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Register a new userDemonstration of a squeezed light enhanced power- and signal-recycled Michelson interferometer
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We report on the experimental combination of three advanced interferometer techniques for gravitational wave detection, namely power-recycling, detuned signal-recycling and squeezed field injection. For the first time we experimentally prove the compatibility of especially the latter two. To achieve a broadband non-classical sensitivity improvement we applied a filter cavity for compensation of quadrature rotation. Signal to noise ratio was improved by up to 2.8 dB beyond the coherent states shot noise. The complete set-up was stably locked for arbitrary times and characterized by injected single-sideband modulation fields.
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In this paper, we study two-photon interference of broadband chaotic light in a Michelson interferometer with two-photon-absorption detector. The theoretical analysis is based on two-photon interference and Feynman path integral theory. The two-photon coherence matrix is introduced to calculate the second-order interference pattern with polarizations being taken into account. Our study shows that the polarization is another dimension, as well as time and space, to tune the interference pattern in the two-photon interference process. It can act as a switch to manipulate the interference process and open the gate to many new experimental schemes.
Differing from the traditional method of achieving subwavelength interference, we have demonstrated the two-photon subwavelength interference effect of broadband chaotic light in a polarization-selective Michelson interferometer with an ultrafast two-photon absorption detector the first time, which is achieved by manipulating two-photon probability amplitudes involved in the interference. In theory, the two-photon polarization coherence matrix and probability amplitudes matrix are combined to develop polarized two-photon interference terms, which explains the experimental results well. In order to make better use of this interferometer to produce the subwavelength effect, we also make a series of error analyses to find out the relationship between the visibility and the degree of polarization error. Our experimental and theoretical results are helpful to understand the two-photon subwavelength interference, which sheds light on the development of the two-photon interference theory of vector light field based on quantum mechanics. These experimental results may help to develop future optical interferometry, optical polarimetry, and subwavelength lithography.
We demonstrate the applicability of the EPR entanglement squeezing scheme for enhancing the shot-noise-limited sensitivity of a detuned dual-recycled Michelson interferometers. In particular, this scheme is applied to the GEO,600 interferometer. The effect of losses throughout the interferometer, arm length asymmetries, and imperfect separation of the signal and idler beams are considered.
Quantum fluctuations in the radiation pressure of light can excite stochastic motions of mechanical oscillators thereby realizing a linear quantum opto-mechanical coupling. When performing a precise measurement of the position of an oscillator, this coupling results in quantum radiation pressure noise. Up to now this effect has not been observed yet. Generally speaking, the strength of radiation pressure noise increases when the effective mass of the oscillator is decreased or when the power of the reflected light is increased. Recently, extremely light SiN membranes with high mechanical Q-values at room temperature have attracted attention as low thermal noise mechanical oscillators. However, the power reflectance of these membranes is much lower than unity which makes the use of advanced interferometer recycling techniques to amplify the radiation pressure noise in a standard Michelson interferometer inefficient. Here, we propose and theoretically analyze a Michelson-Sagnac interferometer that includes the membrane as a common end mirror for the Michelson interferometer part. In this new topology, both, power- and signal-recycling can be used even if the reflectance of the membrane is much lower than unity. In particular, signal-recycling is a useful tool because it does not involve a power increase at the membrane. We derive the formulas for the quantum radiation pressure noise and the shot-noise of an oscillator position measurement and compare them with theoretical models of the thermal noise of a SiN membrane with a fundamental resonant frequency of 75 kHz and an effective mass of 125 ng. We find that quantum radiation pressure noise should be observable with a power of 1 W at the central beam splitter of the interferometer and a membrane temperature of 1 K.
We study the effect of optical squeezing on the performance of a sensitive, quantum-noise-limited optically-pumped magnetometer. We use Bell-Bloom optical pumping to excite a $^{87}$Rb vapor and Faraday rotation to detect spin precession. The sub-$mathrm{pT}/sqrt{mathrm{Hz}}$ sensitivity is limited by spin projection noise (photon shot noise) at low (high) frequencies. Probe polarization squeezing both improves high-frequency sensitivity and increases signal bandwidth. The accompanying polarization anti-squeezing perturbs only an unmeasured spin component, so there is no loss of sensitivity at any frequency. The method is compatible with high-density and multi-pass techniques that reach extreme sensitivity.
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