Resources of polarimetric sensitivity in spin noise spectroscopy

Glasenapp, Ph.; Greilich, A.; Ryzhov, I. I.; Zapasskiĭ, V. S.; Yakovlev, D. R.; Kozlov, G. G.; Bayer, М.

doi:10.1103/physrevb.88.165314

Cited by 29 publications

(28 citation statements)

References 13 publications

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“…Due to weaker coupling to the probe beam, reported SNR ranges from −50 dB to −20 dB in semiconductor systems (See Table 1 in [26]). Several works have studied how to improve the polarimetric sensitivity [29] or to cancel technical noise sources [7,8,10], but without altering the fundamental tradeoff between sensitivity and broadening processes [29].…”

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confidence: 99%

Squeezed-light spin noise spectroscopy

et al. 2016

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We report quantum enhancement of Faraday rotation spin noise spectroscopy by polarization squeezing of the probe beam. Using natural abundance Rb in 100 Torr of N2 buffer gas, and squeezed light from a sub-threshold optical parametric oscillator stabilized 20 GHz to the blue of the D1 resonance, we observe that an input squeezing of 3.0 dB improves the signal-to-noise ratio by 1.5 dB to 2.6 dB over the combined (power)⊗(number density) ranges (0.5 mW to 4.0 mW)⊗(1.5 ×10 12 cm −3 to 1.3 ×10 13 cm −3 ), covering the ranges used in optimized spin noise spectroscopy experiments. We also show that squeezing improves the trade-off between statistical sensitivity and broadening effects, a previously unobserved quantum advantage.The presence of intrinsic fluctuations of a spin system in thermal equilibrium was first predicted by Bloch [1] and experimentally demonstrated in the 1980's by Aleksandrov and Zapasskii [2]. In the last decade, "spin noise spectroscopy" (SNS) has emerged as a powerful technique for determining physical properties of an unperturbed spin system from its noise power spectrum [3,4]. SNS has allowed measurement of g-factors, nuclear spin, isotope abundance ratios and relaxation rates of alkali atoms [5,6], g-factors, relaxation times and doping concentration of electrons in semiconductors [7][8][9][10][11] and localized holes in quantum dot ensembles [12,13] including single hole spin detection [14]. Recently, SNS has been used to study complex optical transitions and broadening processes [15,16], coherent phenomena beyond linear response [17] and cross-correlations of heterogeneous spin systems [18,19].Spin noise has been measured with nuclear magnetic resonance [20,21] and magnetic force microscopy [22][23][24], but the most sensitive and widely used detection technique is Faraday rotation (FR) [2,5,6], in which the spin noise is mapped onto the polarization of an off-resonant probe. In FR-SNS, spin noise near the Larmor frequency competes with quantum noise [25] of the detected photons, i.e., the optical shot noise. The main figure of merit is η, the peak power spectral density (PSD) due to spin noise over the PSD due to shot noise, called "signal strength" [26] or the "signal-to-noise ratio" (SNR). Reported SNR for single-pass atomic ensembles ranges from 0 dB to 13 dB [5,27], and up to 21 dB in atomic multi-pass cells [28]. Due to weaker coupling to the probe beam, reported SNR ranges from −50 dB to −20 dB in semiconductor systems (See Table 1 in [26]). Several works have studied how to improve the polarimetric sensitivity [29] or to cancel technical noise sources [7,8,10], but without altering the fundamental tradeoff between sensitivity and broadening processes [29].For small optical power P and atomic density n, SNR is linear in each: η ∝ nP . At higher values, light scattering and atomic collisions broaden the spin noise resonances, and thus introduce systematic errors in measurements, e.g. of relaxation rates, that are derived from the SNS linewidth [5][6][7]. This trade-off between statis...

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Squeezed-light spin noise spectroscopy

et al. 2016

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“…For this reason, we assume that spectral dependence of the magneto-optical susceptibility is not strong enough to be responsible for reduction of the OSN signal down to unobservable level at positive detuning. Moreover, the magneto-optical susceptibility of the intracavity Al 0.1 Ga 0.9 As (which, is assumed to be the main source of the noise signal) increases (not much [19]) at shorter wavelengths close to the band gap of Al 0.1 Ga 0.9 As. It should have caused rather an increase of the OSN signal in the spectral region of positive detuning, where we observe no OSN signal at all.…”

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confidence: 99%

Optics of spin-noise-induced gyrotropy of an asymmetric microcavity

et al. 2014

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The optical gyrotropy noise of a high-finesse semiconductor Bragg microcavity with an embedded quantum well (QW) is studied at different detunings of the photon mode with respect to the QW exciton resonances. A strong suppression of the noise magnitude for the photon mode frequencies lying above exciton resonances is found. We show that such a critical behavior of the observed optical noise power is specific to asymmetric Fabry-Perot resonators. As follows from our analysis, at a certain level of intracavity loss, the reflectivity of the asymmetric resonator vanishes, while the polarimetric sensitivity to the gyrotropy changes dramatically when moving across the critical point. The results of model calculations are in a good agreement with our experimental data on the spin noise in a single-quantum-well microcavity and are confirmed also by the spectra of the photoinduced Kerr rotation in the pump-probe experiments.

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“…ν L is to good approximation independent of (n, P ) in the ranges we study. This form, a white noise background plus a Lorentzian spectral feature subject to line broadening with increasing probe power is found in solid state [27] as well as atomic systems. Both broadening and narrowing of resonance lines with increasing dopant concentration is observed in solid state systems [47].…”

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“…Non-optical SNS based on resonance force microscopy [19,20] and NV-center magnetometry [21][22][23] have recently emerged, but still the most widely used technique is optical Faraday rotation (FR) to detect spin orientation [24]. This FR-SNS is used to study spin physics in atomic gases [1,17] as well as conduction electrons [25] and localized states in semiconductors [26,27]. Extensions of SNS include measurements of cross-correlations of heterogeneous spin systems [28,29], spin dynamics beyond thermal equilibrium [30] and multidimensional SNS [31,32], see [33] for a review.…”

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“…Non-optical SNS based on resonance force microscopy [19,20] Quantum statistical fluctuations such as shot noise are often limiting in noise spectroscopies [6,27,34], making it important to understand quantum limits and techniques to overcome them. A general framework to estimate the spectra of noisy classical forces influencing quantum systems has been applied to spectroscopy by homodyne detection of an externally-imposed noisy phase [35].…”

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Sensitivity, quantum limits, and quantum enhancement of noise spectroscopies

et al. 2017

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We study the fundamental limits of noise spectroscopy using estimation theory, Faraday rotation probing of an atomic spin system, and squeezed light. We find a simple and general expression for the Fisher information, which quantifies the sensitivity to spectral parameters such as resonance frequency and linewidth. For optically-detected spin noise spectroscopy, we find that shot noise imposes "local" standard quantum limits for any given probe power and atom number, and also "global" standard quantum limits when probe power and atom number are taken as free parameters. We confirm these estimation theory results using non-destructive Faraday rotation probing of hot Rb vapor, observing the predicted optima and finding good quantitative agreement with a firstprinciples calculation of the spin noise spectra. Finally, we show sensitivity beyond the atom-and photon-number-optimized global standard quantum limit using squeezed light. , and quantum information processing [12][13][14][15][16]. By the fluctuation-dissipation theorem, the noise spectrum under thermal equilibrium gives the same information as do driven spectroscopies, with the advantage of characterizing the system in its natural, undisturbed state [17]. Understanding the statistical sensitivity of noise spectroscopy is essential for rigorous use of the technique in any of these fields. We study this problem from the perspective of parameter estimation theory, to derive the covariance matrix for spectral parameters obtained by fitting experimental spectra.We illustrate and test the results using spin noise spectroscopy (SNS), a versatile technique that measures magnetic resonance features from thermal spin fluctations [18]. Non-optical SNS based on resonance force microscopy [19,20] Quantum statistical fluctuations such as shot noise are often limiting in noise spectroscopies [6,27,34], making it important to understand quantum limits and techniques to overcome them. A general framework to estimate the spectra of noisy classical forces influencing quantum systems has been applied to spectroscopy by homodyne detection of an externally-imposed noisy phase [35]. This framework provides fundamental limits but can be applied to noise spectroscopies only in the weak probing regime, due to the assumed "classical," i.e., imperturbable, nature of the estimated force.In contrast, our results make no classicality assumption. For FR-SNS we show two new results concerning the quantum limits of the technique: first, availability of unlimited particle-number resources gives rise to an optimal sensitivity at finite number, in contrast to standard models from quantum metrology [36,37], which have sensitivity monotonic in particle number and thus must assume an externally-imposed constraint to give meaningful results, and second, the number-optimized standard-quantum-limit sensitivity can be surpassed using squeezed-light probes. These theoretical predictions are tested by comparison against FR-SNS of hot rubidium vapor using a quantum-noise-limited probing system [34] and...

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Resources of polarimetric sensitivity in spin noise spectroscopy

Cited by 29 publications

References 13 publications

Squeezed-light spin noise spectroscopy

Squeezed-light spin noise spectroscopy

Optics of spin-noise-induced gyrotropy of an asymmetric microcavity

Sensitivity, quantum limits, and quantum enhancement of noise spectroscopies

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