Pub Date : 2026-02-10DOI: 10.22331/q-2026-02-10-2003
David Layden, Bradley Mitchell, Karthik Siva
Quantum error mitigation techniques mimic noiseless quantum circuits by running several related noisy circuits and combining their outputs in particular ways. How well such techniques work is thought to depend strongly on how noisy the underlying gates are. Weakly-entangling gates, like $R_{ZZ}(theta)$ for small angles $theta$, can be much less noisy than entangling Clifford gates, like CNOT and CZ, and they arise naturally in circuits used to simulate quantum dynamics. However, such weakly-entangling gates are non-Clifford, and are therefore incompatible with two of the most prominent error mitigation techniques to date: probabilistic error cancellation (PEC) and the related form of zero-noise extrapolation (ZNE). This paper generalizes these techniques to non-Clifford gates, and comprises two complementary parts. The first part shows how to effectively transform any given quantum channel into (almost) any desired channel, at the cost of a sampling overhead, by adding random Pauli gates and processing the measurement outcomes. This enables us to cancel or properly amplify noise in non-Clifford gates, provided we can first characterize such gates in detail. The second part therefore introduces techniques to do so for noisy $R_{ZZ}(theta)$ gates. These techniques are robust to state preparation and measurement (SPAM) errors, and exhibit concentration and sensitivity—crucial statistical properties for many experiments. They are related to randomized benchmarking, and may also be of interest beyond the context of error mitigation. We find that while non-Clifford gates can be less noisy than related Cliffords, their noise is fundamentally more complex, which can lead to surprising and sometimes unwanted effects in error mitigation. Whether this trade-off can be broadly advantageous remains to be seen.
{"title":"Theory of quantum error mitigation for non-Clifford gates","authors":"David Layden, Bradley Mitchell, Karthik Siva","doi":"10.22331/q-2026-02-10-2003","DOIUrl":"https://doi.org/10.22331/q-2026-02-10-2003","url":null,"abstract":"Quantum error mitigation techniques mimic noiseless quantum circuits by running several related noisy circuits and combining their outputs in particular ways. How well such techniques work is thought to depend strongly on how noisy the underlying gates are. Weakly-entangling gates, like $R_{ZZ}(theta)$ for small angles $theta$, can be much less noisy than entangling Clifford gates, like CNOT and CZ, and they arise naturally in circuits used to simulate quantum dynamics. However, such weakly-entangling gates are non-Clifford, and are therefore incompatible with two of the most prominent error mitigation techniques to date: probabilistic error cancellation (PEC) and the related form of zero-noise extrapolation (ZNE). This paper generalizes these techniques to non-Clifford gates, and comprises two complementary parts. The first part shows how to effectively transform any given quantum channel into (almost) any desired channel, at the cost of a sampling overhead, by adding random Pauli gates and processing the measurement outcomes. This enables us to cancel or properly amplify noise in non-Clifford gates, provided we can first characterize such gates in detail. The second part therefore introduces techniques to do so for noisy $R_{ZZ}(theta)$ gates. These techniques are robust to state preparation and measurement (SPAM) errors, and exhibit concentration and sensitivity—crucial statistical properties for many experiments. They are related to randomized benchmarking, and may also be of interest beyond the context of error mitigation. We find that while non-Clifford gates can be less noisy than related Cliffords, their noise is fundamentally more complex, which can lead to surprising and sometimes unwanted effects in error mitigation. Whether this trade-off can be broadly advantageous remains to be seen.","PeriodicalId":20807,"journal":{"name":"Quantum","volume":"393 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-10DOI: 10.1051/0004-6361/202557598
A. G. M. Pietrow, M. Baratella, I. V. Ilyin, M. Steffen, K. G. Strassmeier
The determination of the solar oxygen abundance remains a central problem in astrophysics because its accuracy is limited not only by models, but also by systematics. While many of these factors have been thoroughly characterized, the effect of the solar activity cycle has remained unexplored so far. Because of its relative strength and accessibility, the O I infrared triplet is typically the primary choice for abundance studies. Previous investigations have shown, however, that abundances inferred from this triplet tend to be higher than expected on active stars, but no such overabundance effect is observed for the much weaker forbidden O I 6300 Å line. This raises the question of whether a similar trend can be found for the Sun. To address this question, we analyzed synoptic disk-integrated Sun-as-a-star datasets of two decades from the FEROS, HARPS-N, PEPSI, and NEID spectrographs with a focus on the infrared triplet (7772, 7774, and 7775 Å) and the forbidden O I 6300 Å line. The excellent signal-to-noise ratio of the PEPSI observations allowed us to detect a weak but significant variation in the equivalent widths of the infrared triplet that corresponds to an abundance difference of about 0.01 dex between activity minimum and maximum. This value is significantly lower than the typical uncertainties on the solar oxygen abundance. No comparable trend is found in the other datasets because the scatter is higher. Based on these results, we conclude that within the typical uncertainties presented in other works, we can assume the inferred solar oxygen abundance to be stable throughout the solar cycle, but that this effect might be significant for other more active stars.
太阳氧丰度的测定仍然是天体物理学中的一个中心问题，因为它的准确性不仅受到模型的限制，而且受到系统学的限制。虽然这些因素中的许多已经被彻底地描述了，但太阳活动周期的影响至今仍未被探索。由于其相对强度和可接近性，O I红外三重态通常是丰度研究的首选。然而，先前的研究表明，从这个三重态推断出的丰度在活跃恒星上往往比预期的要高，但在更弱的O I 6300 Å线上没有观察到这种过剩效应。这就提出了一个问题：太阳是否也有类似的趋势？为了解决这个问题，我们分析了来自FEROS， HARPS-N， PEPSI和NEID光谱仪的20年来太阳作为恒星的综合圆盘数据集，重点关注红外三重态（7772,7774和7775 Å）和禁止的O I 6300 Å线。PEPSI观测的良好信噪比使我们能够探测到红外三重态等效宽度的微弱但显著的变化，对应于活动最小值和最大值之间约0.01指数的丰度差异。这个值明显低于太阳氧丰度的典型不确定度。在其他数据集中没有发现可比较的趋势，因为散点更高。基于这些结果，我们得出结论，在其他工作中提出的典型不确定性中，我们可以假设推断的太阳氧丰度在整个太阳周期中是稳定的，但这种影响可能对其他更活跃的恒星很重要。
{"title":"Does the solar oxygen abundance change over the solar cycle?","authors":"A. G. M. Pietrow, M. Baratella, I. V. Ilyin, M. Steffen, K. G. Strassmeier","doi":"10.1051/0004-6361/202557598","DOIUrl":"https://doi.org/10.1051/0004-6361/202557598","url":null,"abstract":"The determination of the solar oxygen abundance remains a central problem in astrophysics because its accuracy is limited not only by models, but also by systematics. While many of these factors have been thoroughly characterized, the effect of the solar activity cycle has remained unexplored so far. Because of its relative strength and accessibility, the O I infrared triplet is typically the primary choice for abundance studies. Previous investigations have shown, however, that abundances inferred from this triplet tend to be higher than expected on active stars, but no such overabundance effect is observed for the much weaker forbidden O I 6300 Å line. This raises the question of whether a similar trend can be found for the Sun. To address this question, we analyzed synoptic disk-integrated Sun-as-a-star datasets of two decades from the FEROS, HARPS-N, PEPSI, and NEID spectrographs with a focus on the infrared triplet (7772, 7774, and 7775 Å) and the forbidden O I 6300 Å line. The excellent signal-to-noise ratio of the PEPSI observations allowed us to detect a weak but significant variation in the equivalent widths of the infrared triplet that corresponds to an abundance difference of about 0.01 dex between activity minimum and maximum. This value is significantly lower than the typical uncertainties on the solar oxygen abundance. No comparable trend is found in the other datasets because the scatter is higher. Based on these results, we conclude that within the typical uncertainties presented in other works, we can assume the inferred solar oxygen abundance to be stable throughout the solar cycle, but that this effect might be significant for other more active stars.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"46 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146153541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-10DOI: 10.1088/1475-7516/2026/02/027
Serena Gambino, Roberto Giambò and Orlando Luongo
We investigate relativistic Bondi accretion in the Simpson-Visser spacetime, which, via a single parameter ℓ, interpolates between the Schwarzschild, regular black hole, extremal and wormhole regimes. First, we analyse the neutral Simpson-Visser geometry, recovering Schwarzschild at ℓ=0, and then its charged extension of the Reissner-Nordström metric. In both these cases, we derive the conservation equations and analyse two representative fluid models: a barotropic perfect fluid and a constituent with an exponential density profile. By varying the parameters across regimes, we locate critical (sonic) points and integrate velocity, density, and pressure profiles. Although near-horizon inflow velocities are similar across the different solutions, we find that the critical radius, as well as the resulting accretion rates and luminosities, change significantly depending on the value of the parameter and the type of fluid. Remarkably, the barotropic and exponential cases exhibit different trends in the outer regions. Moreover, by extending the analysis to the charged SV spacetime, we find that the presence of a central charge Q produces additional, albeit modest, shifts in the sonic radius which, in combination with those induced by the regularisation parameter ℓ, could provide a double observational marker. In particular, while ℓ acts predominantly on the position of the critical point, in the barotropic fluid case, the electromagnetic contribution of Q slightly dampens the inflow velocity near the horizon.
{"title":"Bondi accretion disc luminosity around neutral and charged Simpson-Visser spacetimes","authors":"Serena Gambino, Roberto Giambò and Orlando Luongo","doi":"10.1088/1475-7516/2026/02/027","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/027","url":null,"abstract":"We investigate relativistic Bondi accretion in the Simpson-Visser spacetime, which, via a single parameter ℓ, interpolates between the Schwarzschild, regular black hole, extremal and wormhole regimes. First, we analyse the neutral Simpson-Visser geometry, recovering Schwarzschild at ℓ=0, and then its charged extension of the Reissner-Nordström metric. In both these cases, we derive the conservation equations and analyse two representative fluid models: a barotropic perfect fluid and a constituent with an exponential density profile. By varying the parameters across regimes, we locate critical (sonic) points and integrate velocity, density, and pressure profiles. Although near-horizon inflow velocities are similar across the different solutions, we find that the critical radius, as well as the resulting accretion rates and luminosities, change significantly depending on the value of the parameter and the type of fluid. Remarkably, the barotropic and exponential cases exhibit different trends in the outer regions. Moreover, by extending the analysis to the charged SV spacetime, we find that the presence of a central charge Q produces additional, albeit modest, shifts in the sonic radius which, in combination with those induced by the regularisation parameter ℓ, could provide a double observational marker. In particular, while ℓ acts predominantly on the position of the critical point, in the barotropic fluid case, the electromagnetic contribution of Q slightly dampens the inflow velocity near the horizon.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"35 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-10DOI: 10.1088/1361-6382/ae3b91
Anthony W Yu, Molly E Fahey, Kenji Numata, Yvonne Kandem Manewa, Ali Feizi, Frankie Micalizzi, Hua Jiao, Joseph Hart, Xiaozhen Xu, Stewart Wu, Kylan Jersey, Will Drobnick, Pat Burns, Jennifer Lee and Scott Merritt
NASA Goddard Space Flight Center (GSFC) is developing a laser system (LS) for the Laser Interferometer Space Antenna (LISA) mission, led by the European Space Agency with a launch date of 2035. The LS under development at NASA GSFC consists of a laser head, a frequency reference system, and power monitor detector assemblies. The LS development, which began in late 2016, follows the established NASA process in demonstrating the performance requirements through the development of various models to advance the technology readiness level (TRL) (www.nasa.gov/directorates/somd/space-communications-navigation-program/technology-readiness-levels/). The effort began with a successful demonstration of a laboratory breadboard (TRL 4) and has achieved a status of TRL-6 (flight-qualified) through rigorous testing and performance verification for space applications. In this paper, we provide an overview of the development and roadmap for advancing the LISA LS toward spaceflight by the NASA GSFC. Optomechanical and electronic details of each component and subsystems are presented in this paper, as well as test results and technical challenges that have been or are being overcome. As the project progresses, more detailed results will be reported in future publications including representative scientific data in support of the LISA launch, which is planned for 2035.
{"title":"Overview of the NASA LISA laser system development","authors":"Anthony W Yu, Molly E Fahey, Kenji Numata, Yvonne Kandem Manewa, Ali Feizi, Frankie Micalizzi, Hua Jiao, Joseph Hart, Xiaozhen Xu, Stewart Wu, Kylan Jersey, Will Drobnick, Pat Burns, Jennifer Lee and Scott Merritt","doi":"10.1088/1361-6382/ae3b91","DOIUrl":"https://doi.org/10.1088/1361-6382/ae3b91","url":null,"abstract":"NASA Goddard Space Flight Center (GSFC) is developing a laser system (LS) for the Laser Interferometer Space Antenna (LISA) mission, led by the European Space Agency with a launch date of 2035. The LS under development at NASA GSFC consists of a laser head, a frequency reference system, and power monitor detector assemblies. The LS development, which began in late 2016, follows the established NASA process in demonstrating the performance requirements through the development of various models to advance the technology readiness level (TRL) (www.nasa.gov/directorates/somd/space-communications-navigation-program/technology-readiness-levels/). The effort began with a successful demonstration of a laboratory breadboard (TRL 4) and has achieved a status of TRL-6 (flight-qualified) through rigorous testing and performance verification for space applications. In this paper, we provide an overview of the development and roadmap for advancing the LISA LS toward spaceflight by the NASA GSFC. Optomechanical and electronic details of each component and subsystems are presented in this paper, as well as test results and technical challenges that have been or are being overcome. As the project progresses, more detailed results will be reported in future publications including representative scientific data in support of the LISA launch, which is planned for 2035.","PeriodicalId":10282,"journal":{"name":"Classical and Quantum Gravity","volume":"284 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shenglin Wang, Yueying Niu, Wanlin Liu, Kehan Jiang, Kun Zhou, Hongyu Chai, Dan Lu, Xiaoguang Yang, Tao Yang
Silicon photonic integrated circuits (PICs) have emerged as cutting‐edge platforms for optical communication, interconnection, photonic computing, and sensing, delivering exceptional data throughput and energy‐efficient operation. A holy grail is the realization of light sources and photonic components monolithically integrated on a single silicon wafer. However, such integration faces formidable challenges in material engineering and integration techniques, especially for on‐chip light sources. Here, we propose a strategy for developing large‐scale monolithically‐integrated high‐speed interconnect chips via direct epitaxy of quantum dot (QD) materials on CMOS‐compatible (001) silicon substrate. On the basis of an eight‐layer QD epitaxial structure, we simultaneously fabricate direct modulation lasers and waveguide photodetectors (PDs) for emission and reception. Bandwidth measurements for the single QD lasers and PDs reveal 3 dB bandwidths of 4.5 GHz and 2.02 GHz, respectively. Non‐return‐to‐zero (NRZ) signal measurements show that the laser can achieve a maximum direct modulation rate of 12.5 Gbit/s, whereas the PD has a data reception capability of 5 Gbit/s. Moreover, a state‐of‐the‐art link rate of 1.01 GHz for on‐chip optical interconnection between the integrated lasers and PDs is demonstrated through a free‐space optical coupling structure. This work demonstrates a novel method to realize large‐scale monolithically‐integrated chips, which enables future versatile applications.
{"title":"Large‐Scale Monolithically‐Integrated High‐Speed Interconnect Chips via Direct Growth of InAs/GaAs Quantum Dot Lasers and Photodetectors on Si(001)","authors":"Shenglin Wang, Yueying Niu, Wanlin Liu, Kehan Jiang, Kun Zhou, Hongyu Chai, Dan Lu, Xiaoguang Yang, Tao Yang","doi":"10.1002/lpor.202503131","DOIUrl":"https://doi.org/10.1002/lpor.202503131","url":null,"abstract":"Silicon photonic integrated circuits (PICs) have emerged as cutting‐edge platforms for optical communication, interconnection, photonic computing, and sensing, delivering exceptional data throughput and energy‐efficient operation. A holy grail is the realization of light sources and photonic components monolithically integrated on a single silicon wafer. However, such integration faces formidable challenges in material engineering and integration techniques, especially for on‐chip light sources. Here, we propose a strategy for developing large‐scale monolithically‐integrated high‐speed interconnect chips via direct epitaxy of quantum dot (QD) materials on CMOS‐compatible (001) silicon substrate. On the basis of an eight‐layer QD epitaxial structure, we simultaneously fabricate direct modulation lasers and waveguide photodetectors (PDs) for emission and reception. Bandwidth measurements for the single QD lasers and PDs reveal 3 dB bandwidths of 4.5 GHz and 2.02 GHz, respectively. Non‐return‐to‐zero (NRZ) signal measurements show that the laser can achieve a maximum direct modulation rate of 12.5 Gbit/s, whereas the PD has a data reception capability of 5 Gbit/s. Moreover, a state‐of‐the‐art link rate of 1.01 GHz for on‐chip optical interconnection between the integrated lasers and PDs is demonstrated through a free‐space optical coupling structure. This work demonstrates a novel method to realize large‐scale monolithically‐integrated chips, which enables future versatile applications.","PeriodicalId":204,"journal":{"name":"Laser & Photonics Reviews","volume":"9 1","pages":""},"PeriodicalIF":11.0,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146153397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-10DOI: 10.1021/acsphotonics.5c02661
Samuele Brunetta,Samantha Sbarra,Brandon Shuen Yi Loke,Jean-François Carlin,Nicolas Grandjean,Camille-Sophie Brès,Raphaël Butté
In recent years, aluminum nitride (AlN) has emerged as an attractive material for integrated photonics due to its low propagation losses, wide transparency window, and presence of both second- and third-order optical nonlinearities. However, most of the research led on this platform has primarily focused on applications rather than material optimization, although the latter is equally important to ensure its technological maturity. In this work, we show that voids, which are commonly found in crystalline AlN-on-sapphire epilayers, have a detrimental role in related photonic structures, as they can lead to propagation losses exceeding 30 dB cm–1 at 1550 nm. Their impact on light propagation is further quantified through finite-difference time-domain simulations that reveal void-related scattering losses are strongly dependent on their size and density in the layer. As a possible solution, we demonstrate that when introducing a thin sputtered AlN buffer layer prior to initiating AlN epitaxial growth, void-free layers are obtained. They exhibit intrinsic quality factors in microring resonators as high as 2.0 × 106, corresponding to propagation losses lower than 0.2 dB cm–1 at 1550 nm. These void-free layers are further benchmarked for high-power applications through second-harmonic and supercontinuum generation in dispersion-engineered waveguides. Such layers are highly promising candidates for short-wavelength photonic integrated circuit applications, particularly given the strong potential of AlN for visible photonics. Given that volumetric scattering losses scale as λ–4, the platform quality becomes increasingly critical in the visible and ultraviolet range, where our improved layers are expected to deliver enhanced performance.
近年来，氮化铝（AlN）由于其低传播损耗、宽透明窗口以及存在二阶和三阶光学非线性而成为集成光子学领域的一种有吸引力的材料。然而，在这个平台上进行的大多数研究主要集中在应用上，而不是材料优化上，尽管后者对于确保其技术成熟度同样重要。在这项工作中，我们证明了在晶体上蓝宝石上氮化铝涂层中常见的空洞在相关的光子结构中具有有害作用，因为它们可以导致在1550 nm处超过30 dB cm-1的传播损失。它们对光传播的影响通过有限差分时域模拟进一步量化，揭示了与空洞相关的散射损失强烈依赖于它们在层中的大小和密度。作为一种可能的解决方案，我们证明了当在开始AlN外延生长之前引入薄溅射AlN缓冲层时，可以获得无空洞层。它们在微环谐振器中表现出高达2.0 × 106的内在质量因子，对应于在1550 nm处低于0.2 dB cm-1的传播损耗。通过在色散工程波导中产生二次谐波和超连续谱，这些无空隙层进一步成为高功率应用的基准。这种层是短波光子集成电路应用的非常有前途的候选者，特别是考虑到AlN在可见光子学方面的强大潜力。考虑到体积散射损失尺度为λ-4，平台质量在可见光和紫外线范围内变得越来越重要，我们改进的层有望在这些范围内提供增强的性能。
{"title":"Sputtered AlN Buffer Layer for Low-Loss Crystalline AlN-on-Sapphire Integrated Photonics","authors":"Samuele Brunetta,Samantha Sbarra,Brandon Shuen Yi Loke,Jean-François Carlin,Nicolas Grandjean,Camille-Sophie Brès,Raphaël Butté","doi":"10.1021/acsphotonics.5c02661","DOIUrl":"https://doi.org/10.1021/acsphotonics.5c02661","url":null,"abstract":"In recent years, aluminum nitride (AlN) has emerged as an attractive material for integrated photonics due to its low propagation losses, wide transparency window, and presence of both second- and third-order optical nonlinearities. However, most of the research led on this platform has primarily focused on applications rather than material optimization, although the latter is equally important to ensure its technological maturity. In this work, we show that voids, which are commonly found in crystalline AlN-on-sapphire epilayers, have a detrimental role in related photonic structures, as they can lead to propagation losses exceeding 30 dB cm–1 at 1550 nm. Their impact on light propagation is further quantified through finite-difference time-domain simulations that reveal void-related scattering losses are strongly dependent on their size and density in the layer. As a possible solution, we demonstrate that when introducing a thin sputtered AlN buffer layer prior to initiating AlN epitaxial growth, void-free layers are obtained. They exhibit intrinsic quality factors in microring resonators as high as 2.0 × 106, corresponding to propagation losses lower than 0.2 dB cm–1 at 1550 nm. These void-free layers are further benchmarked for high-power applications through second-harmonic and supercontinuum generation in dispersion-engineered waveguides. Such layers are highly promising candidates for short-wavelength photonic integrated circuit applications, particularly given the strong potential of AlN for visible photonics. Given that volumetric scattering losses scale as λ–4, the platform quality becomes increasingly critical in the visible and ultraviolet range, where our improved layers are expected to deliver enhanced performance.","PeriodicalId":23,"journal":{"name":"ACS Photonics","volume":"47 1","pages":""},"PeriodicalIF":7.0,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146152483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-10DOI: 10.1038/s41534-026-01190-6
Evangelos Piliouras, Dennis Lucarelli, Edwin Barnes
The noisy nature of quantum hardware necessitates the implementation of high-fidelity quantum gates in a noise-insensitive manner. While there exist many powerful methods for designing dynamically corrected gates (DCGs), they often use a single cost function to simultaneously achieve a target gate and suppress noise. This can lead to unnecessary tradeoffs that lower gate fidelities and complicate the discovery of globally-optimal solutions. Here, we present a method for single-qubit DCGs called Bézier Ansatz for Robust Quantum (BARQ) control to address these challenges. Rather than numerically optimizing the controls directly, BARQ instead makes use of the Space Curve Quantum Control formalism in which the quantum evolution is mapped to a geometric space curve. In the formulation used by BARQ, the boundary conditions of the space curve dictate the target gate while its shape determines the gate’s noise sensitivity. We eliminate the aforementioned tradeoffs by employing a control-point parameterization that allows the target gate to be fixed upfront and use numerical optimization only for noise-robustness. BARQ introduces a global perspective into the control landscape and provides ample freedom to design experimentally friendly and robust control pulses. The pulse design is facilitated through the developed software package qurveros.
{"title":"An automated geometric space curve approach for designing dynamically corrected gates","authors":"Evangelos Piliouras, Dennis Lucarelli, Edwin Barnes","doi":"10.1038/s41534-026-01190-6","DOIUrl":"https://doi.org/10.1038/s41534-026-01190-6","url":null,"abstract":"The noisy nature of quantum hardware necessitates the implementation of high-fidelity quantum gates in a noise-insensitive manner. While there exist many powerful methods for designing dynamically corrected gates (DCGs), they often use a single cost function to simultaneously achieve a target gate and suppress noise. This can lead to unnecessary tradeoffs that lower gate fidelities and complicate the discovery of globally-optimal solutions. Here, we present a method for single-qubit DCGs called Bézier Ansatz for Robust Quantum (BARQ) control to address these challenges. Rather than numerically optimizing the controls directly, BARQ instead makes use of the Space Curve Quantum Control formalism in which the quantum evolution is mapped to a geometric space curve. In the formulation used by BARQ, the boundary conditions of the space curve dictate the target gate while its shape determines the gate’s noise sensitivity. We eliminate the aforementioned tradeoffs by employing a control-point parameterization that allows the target gate to be fixed upfront and use numerical optimization only for noise-robustness. BARQ introduces a global perspective into the control landscape and provides ample freedom to design experimentally friendly and robust control pulses. The pulse design is facilitated through the developed software package qurveros.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"91 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146152297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-10DOI: 10.1088/2058-9565/ae3b6e
Jin-Min Liang, Shuheng Liu, Shao-Ming Fei and Qiongyi He
The characterization of high-dimensional entanglement plays a crucial role in the field of quantum information science. Conventional entanglement criteria measuring coherent superpositions of multiple basis states face experimental bottlenecks on most physical platforms due to limited multi-channel control. Here, we introduce a practically efficient detection strategy based on randomized product projections. We show that the first-order moments of such projections can be used to estimate entanglement fidelity, thereby enabling practical and efficient certification of the Schmidt number (SN) in high-dimensional bipartite systems. By constructing optimal observables, it is sufficient to merely measure a single basis state, substantially reducing experimental overhead. Moreover, we present an algorithm to obtain a lower bound of the SN with a high confidence level from a limited number of experimental data. Our results open up resource-efficient experimental avenues to detect high-dimensional entanglement and test its implementations in modern information technologies.
{"title":"Detecting high-dimensional entanglement by randomized product projections","authors":"Jin-Min Liang, Shuheng Liu, Shao-Ming Fei and Qiongyi He","doi":"10.1088/2058-9565/ae3b6e","DOIUrl":"https://doi.org/10.1088/2058-9565/ae3b6e","url":null,"abstract":"The characterization of high-dimensional entanglement plays a crucial role in the field of quantum information science. Conventional entanglement criteria measuring coherent superpositions of multiple basis states face experimental bottlenecks on most physical platforms due to limited multi-channel control. Here, we introduce a practically efficient detection strategy based on randomized product projections. We show that the first-order moments of such projections can be used to estimate entanglement fidelity, thereby enabling practical and efficient certification of the Schmidt number (SN) in high-dimensional bipartite systems. By constructing optimal observables, it is sufficient to merely measure a single basis state, substantially reducing experimental overhead. Moreover, we present an algorithm to obtain a lower bound of the SN with a high confidence level from a limited number of experimental data. Our results open up resource-efficient experimental avenues to detect high-dimensional entanglement and test its implementations in modern information technologies.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"92 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-10DOI: 10.1088/1475-7516/2026/02/030
Rutvik Ashish Mahajan, Raghunath Ghara, Nishant Deo and Arnab Mishra
We present an improved matched filter method for detecting large ionized regions in 21 cm observations of the Epoch of Reionization. In addition to detection, the method constrains the properties of these regions, offering insights into the underlying source populations. Extending a previously developed Bayesian framework, we replace the spherical filter with an eight-parameter spheroidal filter, enabling a more flexible characterization of ionized bubbles. This enhancement significantly improves both detectability and recovery of bubble orientations. For a representative reionization scenario with a mean ionization fraction of 0.4 at z = 7, we find that a 10σ detection of the largest ionized region can be achieved with ∼ 1 h of observation using the SKA-low AA4 and AA★ layouts. Our method can help identify regions in the observed field that host large ionized bubbles, making them prime targets for deeper follow-up observations.
{"title":"Enhancing the detectability of ionized regions during the Epoch of Reionization","authors":"Rutvik Ashish Mahajan, Raghunath Ghara, Nishant Deo and Arnab Mishra","doi":"10.1088/1475-7516/2026/02/030","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/030","url":null,"abstract":"We present an improved matched filter method for detecting large ionized regions in 21 cm observations of the Epoch of Reionization. In addition to detection, the method constrains the properties of these regions, offering insights into the underlying source populations. Extending a previously developed Bayesian framework, we replace the spherical filter with an eight-parameter spheroidal filter, enabling a more flexible characterization of ionized bubbles. This enhancement significantly improves both detectability and recovery of bubble orientations. For a representative reionization scenario with a mean ionization fraction of 0.4 at z = 7, we find that a 10σ detection of the largest ionized region can be achieved with ∼ 1 h of observation using the SKA-low AA4 and AA★ layouts. Our method can help identify regions in the observed field that host large ionized bubbles, making them prime targets for deeper follow-up observations.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"314 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-10DOI: 10.1016/j.physletb.2026.140258
Sergei M. Kuzenko, Jonah Ruhl
{"title":"Generalisations of the Russo-Townsend formulation","authors":"Sergei M. Kuzenko, Jonah Ruhl","doi":"10.1016/j.physletb.2026.140258","DOIUrl":"https://doi.org/10.1016/j.physletb.2026.140258","url":null,"abstract":"","PeriodicalId":20162,"journal":{"name":"Physics Letters B","volume":"30 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2026-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146152807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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