Compact superconducting vacuum-gap capacitors with low microwave loss and high mechanical coherence for scalable quantum circuits

Fuente: arXiv
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Hauptverfasser: Youssefi, Amir, Chegnizadeh, Mahdi, Scigliuzzo, Marco, Kippenberg, Tobias J.
Format: Preprint
Veröffentlicht: 2025
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author Youssefi, Amir
Chegnizadeh, Mahdi
Scigliuzzo, Marco
Kippenberg, Tobias J.
author_facet Youssefi, Amir
Chegnizadeh, Mahdi
Scigliuzzo, Marco
Kippenberg, Tobias J.
contents Vacuum-gap capacitors have recently attracted significant interest in superconducting circuit platforms due to their compact design and exceptionally low dielectric losses in the microwave regime. Their intrinsic ability to support mechanical vibrational modes makes them well-suited for circuit optomechanics. However, precise control over the gap size and the realization of high-coherence mechanical modes remain longstanding challenges. Here, we present a detailed and scalable fabrication process for vacuum-gap capacitors that support ultra-high-coherence mechanical motion, exhibit low microwave loss, and occupy a significantly smaller footprint compared to conventional planar geometries. By employing a planarized $\mathrm{SiO}_2$ sacrificial layer, we achieve vacuum gaps on the order of 150 nm. Using this platform, we have recently demonstrated ground-state cooling and motion squeezing of a mechanical oscillator with a quality factor of 40 million, a 100-fold improvement compared to prior works, as well as a single-photon optomechanical coupling rate of approximately 15Hz. Additional achievements include the realization of an optomechanical topological lattice with 24 sites and the observation of quantum collective dynamics in a mechanical hexamer. Collectively, these results underscore the potential of vacuum-gap capacitors as a platform for coupling superconducting qubits to mechanical systems, enabling quantum storage, and probing gravitational effects in quantum mechanics.
format Preprint
id arxiv_https___arxiv_org_abs_2501_03211
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Compact superconducting vacuum-gap capacitors with low microwave loss and high mechanical coherence for scalable quantum circuits
Youssefi, Amir
Chegnizadeh, Mahdi
Scigliuzzo, Marco
Kippenberg, Tobias J.
Quantum Physics
Applied Physics
Vacuum-gap capacitors have recently attracted significant interest in superconducting circuit platforms due to their compact design and exceptionally low dielectric losses in the microwave regime. Their intrinsic ability to support mechanical vibrational modes makes them well-suited for circuit optomechanics. However, precise control over the gap size and the realization of high-coherence mechanical modes remain longstanding challenges. Here, we present a detailed and scalable fabrication process for vacuum-gap capacitors that support ultra-high-coherence mechanical motion, exhibit low microwave loss, and occupy a significantly smaller footprint compared to conventional planar geometries. By employing a planarized $\mathrm{SiO}_2$ sacrificial layer, we achieve vacuum gaps on the order of 150 nm. Using this platform, we have recently demonstrated ground-state cooling and motion squeezing of a mechanical oscillator with a quality factor of 40 million, a 100-fold improvement compared to prior works, as well as a single-photon optomechanical coupling rate of approximately 15Hz. Additional achievements include the realization of an optomechanical topological lattice with 24 sites and the observation of quantum collective dynamics in a mechanical hexamer. Collectively, these results underscore the potential of vacuum-gap capacitors as a platform for coupling superconducting qubits to mechanical systems, enabling quantum storage, and probing gravitational effects in quantum mechanics.
title Compact superconducting vacuum-gap capacitors with low microwave loss and high mechanical coherence for scalable quantum circuits
topic Quantum Physics
Applied Physics
url https://arxiv.org/abs/2501.03211