Quantum Noise in Parametric Amplification

B. Schr�der

Kyo Inoue

Kyo Inoue

Phase-sensitive amplification (PSA) is a particular type of optical parametric amplification (OPA) that features a low-noise property such that the quantum-limited noise figure is 0 dB. The PSA operation is typically achieved when the signal and idler spectra are degenerate in optical parametric interactions, i.e., the degenerate OPA condition. However, for a spectrally broadened incident light, these two spectra can be partially degenerate. The present work investigates the noise property of OPA in such conditions in terms of quantum mechanics. The results quantitatively indicate the intermediate properties between PSA and phase-insensitive amplification.

Kamel Bencheikh, E. Huntziger, Juan Ariel Levenson

We present a calculation of quantum noise for parametric amplification in periodically inverted nonlinear media. An analytical expression is obtained for the noise figure of the amplifier. We show that such optical parametric amplifiers run in a phase-sensitive configuration can achieve noiseless amplification and squeezing, thus constituting a promising way for the integration of noiseless optical amplifiers in a communication line.

Éric Lantz, F. Devaux, A. Mosset

Jun Xin, Xiao-Ming Lu, Hailong Wang +1 more

Amplification of an entangled state is a matter of great significance in quantum communication. However, any parametric amplifier (PA) will introduce added noise into the system which unavoidably degrades the entanglement or even makes it disappear. Recently, it has been experimentally demonstrated that amplification of one half of a two-mode squeezed state is possible while preserving entanglement [Phys. Rev. Lett. 103, 010501 (2009)]. However, such entanglement cannot be maintained when the strength of the amplification is large. To solve this problem, we propose a correlation modulation scheme (CMS), which fully exploits the quantum correlation between the two output states from the PA process, to suppress the added noise from the parametric amplifications. For amplifying an entangled state using a PA, we demonstrate that the CMS not only better maintains but also always preserves the entanglement whatever the strength of the PA. Such a CMS may pave the way to low-noise amplification of an entangled state.