Quantum noise reduction techniques in KAGRA

TL;DR

KAGRA, a cryogenic gravitational-wave detector, employs and plans to implement advanced quantum noise reduction techniques to enhance its sensitivity, addressing quantum noise limitations in gravitational wave detection.

Contribution

This paper reviews the current and upcoming quantum noise reduction techniques planned for KAGRA, highlighting its innovative cryogenic approach and future upgrade strategies.

Findings

Current quantum noise reduction techniques implemented in KAGRA.

Planned future quantum noise reduction methods for KAGRA.

KAGRA's cryogenic design effectively reduces thermal noise, enabling focus on quantum noise mitigation.

Abstract

KAGRA is the first large-scale gravitational-wave detector with cryogenic test masses. Its target sensitivity is limited mostly by quantum noise in the observation frequency band owing to the remarkable reduction of thermal noise at cryogenic temperatures. It is thus essential to reduce quantum noise, and KAGRA is designed to implement two quantum noise reduction techniques. KAGRA has already started considering an upgrade plan, in which a few more new quantum noise reduction techniques will be incorporated. In this article, we report the currently implemented quantum noise reduction techniques for KAGRA and those that will be implemented in the near future.