Biological measurement beyond the quantum limit

Taylor, Michael A.; Janoušek, Jiří; Daria, Vincent Ricardo; Knittel, Joachim; Hage, B.; Bachor, Hans‐A.; Bowen, Warwick P.

doi:10.1038/nphoton.2012.346

Cited by 470 publications

(323 citation statements)

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“…This initial research was mainly pursued as a strategy to mitigate the effects of shot-noise given the possibility of improved optical communication [7] and better sensitivity in gravitational wave detectors [3,8]. In recent years, in addition to being installed in gravitational wave detectors [14], squeezed light has enhanced metrology in more applied settings [15].The vacuum fluctuations arising from the quantum nature of light determine our ability to optically resolve mechanical motion and set limits on the perturbation caused by the act of measurement [16]. A well-suited system to experimentally study quantum measurement is that of cavity-optomechanics, where an optical cavity's resonance frequency can be designed to be sensitive to the position of a mechanical system.…”

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Squeezed light from a silicon micromechanical resonator

Safavi-Naeini

Gröblacher

Hill

et al. 2013

Nature

532

458

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We present the measurement of squeezed light generation using an engineered optomechanical system fabricated from a silicon microchip and composed of a micromechanical resonator coupled to a nanophotonic cavity. Laser light is used to measure the fluctuations in the position of the mechanical resonator at a measurement rate comparable to the free dynamics of the mechanical resonator, and greater than its thermal decoherence rate. By approaching the strong continuous measurement regime we observe, through homodyne detection, non-trivial modifications of the reflected light's vacuum fluctuation spectrum. In spite of the mechanical resonator's highly excited thermal state (10, 000 phonons), we observe squeezing at the level of 4.5 ± 0.5% below that of shot-noise over a few MHz bandwidth around the mechanical resonance frequency of 28 MHz. This squeezing is interpreted as an unambiguous quantum signature of radiation pressure shot-noise.Monitoring a mechanical object's motion, even with the gentle touch of light, fundamentally alters its dynamics. The experimental manifestation of this basic principle of quantum mechanics, its link to the quantum nature of light, and the extension of quantum measurement to the macroscopic realm have all received extensive attention over the last half century [1,2]. The use of squeezed light, with quantum fluctuations below that of the vacuum field, was proposed nearly three decades ago [3] as a means for beating the standard quantum limits in precision displacement and force measurements. Conversely, it has also been proposed that a strong continuous measurement of a mirror's position with light, may itself give rise to squeezed light [4,5]. In this Letter, we present such a continuous position measurement using an engineered optomechanical system fabricated from a silicon microchip and composed of a micromechanical resonator coupled to a nanophotonic cavity. Laser light is used to measure the fluctuations in the position of the mechanical resonator at a measurement rate comparable to the free dynamics of the mechanical resonator, and greater than its thermal decoherence rate. By approaching the strong continuous measurement regime we observe, through homodyne detection, non-trivial modifications of the reflected light's vacuum fluctuation spectrum. In spite of the mechanical resonator's highly excited thermal state (10 4 phonons), we observe squeezing at the level of 4.5 ± 0.5% below that of shot-noise over a few MHz bandwidth around the mechanical resonance frequency of ω m /2π ≈ 28 MHz. This * These authors contributed equally to this work.† Electronic address: opainter@caltech.edu; URL: http://copilot. caltech.edu squeezing is interpreted as an unambiguous quantum signature of radiation pressure shot-noise [6]. The generation of states of light with fluctuations below that of vacuum has been of great theoretical interest since the 1970s [3,[7][8][9]. Early experimental work demonstrated squeezing of a few percent in a large variety of different nonlinear systems, such as neutral...

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confidence: 99%

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confidence: 99%

Squeezed light from a silicon micromechanical resonator

Safavi-Naeini

Gröblacher

Hill

et al. 2013

Nature

532

458

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“…The photoconvective forces we demonstrate here provide a new tool for high bandwidth control of mechanical motion in cryogenic conditions, while the ability to apply forces remotely, combined with the persistence of flow in superfluids, offers the prospect for new applications. DOI: 10.1103/PhysRevX.6.021012 Subject Areas: Photonics, Quantum Physics, SuperfluidityOptical forces are widely utilized in photonic circuits [1,2], micromanipulation [3,4], and biophysics [5,6]. In cavity optomechanics, in particular, optical forces enable cooling and control of microscale mechanical oscillators that can be used for ultrasensitive detection of forces, fields and mass [7][8][9], quantum and classical information systems [10], and fundamental science [11,12].…”

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Microphotonic Forces from Superfluid Flow

et al. 2016

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In cavity optomechanics, radiation pressure and photothermal forces are widely utilized to cool and control micromechanical motion, with applications ranging from precision sensing and quantum information to fundamental science. Here, we realize an alternative approach to optical forcing based on superfluid flow and evaporation in response to optical heating. We demonstrate optical forcing of the motion of a cryogenic microtoroidal resonator at a level of 1.46 nN, roughly 1 order of magnitude larger than the radiation pressure force. We use this force to feedback cool the motion of a microtoroid mechanical mode to 137 mK. The photoconvective forces we demonstrate here provide a new tool for high bandwidth control of mechanical motion in cryogenic conditions, while the ability to apply forces remotely, combined with the persistence of flow in superfluids, offers the prospect for new applications. DOI: 10.1103/PhysRevX.6.021012 Subject Areas: Photonics, Quantum Physics, SuperfluidityOptical forces are widely utilized in photonic circuits [1,2], micromanipulation [3,4], and biophysics [5,6]. In cavity optomechanics, in particular, optical forces enable cooling and control of microscale mechanical oscillators that can be used for ultrasensitive detection of forces, fields and mass [7][8][9], quantum and classical information systems [10], and fundamental science [11,12]. Recent progress has seen radiation pressure used for coherent state swapping [13], ponderomotive squeezing [14], and ground state cooling [15], while static gradient forces have enabled all-optical routing [16] and nonvolatile mechanical memories [17]. Likewise, photothermal forces, where the mechanical element moves in response to mechanical stress from localized optical absorption and heating, have been used to demonstrate cavity cooling of a semiconductor membrane [18,19], single molecule force spectroscopy [20], and rich chaotic dynamics in suspended mirrors [21].Here, we demonstrate an alternative photoconvective approach to optical forcing that allows an order-ofmagnitude stronger mechanical actuation than radiation pressure. In our implementation, this technique utilizes the convection in superfluids, whereby frictionless fluid flow is generated in response to a local heat source. This well-known superfluid fountain effect [22] is a direct manifestation of the phenomenological two-fluid model proposed by Landau [23] and Tisza [24]. The momentum carried by the helium-4 flow is then transferred to a mechanical element via collision and recoil of superfluid atoms. If the heat source is localized upon the mechanical element, the incident superfluid atoms are either converted to a normal fluid counterflow or evaporated [see Figs. 1(a) and 1(b)]. Alternatively, a distant heat source could be utilized with the mechanical element acting to reroute the superflow.Strong actuation forces are important for a range of techniques in quantum optomechanics, and, most particularly, for protocols that utilize precise measurements combined with feedback act...

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“…We observe such quantum correlations in single images obtained with bright pulsed twin-beams with ∼ 10 8 photons in 1 µs pulses, which correspond to a photon flux of 10 14 photon pairs per second. This makes bright twin-beams a useful candidate for quantum imaging and quantum metrology applications that require in-situ real time imaging, such as particle tracking in biological samples [20], Bose-Einstein condensates [21,22], and trapped single atoms [23].As a source of bright twin-beams of light, we use a four-wave mixing (FWM) process in a double-Λ configuration in an atomic vapor. In recent years, twin-beams have gained considerable attention due to their applications in quantum information, quantum computing, and quantum metrology [1,[24][25][26][27][28][29][30][31].…”

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Observation of spatial quantum correlations in the macroscopic regime

2017

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Spatial quantum correlations in the transverse degree of freedom promise to enhance optical resolution, image detection, and quantum communications through parallel quantum information encoding. In particular, the ability to observe these spatial quantum correlations in a single shot will enable such enhancements in applications that require real time imaging, such as particle tracking and in-situ imaging of atomic systems. Here, we report on measurements in the far-field that show spatial quantum correlations in single images of bright twin-beams with 10 8 photons in a 1 µs pulse using an electron-multiplying charge-coupled device camera. A four-wave mixing process in hot rubidium atoms is used to generate narrowband-bright pulsed twin-beams of light. Owing to momentum conservation in this process, the twin-beams are momentum correlated, which leads to spatial quantum correlations in the far field. We show around 2 dB of spatial quantum noise reduction with respect to the shot noise limit. The spatial squeezing is present over a large range of total number of photons in the pulsed twin-beams.PACS numbers: 42.50. Dv, 42.50.Ar, Under certain conditions, the quantum fluctuations in beams of light can be reduced below the shot noise limit (SNL) not only in the temporal domain, but also in the transverse spatial degree of freedom [1]. To date, most of the attention has focused on the study of quantum noise reduction, or squeezing, in the temporal domain [2][3][4][5][6][7][8][9][10][11][12]. Nevertheless, many areas in quantum optics, specifically quantum metrology and quantum imaging, could greatly benefit from the study of the quantum correlations directly in the spatial domain [13][14][15]. This would make it possible to take advantage of the spatial quantum properties of light, such as spatial squeezing, for enhanced spatial resolution and sub shot noise imaging [14].With this in mind, a few groups have recently experimentally demonstrated sub-shot noise spatial correlations using an electron-multiplying charge-coupled device (EMCCD) camera in photon pairs generated through spontaneous parametric down conversion (SPDC) [16][17][18]. As a proof of principle of a potential application of spatial quantum correlations in quantum imaging, Brida et al.[19] imaged a weak absorbing object with significantly higher signal-to-noise ratio than what is possible with classical light. However, the intensity levels were limited by the source and are orders of magnitude lower than what is used in standard imaging techniques. While these initial experiments provided an indication that spatial quantum correlations can lead to significant enhancements, many applications in quantum imaging and quantum metrology require real time imaging and, as such, require the ability to observe the spatial quantum correlations in a single shot with a controllable and macroscopic number of photons. In addition, the use of such a large number of photons can lead to a more sig- * ashok@ou.edu † marino@ou.edu nificant sensitivity enhancement due to t...

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Biological measurement beyond the quantum limit

Cited by 470 publications

References 36 publications

Squeezed light from a silicon micromechanical resonator

Squeezed light from a silicon micromechanical resonator

Microphotonic Forces from Superfluid Flow

Observation of spatial quantum correlations in the macroscopic regime

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