Kunchi Peng

Quantum variances and squeezing of output field from NOPA

Abstract The quadrature phase squeezing of coupled-mode and intensity difference squeezing between signal and idler mode of output field from continuous nondegenerate optical parametric amplifier (NOPA) are theoretically analyzed and compared. The calculation results provide design references for nonclassical light generation system.

Entanglement swapping using nondegenerate optical parametric amplifier

Abstract We introduce a simple, experimentally realizable, entanglement swapping protocol for continuous variables by exploring nondegenerate optical parametric amplifier. Due to adopting the bright EPR beams and the simple direct measurement for Bell-state, the entanglement swapping and the verification of entanglement swapping is within the reach of current technology and significantly simplify the implementation.

CW Nd:MgO:LiNbO/sub 3/ self-frequency-doubling laser at room temperature

A CW Nd:MgO:LiNbO/sub 3/ self-frequency-doubling laser has been demonstrated at room temperature for the first time. The second-harmonic output at lambda =547 nm up to 18 mW was achieved in a simple resonator. >

Intracavity frequency-doubled and frequency-stabilized cw ring Nd:YAP laser

A frequency-doubled and frequency-stabilized ring Nd:YAP laser with a six-mirror cavity is demonstrated. This laser satisfies both the thermal insensitivity and optimal frequency-doubling conditions. A second-harmonic output to 1 W at 0.54 mum is achieved. The intensity fluctuation is less than ?1.5% and the frequency stability is better than ?1 MHz (5 min).

Investigation of the characteristics of the intensity noise of singly resonant active second-harmonic generation

We derive analytical expressions for the quantum-noise spectra of a singly resonant active frequency-doubling laser with single-frequency operation by using a linearized input–output method. For operation of a practical solid-state laser, we analyze separately the contributions of the various noise sources to the final spectrum. The change in resonance in the spectrum from an overdamped- (at higher μ) to an underdamped- (at smaller μ) driven second-order oscillator where μ is the nonlinear coupling coefficient, was experimentally observed with a diode-pumped Nd:YVO4+KTP single-frequency-doubling laser. The experimental result is in good agreement with the theoretical expectation.

Quantum teleportation for continuous variables by means of a phase sensitive nondegenerate optical parametric amplifier

Abstract A simple scheme to realize quantum teleportation with π/2 unitarily rotated transformation for continuous variable is proposed, in which the bright entangled EPR beam is produced by phase sensitive nondegenerate optical parametric amplifier with a fixed relative phase of π/4 between the subharmonic signal and the harmonic pump field. The measurement of “Bell state” is accomplished by means of direct detection of photocurrents.

Suppression of the intensity noise of a laser-diode-pumped single-frequency ring Nd:YVO(4)-KTP green laser by optoelectronic feedback.

We investigate the different characteristics of the intensity noise of a laser-diode-pumped single-frequency ring Nd:YVO (4) laser and a Nd:YVO (4)-KTP green laser. By use of an optoelectronic feedback circuit connected directly to the pump current of the laser diode, the low-frequency intensity noise of the intracavity frequency doubler was suppressed to some extent.

Quantum self-homodyne tomography with an empty cavity

We develop a scheme to reconstruct the optical quantum state of a single-mode bright light field by using the dispersion characteristics of the empty cavity. The input field has a strong coherent component at frequency ω0, which serves as a local oscillator (LO) to measure its two-sideband mode at ω0±Ω. We control the relative phase of the 0–2π range between the LO and the two-sideband mode by scanning the cavity length, so the optical quantum state is tomographically reconstructed. In the proposed scheme the influence of the space-mode mismatch between the LO and measured mode on the quantum efficiency is eliminated, and this scheme can conveniently be used in some quantum optical systems in which LO field cannot be available.

On the determination of the statistical properties of energy levels by level dynamics

Abstract The method for determining the statistical properties of energy levels, given by Yukawa, is improved by means of expressing E Q in terms of γ β . It is also pointed out that the method is not necessarily efficient unless the scale of the system is unchanged. The relationship between classical chaos and the quantum spectra is also discussed.

Application of amplitude-squeezed state light from injection-locked laser diode in quantum teleportation and dense coding

Abstract The novel quantum teleportation and dense coding systems based on applying the amplitude-squeezed state light produced from the injection-locked laser diodes and a simple direct measurement scheme for the Bell state are proposed.