Amount Of Squeezing Research Articles

On the possibility of continuous generation of squeezed states in a quartic anharmonic oscillator

Coherent light interacting with a nonlinear nonabsorbing medium of inversion symmetry is modelled as a quartic anharmonic oscillator if the lowest (i.e. third) order of nonlinearity is considered. The equation of motion of the quadrature operators of such an oscillator is solved approximately in a closed analytical form. The corresponding solution is used to investigate the possibility of finding the continuous squeezed states. It is found that the amount of squeezing is increased with the increase of intensity of the applied field. An improvement of the squeezing is also possible if the coupling strength is increased. We report the squeezing effect of the input vacuum field. The possibility of generating continuous squeezing in an absolute sense (i.e. 100%) of the input radiation field is also discussed.

Photon Statistics and Squeezing in the Two-Atom Thermal Jaynes-Cummings Model

The behavior of the mean photon number, photon number variance and field squeezing is investigated for the two two-level atoms prepared in a multiatom squeezed state coupled to the vacuum or thermal field. The value of superposition angle (θ) of the atomic states is found to affect the photon number variance as well as field squeezing. The bound on the sun-Poissonian field concerning the value of θ and input mean photon number is determined. One of the field quadrature is found to exhibit permanent squeezing for the vacuum input in a small range of the value of θ. It is shown that the input thermal photons degrade the sub-Poissonian character and spontaneous squeezing. However, a considerable amount of squeezing is obtained even in the presence of thermal photons.

Higher-order amplitude squeezing of photons propagating through a semiconductor

Kth power photon amplitude squeezing is studied when the coherent photon propagates through a semiconductor containing the exciton. If the exciton is prepared initially in a coherent state, the photon may become Kth power amplitude squeezed. It is shown that, in the short-time limit, the photon squeezing in the P direction does not appear at all while that in the X direction is possible for all the amplitude powers K. In the latter case, the amount of squeezing is larger for higher power K. The dependences on all the system parameters as well as on the output light detection moment are investigated in detail.

Squeezing characteristics analysis of a fundamental-confined second-harmonic generation system by means of a self-consistent method

We discuss quantum-fluctuation characteristics of a second-harmonic generation system that uses an optical resonator to confine only the fundamental field. It was predicted that the available amount of squeezing is limited to 1.76 dB for the fundamental output and 9.54 dB for the second-harmonic output, respectively, irrespective of system parameters. However, these predictions are based on low-order perturbation theory and are unavailable if the nonlinear coupling between the fundamental and the second harmonic becomes large. We consider the spatial evolution of the fields and reveal that the maximum amount of squeezing depends on the cavity loss: Even an arbitrary amount of squeezing is possible for both the fundamental output and the second-harmonic output. We also consider the possibility of parametric oscillation of empty cavity modes pumped by the generated second harmonic and derive the following prediction: In a system that uses a type I phase-matched crystal, the oscillation of the side mode hardly occurs because of sum-frequency generation with the fundamental and scarcely imposes any limitations on squeezing. On the other hand, a system with a type II phase-matched crystal suffers from the oscillation of the polarization mode orthogonal to that of the fundamental input, and squeezing of the second-harmonic output is limited to 3 dB.

Polaritons in confined systems

Polaritons in confined systems are introduced and their dispersion is calculated. The amount of squeezing of confined excitons-polaritons in GaAs quantum wells is evaluated.

On the correspondence of semiclassical and quantum phases in cyclic evolutions

Based on the exactly solvable case of a harmonic oscillator, we show that the direct correspondence between the Bohr-Sommerfeld phase of semiclassical quantum mechanics and the topological phase of Aharonov and Anandan is restricted to the case of a coherent state. For other Gaussian wave packets the geometric quantum phase strongly depends on the amount of squeezing.

Twiss parameters and evolution of quantum harmonic-oscillator states

In this paper we show that the evolution of a quantum state, driven by a harmonic-oscillator-type Hamiltonian, can be studied using tools exploited to characterize the evolution of a charged beam in a transport channel. The relevance of the Courrent-Snyder invariant and of Twiss-like parameters to characterize,e.g., the amount of squeezing is carefully pointed out.

SU(1, 1) and SU(2) Squeezing in Trilinear Optical Processes

Abstract The squeezing properties in terms of SU(1, 1) and SU(2) operators for the case of trilinear processes are studied. The initial state of the system is supposed to be a coherent state in one of the modes and number states in the remaining modes. It is pointed out that in several cases a considerable amount of squeezing can be achieved. Due to the common mathematical structure the case of a two-mode coupler with intensity dependent coupling is also analysed.

Photocount distribution of two-mode squeezed states.

We derive a closed-form expression for the number probability distribution of a ``generic'' two-mode field in a two-mode squeezed state. We discuss its dependence on the average particle number in the two modes and on the amount of squeezing. We show that the distribution exhibits oscillations for particle numbers appropriately greater than the average, similar to the one-mode case, although the conditions under which such an oscillatory behavior occurs are different. These results are directed to the investigation of nonclassical properties in the radiation field produced by a parametric amplifier operated in a two-mode regime.

Quantum theory of nondegenerate multiwave mixing III Application to single-beam squeezed-state generation

We apply our quantum theory of nondegenerate multiwave mixing [ Phys. Rev. A37, 2017 ( 1988)] to squeezed-state generation experiments with two-level atoms. Our main interest is to predict the amount of squeezing achievable with a Doppler-broadened two-level medium. We are particularly interested in the single-beam configuration, in which all four interacting beams are spatially degenerate. We analytically solve the coupled-mode quantum Langevin equations for nondegenerate four-wave mixing. The solutions are used to compute the amount of squeezing. In the computation the effects of pump–probe phase mismatch, collisions, Doppler broadening, and Gaussian-intensity variation are comprehensively taken into account for the first time to our knowledge. Simple rules of thumb as to where one can see squeezing in both degenerate- and nondegenerate-frequency cases are derived by examining the limit of a short medium. We then present the case of an infinitely long medium, in which maximum squeezing is achieved when there is no pump–probe phase mismatch. With the inclusion of pump–probe phase mismatch, however, the maximum amount of squeezing is obtained with a finite-length medium instead. This prompts us to investigate in detail the finite-length medium case. Our results show that the effects of Doppler broadening and Gaussian-intensity variation can be largely circumvented by detuning the pump frequency more than three Doppler half-widths from resonance and that good broadband squeezing can be achieved even with a Doppler-broadened medium that has a moderate amount of collision broadening. Under these circumstances it is found that the effect of pump self-focusing or defocusing will be the major factor that limits the amount of achievable squeezing. In particular, the spatially varying nonlinear refractive indices seen by the pump and the probe modes are quite different, which causes the former to become spatially mismatched with the latter in the region in which strong squeezing is otherwise expected.

Linewidth of a laser with a squeezed reservoir.

We present a detailed analysis of a laser model with a squeezed reservoir. The steady-state behavior is described by means of the moments and the variance of the field intensity as a function of the pump parameter and the amount of squeezing. The dynamic properties are contained in the eigenfunctions and eigenvalues of the corresponding Fokker-Planck equation. Because of a loss of phase symmetry, the model exhibits interesting features concerning its stationary as well as its dynamic behavior.

Squeezing in Multiphoton Absorption

Abstract The conditions for obtaining squeezing by single-beam multiphoton absorption are examined. For an initial coherent light the amount of squeezing is calculated in the second order of interaction time using the master-equation formalism. A limit formula for the amount of squeezing is found in the case of an initial strong coherent beam. The results are compared with the exact numerical calculations and some remarks are made on the short-time approximation in multiphoton absorption.

Proposal for generation of amplitude-squeezed light (ASL) from laser diodes with electronic feedback

It is generally believed that the amplitude fluctuations of a light beam initially in the coherent state cannot be squeezed below those of shot noise by the simple arrangement of a beamsplitter and a detector, the current from the detector being fed back to the light source or to a modulator. A simple semiclassical theory shows that arbitrary amounts of squeezing can in fact be obtained if a negative opticalconductance device such as a constant-voltage-driven (nonself-oscillating) laser diode is used in place of a conventional detector.

Phase operators for the electromagnetic field by squeezed-state theory

A new set of phase operators for the electromagnetic field has been defined by an extension of squeezed-state theory. In several cases these operators have similar or the same properties as the previously defined (Susskind–Glogower) operators. However, the new operators also have unique properties of their own. The expectation values of the phase operators have been found for a squeezed state and been shown to reduce to the expected classical values in the limit of small amounts of squeezing and large field excitation.