Approaching the quantum limit of precision in absorbance estimation using classical resources

Allen, Euan J.; Sabines-Chesterking, Javier; McMillan, Alex; Joshi, Siddarth Koduru; Turner, Peter S.; Matthews, Jonathan C. F.

doi:10.1103/physrevresearch.2.033243

Cited by 15 publications

(19 citation statements)

References 31 publications

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“…We find that when the power in the electronic sideband is much greater than the power in the electronic noise, Var(N ) contributes negligibly to F(δ m ), and from equation (2)(3)(4)(5)(6)(7), this leads to…”

mentioning

confidence: 90%

“…Because the QNL scales with ∼ 1/ √ n, longer measurements and higher intensity can increase precision. We may also increase precision with more interaction between probe and sample via multiple passes [2,3] or optimising sample concentration [4]. However, there can often exist restrictions on the total optical exposure, the measurement time and sample concentration [5].…”

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confidence: 99%

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Quantum Enhanced Precision Estimation of Transmission with Bright Squeezed Light

Atkinson,

Allen,

Ferranti

et al. 2020

Preprint

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Squeezed light has lower quantum noise in amplitude or phase than the quantum noise limit (QNL) of classical light. This enables enhancing sensitivity -quantified by the signal-to-noise ratio (SNR) -to beyond the QNL in optical techniques such as spectroscopy, gravitational wave detection, magnetometry and imaging. Precision -the variance of repeated estimates -has also been enhanced beyond the QNL using squeezed vacuum to estimate optical phase and transmission. However, demonstrations have been limited to femtowatts of probe power. Here we demonstrate simultaneous precision and sensitivity beyond the QNL for estimating modulated transmission using a squeezed amplitude probe of 0.2 mW average (25 W peak) power. This corresponds to 8 orders of magnitude above the power limitations of previous sub-QNL precision measurements. Our theory and experiment show precision enhancement scales with the amount of squeezing and increases with the resolution bandwidth of detection. We conclude that quantum enhanced precision in estimating a modulated transmission increases when observing dynamics at ∼ kHz and above. This opens the way to performing measurements that compete with the optical powers of current classical techniques, but have superior precision and sensitivity beyond the classical limit.

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confidence: 90%

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confidence: 99%

Quantum Enhanced Precision Estimation of Transmission with Bright Squeezed Light

Atkinson,

Allen,

Ferranti

et al. 2020

Preprint

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“…The optimality of a Fock state probe in intensity sensing has been exploited in various types of sensing, such as in absorption spectroscopy to analyze the organic dye molecule dibenzanthanthrene [225] or haemoglobin [see Figure 12(a)] [219]. Other relevant studies include quantum polarimetry to measure the optical rotation occurring in chiral media [see Figure 12(b)] [213] and an experiment to measure the absorbance of a lossy medium [see Figure 12(c)] [220]. Of particular interest to this review is that the Fock state probe has recently been used in plasmonic sensing [226], whose details will be discussed in section IV A.…”

Section: Quantum-enhanced Intensity Sensingmentioning

confidence: 99%

Quantum Plasmonic Sensors

et al. 2021

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The extraordinary sensitivity of plasmonic sensors is well known in the optics and photonics community. These sensors exploit simultaneously the enhancement and the localization of electromagnetic fields close to the interface between a metal and a dielectric. This enables, for example, the design of integrated biochemical sensors at scales far below the diffraction limit. Despite their practical realization and successful commercialization, the sensitivity and associated precision of plasmonic sensors are starting to reach their fundamental classical limit given by quantum fluctuations of light -known as the shot-noise limit. To improve the sensing performance of these sensors beyond the classical limit, quantum resources are increasingly being employed. This area of research has become known as 'quantum plasmonic sensing' and it has experienced substantial activity in recent years for applications in chemical and biological sensing. This review aims to cover both plasmonic and quantum techniques for sensing, and shows how they have been merged to enhance the performance of plasmonic sensors beyond traditional methods. We discuss the general framework developed for quantum plasmonic sensing in recent years, covering the basic theory behind the advancements made, and describe the important works that made these advancements. We also describe several key works in detail, highlighting their motivation, the working principles behind them, and their future impact. The intention of the review is to set a foundation for a burgeoning field of research that is currently being explored out of intellectual curiosity and for a wide range of practical applications in biochemistry, medicine, and pharmaceutical research.

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“…Effective states for parameter estimation are identified as being non-classical states of light: single-photon states [13,14], multi-photon states [15][16][17], or squeezed states [18][19][20][21] capable of enhancing performance under linear loss or phase for a fixed resource level [11,[22][23][24]. Results thus far have focused on the linear absorption regime, with the exception of work by Mitchell [25] which models the effect of con-strained photon number on the performance of Gaussian states for single-parameter estimation.…”

mentioning

confidence: 99%

“…Classical probe performance.-A classical laser probe is well approximated by a coherent state [34] |α with nin = |α| 2 and Var(n in ) = nin . In direct absorption schemes, the QCRB is saturated by direct transmission measurements [24]. We calculate F (η) and relate it to the FI on the linear absorption coefficient, F (a), using the following formula: F (a) = (∂η/∂a) 2 F (η).…”

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confidence: 99%

Maximising Precision in Saturation-Limited Absorption Measurements

Biele,

Wollmann,

Silverstone

et al. 2021

Preprint

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Quantum fluctuations in the intensity of an optical probe is noise which limits measurement precision in absorption spectroscopy. Increased probe power can offer greater precision, however, this strategy is often constrained by sample saturation. Here, we analyse measurement precision for a generalised absorption model in which we account for saturation and explore its effect on both classical and quantum probe performance. We present a classical probe-sample optimisation strategy to maximise precision and find that optimal probe powers always fall within the saturation regime. We apply our optimisation strategy to two examples, highprecision Doppler broadened thermometry and an absorption spectroscopy measurement of Chlorophyll A. We derive a limit on the maximum precision gained from using a non-classical probe and find a strategy capable of saturating this bound. We evaluate amplitude-squeezed light as a viable experimental probe state and find it capable of providing precision that reaches to within > 85% of the ultimate quantum limit with currently available technology.Absorption spectroscopy exploits light-matter interactions to give precise measurements of sample composition. This technique is widely applied with key use-cases including drug analysis [1], environmental monitoring [2], atomic characterisation [3], and industrial process monitoring [4]. In absorption spectroscopy, exceeding sample-specific probe intensities often leads to irreversible damage through a host of saturation-dependent mechanisms [5,6]. Investigating probe performance in the saturation regime is therefore crucial for simultaneously optimising performance and minimising irreversible damage [7][8][9] of delicate samples such as archaeological finds, living cells, or food products [4,10,11]. Intensity dependent quantum noise within the probe scales favourably with probe power but fundamentally limits the precision of absorption measurements. Consequently, the saturation intensity of the sample places a bound on the achievable measurement precision.

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Approaching the quantum limit of precision in absorbance estimation using classical resources

Cited by 15 publications

References 31 publications

Quantum Enhanced Precision Estimation of Transmission with Bright Squeezed Light

Quantum Enhanced Precision Estimation of Transmission with Bright Squeezed Light

Quantum Plasmonic Sensors

Maximising Precision in Saturation-Limited Absorption Measurements

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