Pub Date : 2024-07-10DOI: 10.1088/2633-4356/ad61b3
Minh-Tuan Luu, Ali Tayefeh Younesi, Ronald Ulbricht
Nitrogen-vacancy (NV) defect centers in diamond are key to applications in quantum sensing and quantum computing. They create localized electronic states in the diamond lattice with distinct population relaxation pathways following photoexcitation that ultimately enable its unique properties. The defect is known to exist in two charge states: neutral and negative, with respectively one and two known optically-active electronic transitions. Here, we report on the observation of a large number of hitherto undiscovered excited electronic states in both charge states as evidenced by distinct optical transitions in the infrared to ultraviolet part of the spectrum. These transitions are observed by monitoring the electronic relaxation of NV centers after photoexcitation using transient absorption spectroscopy, directly probing transient phenomena occurring on timescales from femtoseconds to microseconds. We also for the first time probed the electron transfer dynamics from the 3E state of NV− to nearby single-substitutional nitrogen defects hat leads to the well-known effect of NV photoluminescence quenching.
金刚石中的氮空位（NV）缺陷中心是量子传感和量子计算应用的关键。它们在金刚石晶格中形成局部电子态，在光激发后具有独特的群体弛豫途径，最终使金刚石具有独特的特性。已知这种缺陷存在两种电荷状态：中性和负性，分别有一个和两个已知的光学活性电子跃迁。在此，我们报告了在这两种电荷态中观察到的大量迄今未被发现的激发电子态，它们在光谱的红外至紫外部分有明显的光学转变。这些跃迁是通过使用瞬态吸收光谱监测 NV 中心在光激发后的电子弛豫来观察的，直接探测了从飞秒到微秒级的瞬态现象。我们还首次探测了电子从 NV- 的 3E 态转移到附近的单体制氮缺陷的动态，这导致了众所周知的 NV 光致发光淬灭效应。
{"title":"Nitrogen-vacancy centers in diamond: discovery of additional electronic states","authors":"Minh-Tuan Luu, Ali Tayefeh Younesi, Ronald Ulbricht","doi":"10.1088/2633-4356/ad61b3","DOIUrl":"https://doi.org/10.1088/2633-4356/ad61b3","url":null,"abstract":"\u0000 Nitrogen-vacancy (NV) defect centers in diamond are key to applications in quantum sensing and quantum computing. They create localized electronic states in the diamond lattice with distinct population relaxation pathways following photoexcitation that ultimately enable its unique properties. The defect is known to exist in two charge states: neutral and negative, with respectively one and two known optically-active electronic transitions. Here, we report on the observation of a large number of hitherto undiscovered excited electronic states in both charge states as evidenced by distinct optical transitions in the infrared to ultraviolet part of the spectrum. These transitions are observed by monitoring the electronic relaxation of NV centers after photoexcitation using transient absorption spectroscopy, directly probing transient phenomena occurring on timescales from femtoseconds to microseconds. We also for the first time probed the electron transfer dynamics from the 3E state of NV− to nearby single-substitutional nitrogen defects hat leads to the well-known effect of NV photoluminescence quenching.","PeriodicalId":345750,"journal":{"name":"Materials for Quantum Technology","volume":"10 15","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141661611","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}
Pub Date : 2024-06-14DOI: 10.1088/2633-4356/ad589d
Arne Götze, Xavier Vidal, Nicola Lang, Christian Giese, Patricia Quellmalz, Jan Jeske, Peter Knittel
The use of quantum sensors is promising detailed insights into physical phenomena such as magnetism or superconductivity. One example of such quantum sensors is a microscopic diamond tip containing nitrogen vacancy (NV) centers, which is capable of producing correlated measurements of vectorial magnetic fields and the sample topography on the nanoscale. In this study, we present a chemical vapor deposition (CVD) process to produce diamond tips with NV centers by overgrowing microstructured diamond substrates. The resulting diamond tips exhibit a radius of curvature of approximately 10 nm, suitable for use as a probe in an atomic force microscope (AFM). The magnetic sensitivity of the CVD-grown diamond tips is characterized with pulsed measurements of the optically detected magnetic resonance (ODMR), which yield a minimum magnetic sensitivity of 60 µT/√Hz. The growth of the diamond microstructures is observed to differ from the commonly used geometric model predicting CVD growth of bulk diamond crystals. We identify an empirical model for the growth behavior of the microstructures by taking into account processes described in the step flow growth model for crystals. Additionally, we demonstrate the applicability of the developed CVD growth process to membrane substrates required for the preparation of magnetometry-capable diamond tips.
{"title":"Fabrication of tips for scanning probe magnetometry by diamond growth","authors":"Arne Götze, Xavier Vidal, Nicola Lang, Christian Giese, Patricia Quellmalz, Jan Jeske, Peter Knittel","doi":"10.1088/2633-4356/ad589d","DOIUrl":"https://doi.org/10.1088/2633-4356/ad589d","url":null,"abstract":"\u0000 The use of quantum sensors is promising detailed insights into physical phenomena such as magnetism or superconductivity. One example of such quantum sensors is a microscopic diamond tip containing nitrogen vacancy (NV) centers, which is capable of producing correlated measurements of vectorial magnetic fields and the sample topography on the nanoscale. In this study, we present a chemical vapor deposition (CVD) process to produce diamond tips with NV centers by overgrowing microstructured diamond substrates. The resulting diamond tips exhibit a radius of curvature of approximately 10 nm, suitable for use as a probe in an atomic force microscope (AFM). The magnetic sensitivity of the CVD-grown diamond tips is characterized with pulsed measurements of the optically detected magnetic resonance (ODMR), which yield a minimum magnetic sensitivity of 60 µT/√Hz. The growth of the diamond microstructures is observed to differ from the commonly used geometric model predicting CVD growth of bulk diamond crystals. We identify an empirical model for the growth behavior of the microstructures by taking into account processes described in the step flow growth model for crystals. Additionally, we demonstrate the applicability of the developed CVD growth process to membrane substrates required for the preparation of magnetometry-capable diamond tips.","PeriodicalId":345750,"journal":{"name":"Materials for Quantum Technology","volume":"67 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141337935","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}
Pub Date : 2024-06-13DOI: 10.1088/2633-4356/ad5823
Yueguang Zhou, Yuhui Yang, Yujing Wang, A. Koulas‐Simos, C. Palekar, I. Limame, Shulun Li, Hanqing Liu, H. Ni, Zhichuan Niu, Kresten Yvind, N. Gregersen, M. Pu, S. Reitzenstein
This study investigates nanobeam cavities on a GaAs-on-insulator chip with InAs quantum dots, including design, fabrication, and experimental characterization. The nanobeam cavities are optimized for high photon coupling efficiency and pronounced light-matter coupling. Numerical studies yield Q factors up to about 1400, a coupling efficiency of nearly 70% and a maximum Purcell factor of approximately 100. Experimentally, these devices have a $Q$ factor of about 1300, and comparing the lifetime of quantum dots in on-resonance and off-resonance conditions, a Purcell factor of 10.46±0.14 is obtained. Moreover, in the single-emitter regime, we observe strong multiphoton suppression with g(2)(0) = 0.295. Our results demonstrate the high potential of nanobeam cavity on a GaAs-on-insulator platform for quantum photonic applications.
{"title":"GaAs-on-insulator ridge waveguide nanobeam cavities with integrated InAs quantum dots","authors":"Yueguang Zhou, Yuhui Yang, Yujing Wang, A. Koulas‐Simos, C. Palekar, I. Limame, Shulun Li, Hanqing Liu, H. Ni, Zhichuan Niu, Kresten Yvind, N. Gregersen, M. Pu, S. Reitzenstein","doi":"10.1088/2633-4356/ad5823","DOIUrl":"https://doi.org/10.1088/2633-4356/ad5823","url":null,"abstract":"\u0000 This study investigates nanobeam cavities on a GaAs-on-insulator chip with InAs quantum dots, including design, fabrication, and experimental characterization. The nanobeam cavities are optimized for high photon coupling efficiency and pronounced light-matter coupling. Numerical studies yield Q factors up to about 1400, a coupling efficiency of nearly 70% and a maximum Purcell factor of approximately 100. Experimentally, these devices have a $Q$ factor of about 1300, and comparing the lifetime of quantum dots in on-resonance and off-resonance conditions, a Purcell factor of 10.46±0.14 is obtained. Moreover, in the single-emitter regime, we observe strong multiphoton suppression with g(2)(0) = 0.295. Our results demonstrate the high potential of nanobeam cavity on a GaAs-on-insulator platform for quantum photonic applications.","PeriodicalId":345750,"journal":{"name":"Materials for Quantum Technology","volume":"26 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141346122","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}
Pub Date : 2024-05-21DOI: 10.1088/2633-4356/ad4e8b
Hannes Huebener, Emil Viñas~Boström, Martin Claassen, S. Latini, Angel Rubio
A paradigm shift in the research of optical cavities is taking place, focusing on the properties of materials inside cavities. The possibility to affect changes of material groundstates with or without actual photon population inside cavities is an avenue that promises a novel view of materials science and provides a new knob to control quantum phenomena in materials. Here, we present three theoretical scenarios where such groundstate quantum phase transition is predicted by the coupling of the matter to mere vacuum fluctuations of the cavity, as a realizations of cavity materials engineering in the dark.
{"title":"Quantum materials engineering by structured cavity vacuum fluctuations","authors":"Hannes Huebener, Emil Viñas~Boström, Martin Claassen, S. Latini, Angel Rubio","doi":"10.1088/2633-4356/ad4e8b","DOIUrl":"https://doi.org/10.1088/2633-4356/ad4e8b","url":null,"abstract":"\u0000 A paradigm shift in the research of optical cavities is taking place, focusing on the properties of materials inside cavities. The possibility to affect changes of material groundstates with or without actual photon population inside cavities is an avenue that promises a novel view of materials science and provides a new knob to control quantum phenomena in materials. Here, we present three theoretical scenarios where such groundstate quantum phase transition is predicted by the coupling of the matter to mere vacuum fluctuations of the cavity, as a realizations of cavity materials engineering in the dark.","PeriodicalId":345750,"journal":{"name":"Materials for Quantum Technology","volume":"20 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141117380","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}
Pub Date : 2024-05-14DOI: 10.1088/2633-4356/ad4b8d
Ulrich Wahl, J G Correia, Ângelo Rafael Granadeiro Costa, Afonso Lamelas, Vitor S Amaral, Karl Johnston, G. Magchiels, S. M. Tunhuma, A. Vantomme, L.M.C. Pereira
In order to study the structural formation yield of germanium-vacancy (GeV) centers from implanted Ge in diamond, we have investigated its lattice location by using the β− emission channeling technique from the radioactive isotope 75Ge (t 1/2=83 min) produced at the ISOLDE/CERN facility. 75Ge was introduced via recoil implantation following 30 keV ion implantation of the precursor isotope 75Ga (126 s) with fluences around 2×1012 - 5×1013 cm−2. While for room temperature implantation fractions around 20% were observed in split-vacancy configuration and 45% substitutional Ge, following implantation or annealing up to 900°C, the split-vacancy fraction dropped to 6-9% and the substitutional fraction reached 85-96%. GeV complexes thus show a lower structural formation yield than other impurities, with substitutional Ge being the dominant configuration. Moreover, annealing or high-temperature implantation seem to favour the formation of substitutional Ge over GeV. Our results strongly suggest that GeV complexes are thermally unstable, and transformed to substitutional Ge by capture of mobile carbon interstitials, which is likely to contribute to the difficulties in achieving high formation yields of these optically active centers.
为了研究金刚石中植入 Ge 的锗空位（GeV）中心的结构形成率，我们利用 ISOLDE/CERN 设施生产的放射性同位素 75Ge（t 1/2=83 分钟）的 β 发射通道技术研究了其晶格位置。75Ge 是在对前体同位素 75Ga 进行 30 keV 离子注入（126 秒）后，通过反冲植入法引入的，注入流量约为 2×1012 - 5×1013 cm-2。室温植入时，分空位构型的 Ge 占 20%，取代型 Ge 占 45%，而植入或退火至 900°C 后，分空位构型的 Ge 占 6-9%，取代型 Ge 占 85-96%。因此，与其他杂质相比，GeV 复合物的结构形成率较低，取代型 Ge 是主要构型。此外，退火或高温植入似乎更有利于形成取代型 Ge 而不是 GeV。我们的研究结果有力地表明，GeV 复合物热不稳定，并通过捕获移动碳间隙转化为取代型 Ge，这可能是导致这些光学活性中心难以获得高形成率的原因。
{"title":"Structural formation yield of GeV centers from implanted Ge in diamond","authors":"Ulrich Wahl, J G Correia, Ângelo Rafael Granadeiro Costa, Afonso Lamelas, Vitor S Amaral, Karl Johnston, G. Magchiels, S. M. Tunhuma, A. Vantomme, L.M.C. Pereira","doi":"10.1088/2633-4356/ad4b8d","DOIUrl":"https://doi.org/10.1088/2633-4356/ad4b8d","url":null,"abstract":"\u0000 In order to study the structural formation yield of germanium-vacancy (GeV) centers from implanted Ge in diamond, we have investigated its lattice location by using the β− emission channeling technique from the radioactive isotope 75Ge (t\u0000 1/2=83 min) produced at the ISOLDE/CERN facility. 75Ge was introduced via recoil implantation following 30 keV ion implantation of the precursor isotope 75Ga (126 s) with fluences around 2×1012 - 5×1013 cm−2. While for room temperature implantation fractions around 20% were observed in split-vacancy configuration and 45% substitutional Ge, following implantation or annealing up to 900°C, the split-vacancy fraction dropped to 6-9% and the substitutional fraction reached 85-96%. GeV complexes thus show a lower structural formation yield than other impurities, with substitutional Ge being the dominant configuration. Moreover, annealing or high-temperature implantation seem to favour the formation of substitutional Ge over GeV. Our results strongly suggest that GeV complexes are thermally unstable, and transformed to substitutional Ge by capture of mobile carbon interstitials, which is likely to contribute to the difficulties in achieving high formation yields of these optically active centers.","PeriodicalId":345750,"journal":{"name":"Materials for Quantum Technology","volume":"30 50","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140980450","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}
Pub Date : 2024-05-14DOI: 10.1088/2633-4356/ad4b8c
D. Lozano, M. Mongillo, Xiaoyu Piao, S. Couet, Danny Wan, Y. Canvel, A. M. Vadiraj, T. Ivanov, J. Verjauw, R. Acharya, J. Van Damme, Mohiyaddin A. Fahd, J. Jussot, P. P. Gowda, Antoine Pacco, B. Raes, J. van de Vondel, Iuliana Radu, Bogdan Govoreanu, J. Swerts, Anton Potocnik, Kristiaan DeGreve
The performance of state-of-the-art superconducting quantum devices is currently limited by microwave dielectric loss at different interfaces. α-tantalum is a superconductor that has proven effective in reducing dielectric loss and improving device performance due to its thin low-loss oxide. Here, we demonstrate the fabrication of high-quality factor α-tantalum coplanar-waveguide resonators directly on pristine 300 mm silicon wafers over a variety of metal deposition conditions and perform a comprehensive material and electrical characterization study. Additionally, we apply a surface treatment based on hydrofluoric acid that allows us to modify different resonators surfaces, leading to a reduction in two-level system (TLS) loss in the devices by a factor of three. This loss reduction can be entirely attributed to the removal of surface oxides. Our study indicates that large scale manufacturing of low-loss superconducting circuits should indeed be feasible and suggests a viable avenue to materials-driven advancements in superconducting circuit performance.
{"title":"Low-loss α-tantalum coplanar waveguide resonators on silicon wafers: fabrication, characterization and surface modification","authors":"D. Lozano, M. Mongillo, Xiaoyu Piao, S. Couet, Danny Wan, Y. Canvel, A. M. Vadiraj, T. Ivanov, J. Verjauw, R. Acharya, J. Van Damme, Mohiyaddin A. Fahd, J. Jussot, P. P. Gowda, Antoine Pacco, B. Raes, J. van de Vondel, Iuliana Radu, Bogdan Govoreanu, J. Swerts, Anton Potocnik, Kristiaan DeGreve","doi":"10.1088/2633-4356/ad4b8c","DOIUrl":"https://doi.org/10.1088/2633-4356/ad4b8c","url":null,"abstract":"\u0000 The performance of state-of-the-art superconducting quantum devices is currently limited by microwave dielectric loss at different interfaces. α-tantalum is a superconductor that has proven effective in reducing dielectric loss and improving device performance due to its thin low-loss oxide. Here, we demonstrate the fabrication of high-quality factor α-tantalum coplanar-waveguide resonators directly on pristine 300 mm silicon wafers over a variety of metal deposition conditions and perform a comprehensive material and electrical characterization study. Additionally, we apply a surface treatment based on hydrofluoric acid that allows us to modify different resonators surfaces, leading to a reduction in two-level system (TLS) loss in the devices by a factor of three. This loss reduction can be entirely attributed to the removal of surface oxides. Our study indicates that large scale manufacturing of low-loss superconducting circuits should indeed be feasible and suggests a viable avenue to materials-driven advancements in superconducting circuit performance.","PeriodicalId":345750,"journal":{"name":"Materials for Quantum Technology","volume":"12 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140981736","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}
Pub Date : 2024-02-14DOI: 10.1088/2633-4356/ad2980
C. Tai, Jiun-Yun Li
Silicon has been a core material for digital computing owing to its high mobility, stability oxide interface, mature manufacturing technologies for more than half a century. While Moore’s law seems to further advance via various technologies to extend its expiration date, some intractable problems that requires processing times growing exponentially cannot be solved in a reasonable scale of time. Meanwhile, quantum computing is a promising tool to perform calculations much more efficiently than classical computing for certain types of problems. To realize a practical quantum computer, quantum dots on group-IV semiconductor heterostructures are promising due to the long decoherence time, scalability, and compatibility with the Si VLSI technology. In this review, we start with the advancement of group-IV undoped heterostructures since 2000 and review carrier transport properties in these undoped heterostructure. We also review the hole effective masses, spin-orbit coupling, and effective g-factors in the Ge-based heterostructures and conclude with a brief summary.
半个多世纪以来，硅凭借其高流动性、稳定的氧化物界面和成熟的制造技术，一直是数字计算的核心材料。虽然摩尔定律似乎在通过各种技术进一步推进，以延长其失效日期，但一些需要处理时间呈指数增长的棘手问题却无法在合理的时间范围内得到解决。与此同时，量子计算是一种很有前途的工具，对于某些类型的问题，它的计算效率远远高于经典计算。要实现实用的量子计算机，第四族半导体异质结构上的量子点具有退相干时间长、可扩展性强以及与硅超大规模集成电路技术兼容等优点，因此大有可为。在这篇综述中，我们首先介绍了自 2000 年以来第四族非掺杂异质结构的发展，并回顾了这些非掺杂异质结构中的载流子传输特性。我们还回顾了 Ge 基异质结构中的空穴有效质量、自旋轨道耦合和有效 g 因子，最后做了简要总结。
{"title":"Recent progress in undoped group-IV heterostructures for quantum technologies","authors":"C. Tai, Jiun-Yun Li","doi":"10.1088/2633-4356/ad2980","DOIUrl":"https://doi.org/10.1088/2633-4356/ad2980","url":null,"abstract":"\u0000 Silicon has been a core material for digital computing owing to its high mobility, stability oxide interface, mature manufacturing technologies for more than half a century. While Moore’s law seems to further advance via various technologies to extend its expiration date, some intractable problems that requires processing times growing exponentially cannot be solved in a reasonable scale of time. Meanwhile, quantum computing is a promising tool to perform calculations much more efficiently than classical computing for certain types of problems. To realize a practical quantum computer, quantum dots on group-IV semiconductor heterostructures are promising due to the long decoherence time, scalability, and compatibility with the Si VLSI technology. In this review, we start with the advancement of group-IV undoped heterostructures since 2000 and review carrier transport properties in these undoped heterostructure. We also review the hole effective masses, spin-orbit coupling, and effective g-factors in the Ge-based heterostructures and conclude with a brief summary.","PeriodicalId":345750,"journal":{"name":"Materials for Quantum Technology","volume":"55 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139777902","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}
Pub Date : 2024-02-14DOI: 10.1088/2633-4356/ad2980
C. Tai, Jiun-Yun Li
Silicon has been a core material for digital computing owing to its high mobility, stability oxide interface, mature manufacturing technologies for more than half a century. While Moore’s law seems to further advance via various technologies to extend its expiration date, some intractable problems that requires processing times growing exponentially cannot be solved in a reasonable scale of time. Meanwhile, quantum computing is a promising tool to perform calculations much more efficiently than classical computing for certain types of problems. To realize a practical quantum computer, quantum dots on group-IV semiconductor heterostructures are promising due to the long decoherence time, scalability, and compatibility with the Si VLSI technology. In this review, we start with the advancement of group-IV undoped heterostructures since 2000 and review carrier transport properties in these undoped heterostructure. We also review the hole effective masses, spin-orbit coupling, and effective g-factors in the Ge-based heterostructures and conclude with a brief summary.
半个多世纪以来，硅凭借其高流动性、稳定的氧化物界面和成熟的制造技术，一直是数字计算的核心材料。虽然摩尔定律似乎在通过各种技术进一步推进，以延长其失效日期，但一些需要处理时间呈指数增长的棘手问题却无法在合理的时间范围内得到解决。与此同时，量子计算是一种很有前途的工具，对于某些类型的问题，它的计算效率远远高于经典计算。要实现实用的量子计算机，第四族半导体异质结构上的量子点具有退相干时间长、可扩展性强以及与硅超大规模集成电路技术兼容等优点，因此大有可为。在这篇综述中，我们首先介绍了自 2000 年以来第四族非掺杂异质结构的发展，并回顾了这些非掺杂异质结构中的载流子传输特性。我们还回顾了 Ge 基异质结构中的空穴有效质量、自旋轨道耦合和有效 g 因子，最后做了简要总结。
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Pub Date : 2024-02-02DOI: 10.1088/2633-4356/ad2522
Ponraj Vijayan, R. Joos, Marco Werner, Jakob Hirlinger-Alexander, Matthias Seibold, Sergej Vollmer, R. Sittig, S. Bauer, Fiona Braun, S. Portalupi, M. Jetter, P. Michler
Photonic integrated circuits based on the silicon-on-insulator platform currently allow high-density integration of optical and electro-optical components on the same chip. This high complexity is also transferred to quantum photonic integrated circuits, where non-linear processes are used for the generation of quantum light on the silicon chip. However, these intrinsically probabilistic light emission processes pose challenges to the ultimately achievable scalability. Here, an interesting solution would be employing on-demand sources of quantum light based on III-V platforms, which are nonetheless very complex to grow directly on silicon. In this paper, we show the integration of InAs quantum dots on silicon via the growth on a wafer bonded GaAs/Si template. To ensure emission in the telecom C-band (∼1550 nm), a metamorphic buffer layer approach is utilized. We show that the deposited single quantum dots show similar performance to their counterparts directly grown on the well-established GaAs platform. Our results demonstrate that on-demand telecom emitters can be directly and effectively integrated on silicon, without compromises on the performances of either the platforms
目前，基于硅绝缘体平台的光子集成电路可在同一芯片上实现光学和电子光学元件的高密度集成。量子光子集成电路也能实现这种高复杂性，在硅芯片上利用非线性过程产生量子光。然而，这些固有的概率光发射过程对最终实现可扩展性提出了挑战。在此，一种有趣的解决方案是采用基于 III-V 平台的按需量子光源，但直接在硅片上生长这种光源非常复杂。在本文中，我们展示了通过在晶圆键合砷化镓/硅模板上生长，在硅上集成砷化镓量子点的过程。为了确保在电信 C 波段（∼1550 nm）的发射，我们采用了变质缓冲层方法。我们的研究表明，沉积的单量子点与直接生长在成熟的砷化镓平台上的量子点性能相似。我们的研究结果表明，按需电信发射器可以直接有效地集成到硅上，而不会影响平台的性能。
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Pub Date : 2024-02-02DOI: 10.1088/2633-4356/ad2521
S. Hansen,, Guillermo Arregui Bravo, A. Babar, R. Christiansen, Søren Stobbe
The scalability of integrated photonics hinges on low-loss chip-scale components, which are important for classical applications and crucial in the quantum domain. An important component is the power splitter, which is an essential building block for interferometric devices. Here, we use inverse design by topology optimization to devise a generic design framework for developing power splitters in any material platform, although we focus the present work on silicon photonics. We report on the design, fabrication, and characterization of silicon power splitters and explore varying domain sizes and wavelength spans. This results in a set of power splitters tailored for ridge, suspended, and embedded silicon waveguides with an emphasis on compact size and wide bandwidths. The resulting designs have a footprint of 2 μm x 3 μm and exhibit a remarkable 0.5-dB bandwidths exceeding 300 nm for the ridge and suspended power splitters and 600 nm for the embedded power splitter. We fabricate the power splitters in suspended silicon circuits and characterize the resulting devices using a cutback method. The experiments confirm the low excess loss, and we measure a 0.5-dB bandwidth of at least 245 nm -- limited by the wavelength range of our lasers.
{"title":"Inverse design and characterization of compact, broadband, and low-loss chip-scale photonic power splitters","authors":"S. Hansen,, Guillermo Arregui Bravo, A. Babar, R. Christiansen, Søren Stobbe","doi":"10.1088/2633-4356/ad2521","DOIUrl":"https://doi.org/10.1088/2633-4356/ad2521","url":null,"abstract":"\u0000 The scalability of integrated photonics hinges on low-loss chip-scale components, which are important for classical applications and crucial in the quantum domain. An important component is the power splitter, which is an essential building block for interferometric devices. Here, we use inverse design by topology optimization to devise a generic design framework for developing power splitters in any material platform, although we focus the present work on silicon photonics. We report on the design, fabrication, and characterization of silicon power splitters and explore varying domain sizes and wavelength spans. This results in a set of power splitters tailored for ridge, suspended, and embedded silicon waveguides with an emphasis on compact size and wide bandwidths. The resulting designs have a footprint of 2 μm x 3 μm and exhibit a remarkable 0.5-dB bandwidths exceeding 300 nm for the ridge and suspended power splitters and 600 nm for the embedded power splitter. We fabricate the power splitters in suspended silicon circuits and characterize the resulting devices using a cutback method. The experiments confirm the low excess loss, and we measure a 0.5-dB bandwidth of at least 245 nm -- limited by the wavelength range of our lasers.","PeriodicalId":345750,"journal":{"name":"Materials for Quantum Technology","volume":"69 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139810814","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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