CAREER: Quantum silicon phononics: Harnessing long-lived phonons for memories and interconnects

在过去的二十年里，量子技术稳步发展，有望解决计算、通信和传感等领域的广泛应用。到目前为止，为量子技术开发物理平台的大部分努力都集中在作为量子信息载体的光子，以及用于存储和处理量子信息的原子和固态量子比特。声子是固体材料振动中的能量量子，最近已成为量子技术的一种可行资源。由于声子能够与广泛的系统相互作用，它们可以作为互连，将量子信号从量子计算机可能运行的电域传递到光域，在光域中，光纤可以实现远距离量子通信。此外，在纳米工程设备中，声子可以很好地与环境隔离，有可能提供存储量子态的存储元件。要将这些物理特性转化为实验能力，并随后获得技术优势，需要将机械设备与其他量子硬件平台连接起来。该项目旨在为长寿命机械谐振器创造可扩展的芯片级光电量子接口。此外，该项目旨在通过将所开发的接口用于在电、光和机械量子设备之间产生量子纠缠的实验演示来评估所开发的接口的实际好处。由单晶硅制成的GHz频率声谐振器具有极低的损耗(在低温下达到500亿品质因数)和易于与电信波段光学光子接口的独特特性。然而，尽管之前已经证明了声子的量子操纵是通过压电耦合到超导量子比特上的，但硅中缺乏压电性使得无法直接与量子比特集成。该项目旨在通过开发新的机制来克服这一挑战，在一个单片绝缘体上硅平台上，开发带有超导量子比特的GHz频率机械谐振器和腔光机械系统的机电耦合新机制。为了实现这一目标，该项目将开发基于声子晶体的静电换能器和基于无序超导体动力学电感的高阻微波腔。集成这些组件，PI旨在实现对具有跨量子比特的机电谐振器的完全量子控制，并演示微波光子到光学光子的电光机械转换。在这种方法中，没有有损的压电材料和对耐光超导体的依赖，预计将转化为极长的机械寿命和微波-光学频率转换效率的数量级改进。该项目旨在利用这些改进在实验室规模的混合网络中演示量子纠缠操作，该网络由跨量子比特(充当处理器)、声子晶体谐振器(存储元件)和电信频带光子(互连)组成。展示这种混合量子网络对于未来在提供对量子计算云、分布式量子计算和量子感知的安全远程访问方面的真实世界应用至关重要。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Over the last two decades, quantum technologies have progressed steadily, promising solutions to a wide range of applications in computation, communication, and sensing. The bulk of efforts in developing physical platforms for quantum technologies has so far focused on photons as carriers of quantum information and atomic and solid-state qubits for storing and processing quantum information. Phonons, the quanta of energy in vibrations in solid-state materials, have recently emerged as a viable resource for quantum technologies. Due to their ability to interact with a wide range of systems, phonons can serve as interconnects to pass quantum signals from the electrical domain, where quantum computers are likely to operate, to the optical domain, where optical fibers enable long-distance quantum communication. Additionally, phonons can be well isolated from their environments in nano-engineered devices, potentially providing memory elements for storing quantum states. Developing these physical properties into experimental capabilities and, subsequently, a technological advantage requires methods of interfacing mechanical devices with other quantum hardware platforms. This project aims to create scalable, chip-scale optical and electrical quantum interfaces to long-lived mechanical resonators. Furthermore, the project aims to assess the practical benefits of the developed interfaces by using them in experimental demonstrations that create quantum entanglement between electrical, optical, and mechanical quantum devices.GHz-frequency acoustic resonators made from single-crystal silicon offer the unique properties of exceptionally low loss (reaching 50-billion quality factors at low temperatures) and the ease of interfacing with telecom-band optical photons. However, while quantum manipulations of phonons have been previously demonstrated with piezoelectric coupling to superconducting qubits, the absence of piezoelectricity in silicon forbids direct integration with qubits. This project aims to overcome this challenge by developing new mechanisms for electromechanical coupling of GHz-frequency mechanical resonators with superconducting qubits and cavity optomechanical systems in a monolithic silicon-on-insulator platform. To achieve this goal, the project will develop electrostatic transducers based on phononic crystals and high-impedance microwave cavities based on kinetic inductance in disordered superconductors. Integrating these components, the PI aims to realize full quantum control of electromechanical resonators with transmon qubits and demonstrate electro-optomechanical conversion of microwave photons to optical photons. The absence of lossy piezoelectric materials and the reliance on light-resistant superconductors in this approach is expected to translate to exceptionally long mechanical lifetimes and orders-of-magnitude improvement in the efficiency of microwave-to-optical frequency conversion. The project aims to take benefit of these improvements for demonstrating quantum entangling operations in a lab-scale hybrid network made from transmon qubits (acting as processors), phononic crystal resonators (memory elements), and telecommunication band photons (interconnects). Demonstrating such a hybrid quantum network would be essential for future real-world applications in providing secure remote access to quantum computing clouds, distributed quantum computing, and quantum-enabled sensing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.