S. Engo | The University of Ngaoundéré (original) (raw)
Papers by S. Engo
The model of quantum associative memories proposed here is quietly similar to that of Rigui Zhou ... more The model of quantum associative memories proposed here is quietly similar to that of Rigui Zhou et al. [1] based on quantum matrix with binary decision diagram and nonlinear search algorithm put forth by David Rosenbaum [2] and Abrams and Llyod [3] respectively. Our model that simplifies and generalizes that of Ref. [1], gives the possibility to retrieve one of the sought states in multi-values retrieving, when a measure on the first register is done. If n is the number of qubit of the first register, p ≤ 2n the number of stored patterns, q ≤ p the number of stored patterns if the values of t are known (i.e., t qubits have been measured or are already be disentangled to others, or the oracle acts on a subspace of (n − t) qubits), m ≤ q the number of values x for which f(x) = 1, c = ceil(log2 q) the least integer greater or equal to log2 q, and r = int(log2m) the integer part of log2m, then the time complexity of our algorithm is O(c − r). It is better than Grover’s algorithm and it...
arXiv: Medical Physics, 2013
In this paper we present a model of Quantum Associative Memory which can be a helpful tool for ph... more In this paper we present a model of Quantum Associative Memory which can be a helpful tool for physicians without experience or laboratory facilities, for the diagnosis of four tropical diseases (malaria, typhoid fever, yellow fever and dengue) which have similar symptoms. The memory can distinguish single infection from multi-infection. The algorithm used for Quantum Associative Memory is an improve model of original algorithm made by Ventura for Quantum Associative Memory. From the simulation results given, it appears that the efficiency of recognition is good when a particular symptom of a disease with a similar symptoms are inserted.
Journal of the Optical Society of America B
Optomechanical systems are known to exhibit self-sustained limit cycles once driven above the par... more Optomechanical systems are known to exhibit self-sustained limit cycles once driven above the parametric instability point. This breaks down the linearized approximation and induces novel nonlinear effects such as dynamical multistability, staircase behavior, and the generation of optical high-order sideband combs (HOSCs). Here, we study the classical nonlinear dynamics of optomechanical systems. We combine numerical simulations and analytical investigation to predict dynamical multistability in the resolved sideband regime. A way to predict the onset of the period doubling process and to control the multistability is analytically provided by tuning the optical linewidth. Indeed, the multistability behavior first changes to a staircase shape and gradually disappears as the system approaches the unresolved sideband limit. We exploit the multistable attractors to generate optical HOSCs by acting solely on the initial values instead of increasing the driving strength. This is the figure of merit of our proposal to relate multistability to the HOSC. As a result, the properties (bandwidth, intensity) of the combs are improved as the mechanical resonator moves towards upper attractors. This work opens a way for low-power HOSC generation in optomechanics and the related technological applications.
Physical Review A, 2017
In dissipative optomechanical systems, the total damping hits negative values at the parametric i... more In dissipative optomechanical systems, the total damping hits negative values at the parametric instability point. This also corresponds to the phonon lasing threshold, where the mechanical resonator enters in the self-induced oscillations regime. This paper shows that the two mentioned phenomena are delayed from each other when the optomechanical systems operate close to their conservative limit, where the mechanical damping is very small. In fact, the total damping can be negative and very small for a while before the phonon lasing happens. As a result, the linearized theory is extended over the negative damping region where the mechanical displacements remain very small. It follows that nonlinear behavior as the dynamical multistability is retarded in such systems.
The model of quantum associative memories proposed here is quietly similar to that of Rigui Zhou ... more The model of quantum associative memories proposed here is quietly similar to that of Rigui Zhou \etal \cite{zhou2012} based on quantum matrix with binary decision diagram and nonlinear search algorithm put forth by David Rosenbaum \cite{Rosenbaum2010} and Abrams and Llyod \cite{Abrams1998} respectively. Our model that simplifies and generalizes that of Ref. \cite{zhou2012}, gives the possibility to retrieve one of the desired states in multi-values retrieving, when a measure on the first register is done. If nnn is the number of qubit of the first register, pleq2np\leq2^npleq2n the number of stored patterns, qleqpq\leq pqleqp the number of stored patterns if the values of ttt are known (i.e., ttt qubits have been measured or are already be disentangled to others, or the oracle acts on a subspace of (n−t)(n-t)(n−t) qubits), mleqqm\leq qmleqq the number of values xxx for which f(x)=1f(x)=1f(x)=1, c=mathttceil(log_2q)c=\mathtt{ceil}(\log_2 {q})c=mathttceil(log2q) the least integer greater or equal to log2q\log_2{q}log2q, and r=mathttint(log2m)r=\mathtt{int} (\log_2 {m})r=mathttint(log_2m) the integer part ...
arXiv:1405.4483v1 [quant-ph] 18 May 2014, May 18, 2014
International Journal of Theoretical Physics, 2013
Phys. Rev. A 86, 043816 (2012) [6 pages]
"Abstract: In this paper, we apply the technique of back-action cooling to investigate the e... more "Abstract: In this paper, we apply the technique of back-action cooling to investigate the effects of both optical and mechanical nonlinearities in optomechanical cooling systems. It is shown that cooling of the nanomechanical oscillator to its ground state is limited by the effects of these nonlinearities. The qualitative result is justified quantitatively by comparing, for the same parameters, our analytical minimum phonon number with the experimental one."
![Research paper thumbnail of Publisher's Note: Optomechanical systems close to the conservative limit [Phys. Rev. A 95 , 013831 (2017)]](https://attachments.academia-assets.com/83232941/thumbnails/1.jpg)
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Journal of Physics B: Atomic, Molecular and Optical Physics, 1995
Physics Letters A, 1993
Analytic wave functions are obtained from the Klein-Gordon equation by using the quantum-defect t... more Analytic wave functions are obtained from the Klein-Gordon equation by using the quantum-defect theory in the semiclassical Coulomb approximation. From this result, analytic expressions for relativistic electric dipole radial integrals between highly excited Rydberg states chilambda, chi'lambda' are calculated in terms of Anger functions plus an algebraic part combination of sin (pis) and cos(pis), where s=(sigma'/gs)(chi'-chi)-(sigma/sigma')(chi-chi), chi=sqrt(chichi') . chi, lambda,
The model of quantum associative memories proposed here is quietly similar to that of Rigui Zhou ... more The model of quantum associative memories proposed here is quietly similar to that of Rigui Zhou et al. [1] based on quantum matrix with binary decision diagram and nonlinear search algorithm put forth by David Rosenbaum [2] and Abrams and Llyod [3] respectively. Our model that simplifies and generalizes that of Ref. [1], gives the possibility to retrieve one of the sought states in multi-values retrieving, when a measure on the first register is done. If n is the number of qubit of the first register, p ≤ 2n the number of stored patterns, q ≤ p the number of stored patterns if the values of t are known (i.e., t qubits have been measured or are already be disentangled to others, or the oracle acts on a subspace of (n − t) qubits), m ≤ q the number of values x for which f(x) = 1, c = ceil(log2 q) the least integer greater or equal to log2 q, and r = int(log2m) the integer part of log2m, then the time complexity of our algorithm is O(c − r). It is better than Grover’s algorithm and it...
arXiv: Medical Physics, 2013
In this paper we present a model of Quantum Associative Memory which can be a helpful tool for ph... more In this paper we present a model of Quantum Associative Memory which can be a helpful tool for physicians without experience or laboratory facilities, for the diagnosis of four tropical diseases (malaria, typhoid fever, yellow fever and dengue) which have similar symptoms. The memory can distinguish single infection from multi-infection. The algorithm used for Quantum Associative Memory is an improve model of original algorithm made by Ventura for Quantum Associative Memory. From the simulation results given, it appears that the efficiency of recognition is good when a particular symptom of a disease with a similar symptoms are inserted.
Journal of the Optical Society of America B
Optomechanical systems are known to exhibit self-sustained limit cycles once driven above the par... more Optomechanical systems are known to exhibit self-sustained limit cycles once driven above the parametric instability point. This breaks down the linearized approximation and induces novel nonlinear effects such as dynamical multistability, staircase behavior, and the generation of optical high-order sideband combs (HOSCs). Here, we study the classical nonlinear dynamics of optomechanical systems. We combine numerical simulations and analytical investigation to predict dynamical multistability in the resolved sideband regime. A way to predict the onset of the period doubling process and to control the multistability is analytically provided by tuning the optical linewidth. Indeed, the multistability behavior first changes to a staircase shape and gradually disappears as the system approaches the unresolved sideband limit. We exploit the multistable attractors to generate optical HOSCs by acting solely on the initial values instead of increasing the driving strength. This is the figure of merit of our proposal to relate multistability to the HOSC. As a result, the properties (bandwidth, intensity) of the combs are improved as the mechanical resonator moves towards upper attractors. This work opens a way for low-power HOSC generation in optomechanics and the related technological applications.
Physical Review A, 2017
In dissipative optomechanical systems, the total damping hits negative values at the parametric i... more In dissipative optomechanical systems, the total damping hits negative values at the parametric instability point. This also corresponds to the phonon lasing threshold, where the mechanical resonator enters in the self-induced oscillations regime. This paper shows that the two mentioned phenomena are delayed from each other when the optomechanical systems operate close to their conservative limit, where the mechanical damping is very small. In fact, the total damping can be negative and very small for a while before the phonon lasing happens. As a result, the linearized theory is extended over the negative damping region where the mechanical displacements remain very small. It follows that nonlinear behavior as the dynamical multistability is retarded in such systems.
The model of quantum associative memories proposed here is quietly similar to that of Rigui Zhou ... more The model of quantum associative memories proposed here is quietly similar to that of Rigui Zhou \etal \cite{zhou2012} based on quantum matrix with binary decision diagram and nonlinear search algorithm put forth by David Rosenbaum \cite{Rosenbaum2010} and Abrams and Llyod \cite{Abrams1998} respectively. Our model that simplifies and generalizes that of Ref. \cite{zhou2012}, gives the possibility to retrieve one of the desired states in multi-values retrieving, when a measure on the first register is done. If nnn is the number of qubit of the first register, pleq2np\leq2^npleq2n the number of stored patterns, qleqpq\leq pqleqp the number of stored patterns if the values of ttt are known (i.e., ttt qubits have been measured or are already be disentangled to others, or the oracle acts on a subspace of (n−t)(n-t)(n−t) qubits), mleqqm\leq qmleqq the number of values xxx for which f(x)=1f(x)=1f(x)=1, c=mathttceil(log_2q)c=\mathtt{ceil}(\log_2 {q})c=mathttceil(log2q) the least integer greater or equal to log2q\log_2{q}log2q, and r=mathttint(log2m)r=\mathtt{int} (\log_2 {m})r=mathttint(log_2m) the integer part ...
arXiv:1405.4483v1 [quant-ph] 18 May 2014, May 18, 2014
International Journal of Theoretical Physics, 2013
Phys. Rev. A 86, 043816 (2012) [6 pages]
"Abstract: In this paper, we apply the technique of back-action cooling to investigate the e... more "Abstract: In this paper, we apply the technique of back-action cooling to investigate the effects of both optical and mechanical nonlinearities in optomechanical cooling systems. It is shown that cooling of the nanomechanical oscillator to its ground state is limited by the effects of these nonlinearities. The qualitative result is justified quantitatively by comparing, for the same parameters, our analytical minimum phonon number with the experimental one."
Journal of Physics B: Atomic, Molecular and Optical Physics, 1995
Physics Letters A, 1993
Analytic wave functions are obtained from the Klein-Gordon equation by using the quantum-defect t... more Analytic wave functions are obtained from the Klein-Gordon equation by using the quantum-defect theory in the semiclassical Coulomb approximation. From this result, analytic expressions for relativistic electric dipole radial integrals between highly excited Rydberg states chilambda, chi'lambda' are calculated in terms of Anger functions plus an algebraic part combination of sin (pis) and cos(pis), where s=(sigma'/gs)(chi'-chi)-(sigma/sigma')(chi-chi), chi=sqrt(chichi') . chi, lambda,