Yu, Haocun

Date:   Wednesday, August 26, 2020
Time:   15:00
Place:   scheduled Zoom meeting
Host:    Renato Renner

Surpassing the SQL Using Quantum Correlations in LIGO

Haocun Yu
MIT, USA

When using light to measure the position of a particle, what is the limit to the precision? Continuous measurement of minuscule forces and displacements with ever greater precision encounters the standard quantum limit (SQL), which is imposed by the Heisenberg uncertainty principle. When light is used as the probe, the SQL arises from the balance between the photon radiation pressure noise and the shot noise. The only possibility to surpass the SQL is by introducing correlations between the position/momentum uncertainty of the object and the photon number/phase uncertainty of the light it reflects. I will give a talk on an experiment showing this type of quantum correlation is naturally produced in the 4km Laser Interferometer Gravitational-wave Observatory (LIGO). Then by exploiting this correlation, the quantum uncertainty in the phases of the 200 kW laser beams and in the positions of the 40 kg mirrors of the Advanced LIGO detectors yield a joint quantum noise a factor of 1.4 (3 dB) below the SQL.
external pagehttps://www.nature.com/articles/s41586-020-2420-8call_made