Evading Vacuum Noise: Wigner Projections or Husimi Samples?

Coherent beam combining refers to the process of generating a bright output beam by merging independent input beams of individually diffusing relative phases by locking them to each other. We report the first quantum mechanical noise limit calculations for coherent beam combining and compare our results to quantum-limited amplification. Our coherent beam combining scheme is based on an optical Fourier transformation which renders the scheme compatible with integrated optics combined with feed-back stabilization of the relative phases. The scheme can be layed out for an arbitrary number of input beams and approaches the shot noise limit for a large number of inputs.

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“…The measurement on the non-commuting observables results in the 3 dB penalty, as e.g. characteristic in heterodyne detection [25].…”

Section: A4 Quantum-limited Linear Amplification By Multiple Amplifmentioning

confidence: 99%

The standard quantum limit of coherent beam combining

et al. 2019

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“…In Refs. [43] and [44], we theoretically and experimentally compared the two measurement schemes, using a polarization-squeezing setup [45][46][47][48][49][50] for the latter. We analyzed the physical implications of having the unavoidable Arthurs-Kelly type noise that is inherent in the joint measurement heterodyne scheme on moment reconstruction.…”

Section: Introductionmentioning

confidence: 99%

Superiority of heterodyning over homodyning: An assessment with quadrature moments

Teo¹,

Mueller²,

Jeong³

et al. 2017

Phys. Rev. A

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We examine the moment-reconstruction performance of both the homodyne and heterodyne (doublehomodyne) measurement schemes for arbitrary quantum states and introduce moment estimators that optimize the respective schemes for any given data. In the large-data limit, these estimators are as efficient as the maximum-likelihood estimators. We then illustrate the superiority of the heterodyne measurement for the reconstruction of the first and second moments by analyzing Gaussian states and many other significant nonclassical states. Finally, we present an extension of our theories to two-mode sources, which can be straightforwardly generalized to all other multimode sources.

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“…Homodyne detection yields continuously distributed quadrature projections, which in practice are sometimes deliberately discretized. In optical quantum information processing [19][20][21][22][23] this is exemplified by quantum key distribution protocols [24], and by tests of Bell's inequalities [25][26][27][28][29], which inherently require to discretize the homodyne outcomes to binary values.Optical homodyne detectors are ubiquitous in telecommunications and can even be found on optical satellites already in orbit. Such satellites are promising candidates for exploring quantum technology and bringing fundamental tests of quantum mechanics to space both rapidly and cost-effectively.…”

mentioning

confidence: 99%

“…Binary Homodyne Detection-In the following, we introduce the binary homodyne observable and describe how its expectation value can be controlled via a coherent displacement. We consider detecting a Gaussian state, for which the ellipticity [23], i.e. the ratio between the major-and minor semi-axis of its phase space distribution, is unknown but has one of two possible values.…”

mentioning

confidence: 99%

Binary Homodyne Detection for Observing Quadrature Squeezing in Satellite Links

Müller

Seshadreesan

Peuntinger

et al. 2018

CLEO Pacific Rim Conference

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Optical satellite links open up new prospects for realizing quantum physical experiments over unprecedented length scales. We analyze and affirm the feasibility of detecting quantum squeezing in an optical mode with homodyne detection of only one bit resolution, as is found in satellites already in orbit. We show experimentally that, in combination with a coherent displacement, a binary homodyne detector can still detect quantum squeezing efficiently even under high loss. The sample overhead in comparison to non-discretized homodyne detection is merely a factor of 3.3.The laws of quantum mechanics have been validated by numerous fundamental tests [1]. With the advent of optical satellite links [2][3][4][5][6] it is now possible to also validate quantum mechanics over vast distances and a varying gravitational potentials. This includes nonclassical states [7] such as quadrature squeezed states of the light field [8,9]. Squeezing is efficiently measured via homodyne detection [10], a measurement technique of utmost importance not only in optics, but in diverse physical architectures such as optomechanical resonators [11], superconducting qubits [12,13], spin ensembles [14-17] and Bose-Einstein condensates [18]. Homodyne detection yields continuously distributed quadrature projections, which in practice are sometimes deliberately discretized. In optical quantum information processing [19][20][21][22][23] this is exemplified by quantum key distribution protocols [24], and by tests of Bell's inequalities [25][26][27][28][29], which inherently require to discretize the homodyne outcomes to binary values.Optical homodyne detectors are ubiquitous in telecommunications and can even be found on optical satellites already in orbit. Such satellites are promising candidates for exploring quantum technology and bringing fundamental tests of quantum mechanics to space both rapidly and cost-effectively. Satellite links, however, imply considerable channel loss which reduces the observable squeezing value. Moreover, as currently the primary application of optical satellites is classical communication via binary phase-shift keying, only the sign of the homodyne signal is relevant and the data is often projected into binary outcomes during signal processing [30,31]. The question arises whether under such strong technical constraints quadrature squeezing can still be detected.Extreme discretization into binary outcomes has been studied extensively for photon number measurements. Photon "on-off" detection and the photon number parity measurement were shown to allow for (near-) optimal applications in quantum state discrimination [32][33][34][35][36] and quantum optical metrology [37-42]. Discretized homodyne detection schemes were used for witnessing single photon entanglement [43] and for super-resolved imaging with coherent states [44].In this Letter, we investigate fundamental limits of discretized homodyne measurements, particularly focusing on the detection of quadrature squeezing. We consider the extreme case of a binary homody...

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Evading Vacuum Noise: Wigner Projections or Husimi Samples?

Cited by 22 publications

References 47 publications

The standard quantum limit of coherent beam combining

The standard quantum limit of coherent beam combining

Superiority of heterodyning over homodyning: An assessment with quadrature moments

Binary Homodyne Detection for Observing Quadrature Squeezing in Satellite Links

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