Noise Suppression by Noise

Vilar, José M. G.; Rubı́, J. M.

doi:10.1103/physrevlett.86.950

Cited by 67 publications

(57 citation statements)

References 24 publications

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“…Unavoidable internal and external noises enhance chaos: LLE and multifractal dimension of attrac-tors increase with respect to the deterministic case. It is known that adding external noise may suppress or enhance the effects of internal noise on a given system [39]. In our system, increasing the complexity of the chaotic attractor by adding controlled sources of external noise may speed up random number generation.…”

Section: Resultsmentioning

confidence: 99%

Noise-enhanced spontaneous chaos in semiconductor superlattices at room temperature

Alvaro¹,

Carretero²,

Bonilla³

2014

EPL

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Physical systems exhibiting fast spontaneous chaotic oscillations are used to generate high-quality true random sequences in random number generators. The concept of using fast practical entropy sources to produce true random sequences is crucial to make storage and transfer of data more secure at very high speeds. While the first high-speed devices were chaotic semiconductor lasers, the discovery of spontaneous chaos in semiconductor superlattices at room temperature provides a valuable nanotechnology alternative. Spontaneous chaos was observed in 1996 experiments at temperatures below liquid nitrogen. Here we show spontaneous chaos at room temperature appears in idealized superlattices for voltage ranges where sharp transitions between different oscillation modes occur. Internal and external noises broaden these voltage ranges and enhance the sensitivity to initial conditions in the superlattice snail-shaped chaotic attractor thereby rendering spontaneous chaos more robust.

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Section: Resultsmentioning

confidence: 99%

Noise-enhanced spontaneous chaos in semiconductor superlattices at room temperature

Alvaro¹,

Carretero²,

Bonilla³

2014

EPL

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“…(2). This novel effect of damping revealed here is highly counter-intuitive and somewhat reminiscent of the "noise suppression by noise" recently reported in the classical statistical physics [16].…”

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confidence: 89%

Squeezing Enhancement by Damping in a Driven Atom-Cavity System

et al. 2002

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In a driven atom-cavity coupled system in which the twolevel atom is driven by a classical field, the cavity mode which should be in a coherent state in the absence of its reservoir, can be squeezed by coupling to its reservoir. The squeezing effect is enhanced as the damping rate of the cavity is increased to some extent. 42.50.Lc, 42.50.Dv, A quantum-mechanical harmonic oscillator undergoes continuous amplitude fluctuation even in its ground state. This fluctuation, also known as the vacuum fluctuation, arises from the nonvanishing commutation relation, [a, a † ] = 1, where a (a † ) is the annihilation (creation) operator of the harmonic oscillator. One can make, however, the fluctuation of one quadrature amplitude decrease below the vacuum-state (or the coherent state) level at the cost of that of the other quadrature.This mechanism, known as squeezing [1], is most commonly generated by the inherent nonlinearity of the interaction involved, which is seen from the definition of the squeezing operator S(r) = exp[(r/2){(a † ) 2 − a 2 }], r being the squeezing parameter. Squeezing mechanism may thus be interpreted as making pairs of correlated oscillator quanta. In most cases, the oscillator is inevitably damped by its coupling to the reservoir, and the squeezing is degraded since the coupling introduces the reservoir fluctuations to the oscillator. For instance, the known schemes for generating the squeezed light employ the nonlinear processes [2] such as parametric amplification [3] or four-wave mixing [4]. Usually, the interacting medium is put inside an optical cavity in order to build up the field by increasing the interaction time [3]. But the cavity damping destroys the quantum correlation of the field via loss of the correlated photon pairs.In the conventional squeezing schemes, therefore, damping has been considered to play a negative role. In this work, by contrast, we show that squeezing is manifested by damping in a counter-intuitive way, when the cavity is coupled to its reservoir under indirect pumping. The coupling strengths to each mode of the reservoir oscillators are related to the damping rate, κ, of the cavity mode by the fluctuation-dissipation theorem [5]. We will show that the squeezing effect is enhanced as κ is increased to some degree.In our model, the target harmonic oscillator, i.e., the cavity mode, is coupled to a two-level atom driven by a resonant classical field, instead of being pumped directly.Although the system has the inherent nonlinear property due to the saturability of the two-level atom, the nonlinearity producing the squeezing effect does not reveal itself without the cavity damping. In addition, the unconventional features of the squeezing enhancement by damping can be seen from its characteristic condition 2Ωκ/g 2 ∼ 1, where g is the atom-cavity coupling constant and Ω, the Rabi frequency of the driving field. This condition shows that the Rabi frequency should be inversely proportional to the cavity damping rate for the optimal squeezing. This relation is in a strikin...

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“…An important study about the constructive aspects of noise and fluctuations in different non-linear systems has shown that the addition of external random perturbations to systems with intrinsic noise may affect the dynamics of the system in a counterintuitive way, resulting in a reduction of the total noise of the system [4]. The opportunity to reduce the diffusion noise in semiconductor bulk materials by adding a random fluctuating contribution to the driving static electric field has (985) been tested in Ref.…”

Section: Introductionmentioning

confidence: 99%

External Noise Effects on the Electron Velocity Fluctuations in Semiconductors

2008

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We investigate the modification of the intrinsic carrier noise spectral density induced in low-doped semiconductor materials by an external correlated noise source added to the driving high-frequency periodic electric field. A Monte Carlo approach is adopted to numerically solve the transport equation by considering all the possible scattering phenomena of the hot electrons in the medium. We show that the noise spectra are strongly affected by the intensity and the correlation time of the external random electric field. Moreover, this random field can cause a suppression of the total noise power.

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Noise Suppression by Noise

Cited by 67 publications

References 24 publications

Noise-enhanced spontaneous chaos in semiconductor superlattices at room temperature

Noise-enhanced spontaneous chaos in semiconductor superlattices at room temperature

Squeezing Enhancement by Damping in a Driven Atom-Cavity System

External Noise Effects on the Electron Velocity Fluctuations in Semiconductors

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