Mechanical Squeezing via Fast Continuous Measurement

Mechanical squeezing via parametric amplification and weak measurement.

Nonlinear forces allow motion of a mechanical oscillator to be squeezed below the zero-point motion. Of existing methods, mechanical parametric amplification is relatively accessible, but previously thought to be limited to 3 dB of squeezing in the steady state. We consider the effect of applying continuous weak measurement and feedback to this system. If the parametric drive is optimally detun...

Strong thermomechanical squeezing via weak measurement.

We experimentally surpass the 3 dB limit to steady-state parametric squeezing of a mechanical oscillator. The localization of an atomic force microscope cantilever, achieved by optimal estimation, is enhanced by up to 6.2 dB in one position quadrature when a detuned parametric drive is used. This squeezing is, in principle, limited only by the oscillator Q factor. Used on low temperature, high ...

Quantum state reconstruction via continuous measurement.

We present a new procedure for quantum state reconstruction based on weak continuous measurement of an ensemble average. By applying controlled evolution to the initial state, new information is continually mapped onto the measured observable. A Bayesian filter is then used to update the state estimate in accordance with the measurement record. This generalizes the standard paradigm for quantum...

Polarization squeezing and continuous-variable polarization entanglement

Natalia Korolkova, Gerd Leuchs, Rodney Loudon, Timothy C. Ralph, and Christine Silberhorn Lehrstuhl für Optik, Physikalisches Institut, Friedrich-Alexander-Universität, Staudtstrasse 7/B2, D-91058 Erlangen, Germany Department of Electronic Systems Engineering, Essex University, Colchester CO4 3SQ, United Kingdom Department of Physics, University of Queensland, St. Lucia, Queensland 4072, Austra...

Spin squeezing via quantum feedback