2023-08-16 スイス連邦工科大学ローザンヌ校(EPFL)
◆スイスのEPFLの研究チームは、超伝導回路光機械プラットフォームを開発し、超低いデコヒーレンス率と高い量子制御信頼性を実現。真空ギャップドラムヘッドコンデンサーという要素が突破の鍵であり、これによって機械共鳴子の損失を大幅に減少させ、最長7.7ミリ秒の量子状態寿命を達成。量子状態の高い信頼性や機械圧縮を実現し、量子コンピューティングや通信への応用が期待されています。
＜関連情報＞
- https://actu.epfl.ch/news/a-quantum-leap-in-mechanical-oscillator-technology/
- https://www.nature.com/articles/s41567-023-02135-y
ミリ秒の量子デコヒーレンスを持つスクイーズド機械発振器 A squeezed mechanical oscillator with millisecond quantum decoherence
Amir Youssefi,Shingo Kono,Mahdi Chegnizadeh & Tobias J. Kippenberg
Nature Physics Published:10 August 2023
DOI:https://doi.org/10.1038/s41567-023-02135-y
Abstract
An enduring challenge in constructing mechanical-oscillator-based hybrid quantum systems is to ensure engineered coupling to an auxiliary degree of freedom and maintain good mechanical isolation from the environment, that is, low quantum decoherence, consisting of thermal decoherence and dephasing. Here we overcome this challenge by introducing a superconducting-circuit-based optomechanical platform that exhibits low quantum decoherence and has a large optomechanical coupling, which allows us to prepare the quantum ground and squeezed states of motion with high fidelity. We directly measure a thermal decoherence rate of 20.5 Hz (corresponding to T1 = 7.7 ms) as well as a pure dephasing rate of 0.09 Hz, yielding a 100-fold improvement in the quantum state lifetime compared with prior optomechanical systems. This enables us to reach a motional ground-state occupation of 0.07 quanta (93% fidelity) and realize mechanical squeezing of –2.7 dB below the zero-point fluctuation. Furthermore, we observe the free evolution of the mechanical squeezed state, preserving its non-classical nature over millisecond timescales. Such ultralow quantum decoherence not only increases the fidelity of quantum control and measurement of macroscopic mechanical systems but may also benefit interfacing with qubits, and places the system in a parameter regime suitable for tests of quantum gravity.
