Quantum squeezing of optical dissipative structures

Abstract

We show that any optical dissipative structure supported by degenerate optical parametric oscillators contains a special transverse mode that is free from quantum fluctuations when measured in a balanced homodyne detection experiment. The phenomenon is not critical as it is independent of the system parameters and, in particular, of the existence of bifurcations. This result is a consequence of the spatial symmetry breaking introduced by the dissipative structure. Effects that could degrade the squeezing level are considered. Introduction. Vacuum quantum fluctuations constitute the ultimate noise source affecting any coherent radiator, like a laser. These fluctuations define the so-called standard quantum limit as they set the maximum precision attainable with classical optical techniques, even rendering the latter useless in some applications such as precision metrology [1] and quantum information protocols [2,3]. It is possible however to break this limit with the help of quantum states of light: Squeezed states [2,3], displaying fluctuations below the standard quantum limit in one of the field quadratures, play a prominent role in this regard, and are by now routinely generated, e.g., by single-mode optical parametric oscillators/amplifiers [1,2,3,4].

Multimode nonclassical light generation through the optical-parametric-oscillator threshold

“…This property of "non-critially squeezed light" has been further explored by the Valencia group [10] in the context of quantum imaging, which has found other squeezing effects that are independent of the pumping level. These effects are related to spatial symmetry-breaking, either translational [9] or rotational [10]: in a cavity of cylindrical symmetry, the parametric gain is the same for Gaussian modes TEM 01 where the two lobes are aligned along any direction in the transverse plane. However, above the oscillation threshold, a unique TEM 01 mode is produced.…”

Theory of quantum fluctuations of optical dissipative structures and its application to the squeezing properties of bright cavity solitons

“…This could be quantitatively important as a possible noise reduction could be blurred by the diffusion of the structure [25].…”

“…In [25] we already advanced a particular property of quantum fluctuations which is specific to pattern formation (i.e., that is absent when the emission is homogeneous in space), which can be put in short as follows: Due to the translational invariance of the problem (the position of the pattern in the transverse plane is not fixed when the pumping is spatially homogeneous), there is a particular transverse mode that is free from quantum fluctuations (in the linear approximation), a perfectly squeezed mode. And this occurs irrespectively of the value of the parameters of the system.…”

Spatial fluctuations in an optical parametric oscillator below threshold with an intracavity photonic crystal

“…We calculate intensity fluctuations and correlations as well as quadrature squeezing and entanglement showing the effect of the modulation. The homogeneous, multimode OPO was shown to present squeezing, entanglement, and twin-beam correlations between spatial modes below threshold [40][41][42] and above threshold in the presence of stable patterns or even frozen chaos [39,43]. Similar effects have been predicted in Kerr media [44] and in second-harmonic generation [45], and in recent years there have been several successful experimental realizations [13][14][15][16][46][47][48][49].…”