Last time we established the quantum version of coupled-mode theory for spontaneous parametric downconversion (SPDC). We exhibited the exact solutions for the output signal and idler beams, their jointly Gaussian state characterization when the input beams are in their vacuum states, and the low-gain regime approximations for the correlation functions that characterize that state. We also intro...

We investigate the effect of a degenerate optical parametric amplifier (OPA) placed inside an optomechanical cavity on the steady-state entanglement of two cavity modes, which jointly interact with a mechanical resonator. Two cavity modes are respectively driven at the red and blue sideband associated with the mechanical resonator, which generates entanglement between them in the limit of resol...

The gravitational wave equations form a parametric resonance system during oscillatory reheating after inflation, when cast in terms of the electric and magnetic parts of the Weyl tensor. This is in direct analogy with preheating. For chaotic inflation with a quadratic potential, this analogy is exact. The resulting amplification of the gravitational wave spectrum begins in the broad resonance ...

Supplementary Fig. S1 shows the schematic experimental set-up. We used a noncollinear optical parametric amplifier (NOPA) [1]–[3] as a light source for the pump–probe experiment [4]–[6]. The laser source of this system was a commercial regenerative amplifier (Spitfire; Spectra Physics). Its central wavelength, pulse duration, repetition rate and average output power were 790 nm, 50 fs, 5 kHz an...

We report an experimental demonstration of optical parametric generation in a periodically poled KTiOPO4 crystal based on the principle of mirrorless optical parametric oscillation. A femtosecond pump pulse spectrally centered at 792 nm from a Ti:sapphire amplifier is prechirped to minimize Kerr effects. The pump pulse is then injected into the nonlinear crystal and down converted to signal and...

We theoretically and experimentally demonstrate coherence phenomena of nonlinear coupled oscillators in optical parametric process. The mode splitting in transmission spectra of phase-sensitive optical parametric amplifier is observed. Especially, we show a very narrow dip and peak, which are the shape of δ function, appear in the transmission profile. The origin of the coherence phenomenon in ...

We analyze the output of a degenerate optical parametric amplifier using a different approach to understanding and characterizing multimode squeezed light. This approach is based on the concept of eigenmodes of the squeezing and predicts the mode structure of the local oscillator that should be used in order to measure the smallest quadrature noise. Although the importance of mode matching is w...

We discuss a dynamical mechanism of pion production from disoriented chiral condensates (DCC). It leads to an explosive production of pions via the parametric amplification mechanism, which is similar to the reheating mechanism in inflationary cosmology. Classically, it is related with the instability in the solutions of the Mathieu equation and we explore the quantum aspects of the mechanism. ...

Using homodyning with weak coherent fields and photon counting, we have observed violations of Bell-type inequalities by the generalized Einstein-Podolsky-Rosen state produced in a pulsed nondegenerate optical parametric amplifier, as predicted by Grangier et al. [Phys. Rev. A 38, 3132 (1988)]. The maximum observed visibility of the interference pattern was 89 6 4 %. This interference can be re...

We experimentally demonstrate a single-pumped, non-degenerate phase-sensitive parametric amplifier with a precise control of phase and amplitude of the in-going waves and investigate in detail its gain, attenuation and saturation properties in comparison with operation in phase insensitive amplifier (PIA) mode. We experimentally observe the variation of the gain and attenuation as a function of...