粒子穿越晶体时的声子摩擦损耗：线性响应理论

高Q光学机械声子带隙屏蔽薄膜谐振器中声子隧穿损耗抑制的演示

Demonstration of suppressed phonon tunneling losses in phononic bandgap shielded membrane resonators for high-Q optomechanics

介电膜具有优异的力学和光学性能，是量子光力学研究中最有前途的平台之一。众所周知，作为机械谐振器的应力氮化硅纳米膜的性能取决于它们的框架如何被夹持到样品底座上，这在实践中通常需要精细且难以复制的安装解决方案。在这里，我们证明了集成在膜的硅框架的声子带隙屏蔽消除了这种依赖性，通过抑制耗散声子隧穿。我们干蚀刻膜的框架，使其呈现$\mathrm{cm}$大小的桥的形式，其具有1维周期性图案，其声子态密度被定制为在MHz范围内围绕膜的高$Q$模式呈现一个或多个全带隙。我们量化的有效性，这种声子带隙屏蔽的光学干涉测量抑制传输的振动，以及框架夹紧条件对膜模式的影响。我们发现supply-up到$40~\mathrm{dB}$，并为三个不同的实现声子结构，始终观察到显着的抑制膜的模式对样品夹紧的依赖性-如果模式的频率位于带隙。因此，我们实现了$5\times 10^{6}$的膜模式品质因数，样品被紧紧地螺栓连接到低温恒温器的$8~\mathrm{K}$ -冷指。$Q\times f$-$6\times 10^{12}~\mathrm{Hz}$在$300~\mathrm{K}$和$14\times 10^{12}~\mathrm{Hz}$在$8~\mathrm{K}$的产品被观察到，满足机械振动到其量子基态的光学冷却的主要要求之一。

Ultra-coherent nanomechanical resonators based on density phononic crystal engineering

Micro- and nanomechanical systems with exceptionally low dissipation rates are enabling the next-generation technologies of ultra-sensitive detectors and quantum information systems. New techniques and methods for lowering the dissipation rate have in recent years been discovered and allowed for the engineering of mechanical oscillators with phononic modes that are extremely well isolated from the environment and thus possessing quality factors close to and beyond 1 billion. A powerful strategy for isolating and controlling a single phononic mode is based on phononic crystal engineering. Here …

Superfluid Optomechanics with Phononic Nanostructures

In quantum optomechanics, finding materials and strategies to limit losses has been crucial to the progress of the field. Recently, superfluid 4He was proposed as a promising mechanical element for quantum optomechanics. This quantum fluid shows highly desirable properties (e.g. extremely low acoustic loss) for a quantum optomechanical system. In current implementations, superfluid optomechanical systems suffer from external sources of loss, which spoils the quality factor of resonators. In this work, we propose a new implementation, exploiting nanofluidic confinement. Our approach, based on a…

Loss channels affecting lithium niobate phononic crystal resonators at cryogenic temperature

We investigate the performance of microwave-frequency phononic crystal resonators fabricated on thin-film lithium niobate for integration with superconducting quantum circuits. For different design geometries at millikelvin temperatures, we achieve mechanical internal quality factors $Q_i$ above $10^5 - 10^6$ at high microwave drive power, corresponding to $5\times10^6$ phonons inside the resonator. By sweeping the defect size of resonators with identical mirror cell designs, we are able to indirectly observe signatures of the complete phononic bandgap via the resonators' internal quality fact…

超导量子比特的声子库工程

Phononic bath engineering of a superconducting qubit

本研究将超导量子比特耦合到压电表面声波声子库，通过调控声子耗散塑造量子比特损耗谱，实现了叠加态的制备与动力学稳定，为开放量子系统研究提供新平台，深化了对超导量子比特机械损耗的认知。

Analytic understanding and control of dynamical friction

Recent model simulations discovered unexpected non-monotonic features in the wear-free dry phononic friction as a function of the sliding speed. Here we demonstrate that a rather straight- forward application of linear-response theory, appropriate in a regime of weak slider-substrate in- teraction, predicts frictional one-phonon singularities which imply a non-trivial dependence of the dynamical friction force on the slider speed and/or coupling to the substrate. The explicit formula which we derive reproduces very accurately the classical atomistic simulations when available. By modifying the…