Nicolai Grosse

Australian National University, Canberra, Australian Capital Territory, Australia

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Publications (21)76.27 Total impact

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    ABSTRACT: We present methods of transforming the standard quadrature amplitude squeezing of a continuous-wave light beam to its Stokes parameters and transverse spatial modes statistics. These two states of light are called polarization squeezing and spatial squeezing, respectively. We present experimental results of the quadrature amplitude, polarization and spatial squeezing obtained with a common experimental setup based on optical parametric amplifiers. The transformations from quadrature amplitude to polarization and spatial squeezing are achieved with only simple linear optics.
    Proceedings of SPIE - The International Society for Optical Engineering 01/2011; DOI:10.1117/12.497081 · 0.20 Impact Factor
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    ABSTRACT: We report on the generation of entangled states of light between the wavelengths 810 and 1550 nm in the continuous variable regime. The fields were produced by type I optical parametric oscillation in a standing-wave cavity build around a periodically poled potassium titanyl phosphate crystal, operated above threshold. Balanced homodyne detection was used to detect the non-classical noise properties, while filter cavities provided the local oscillators by separating carrier fields from the entangled sidebands. We were able to obtain an inseparability of I=0.82, corresponding to about -0.86 dB of non-classical quadrature correlation.
    11/2010; DOI:10.1063/1.3630183
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    ABSTRACT: We have experimentally demonstrated how two beams of light separated by an octave in frequency can become entangled after their interaction in a chi;{(2)} nonlinear medium. The entangler was a nonlinear optical resonator that was strongly driven by coherent light at the fundamental and second-harmonic wavelengths. An interconversion between the fields created quantum correlations in the amplitude and phase quadratures, which were measured by two independent homodyne detectors. Analysis of the resulting correlation matrix revealed a wave function inseparability of 0.74(1)<1, thereby satisfying the criterion of entanglement.
    Physical Review Letters 06/2008; 100(24):243601. DOI:10.1103/PhysRevLett.100.243601 · 7.51 Impact Factor
  • Nicolai B. Grosse · Syed M. Assad · Moritz Mehmet · Thomas Symul · Ping Koy Lam
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    ABSTRACT: We theoretically investigate EPR entanglement in continuous-variable quadrature measurements between the fundamental and second-harmonic fields generated in the degenerate second-order nonlinear optical process. The parameters that optimize entanglement are found.
    Quantum-Atom Optics Downunder; 12/2007
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    ABSTRACT: We experimentally demonstrate a homodyne detection technique for measuring second-order coherence of quantum states of light at sideband frequencies. Our scheme is based on the original Hanbury-Brown-Twiss intensity interferometer with only homodyne detections. We show that for displaced squeezed states, strongly bunched or anti-bunched light are related to regimes of Bell's inequality violation for a Franson interferometer. For strong bunching, the entanglement is manifested by the pair detection of photons, while anti-bunching produces "hole"-entanglement.
    Quantum-Atom Optics Downunder; 12/2007
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    ABSTRACT: We consider the quantum cloning of continuous variable entangled states. This is achieved by introducing two symmetric entanglement cloning machines (or e-cloners): a local e-cloner and a global e-cloner; where we look at the preservation of entanglement in the clones under the condition that the fidelity of the clones is maximized. These cloning machines are implemented using simple linear optical elements such as beam splitters and homodyne detection along with squeeze gates. We show that the global e-cloner out-performs the local e-cloner both in terms of the fidelity of the cloned states as well as the strength of the entanglement of the clones. There is a minimum strength of entanglement (3dB for the inseparability criterion and 5.7dB for the EPR paradox criterion) of the input state of the global e-cloner that is required to preserve the entanglement in the clones. Comment: 11 pages, 6 figures
    Physical Review A 10/2007; 77(5). DOI:10.1103/PhysRevA.77.052313 · 2.99 Impact Factor
  • N.B. Grosse · T. Symul · M. Stobinska · T.C. Ralph · P.K. Lam
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    ABSTRACT: Photon anti-bunching, or the tendency of photons to be detected apart from one another, is characterized by the second-order coherence function which has previously been measured using discrete-variable (DV) single-photon counting methods. The authors theoretically propose and experimentally demonstrate a continuous-variable (CV) technique for measuring the second-order coherence of quantum states of light at sideband frequencies. The scheme is based on the original Hanbury-Brown-Twiss (HBT) intensity interferometer, but instead uses optical homodyne detection in each arm, to obtain the second-order coherence from a set of quadrature amplitude correlation measurements (each of which can be independently time-averaged).
    Lasers and Electro-Optics, 2007 and the International Quantum Electronics Conference. CLEOE-IQEC 2007. European Conference on; 07/2007
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    ABSTRACT: We present a technique for measuring the second-order coherence function g(2)(tau) of light using a Hanbury Brown-Twiss intensity interferometer modified for homodyne detection. The experiment was performed entirely in the continuous-variable regime at the sideband frequency of a bright carrier field. We used the setup to characterize g(2)(tau) for thermal and coherent states and investigated its immunity to optical loss. We measured g(2)(tau) of a displaced-squeezed state and found a best antibunching statistic of g(2)(0)=0.11+/-0.18.
    Physical Review Letters 05/2007; 98(15):153603. DOI:10.1103/PhysRevLett.98.153603 · 7.51 Impact Factor
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    ABSTRACT: We investigate an optical scheme to conditionally engineer quantum states using a beam splitter, homodyne detection and a squeezed vacuum as an ancillar state. This scheme is efficient in producing non-Gaussian quantum states such as squeezed single photons and superpositions of coherent states (SCSs). We show that a SCS with well defined parity and high fidelity can be generated from a Fock state of $n\leq4$, and conjecture that this can be generalized for an arbitrary $n$ Fock state. We describe our experimental demonstration of this scheme using coherent input states and measuring experimental fidelities that are only achievable using quantum resources.
    Physical Review A 07/2006; 74(3). DOI:10.1103/PHYSREVA.74.033813 · 2.99 Impact Factor
  • Nicolai B Grosse · Warwick P Bowen · Kirk McKenzie · Ping Koy Lam
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    ABSTRACT: We investigate the second-order non-linear interaction as a means to generate entanglement between fields of differing wavelengths. And show that perfect entanglement can, in principle, be produced between the fundamental and second harmonic fields in these processes. Neither pure second harmonic generation, nor parametric oscillation optimally produce entanglement, such optimal entanglement is rather produced by an intermediate process. An experimental demonstration of these predictions should be imminently feasible.
    Physical Review Letters 03/2006; 96(6):063601. DOI:10.1103/PhysRevLett.96.063601 · 7.51 Impact Factor
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    ABSTRACT: We present a scheme to conditionally engineer an optical quantum system via continuous-variable measurements. This scheme yields high-fidelity squeezed single photon and superposition of coherent states, from input single and two photon Fock states respectively. The input Fock state is interacted with an ancilla squeezed vacuum state using a beam-splitter. We transform the quantum system by post-selecting on the continuous-observable measurement outcome of the ancilla state. We experimentally demonstrate the principles of this scheme using displaced coherent states and measure experimentally fidelities that are only achievable using quantum resources. Comment: 4 pages, 5 figures, published
    Physical Review A 12/2005; 73(4). DOI:10.1103/PhysRevA.73.041801 · 2.99 Impact Factor
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    ABSTRACT: Quantum optical states which have no coherent amplitude, such as squeezed vacuum states, can not rely on standard readout techniques to generate error signals for control of the quadrature phase. Here we investigate the use of asymmetry in the quadrature variances to obtain a phase-sensitive readout and to lock the phase of a squeezed vacuum state, a technique which we call noise locking (NL). We carry out a theoretical derivation of the NL error signal and the associated stability of the squeezed and anti-squeezed lock points. Experimental data for the NL technique both in the presence and absence of coherent fields are shown, including a comparison with coherent locking techniques. Finally, we use NL to enable a stable readout of the squeezed vacuum state on a homodyne detector.
    Journal of Optics B Quantum and Semiclassical Optics 06/2005; 7(10). DOI:10.1088/1464-4266/7/10/032 · 1.81 Impact Factor
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    ABSTRACT: We demonstrate the generation of broadband continuous-wave optical squeezing from 280 Hz-100 kHz using a below-threshold optical parametric oscillator (OPO). The squeezed state phase was controlled using a noise locking technique. We show that low frequency noise sources, such as seed noise, pump noise, and detuning fluctuations, present in optical parametric amplifiers, have negligible effect on squeezing produced by a below-threshold OPO. This low frequency squeezing is ideal for improving the sensitivity of audio frequency measuring devices such as gravitational-wave detectors.
    Physical Review Letters 11/2004; 93(16):161105. DOI:10.1103/PhysRevLett.93.161105 · 7.51 Impact Factor
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    ABSTRACT: We demonstrate the possibility of surpassing the quantum noise limit for simultaneous multi-axis spatial displacement measurements that have zero mean values. The requisite resources for these measurements are squeezed light beams with exotic transverse mode profiles. We show that, in principle, lossless combination of these modes can be achieved using the non-degenerate Gouy phase shift of optical resonators. When the combined squeezed beams are measured with quadrant detectors, we experimentally demonstrate a simultaneous reduction in the transverse x- and y-displacement fluctuations of 2.2 and 3.1 dB below the quantum noise limit.
    Journal of Optics B Quantum and Semiclassical Optics 08/2004; DOI:10.1088/1464-4266/6/8/007 · 1.81 Impact Factor
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    ABSTRACT: Quantum noise of the electromagnetic field is one of the limiting noise sources in interferometric gravitational wave detectors. Shifting the spectrum of squeezed vacuum states downwards into the acoustic band of gravitational wave detectors is therefore of challenging demand to quantum optics experiments. We demonstrate a system that produces nonclassical continuous variable states of light that are squeezed at sideband frequencies below 100 kHz. A single optical parametric amplifier (OPA) is used in an optical noise cancellation scheme providing squeezed vacuum states with coherent bright phase modulation sidebands at higher frequencies. The system has been stably locked to a reference laser beam for half an hour limited by thermal stability of our laboratory.
    Optics Communications 02/2004; 240(1-3-240):185-190. DOI:10.1016/j.optcom.2004.06.030 · 1.54 Impact Factor
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    ABSTRACT: The quantum nature of light imposes a limit to the detection of all properties of a laser beam. We show how we can reduce this limit for a measurement of the position of a light beam on a quadrant detector, simultaneously in two tranverse directions. This quantum laser pointer can measure the beam direction with greater precision than a usual laser. We achieve this by combining three beams, one intense coherent and two vacuum squeeezed beams, with minimum losses into one spatially multimode beam optimized for this application.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
  • Proceedings of SPIE - The International Society for Optical Engineering 02/2004; · 0.20 Impact Factor
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    ABSTRACT: The existence of quantum fluctuations of light inevitably degrades the quality of information extraction from any optical image. We define the corresponding limit when the image is carried by coherent light ("standard quantum limit"). We then show that single-transverse-mode non-classical light, such as TEM00 sub-Poissonian light, cannot be used to go beyond this limit. We describe two experimental techniques for generating multimode non-classical light: the first one uses an Optical Parametric Oscillator inserted in a confocal cavity; the second one synthesizes the multi-transverse mode beam from its single mode components. We finally show that this latter technique has allowed us to beat the standard quantum limit in the ultra-precise positioning of the center of a light beam in the transverse plane.
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    ABSTRACT: The measurement sensitivity of the pointing direction of a laser beam is ultimately limited by the quantum nature of light. To reduce this limit, we have experimentally produced a quantum laser pointer, a beam of light whose direction is measured with a precision greater than that possible for a usual laser beam. The laser pointer is generated by combining three different beams in three orthogonal transverse modes, two of them in a squeezed-vacuum state and one in an intense coherent field. The result provides a demonstration of multichannel spatial squeezing, along with its application to the improvement of beam positioning sensitivity and, more generally, to imaging.
    Science 09/2003; 301(5635):940-3. DOI:10.1126/science.1086489 · 31.48 Impact Factor
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    ABSTRACT: We present methods of transforming the standard quadrature amplitude squeezing of a continuous-wave light beam to its Stokes parameters and transverse spatial modes statistics. These two states of light are called polarization squeezing and spatial squeezing, respectively. We present experimental results of the quadrature amplitude, polarization and spatial squeezing obtained with a common experimental setup based on optical parametric amplifiers. The transformations from quadrature amplitude to polarization and spatial squeezing are achieved with only simple linear optics.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.