Optical levitation is a subfield of optomechanics, in which a nanometer-size particle is trapped in a vacuum chamber at the focal spot of a laser focused through a microscope objective [1]. The laser beam produces an optical force equivalent to a mechanical spring and the system can be regarded as a simple mass-spring resonator displaying pristine vibrational oscillations in the kHz regime. Because levitated systems outperform other types of mechanical resonators, they are currently exploited to achieve high-sensitivity metrology, detect gravitational waves or search for dark matter. Yet, despite their simplicity, levitated systems provide a remarkable interaction between the mechanical motion of the particle and the light field, which can be
harnessed to generate quantum properties.
Ponderomotive squeezing, also known as
the mechanically-assisted quantum squeezing of light, provides an interesting illustration of such a property. Here, the intensity fluctuations of the optical field produce small displacements of the particle, which in turn modulate the phase of the photons that are reflected back from the nano-object. Therefore, one induces a correlation between intensity and phase fluctuations onto the reflected optical field that give rise to
quantum-squeezed states of light (i.e., with an uncertainty below that of “classical” states). Achieved here on an extremely simple configuration, such squeezed states are of formidable importance to perform measurements below the standard quantum limit (and especially looked after in environments like the LIGO/VIRGO gravitational waves platforms). Yet, despite early demonstrations [2,3], squeezing performances currently reported with levitated objects are
rather limited due to the moderate strength of the light- matter interaction between the nano-object and the optical field.
In this internship, the candidate will
experimentally study how quantum squeezing can be improved through a spatial modulation of the optical field. Using a spatial light modulator, the incoming light field will be spatially shaped to maximize the radiation pressure (i.e., optical force) exerted onto the nano-object [4] and thus bolster light-matter interaction and squeezing. The student will be closely guided by the advisor and will acquire both theoretical and experimental skills on
optomechanics, levitation, quantum optics and in spatial modulation techniques.
A funding is available to expand this internship through a PhD.
[1] Millen et al., Reports on Progress in Physics, 83(2), 026401.
[2] Magrini et al., Physical Review Letters, 129(5), 053601.
[3] Militaru et al., Physical Review Letters, 129(5), 053602.
[4] Hüpfl and Bachelard et al., Physical Review Letters, 130(8), 083203.