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| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2503.14798 |
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| _version_ | 1866910883286876160 |
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| author | Bland, Matthew P. Bahrami, Faranak Martinez, Jeronimo G. C. Prestegaard, Paal H. Smitham, Basil M. Joshi, Atharv Hedrick, Elizabeth Pakpour-Tabrizi, Alex Kumar, Shashwat Jindal, Apoorv Chang, Ray D. Yang, Ambrose Cheng, Guangming Yao, Nan Cava, Robert J. de Leon, Nathalie P. Houck, Andrew A. |
| author_facet | Bland, Matthew P. Bahrami, Faranak Martinez, Jeronimo G. C. Prestegaard, Paal H. Smitham, Basil M. Joshi, Atharv Hedrick, Elizabeth Pakpour-Tabrizi, Alex Kumar, Shashwat Jindal, Apoorv Chang, Ray D. Yang, Ambrose Cheng, Guangming Yao, Nan Cava, Robert J. de Leon, Nathalie P. Houck, Andrew A. |
| contents | Materials improvements are a powerful approach to reducing loss and decoherence in superconducting qubits because such improvements can be readily translated to large scale processors. Recent work improved transmon coherence by utilizing tantalum (Ta) as a base layer and sapphire as a substrate. The losses in these devices are dominated by two-level systems (TLSs) with comparable contributions from both the surface and bulk dielectrics, indicating that both must be tackled to achieve major improvements in the state of the art. Here we show that replacing the substrate with high-resistivity silicon (Si) dramatically decreases the bulk substrate loss, enabling 2D transmons with time-averaged quality factors (Q) exceeding 1.5 x 10^7, reaching a maximum Q of 2.5 x 10^7, corresponding to a lifetime (T_1) of up to 1.68 ms. This low loss allows us to observe decoherence effects related to the Josephson junction, and we use improved, low-contamination junction deposition to achieve Hahn echo coherence times (T_2E) exceeding T_1. We achieve these material improvements without any modifications to the qubit architecture, allowing us to readily incorporate standard quantum control gates. We demonstrate single qubit gates with 99.994% fidelity. The Ta-on-Si platform comprises a simple material stack that can potentially be fabricated at wafer scale, and therefore can be readily translated to large-scale quantum processors. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_14798 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | 2D transmons with lifetimes and coherence times exceeding 1 millisecond Bland, Matthew P. Bahrami, Faranak Martinez, Jeronimo G. C. Prestegaard, Paal H. Smitham, Basil M. Joshi, Atharv Hedrick, Elizabeth Pakpour-Tabrizi, Alex Kumar, Shashwat Jindal, Apoorv Chang, Ray D. Yang, Ambrose Cheng, Guangming Yao, Nan Cava, Robert J. de Leon, Nathalie P. Houck, Andrew A. Quantum Physics Materials Science Materials improvements are a powerful approach to reducing loss and decoherence in superconducting qubits because such improvements can be readily translated to large scale processors. Recent work improved transmon coherence by utilizing tantalum (Ta) as a base layer and sapphire as a substrate. The losses in these devices are dominated by two-level systems (TLSs) with comparable contributions from both the surface and bulk dielectrics, indicating that both must be tackled to achieve major improvements in the state of the art. Here we show that replacing the substrate with high-resistivity silicon (Si) dramatically decreases the bulk substrate loss, enabling 2D transmons with time-averaged quality factors (Q) exceeding 1.5 x 10^7, reaching a maximum Q of 2.5 x 10^7, corresponding to a lifetime (T_1) of up to 1.68 ms. This low loss allows us to observe decoherence effects related to the Josephson junction, and we use improved, low-contamination junction deposition to achieve Hahn echo coherence times (T_2E) exceeding T_1. We achieve these material improvements without any modifications to the qubit architecture, allowing us to readily incorporate standard quantum control gates. We demonstrate single qubit gates with 99.994% fidelity. The Ta-on-Si platform comprises a simple material stack that can potentially be fabricated at wafer scale, and therefore can be readily translated to large-scale quantum processors. |
| title | 2D transmons with lifetimes and coherence times exceeding 1 millisecond |
| topic | Quantum Physics Materials Science |
| url | https://arxiv.org/abs/2503.14798 |