Quantum Enhanced Optical Measurements: From Ultra-High Sensitivity in Absorption Measurements to Ghost Microscopy

Quantum enhanced optical measurement protocols aim at reducing the uncertainty in the estimation of some physical quantities of a system below the shot-noise limit, classically unavoidable. In particular when small number of photons is used the shot noise can be the main source of uncertainty, in these cases the use of quantum light is of great interest. Note that there are several situations where the number of photons in the probe can not be increased arbitrarily, as when fragile biological samples are under investigation. Two different imaging protocols are discussed in the following.

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Optical Measurements of Weak Absorption Beyond Shot-Noise Limit

Quantum Communication, Computing, and Measurement ◽

10.1007/978-1-4615-5923-8_48 ◽

1997 ◽

pp. 445-453

Author(s):

Wang Hai ◽

Xie Changde ◽

Pan Qing ◽

Xue Chenyang ◽

Zhang Yun ◽

...

Keyword(s):

Shot Noise ◽

Optical Measurements ◽

Weak Absorption ◽

Noise Limit ◽

Shot Noise Limit

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Surpassing the shot-noise limit by homodyne-mediated feedback

Optics Letters ◽

10.1364/ol.41.003932 ◽

2016 ◽

Vol 41 (17) ◽

pp. 3932 ◽

Cited By ~ 4

Author(s):

Guofeng Zhang ◽

Hanjie Zhu

Keyword(s):

Shot Noise ◽

Noise Limit ◽

Shot Noise Limit

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Overcoming detection loss and noise in squeezing-based optical sensing

npj Quantum Information ◽

10.1038/s41534-021-00407-0 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Gaetano Frascella ◽

Sascha Agne ◽

Farid Ya. Khalili ◽

Maria V. Chekhova

Keyword(s):

Shot Noise ◽

Optical Sensing ◽

Detection Efficiency ◽

Signal To Noise Ratio ◽

Real Life ◽

Squeezed States ◽

Squeezed Light ◽

Noise Limit ◽

Imaging And Spectroscopy ◽

Shot Noise Limit

AbstractAmong the known resources of quantum metrology, one of the most practical and efficient is squeezing. Squeezed states of atoms and light improve the sensing of the phase, magnetic field, polarization, mechanical displacement. They promise to considerably increase signal-to-noise ratio in imaging and spectroscopy, and are already used in real-life gravitational-wave detectors. But despite being more robust than other states, they are still very fragile, which narrows the scope of their application. In particular, squeezed states are useless in measurements where the detection is inefficient or the noise is high. Here, we experimentally demonstrate a remedy against loss and noise: strong noiseless amplification before detection. This way, we achieve loss-tolerant operation of an interferometer fed with squeezed and coherent light. With only 50% detection efficiency and with noise exceeding the level of squeezed light more than 50 times, we overcome the shot-noise limit by 6 dB. Sub-shot-noise phase sensitivity survives up to 87% loss. Application of this technique to other types of optical sensing and imaging promises a full use of quantum resources in these fields.

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Optimization of Detectability in Laser-Based Polarimeters

Applied Spectroscopy ◽

10.1366/0003702894204425 ◽

1989 ◽

Vol 43 (8) ◽

pp. 1337-1341 ◽

Cited By ~ 6

Author(s):

Xiaobing Xi ◽

Edward S. Yeung

Keyword(s):

Shot Noise ◽

Experimental Verification ◽

High Frequency ◽

Ohmic Heating ◽

Unit Length ◽

Power Input ◽

Upper Limit ◽

High Modulation ◽

Noise Limit ◽

Shot Noise Limit

To optimize the performance of a laser-based polarimeter, a mathematical simulation was performed. High-modulation currents allow a corresponding increase in signal. However, the effect of ohmic heating puts an upper limit on the power input to the solenoid. With this constraint, one can systematically choose the wire diameter and the number of turns per unit length. An experimental verification of the optimized parameters provided performance approaching the shot-noise limit. By using higher modulation currents, one can operate at 1 kHz to achieve detectability in the microdegree range, without the complications of high-frequency (100 kHz) modulation.

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