Introduction to quantum noise, measurement and amplification. Quantum correlations of light from a room-temperature mechanical oscillator. Quantum nondemolition measurement of a nonclassical state of a massive object. Quantum squeezing of motion in a mechanical resonator. Mechanically detecting and avoiding the quantum fluctuations of a microwave field. Improving broadband displacement detection with quantum correlations. Measurement-based quantum control of mechanical motion. Rossi, M., Mason, D., Chen, J., Tsaturyan, Y. Approaching the quantum limit of a nanomechanical resonator. Optically measuring force near the standard quantum limit.
A gravitational wave observatory operating beyond the quantum shot-noise limit. Quantum variation measurement of a force. In Quantum Optics, Experimental Gravitation, and Measurement Theory (eds Meystre, P. Classical and quantum restrictions on the detection of weak disturbances of a macroscopic oscillator. This achieves an outstanding goal in mechanical quantum sensing and further enhances the prospects of using such devices for state-of-the-art force sensing applications.īraginsky, V. Here, we exploit strong quantum correlations in an ultracoherent optomechanical system to demonstrate off-resonant force and displacement sensitivity reaching 1.5 dB below the SQL. However, so far, no experimental system has successfully demonstrated an interferometric displacement measurement with sensitivity (including all relevant noise sources-thermal, backaction and imprecision) below the SQL. In the half-century since the SQL was established, systems ranging from LIGO 5 to ultracold atoms 6 and nanomechanical devices 7, 8 have pushed displacement measurements towards this limit, and a variety of sub-SQL techniques have been tested in proof-of-principle experiments 9, 10, 11, 12, 13.
To go beyond this limit, one must devise more sophisticated measurement techniques, which either ‘evade’ the backaction of the measurement 2 or achieve clever cancellation of the unwanted noise at the detector 3, 4. In the case of interferometric displacement measurements, these restrictions impose a standard quantum limit (SQL), which optimally balances the precision of a measurement with its unwanted backaction 1. Quantum mechanics dictates that the precision of physical measurements must always comply with certain noise constraints.
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