QOOMS

Quantum optics with optomechanical systems

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 Obiettivo del progetto (Objective)

'Interferometric measurements are by far the most sensitive displacement measurements , with sensitivities better than 10-20m/sqrt(Hz) either for large-scale gravitational-wave interferometers or table-top interferometers.

In these measurements, there are two quantum limits one has to deal with, even after the classical noise has been substantially lowered: quantum phase noise and quantum radiation-pressure noise. The currently operated gravitational-wave interferometers are limited by quantum phase noise at high frequency and the second generation (Advanced Ligo and Advanced Virgo), scheduled for the middle of the decade, will also be limited by quantum-radiation pressure noise at low frequency. Though ubiquitous, such effects are so weak that they have not been experimentally demonstrated yet.

The objectives of this project are the followings: -Design and operate an optomechanical resonator where quantum radiation-pressure noise prevails over thermal noise. -Use it in quantum optics experiments: squeezing and quantum non-demolition measurement. -On a longer term, inject squeezed light into a quantum radiation-pressure noise driven interferometer.'

Introduzione (Teaser)

An EU-funded project sought to shed further insight into the noise caused by radiation pressure between laser and matter interaction by using optomechanical cavities.

Descrizione progetto (Article)

Interferometry is widely used in measuring small displacements with very high sensitivity values. However, even if all classical sources of error have been eliminated from the measurement process, quantum noise is limiting gravitational wave or table-top interferometer sensitivities.

To further study this phenomenon, the EU-funded project 'Quantum optics with optomechanical systems' (QOOMS) developed an optomechanical resonator where quantum radiation pressure noise (QRPN) prevailed over thermal noise. The resonator's highly reflective mirror surfaces allowed high optical finesse and increased the intracavity intensity fluctuations that give rise to QRPN.

Scientists used a set-up where correlations between two light beams were created and sent into a high-finesse optical Fabry-Perot cavity. Monitoring correlations between the intensity of the first beam and the phase of the probe beam enabled them to demonstrate the QRPN effects. As contamination was apparent in measurements, scientists operated the cavity in a cryostat, thus reducing thermal noise by two orders of magnitude.

QOOMS also developed a quartz micro-mechanical resonator and integrated it in the set-up. Several techniques were developed for coating the high-reflectivity mirror on top of the resonator. The high optical finesse provided by such low-loss coatings dramatically increased both displacement sensitivity and QRPN effects.

Project work significantly enhanced knowledge about quantum noise in interferometric measurements.