Proceedings of the National Academy of Sciences, 2019
Significance Antiferromagnets can host strong quantum fluctuations in their ground state if they ... more Significance Antiferromagnets can host strong quantum fluctuations in their ground state if they combine both low dimensionality and low spin. Materials based on copper oxides (spin-1/2 ions in layered or 1D structures) are unique in optimizing the tendency to strong quantum fluctuations. As a bonus, they show extremely large magnetic interactions, which lead to interesting quantum effects at relatively high temperatures as anomalous transport properties and high- T c superconductivity in doped systems. Obtaining similar features with other ions has been a long-standing goal. We show that silver and fluorine (which are next to copper and oxygen in the periodic table) in the commercial compound A g F 2 reach the goal, paving the way for a different generation of quantum materials.
Proceedings of 5th European Quantum Electronics Conference
Controlling chaos represents one of the most interesting and challenging programs in the field of... more Controlling chaos represents one of the most interesting and challenging programs in the field of nonlinear dynamics. In the past few years different methods have been proposed based on (i) the determination of the stable and unstable directions in the PoincarP section,' (ii) on a self-controlling feedback procedure' and (iii) on the introduction of small perturbations? In this paper, accordingly to method (iii), we show that a small parametric perturbation stabilizes the chaotic behavior of a CO' laser with modulated losses. It is well knownq that in a single-mode CO2 laser the intensity undergoes a subharmonic sequence of bifurcations leading to chaos when we increase the amplitude V, of a sinusoidal voltage signal V(t) = Vo + V, sin (2nFt) (V, = 600 V, F = 100 KHz) applied to an intracavity electro-optic crystal. The stabilization of periodic orbits within the chaotic region has been obtained by slight modulations of the control parameter V,. Such perturbations consist of sinusoidal signals at f = f, = 50 KHz and f = f2 = 25 KHz with amplitude e and an adjustable phase offset a = mn with respect to the fundamental sign V(t), that is,
The dynamics of a single mode CO 2 laser with modulated losses has been controlled over the basin... more The dynamics of a single mode CO 2 laser with modulated losses has been controlled over the basin of attraction of one of the periodic orbits contained within the strange attractor. Applying the perturbation being the lowest subharmonic of the fundamental driving force, we have studied the statistics of chaotic and periodic transient time intervals preceding the stabilization or destabilization of a given periodic orbit in the vicinity of the bifurcation points. An experimental evidence of the exponential probability distribution of chaotic transients, predicted by the theory, has been demonstrated for the first time.
In a homogeneously broadened CO2laser [1] only the polarization can be adiabatically eliminated (... more In a homogeneously broadened CO2laser [1] only the polarization can be adiabatically eliminated (class B lasers), so that the dynamics is ruled by two rate equations for the field and population inversion ( I = E 2 / E s 2 is the field squared and normalized to saturation intensity E S 2 = γ ⊥ γ IL 4 g 2   , G = 2 g 2 / γ 1 is the coupling factor, d is the population inversion normalized to the pump value Δo, with g = wµ2/ħϵoV and γ1, γILfor the polarization and population inversion decay rates).
... Such a system is described by two rate equations for the intensity x(t) and population invers... more ... Such a system is described by two rate equations for the intensity x(t) and population inversion y(t): x=-Kox(l+f(u)-Y) , Y=-YI1(Y+xY-Yo) , (la) (lb) where Ko-(clL)(T+Dr) is the nonmodulated cavity parameter, L is cavity length, T and Df are the effective ... [4] J. Dupr , F. Meyer and C ...
A single mode CO2 laser near threshold behaves differently depending on whether the threshold is ... more A single mode CO2 laser near threshold behaves differently depending on whether the threshold is reached by varying the pump or the cavity losses. Only in the first case we observe a delayed bifurcation. Our experimental results are explained by a four level molecular model which takes into account the coupling between the two resonant levels and the rotational manifold.
Proceedings of the National Academy of Sciences, 2019
Significance Antiferromagnets can host strong quantum fluctuations in their ground state if they ... more Significance Antiferromagnets can host strong quantum fluctuations in their ground state if they combine both low dimensionality and low spin. Materials based on copper oxides (spin-1/2 ions in layered or 1D structures) are unique in optimizing the tendency to strong quantum fluctuations. As a bonus, they show extremely large magnetic interactions, which lead to interesting quantum effects at relatively high temperatures as anomalous transport properties and high- T c superconductivity in doped systems. Obtaining similar features with other ions has been a long-standing goal. We show that silver and fluorine (which are next to copper and oxygen in the periodic table) in the commercial compound A g F 2 reach the goal, paving the way for a different generation of quantum materials.
Proceedings of 5th European Quantum Electronics Conference
Controlling chaos represents one of the most interesting and challenging programs in the field of... more Controlling chaos represents one of the most interesting and challenging programs in the field of nonlinear dynamics. In the past few years different methods have been proposed based on (i) the determination of the stable and unstable directions in the PoincarP section,' (ii) on a self-controlling feedback procedure' and (iii) on the introduction of small perturbations? In this paper, accordingly to method (iii), we show that a small parametric perturbation stabilizes the chaotic behavior of a CO' laser with modulated losses. It is well knownq that in a single-mode CO2 laser the intensity undergoes a subharmonic sequence of bifurcations leading to chaos when we increase the amplitude V, of a sinusoidal voltage signal V(t) = Vo + V, sin (2nFt) (V, = 600 V, F = 100 KHz) applied to an intracavity electro-optic crystal. The stabilization of periodic orbits within the chaotic region has been obtained by slight modulations of the control parameter V,. Such perturbations consist of sinusoidal signals at f = f, = 50 KHz and f = f2 = 25 KHz with amplitude e and an adjustable phase offset a = mn with respect to the fundamental sign V(t), that is,
The dynamics of a single mode CO 2 laser with modulated losses has been controlled over the basin... more The dynamics of a single mode CO 2 laser with modulated losses has been controlled over the basin of attraction of one of the periodic orbits contained within the strange attractor. Applying the perturbation being the lowest subharmonic of the fundamental driving force, we have studied the statistics of chaotic and periodic transient time intervals preceding the stabilization or destabilization of a given periodic orbit in the vicinity of the bifurcation points. An experimental evidence of the exponential probability distribution of chaotic transients, predicted by the theory, has been demonstrated for the first time.
In a homogeneously broadened CO2laser [1] only the polarization can be adiabatically eliminated (... more In a homogeneously broadened CO2laser [1] only the polarization can be adiabatically eliminated (class B lasers), so that the dynamics is ruled by two rate equations for the field and population inversion ( I = E 2 / E s 2 is the field squared and normalized to saturation intensity E S 2 = γ ⊥ γ IL 4 g 2   , G = 2 g 2 / γ 1 is the coupling factor, d is the population inversion normalized to the pump value Δo, with g = wµ2/ħϵoV and γ1, γILfor the polarization and population inversion decay rates).
... Such a system is described by two rate equations for the intensity x(t) and population invers... more ... Such a system is described by two rate equations for the intensity x(t) and population inversion y(t): x=-Kox(l+f(u)-Y) , Y=-YI1(Y+xY-Yo) , (la) (lb) where Ko-(clL)(T+Dr) is the nonmodulated cavity parameter, L is cavity length, T and Df are the effective ... [4] J. Dupr , F. Meyer and C ...
A single mode CO2 laser near threshold behaves differently depending on whether the threshold is ... more A single mode CO2 laser near threshold behaves differently depending on whether the threshold is reached by varying the pump or the cavity losses. Only in the first case we observe a delayed bifurcation. Our experimental results are explained by a four level molecular model which takes into account the coupling between the two resonant levels and the rotational manifold.
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