number of terms) superposition of coherent states. This allows us to define a resource theory, where linear optical operations are “free” (i.e., do not increase the rank), and the simulation complexity for an <i>m</i>-mode system scales quadratically in <i>m</i>, in stark contrast to the Hilbert space dimension. We outline this approach explicitly in the Fock basis, relevant in particular for Boson sampling, where the simulation time (space) complexity for computing output amplitudes, to arbitrary accuracy, scales as <i>O</i>(<i>m</i><sup>2</sup> 2<sup><i>n</i></sup>) [<i>O</i>(<i>m</i>2<sup><i>n</i></sup>)] for <i>n</i> photons distributed among <i>m</i> modes. We additionally demonstrate that linear optical simulations with the <i>n</i> photons initially in the same mode scales efficiently, as <i>O</i>(<i>m</i><sup>2</sup> <i>n</i>). This paradigm provides a practical notion of “non-classicality,” i.e., the classical resources required for simulation. Moreover, by making connections to the stellar rank formalism, we show this comes from two independent contributions, the number of single-photon additions and the amount of squeezing.","PeriodicalId":501828,"journal":{"name":"Optica Quantum","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138693321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Trevor J. Steiner, Maximilian Shen, Joshua E. Castro, John E. Bowers, and Galan Moody
Using an aluminum gallium arsenide microring resonator, we demonstrate a bright quantum optical microcomb with >300 nm (>40 THz) bandwidth and more than 20 sets of time–energy entangled modes, enabling spectral demultiplexing with simple, off-the-shelf commercial telecom components. We report high-rate continuous entanglement distribution for two sets of entangled-photon pair frequency modes exhibiting up to 20 GHz/mW2 pair generation rate. As an illustrative example of entanglement distribution, we perform a continuous-wave time-bin quantum key distribution protocol with 8 kbps sifted key rates while maintaining less than 10% error rate and sufficient two-photon visibility to ensure security of the channel. When the >20 frequency modes are multiplexed, we estimate >100 kbps entanglement-based key rates or the creation of a multi-user quantum communications network. The entire system requires less than 110 µW of on-chip optical power, demonstrating an efficient source of entangled frequency modes for quantum communications. As a proof of principle, a quantum key is distributed across 12 km of deployed fiber on the University of California Santa Barbara (UCSB) campus and used to encrypt a 21 kB image with <9{% } error.
{"title":"Continuous entanglement distribution from an AlGaAs-on-insulator microcomb for quantum communications","authors":"Trevor J. Steiner, Maximilian Shen, Joshua E. Castro, John E. Bowers, and Galan Moody","doi":"10.1364/opticaq.510032","DOIUrl":"https://doi.org/10.1364/opticaq.510032","url":null,"abstract":"Using an aluminum gallium arsenide microring resonator, we demonstrate a bright quantum optical microcomb with >300 nm (>40 THz) bandwidth and more than 20 sets of time–energy entangled modes, enabling spectral demultiplexing with simple, off-the-shelf commercial telecom components. We report high-rate continuous entanglement distribution for two sets of entangled-photon pair frequency modes exhibiting up to 20 GHz/mW<sup>2</sup> pair generation rate. As an illustrative example of entanglement distribution, we perform a continuous-wave time-bin quantum key distribution protocol with 8 kbps sifted key rates while maintaining less than 10% error rate and sufficient two-photon visibility to ensure security of the channel. When the >20 frequency modes are multiplexed, we estimate >100 kbps entanglement-based key rates or the creation of a multi-user quantum communications network. The entire system requires less than 110 µW of on-chip optical power, demonstrating an efficient source of entangled frequency modes for quantum communications. As a proof of principle, a quantum key is distributed across 12 km of deployed fiber on the University of California Santa Barbara (UCSB) campus and used to encrypt a 21 kB image with <span><span><9{% }</span><script type=\"math/tex\"><9{% }</script></span> error.","PeriodicalId":501828,"journal":{"name":"Optica Quantum","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138693322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhifan Zhou, Luís E. E. de Araujo, Matt DiMario, B. E. Anderson, Jie Zhao, Kevin M. Jones, and Paul D. Lett
We investigate experimentally the nonlocal phase modulation of multiple-frequency-mode, continuous-variable entangled twin beams. We use a pair of electro-optical phase modulators to modulate the entangled probe and conjugate light beams produced by four-wave mixing in hot rubidium vapor. A single phase modulator in either one of the twin beams reduces the two-mode squeezing signal. The overall quantum entanglement is preserved, however, as the modulator nonlocally distributes the beam correlations among frequency modes of the multimode fields. The two-mode squeezing can be recovered by reversing the mixing with an additional out-of-phase electro-optical phase modulator (EOM) in the other beam.
{"title":"Nonlocal phase modulation of multimode, continuous-variable twin beams","authors":"Zhifan Zhou, Luís E. E. de Araujo, Matt DiMario, B. E. Anderson, Jie Zhao, Kevin M. Jones, and Paul D. Lett","doi":"10.1364/opticaq.505870","DOIUrl":"https://doi.org/10.1364/opticaq.505870","url":null,"abstract":"We investigate experimentally the nonlocal phase modulation of multiple-frequency-mode, continuous-variable entangled twin beams. We use a pair of electro-optical phase modulators to modulate the entangled probe and conjugate light beams produced by four-wave mixing in hot rubidium vapor. A single phase modulator in either one of the twin beams reduces the two-mode squeezing signal. The overall quantum entanglement is preserved, however, as the modulator nonlocally distributes the beam correlations among frequency modes of the multimode fields. The two-mode squeezing can be recovered by reversing the mixing with an additional out-of-phase electro-optical phase modulator (EOM) in the other beam.","PeriodicalId":501828,"journal":{"name":"Optica Quantum","volume":"32 2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138693378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tareq Jaouni, Xiaoqin Gao, Sören Arlt, Mario Krenn, and Ebrahim Karimi
Vaidman, Aharanov, and Albert [Phys. Rev. Lett. 58(14), 1385 (1987) [CrossRef] ] put forward a puzzle called the mean king’s problem (MKP) that can be solved only by harnessing quantum entanglement. Prime-powered solutions to the problem have been shown to exist, but they have not yet been experimentally realized for any dimension beyond two. We propose a general first-of-its-kind experimental scheme for solving the MKP in prime dimensions (D). Our search is guided by the digital discovery framework Pytheus, which finds highly interpretable graph-based representations of quantum optical experimental setups; using it, we find specific solutions and generalize to higher dimensions through human insight. As proof of principle, we present a detailed investigation of our solution for the three-, five-, and seven-dimensional cases. We obtain maximum success probabilities of 82.3%, 56.2%, and 35.5%, respectively. We therefore posit that our computer-inspired scheme yields solutions that implement Alice’s strategy with quantum advantage, demonstrating its promise for experimental implementation in quantum communication tasks.
{"title":"Experimental solutions to the high-dimensional mean king’s problem","authors":"Tareq Jaouni, Xiaoqin Gao, Sören Arlt, Mario Krenn, and Ebrahim Karimi","doi":"10.1364/opticaq.502451","DOIUrl":"https://doi.org/10.1364/opticaq.502451","url":null,"abstract":"Vaidman, Aharanov, and Albert [Phys. Rev. Lett. <b>58</b>(14), 1385 (1987) [CrossRef] <span> </span>] put forward a puzzle called the mean king’s problem (MKP) that can be solved only by harnessing quantum entanglement. Prime-powered solutions to the problem have been shown to exist, but they have not yet been experimentally realized for any dimension beyond two. We propose a general first-of-its-kind experimental scheme for solving the MKP in prime dimensions (<i>D</i>). Our search is guided by the digital discovery framework <span style=\"font-variant: small-caps\">Pytheus</span>, which finds highly interpretable graph-based representations of quantum optical experimental setups; using it, we find specific solutions and generalize to higher dimensions through human insight. As proof of principle, we present a detailed investigation of our solution for the three-, five-, and seven-dimensional cases. We obtain maximum success probabilities of <span><span style=\"color: inherit;\"><span><span>82.3</span><span><span>%</span></span></span></span><script type=\"math/tex\">82.3{% }</script></span>, <span><span style=\"color: inherit;\"><span><span>56.2</span><span><span>%</span></span></span></span><script type=\"math/tex\">56.2{% }</script></span>, and <span><span style=\"color: inherit;\"><span><span>35.5</span><span><span>%</span></span></span></span><script type=\"math/tex\">35.5 {% }</script></span>, respectively. We therefore posit that our computer-inspired scheme yields solutions that implement Alice’s strategy with quantum advantage, demonstrating its promise for experimental implementation in quantum communication tasks.","PeriodicalId":501828,"journal":{"name":"Optica Quantum","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138693379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Correlations for symmetric states: what subsets of photons are doing within a beam of light","authors":"Aaron Goldberg","doi":"10.1364/opticaq.501218","DOIUrl":"https://doi.org/10.1364/opticaq.501218","url":null,"abstract":"","PeriodicalId":501828,"journal":{"name":"Optica Quantum","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139217270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maximilian Protte, Timon Schapeler, Jan Sperling, T. Bartley
Superconducting nanowire single-photon detectors (SNSPDs) have been widely used to study the discrete nature of quantum states of light in the form of photon-counting experiments. We show that SNSPDs can also be used to study continuous variables of optical quantum states by performing homodyne detection at a bandwidth of $400~mathrm{kHz}$. By measuring the interference of a continuous-wave field of a local oscillator with the field of the vacuum state using two SNSPDs, we show that the variance of the difference in count rates is linearly proportional to the photon flux of the local oscillator over almost five orders of magnitude. The resulting shot-noise clearance of $(46.0pm1.1)~mathrm{dB}$ is the highest reported clearance for a balanced optical homodyne detector, demonstrating their potential for measuring highly squeezed states in the continuous-wave regime. In addition, we measured a $mathrm{CMRR}=22.4~mathrm{dB}$. From the joint click counting statistics, we also measure the phase-dependent quadrature of a weak coherent state to demonstrate our device's functionality as a homodyne detector.
{"title":"Low-noise Balanced Homodyne Detection with Superconducting Nanowire Single-Photon Detectors","authors":"Maximilian Protte, Timon Schapeler, Jan Sperling, T. Bartley","doi":"10.1364/opticaq.502201","DOIUrl":"https://doi.org/10.1364/opticaq.502201","url":null,"abstract":"Superconducting nanowire single-photon detectors (SNSPDs) have been widely used to study the discrete nature of quantum states of light in the form of photon-counting experiments. We show that SNSPDs can also be used to study continuous variables of optical quantum states by performing homodyne detection at a bandwidth of $400~mathrm{kHz}$. By measuring the interference of a continuous-wave field of a local oscillator with the field of the vacuum state using two SNSPDs, we show that the variance of the difference in count rates is linearly proportional to the photon flux of the local oscillator over almost five orders of magnitude. The resulting shot-noise clearance of $(46.0pm1.1)~mathrm{dB}$ is the highest reported clearance for a balanced optical homodyne detector, demonstrating their potential for measuring highly squeezed states in the continuous-wave regime. In addition, we measured a $mathrm{CMRR}=22.4~mathrm{dB}$. From the joint click counting statistics, we also measure the phase-dependent quadrature of a weak coherent state to demonstrate our device's functionality as a homodyne detector.","PeriodicalId":501828,"journal":{"name":"Optica Quantum","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139353469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vasileios Niaouris, Samuel H. D'Ambrosia, C. Zimmermann, Xingyi Wang, Ethan Hansen, Michael Titze, E. Bielejec, Kai Fu
We study the donor-bound exciton optical linewidth properties of Al, Ga and In donor ensembles in single-crystal zinc oxide (ZnO). Neutral shallow donors (D$^0$) in ZnO are spin qubits with optical access via the donor-bound exciton (D$^0$X). This spin-photon interface enables applications in quantum networking, memories and transduction. Essential optical parameters which impact the spin-photon interface include radiative lifetime, optical inhomogeneous and homogeneous linewidth and optical depth. The ensemble photoluminescence linewidth ranges from 4-11 GHz, less than two orders of magnitude larger than the expected lifetime-limited linewidth. The ensemble linewidth remains narrow in absorption measurements through the 300 $mu$m-thick sample, which has an estimated optical depth up to several hundred. Homogeneous broadening of the ensemble line due to phonons is consistent with thermal population relaxation between D$^0$X states. This thermal relaxation mechanism has negligible contribution to the total linewidth at 2 K. We find that inhomogeneous broadening due to the disordered isotopic environment in natural ZnO is significant, ranging from 1.9 GHz - 2.2 GHz. Two-laser spectral anti-hole burning measurements, which can be used to measure the homogeneous linewidth in an ensemble, however, reveal spectral anti-hole linewidths similar to the single laser ensemble linewidth. Despite this broadening, the high homogeneity, large optical depth and potential for isotope purification indicate that the optical properties of the ZnO donor-bound exciton are promising for a wide range of quantum technologies and motivate a need to improve the isotope and chemical purity of ZnO for quantum technologies.
{"title":"Contributions to the optical linewidth of shallow donor-bound excitonic transition in ZnO","authors":"Vasileios Niaouris, Samuel H. D'Ambrosia, C. Zimmermann, Xingyi Wang, Ethan Hansen, Michael Titze, E. Bielejec, Kai Fu","doi":"10.1364/opticaq.501568","DOIUrl":"https://doi.org/10.1364/opticaq.501568","url":null,"abstract":"We study the donor-bound exciton optical linewidth properties of Al, Ga and In donor ensembles in single-crystal zinc oxide (ZnO). Neutral shallow donors (D$^0$) in ZnO are spin qubits with optical access via the donor-bound exciton (D$^0$X). This spin-photon interface enables applications in quantum networking, memories and transduction. Essential optical parameters which impact the spin-photon interface include radiative lifetime, optical inhomogeneous and homogeneous linewidth and optical depth. The ensemble photoluminescence linewidth ranges from 4-11 GHz, less than two orders of magnitude larger than the expected lifetime-limited linewidth. The ensemble linewidth remains narrow in absorption measurements through the 300 $mu$m-thick sample, which has an estimated optical depth up to several hundred. Homogeneous broadening of the ensemble line due to phonons is consistent with thermal population relaxation between D$^0$X states. This thermal relaxation mechanism has negligible contribution to the total linewidth at 2 K. We find that inhomogeneous broadening due to the disordered isotopic environment in natural ZnO is significant, ranging from 1.9 GHz - 2.2 GHz. Two-laser spectral anti-hole burning measurements, which can be used to measure the homogeneous linewidth in an ensemble, however, reveal spectral anti-hole linewidths similar to the single laser ensemble linewidth. Despite this broadening, the high homogeneity, large optical depth and potential for isotope purification indicate that the optical properties of the ZnO donor-bound exciton are promising for a wide range of quantum technologies and motivate a need to improve the isotope and chemical purity of ZnO for quantum technologies.","PeriodicalId":501828,"journal":{"name":"Optica Quantum","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139355846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Optical fiber networks are part of important critical infrastructure and known to be prone to eavesdropping attacks. Hence cryptographic methods have to be used to protect communication. Quantum key distribution (QKD), at its core, offers information theoretical security based on the laws of physics. In deployments one has to take into account practical security and resilience. The latter includes the localization of a possible eavesdropper after an anomaly has been detected by the QKD system to avoid denial-of-service. Here, we present a novel approach to eavesdropper location that can be employed in quantum as well as classical channels using stimulated Brillouin scattering. The tight localization of the acoustic wave inside the fiber channel using correlated pump and probe waves allows to discover the coordinates of a potential threat within centimeters. We demonstrate that our approach outperforms conventional OTDR in the task of localizing an evanescent outcoupling of 1% with cm precision inside standard optical fibers. The system is furthermore able to clearly distinguish commercially available standard SMF28 from different manufacturers, paving the way for fingerprinted fibers in high security environments.
{"title":"Eavesdropper localization for quantum and classical channels via nonlinear scattering","authors":"A. Popp, F. Sedlmeir, B. Stiller, C. Marquardt","doi":"10.1364/opticaq.502944","DOIUrl":"https://doi.org/10.1364/opticaq.502944","url":null,"abstract":"Optical fiber networks are part of important critical infrastructure and known to be prone to eavesdropping attacks. Hence cryptographic methods have to be used to protect communication. Quantum key distribution (QKD), at its core, offers information theoretical security based on the laws of physics. In deployments one has to take into account practical security and resilience. The latter includes the localization of a possible eavesdropper after an anomaly has been detected by the QKD system to avoid denial-of-service. Here, we present a novel approach to eavesdropper location that can be employed in quantum as well as classical channels using stimulated Brillouin scattering. The tight localization of the acoustic wave inside the fiber channel using correlated pump and probe waves allows to discover the coordinates of a potential threat within centimeters. We demonstrate that our approach outperforms conventional OTDR in the task of localizing an evanescent outcoupling of 1% with cm precision inside standard optical fibers. The system is furthermore able to clearly distinguish commercially available standard SMF28 from different manufacturers, paving the way for fingerprinted fibers in high security environments.","PeriodicalId":501828,"journal":{"name":"Optica Quantum","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139368608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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