Quantum Optics Seminar by Farid Khalili

Quantum speedmeter and atomic spin systems

The sensitivity of the modern laser interferometric gravitational-wave detectors is limited by quantum fluctuations of the probing light over most of the sensitive frequency range. In particular, the design sensitivity of the pair of Advanced LIGO interferometers roughly corresponds to the point of balance between the quantum measurement noise and the quantum back-action noise, which is known as the Standard Quantum Limit (SQL).


The SQL is not a fundamental limit, and several methods have been proposed for overcoming it. One of the most promising approaches for surpassing the SQL is based on the quantum speed meter, whose basic idea is to measure the velocity of the probe mass(es) instead of their position. In my talk, I describe this concept and its possible implementations, as well as the prospects of improving it by means of the atomic spin systems.