Extremely coherent mechanical oscillators and circuit cavity electro-optics
The quest for mechanical oscillators with ultralow dissipation is motivated by classical and quantum sensing and technology, and precision measurements. For decades, the most coherent mechanical oscillators were acoustic vibrations in kg-scale crystalline bars. Recently a paradigm shift has occurred. The combination of elastic strain engineering – a technique used in microelectronics – with phononic mode engineering has resulted in 1D nano-strings with a mechanical quality factor Q of 0.8 billion – the highest ever achieved at room temperature. Remarkably, these new techniques have major untapped potential, as they have only been applied to non-crystalline materials in 1D. We propose a new generation of strain-engineered crystalline and superconducting mechanical oscillators whose Q-factors are predicted to exceed 100 billion in up to 2 dimensions. We will seek to reach this theoretical limit, probe new dissipation mechanisms, and utilize these oscillators for quantum optomechanics in new regimes and achieve room temperature ground state cooling and ponderomotive squeezing. Likewise, we will apply these techniques to create highly coherent superconducting electromechanical devices at milli-Kelvin temperatures, enabling quantum-enhanced force sensing and 1 second decoherence times. Secondly, we will explore a fundamentally new method for measurement and manipulation of microwave fields with optical fields – the nascent field of circuit Cavity-Electro-Optics (cCEO). First recognized over a decade ago, it is possible with optical fields to cool, amplify or interferometrically read out microwaves. Yet to date this regime has remained in accessible due to insufficient coupling strength between the microwave and optical fields. We will overcome this challenge based on a new circuit architecture, allowing laser cooling and laser amplification of microwaves and electro-optical masing using optical backaction, and thereby opening an entirely new way to manipulate microwaves.