Super-bunched bright squeezed vacuum state

In this paper we experimentally study the statistical properties of a bright squeezed vacuum state containing up to 10^13 photons per mode (10 uJ per pulse), produced via high gain parametric down conversion (PDC). The effects of bunching and superbunching of photons were observed for a single mode PDC radiation by second-order intensity correlation function measurements with analog detectors.Comment: 4 pages, 3 figures, submitted to Optics Letter

Quantum tomography enhanced through parametric amplification

Quantum tomography is the standard method of reconstructing the Wigner function of quantum states of light by means of balanced homodyne detection. The reconstruction quality strongly depends on the photodetectors quantum efficiency and other losses in the measurement setup. In this article we analyze in detail a protocol of enhanced quantum tomography, proposed by Leonhardt and Paul [1] which allows one to reduce the degrading effect of detection losses. It is based on phase-sensitive parametric amplification, with the phase of the amplified quadrature being scanned synchronously with the local oscillator phase. Although with sufficiently strong amplification the protocol enables overcoming any detection inefficiency, it was so far not implemented in the experiment, probably due to the losses in the amplifier. Here we discuss a possible proof-of-principle experiment with a traveling-wave parametric amplifier. We show that with the state-of-the-art optical elements, the protocol enables high fidelity tomographic reconstruction of bright non-classical states of light. We consider two examples: bright squeezed vacuum and squeezed single-photon state, with the latter being a non-Gaussian state and both strongly affected by the losses

Aplikasi Macam Pupuk Organik Padat pada Padi Hibrida F2

Padi hibrida merupakan salah satu kunci untuk meningkatkan produksi beras dunia. Namun, benih padi hibrida hanya dapat digunakan untuk satu kali musim tanam, sehingga perlu adanya upaya yang harus dilakukan untuk mempertahankan produksi padi hibrida pada keturunan kedua (F2). Beberapa hal yang dapat dilakukan antara lain adalah dengan pemberian pupuk yang berimbang dan penerapan pengelolaan hara terpadu, salah satunya dengan penggunaan pupuk organik padat. Penelitian dilaksanakan di Desa Joho, Kecamatan Mojolaban, Kabupaten Sukoharjo pada bulan Januari hingga Juni 2016 dengan menggunakan rancangan penelitian Split Plot Rancangan Acak Kelompok Lengkap (RAKL) dengan 2 faktor perlakuan, yaitu macam pupuk organik padat dan varietas padi serta ulangan sebanyak 3 kali. Hasil penelitian menunjukkan bahwa perlakuan macam pupuk organik padat dan varietas padi memberikan pengaruh terhadap semua variabel pengamatan, kecuali pada variabel bobot 1000 butir gabah bernas dan hasil panen per petak

Spectral properties of high-gain parametric down-conversion

High-gain parametric down-conversion (PDC) is a source of bright squeezed vacuum, which is a macroscopic nonclassical state of light and a promising candidate for quantum information applications. Here we study its properties, such as the intensity spectral width and the spectral width of pairwise correlations.Comment: 9 pages, 5 figure

Experimental demonstration of negative-valued polarization quasiprobability distribution

Polarization quasiprobability distribution defined in the Stokes space shares many important properties with the Wigner function for position and momentum. Most notably, they both give correct one-dimensional marginal probability distributions and therefore represent the natural choice for the probability distributions in classical hidden-variable models. In this context, negativity of the Wigner function is considered as proof of nonclassicality for a quantum state. On the contrary, the polarization quasiprobability distribution demonstrates negativity for all quantum states. This feature comes from the discrete nature of Stokes variables; however, it was not observed in previous experiments, because they were performed with photon-number averaging detectors. Here we reconstruct the polarization quasiprobability distribution of a coherent state with photon-number resolving detectors, which allows us to directly observe for the first time its negativity. Furthermore we derive a theoretical polarization quasiprobability distribution for any linearly polarized quantum state

Direct measurement of the coupled spatiotemporal coherence of parametric down-conversion under negative group-velocity dispersion

We present a direct measurement of the spatiotemporal coherence of parametric down-conversion in the range of negative group-velocity dispersion. In this case, the frequency-angular spectra are ring-shaped, and temporal coherence is coupled to spatial coherence. Correspondingly, the lack of coherence due to spatial displacement can be compensated for with the introduction of time delay. We show a simple technique, based on a modified Mach– Zehnder interferometer, which allows us to measure time coherence and near-field space coherence simultaneously, with complete control over both variables. This technique is also suitable for the measurement of second-order coher- ence, where the main applications are related to two-photon spectroscopy

Macroscopic Hong-Ou-Mandel interference

We report on a Hong-Ou-Mandel interference experiment for twin beams with photon numbers per mode as large as 10(6) generated via high-gain parametric down conversion (PDC). The standard technique of coincidence counting leads in this case to a dip with a very low visibility. By measuring, instead of coincidence counting rate, the variance of the photon-number difference, we observe an extremely well-pronounced peak. From the shape of the peak, one can infer information about the spectral properties of the PDC radiation, including the number of frequency/temporal modes

Study of broadband multimode light via non-phase-matched sum frequency generation

We propose non-phase-matched sum frequency generation (SFG) as a method for characterizing broadband multimode light. Both the central wavelength and the bandwidth are in this case not limited by the phase matching condition. As an example, we consider bright squeezed vacuum (BSV) generated through high-gain parametric down conversion (PDC). In the spectrum of SFG from BSV, we observe the coherent peak and the incoherent background. We show that the ratio of their widths is equal to the number of frequency modes in BSV, which in the case of low-gain PDC gives the degree of frequency entanglement for photon pairs. By generating the sum frequency in the near-surface region of a nonlinear crystal, we increase the SFG efficiency and get rid of the modulation caused by chromatic dispersion, known as Maker fringes. This allows one to use non-phasematched SFG as a wavelength-independent autocorrelator. Furthermore, we demonstrate efficient non-phase-matched three- and four-frequency summation of broadband multimode light, hardly possible under phase matching. We show that the latter contains the coherent peak while the former does not