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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/2503.10623 |
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| _version_ | 1866909536786317312 |
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| author | Huang, Jordan DiNapoli, Thomas J. Rockwood, Gavin Yuan, Ming Narasimhan, Prathyankara Gupta, Eesh Bal, Mustafa Crisa, Francesco Garattoni, Sabrina Lu, Yao Jiang, Liang Chakram, Srivatsan |
| author_facet | Huang, Jordan DiNapoli, Thomas J. Rockwood, Gavin Yuan, Ming Narasimhan, Prathyankara Gupta, Eesh Bal, Mustafa Crisa, Francesco Garattoni, Sabrina Lu, Yao Jiang, Liang Chakram, Srivatsan |
| contents | Circuit quantum electrodynamics (cQED) with superconducting cavities coupled to nonlinear circuits like transmons offers a promising platform for hardware-efficient quantum information processing. We address critical challenges in realizing this architecture by weakening the dispersive coupling while also demonstrating fast, high-fidelity multimode control by dynamically amplifying gate speeds through transmon-mediated sideband interactions. This approach enables transmon-cavity SWAP gates, for which we achieve speeds up to 30 times larger than the bare dispersive coupling. Combined with transmon rotations, this allows for efficient, universal state preparation in a single cavity mode, though achieving unitary gates and extending control to multiple modes remains a challenge. In this work, we overcome this by introducing two sideband control strategies: (1) a shelving technique that prevents unwanted transitions by temporarily storing populations in sideband-transparent transmon states and (2) a method that exploits the dispersive shift to synchronize sideband transition rates across chosen photon-number pairs to implement transmon-cavity SWAP gates that are selective on photon number. We leverage these protocols to prepare Fock and binomial code states across any of ten modes of a multimode cavity with millisecond cavity coherence times. We demonstrate the encoding of a qubit from a transmon into arbitrary vacuum and Fock state superpositions, as well as entangled NOON states of cavity mode pairs\textemdash a scheme extendable to arbitrary multimode Fock encodings. Furthermore, we implement a new binomial encoding gate that converts arbitrary transmon superpositions into binomial code states in $\qty{4}{\micro\second}$ (less than $1/χ$), achieving an average post-selected final state fidelity of $\qty{96.3}{\percent}$ across different fiducial input states. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_10623 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Fast Sideband Control of a Weakly Coupled Multimode Bosonic Memory Huang, Jordan DiNapoli, Thomas J. Rockwood, Gavin Yuan, Ming Narasimhan, Prathyankara Gupta, Eesh Bal, Mustafa Crisa, Francesco Garattoni, Sabrina Lu, Yao Jiang, Liang Chakram, Srivatsan Quantum Physics Circuit quantum electrodynamics (cQED) with superconducting cavities coupled to nonlinear circuits like transmons offers a promising platform for hardware-efficient quantum information processing. We address critical challenges in realizing this architecture by weakening the dispersive coupling while also demonstrating fast, high-fidelity multimode control by dynamically amplifying gate speeds through transmon-mediated sideband interactions. This approach enables transmon-cavity SWAP gates, for which we achieve speeds up to 30 times larger than the bare dispersive coupling. Combined with transmon rotations, this allows for efficient, universal state preparation in a single cavity mode, though achieving unitary gates and extending control to multiple modes remains a challenge. In this work, we overcome this by introducing two sideband control strategies: (1) a shelving technique that prevents unwanted transitions by temporarily storing populations in sideband-transparent transmon states and (2) a method that exploits the dispersive shift to synchronize sideband transition rates across chosen photon-number pairs to implement transmon-cavity SWAP gates that are selective on photon number. We leverage these protocols to prepare Fock and binomial code states across any of ten modes of a multimode cavity with millisecond cavity coherence times. We demonstrate the encoding of a qubit from a transmon into arbitrary vacuum and Fock state superpositions, as well as entangled NOON states of cavity mode pairs\textemdash a scheme extendable to arbitrary multimode Fock encodings. Furthermore, we implement a new binomial encoding gate that converts arbitrary transmon superpositions into binomial code states in $\qty{4}{\micro\second}$ (less than $1/χ$), achieving an average post-selected final state fidelity of $\qty{96.3}{\percent}$ across different fiducial input states. |
| title | Fast Sideband Control of a Weakly Coupled Multimode Bosonic Memory |
| topic | Quantum Physics |
| url | https://arxiv.org/abs/2503.10623 |