Collaborative Research: Cosmic Explorer Optical Design

The US has played a leading role in the global effort toward the observation of gravitational waves for several decades, resulting in the Nobel Physics Prize in 2017 for the first detection of waves from a binary black hole merger by the Advanced LIGO detectors, and many more astrophysical revelations since. Cosmic Explorer is the means by which the US will maintain that leadership in the decades to come. The Cosmic Explorer concept for a next-generation gravitational wave observatory seeks to answer fundamental questions about our universe such as: How did black holes form throughout cosmic time? What is the physics of extreme matter? What is the true nature of strong gravity? This project supports the conceptual design of the laser interferometers that will enable the Cosmic Explorer gravitational wave detectors to achieve cosmological range and exquisite fidelity in their observations. The team assembled for this award brings to bear decades of relevant experience and will build on the lessons learned from Advanced LIGO, leveraging legacy and novel concepts and technologies to produce a robust conceptual optical design. In the process of producing this optical design, the award will also serve to develop the workforce that will be essential for completing the further stages of design, installation and commissioning of the Cosmic Explorer detectors. By putting Cosmic Explorer more firmly on the path to actualization, this award will ensure that gravitational wave science continues inspiring young scientists across the country to fulfill their potential as the world-leading researchers of the future.At the heart of the Cosmic Explorer concept are 40-km and 20-km laser interferometers operating with unprecedented strain sensitivity, an order of magnitude greater than that of Advanced LIGO. The improved sensitivity is primarily afforded by the increase in scale, as opposed to the implementation of as-yet unverified technological advancements, thereby reducing technical risk. Nonetheless, the increase in scale itself presents unique challenges for the optical design of the Cosmic Explorer interferometers, such as decreased frequency spacing of parasitic optical modes, control band-width limitations due to the cavity delay, and tighter noise requirements for auxiliary degrees of freedom at low frequencies. Moreover, with the design of an entirely new facility comes the opportunity to develop the optical layout and the infrastructure in parallel, minimizing facility constraints impact on instrument performance, and therefore the achievable science. The work supported by this award will produce a parametric conceptual optical design for the Cosmic Explorer interferometers, informing all other detector subsystem requirements, ahead of a conceptual design review anticipated to take place roughly five years from the award start date. The optical design has been divided into four main work-packages, each led by one of the four collaborating institutions: Core Interferometer, Interferometer Sensing and Control, Laser Stabilization and Lock Acquisition, and Readout and Quantum Enhancement. The tasks contained within these work packages will be addressed using a range of analytical and numerical simulation techniques and will be coordinated with the broader Cosmic Explorer conceptual design through the Cosmic Explorer Systems Team.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.