Quantum Optics and Optomechanics: From Fundamental Tests To Quantum Tools of the Future

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

This award supports research in relativity and relativistic astrophysics, and it addresses the priority areas of NSF's "Windows on the Universe" Big Idea. Quantum mechanics is the branch of physics used to explain the microscopic atomic and subatomic scale world. Quantum behavior is inherently different than the human experience of the macroscopic world. Hallmarks of quantum systems include fundamental uncertainty and entanglement. These quantum phenomena can be exploited to make more precise measurements of physical quantities. For example, quantum engineering allows scientists to measure the distance between the mirrors of a gravitational wave detector (GWD) with sub-attometer precision. This project pertains to an ongoing experimental program to develop quantum systems to probe fundamental quantum phenomena, as well as for applications to precision quantum noise-limited measurement. The emphasis of the research group is understanding and manipulating quantum noise in GWDs, which is important both for improved performance of GWDs, and also for probing fundamental quantum phenomena such as squeezing and entanglement on macroscopic scales. Diversity underpins the scientific and personnel aspects of the proposed work. The scientific diversity arises from the necessarily cross-disciplinary nature of the proposed research: it combines the techniques and formalism of quantum optics, optomechanics, and quantum measurement science with GWDs. The personnel diversity is the outcome of deliberate recruitment of women and minority students by the PI (herself a member of multiple minority groups), through her own efforts as well as those of the outreach programs of the LIGO Laboratory and MIT. Additionally, quantum science is popular with students (over a dozen Ph.D. and undergraduate theses have derived from this research program), and generates considerable enthusiasm with the public as well. The proposed experimental program aims to study multiple manifestations of quantum fluctuations and their effect on optical measurements and on motion of macroscopic objects. This allows for testing fundamental tenets of quantum mechanics, and also for making advances in quantum technologies for optical sensing and precision force and position measurement. The group is carrying out two experiments that exploit quantum fluctuations of light and mechanical motion. One experiment explores quantum effects in optomechanical systems where the radiation-pressure interaction between light and mechanical motion is engineered to dominate. Cavity optomechanics experiments with mechanical oscillators spanning nanogram- to kilogram-scales have featured prominently in this research program, where the interaction between light and mechanical motion is used to generate and manipulate quantum states. These experiments have successfully demonstrated optical cooling and trapping techniques for macroscopic mirrors, have enabled direct observation and evasion of quantum radiation pressure (backaction) noise that is a major limiting noise source in Advanced LIGO, and generation of broadband optomechanical squeezing as a promising alternative method for generating squeezed states of light suitable for future GW detectors. An important feature of this optomechanics platform is that it is designed to achieve the quantum regime with macroscopic mechanical oscillators that are not cryogenically pre-cooled. The immediate next goals are to observe conditionally squeezed mechanical states on the path toward creating quantum states of mirrors that are part of a room temperature optomechanics platform. The other experiment advances squeezed light technology for precision measurement. Specifically, the group is working on a compact squeezed light source based on nonlinear optical materials that is to be used to study and reduce quantum noise in linear optical amplification processes, and will be a steppingstone to an eventual squeezer-on-a-chip. 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.