Quantum from Classical: Approaching the Single-Quantum Strong Coupling Regime

众所周知，像棒球或行星这样的宏观物体的物理行为，是由牛顿发展的经典力学定律非常精确地描述的，许多人从大一物理课程中就很熟悉了。 同样可以理解的是，微观物体的行为，如原子和分子，是由量子物理学的神秘和反直觉定律描述的。 经典行为和量子行为之间的界限究竟在哪里还不清楚。 为了研究这个问题，这项研究将研究通常表现为经典的力学系统的行为，目的是使它们表现为量子力学。 这将通过使用超导设备来实现，以在光和机械谐振器之间产生非常强的耦合;光将用于诱导和读出量子行为。 这类研究将更好地划定经典物理和量子物理之间的界限，并帮助我们理解量子现象对我们周围日常世界的影响。 该项目将资助两名研究生，他们将接受微波测量、纳米制造和低温物理等实验技术的培训，这些技术在学术界和高科技产业中都有广泛的应用。 PI还将与当地高中物理教师合作，帮助丰富当地课程，让高中生接触尖端科学。技术摘要该研究将通过研究由一个小型机械谐振器与超导微波腔强耦合组成的系统，研究经典物理和量子物理之间的边界性质。 两者之间的耦合将由单个库珀对晶体管（一种逐个传输库珀对的超导器件）介导。 库珀对晶体管的存在将允许腔中的光子与机械谐振器中的量子晶格振动（声子）之间的非常强的非线性耦合。 这种耦合将是如此之强，当适当地增强时，应该可以用单个光子测量或影响单个声子。 通过利用这种强的非线性耦合，应该可以使用微波腔中的光子在机械谐振器中诱导高度量子力学的运动状态。 对这种相互作用的详细研究可以更好地理解量子和经典行为之间的界面。 该项目将资助两名研究生，他们将接受微波测量、纳米制造和低温物理等实验技术的培训，这些技术在学术界和高科技行业都得到了广泛应用。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical AbstractIt is well understood that the physical behavior of macroscopic objects, like baseballs or planets, is described very accurately by the laws of classical mechanics developed by Newton and familiar to many from a course in freshman physics. It is equally well understood that the behavior of microscopic objects, like atoms and molecules, is described by the mysterious and counter-intuitive laws of quantum physics. What is not clear is exactly where the boundary between classical behavior and quantum behavior lies. In order to investigate this question, this research will examine the behavior of mechanical systems that would normally behave classically, with the goal of causing them to instead behave quantum mechanically. This will be accomplished by using a superconducting device to cause very strong coupling between light and a mechanical resonator; the light will be used to both induce and read out the quantum behavior. Investigations of this sort will better delineate the border between classical and quantum physics, and help us understand the influence of quantum phenomena on the everyday world around us. Two graduate students will be supported by this project, and will be trained in such experimental techniques as microwave measurement, nanoscale fabrication and low-temperature physics that are widely used both in academia and in high-technology industry. The PI will also collaborate with a local high school physics teacher to help enrich the local curriculum and expose high school students to cutting-edge science.Technical AbstractThe research supported by this grant will investigate the nature of the boundary between classical and quantum physics by study of systems consisting of a small mechanical resonator strongly coupled to a superconducting microwave cavity. Coupling between the two will be mediated by a single Cooper pair transistor (a superconducting device that transfers Cooper pairs one by one). The presence of the Cooper pair transistor will allow a very strong, nonlinear coupling between photons in the cavity and quantum lattice vibrations (phonons) in the mechanical resonator. This coupling will be so strong, when properly enhanced, that it should be possible to measure or influence a single phonon with a single photon. By making use of this strong, nonlinear coupling, it should be possible to use photons in the microwave cavity to induce highly quantum mechanical states of motion in the mechanical resonator. A detailed study of this interaction could lead to a better understanding of the interface between quantum and classical behavior. Two graduate students will be supported by this project, and will be trained in such experimental techniques as microwave measurement, nanoscale fabrication and low-temperature physics that are widely used both in academia and in high-technology industryThis 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.