共查询到20条相似文献,搜索用时 31 毫秒
1.
We report an experimental demonstration of a heterodyne polarization rotation measurement with a noise floor 4.8 dB below the optical shot noise by use of classically phase-locked quantum twin beams emitted above threshold by an ultrastable type II Na:KTP cw optical parametric oscillator. We believe that this is the largest noise reduction achieved to date in optical phase-difference measurements. 相似文献
2.
N. H. Adamyan H. H. Adamyan G. Yu. Kryuchkyan 《Physics of Particles and Nuclei Letters》2009,6(7):577-580
We investigate time-dependent properties of Einstein-Podolsky-Rosen (EPR) light beams generated in nondegenerate optical parametric
oscillator (NOPO) driven by a sequence of laser pulses with Gaussian time-dependent envelops. The peculiarities of EPR beams
are discussed on the base of quadrature squeezing and also in the framework of phase-space Wigner functions for EPR beams
which are combined on a half beam splitter. We also investigate the Wigner functions of intensity-correlated twin beams following
the conditional photon state-preparation scheme. It is demonstrated that the Wigner functions involve negative values in parts
of the phase space for the schemes with one-, two-, and three-photons. 相似文献
3.
We experimentally demonstrate the creation of two correlated beams generated by a nondegenerate four-wave-mixing amplifier at λ=795 nm in hot rubidium vapor. We achieve intensity difference squeezing at frequencies as low as 1.5 kHz which is so far the lowest frequency to observe squeezing in an atomic system. The squeezing spans from 5.5 to 16.5 MHz with a maximum squeezing of -5 dB at 1 MHz. We can control the squeezing bandwidth by changing the pump power. Both low frequency and controllable bandwidth squeezing show great potential in sensitivity detection and precise control of the atom optics measurement. 相似文献
4.
Experimental characterization of quantum-correlated twin beams and a quantum channel with twin beams
We report the generation and characterization of quantum-correlated twin beams and their application to a quantum channel. Compared with our previous results, the characterization of twin beams and the quantum channel have been studied with 7.0-dB intensity difference squeezing. The measured inference variance of twin beams is decreased to 0.40 ± 0.02. For the quantum channel, the bit error rate will be 0.035 by using 7.0-dB intensity difference squeezing compared with our previous result of 0.067 by using 4.9-dB intensity difference squeezing. 相似文献
5.
Measurement slight amounts of absorption of light with accuracy beyond the standard quantum limit has been experimentally demonstrated. The quantum-correlated twin beams used in the measurement were generated from a nondegenerate optical parametric oscillator including an alpha-cut KTiOPO(4) crystal pumped by an intracavity frequency-doubled Nd:YAG laser. The noise in the intensity difference between the twin beams was reduced by 88% below the standard quantum limit (SQL). The signal-to-noise ratio was improved by 7 dB with respect to the SQL of the total light employed in the experiment and by 4 dB with respect to that of the signal light. 相似文献
6.
Villar AS Cruz LS Cassemiro KN Martinelli M Nussenzveig P 《Physical review letters》2005,95(24):243603
We present the first measurement of squeezed-state entanglement between the twin beams produced in an optical parametric oscillator operating above threshold. In addition to the usual squeezing in the intensity difference between the twin beams, we have measured squeezing in the sum of phase quadratures. Our scheme enables us to measure such phase anticorrelations between fields of different frequencies. In the present measurements, wavelengths differ by approximately 1 nm. Entanglement is demonstrated according to the Duan et al. criterion [Phys. Rev. Lett. 84, 2722 (2000)] Delta2p- + Delta2q+ = 1.41(2) < 2. This experiment opens the way for new potential applications such as the transfer of quantum information between different parts of the electromagnetic spectrum. 相似文献
7.
Twin beams generated by OPOs show quantum noise reduction. For type I crystals they reduce in the degenerate case to a single mode, which below threshold exhibits some degree of squeezing. In the nondegenerate case squeezing occurs in the spectrum of their intensity difference. After a theoretical analysis of their spectral properties in both non- and degenerate cases, measured intensity noise correlation and single beam spectra are discussed for pump powers up to 14 times the threshold value. 相似文献
8.
We have measured -3.5 dB (-8.1 dB corrected for losses) relative intensity squeezing between probe and conjugate beams generated by stimulated, nondegenerate four-wave mixing in hot rubidium vapor. Unlike early observations of squeezing in atomic vapors based on saturation of a two-level system, our scheme uses a resonant nonlinearity based on ground-state coherences in a three-level system. Since this scheme produces narrowband, squeezed light near an atomic resonance, it is of interest for experiments involving cold atoms or atomic ensembles. 相似文献
9.
A Raman transition induced by a twin photon beam with quantum correlation, which is generated by nondegenerate parametric down-conversion, is theoretically analysed. The signal intensity of induced Raman scattering for the twin photon beam is twice as large as that for two coherent beams without correlation. Application of the twin photon beam is proposed for optical measurements of ESR spectra, which are useful for investigation of dislocations in semiconductor materials. 相似文献
10.
We generate intensity-difference-squeezed Laguerre-Gauss twin beams of light carrying orbital angular momentum by using four-wave mixing in a hot atomic vapor. The conservation of orbital angular momentum in the four-wave mixing process is studied as well as the spatial distribution of the quantum correlations obtained with different configurations of orbital angular momentum. Intensity-difference squeezing of up to -6.7 dB is demonstrated with beams carrying orbital angular momentum. Delocalized spatial correlations between the twin beams are observed. 相似文献
11.
We report the first experimental demonstration of conditional preparation of a nonclassical state of light in the continuous variable regime. Starting from a nondegenerate optical parametric oscillator which generates above threshold quantum intensity correlated signal and idler "twin beams," we keep the recorded values of the signal intensity only when the idler intensity falls inside a band narrower than its standard deviation. By this very simple technique, we generate a sub-Poissonian state 4.4 dB (64%) below shot noise from twin beams exhibiting 7.5 dB (82%) of noise reduction in the intensity difference. 相似文献
12.
R. Bruckmeier K. Schneider H. Hansen M. Schalke S. Schiller J. Mlynek 《Applied physics. B, Lasers and optics》1997,64(2):203-212
QND measurements of the amplitude quadrature of continuous-wave light are performed with a monolithic dual-port degenerate
optical parametric amplifier (OPA). Operated with a vacuum meter input, both output beams are squeezed and 33% correlated,
demonstrating individually squeezed twin beams. The sum of the signal and meter transfer coefficients is 1.05, demonstrating
operation as a quantum optical tap. The device exhibits quantum state preparation ability for both signal and meter output,
reaching the conditional variances of dB and dB, respectively. An improved quantum measurement is realized by injecting 3.4 dB amplitude-squeezed light into the meter
input port of the OPA. This achieves increased correlation and squeezing of the output beams, and both improved operation
as a quantum optical tap and as a quantum state preparator. The all-solid-state system was operated for up to 5 hours with
high stability.
Received: 25 July 1996 相似文献
13.
We investigate time-modulated EPR entangled states and intensity quantum correlation of twin light beams in application to
time-resolved quantum communication. As a proper device generating such states, the nondegenerate optical parametric oscillator
driven by the time-modulated pump field is considered.
The text was submitted by the authors in English. 相似文献
14.
YE Sai-Yun 《理论物理通讯》2006,46(6):1065-1068
Squeezing properties in the nondegenerate two-photon Jaynes-Cummings model are investigated. The effects of direct selective atomic measurement and the application of the classical field followed by atomic measurement are analyzed. Different values of the parameters of the classical field are taken into account. It is found that the field squeezing can be enhanced by measurement. 相似文献
15.
YE Sai-Yun 《理论物理通讯》2006,46(12)
Squeezing properties in the nondegenerate two-photon Jaynes-Cummings model are investigated. The effects of direct selective atomic measurement and the application of the classical field followed by atomic measurement are analyzed. Different values of the parameters of the classical field are taken into account. It is found that the field squeezing can be enhanced by measurement. 相似文献
16.
We present the results of an experiment in which we observed photon-number statistics of twin beams emerging from a nondegenerate optical parametric oscillator. We generated the photocurrent for recording by detecting the light and mixing it with a standard electrical oscillator. The measured photocurrent variances exhibited a quantum correlation of as much as -4.9 dB between signal and idler, whereas their photon number distributions were super-Poissonian. We also obtained the difference photon-number distribution. 相似文献
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19.
We present a continuous-variable experimental analysis of a two-photon Fock state of free-propagating light. This state is obtained from a pulsed nondegenerate parametric amplifier, which produces two intensity-correlated twin beams. Counting two photons in one beam projects the other beam in the desired two-photon Fock state, which is analyzed by using a pulsed homodyne detection. The Wigner function of the measured state is clearly negative. We developed a detailed analytic model which allows a fast and efficient analysis of the experimental results. 相似文献
20.
We report on a novel and efficient source of polarization squeezing that uses a single pass through an optical fiber. Using the fiber's two orthogonal polarization axes produces two identical squeezed beams. Combining these in a Stokes measurement generates polarization squeezing of up to 5.1 +/- 0.3 dB. Furthermore, this scheme enables us to directly measure, for both polarizations, the noise of any given quadrature. 相似文献