共查询到20条相似文献,搜索用时 15 毫秒
1.
Received: 12 June 1998 相似文献
2.
H.P. Breuer B. Kappler F. Petruccione 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(1):9-13
A fast simulation algorithm for the calculation of multitime correlation functions of open quantum systems is presented. It
is demonstrated that any stochastic process which “unravels” the quantum Master equation can be used for the calculation of
matrix elements of reduced Heisenberg picture operators, and thus for the calculation of multitime correlation functions,
by extending the stochastic process to a doubled Hilbert space. The numerical performance of the stochastic simulation algorithm
is investigated by means of a standard example.
Received: 30 May 1997 / Revised: 4 November 1997 / Accepted: 7 November 1997 相似文献
3.
S. Yuan J.-Y. Gao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):267-272
A new scheme of the influence of quantum interference on the spontaneous emission in a coherently driven three-level medium
is presented in this paper. The results are the same with that discussed by [S.-Y. Zhu, L.M. Narducci, M.O. Scully, Phys.
Rev. A 52, 4791 (1995)] under resonance conditions, but they are different when the driven field is detuned.
Received 8 September 1999 and Received in final form 13 January 2000 相似文献
4.
Spatial and temporal properties of parametric fluorescence around degeneracy in a type I LBO crystal
F. Devaux E. Lantz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(1):117-124
We present a theoretical and experimental study of the spatio-temporal properties of the spontaneous parametric emission generated
in a type I LBO crystal around degeneracy. The number of quasi-phase-matched modes is shown to be equal to the number of spatio-temporal
degrees of freedom of the image that can be parametrically amplified. From this number, we demonstrate the possibility of
predicting the total number of photons generated by parametric fluorescence. Correlation is observed between spatial intensity
fluctuations corresponding to pairs of signal-idler modes.
Received 18 February 1999 and Received in final form 9 June 1999 相似文献
5.
C. Wiele F. Haake K. Rzażewski 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(3):405-409
We solve the superradiant laser model in two limiting cases. First the stationary low-pumping regime is considered where a
first-order phase transition in the semiclassical solution occurs. This discontinuity is smeared out in the quantum regime.
Second, we solve the model in the non-stationary regime where we find a temporally periodic solution. For a certain parameter
range well-separated pulses may occur.
Received: 19 June 1998 / Accepted: 19 October 1998 相似文献
6.
A. Casado A. Fernández-Rueda T. Marshall J. Martínez R. Risco-Delgado E. Santos 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(3):465-472
The theory of parametric down conversion within the framework of the Wigner representation has been treated recently in a
series of papers using the standard model Hamiltonian. Here we take a more fundamental point of view studying the mechanism,
inside the crystal, for the production of the signal and idler beams. We begin from the evolution equations for the quantum
field operators, pass to the Wigner function and solve the resulting (Maxwell) equations with the use of the Green's function
method. We derive the time dependence of the coincidence detection probability as a function of the parameters of the nonlinear
crystal (in particular the length) the radius of the pumping beam, and the bandwidth of the filters in front of the detectors.
Received 24 January 2000 and Received in final form 24 March 2000 相似文献
7.
F.E. van Dorsselaer G. Nienhuis 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(2):175-180
We present a scheme for stochastic quantum-state diffusion (QSD) with adaptive noise to calculate the time evolution of an
arbitrary observable of an open system. The method is based on the fact that the observable is much less sensitive to adaptive
noise than to noise with a random phase. Hence, the individual realisations of the expectation value of the observable stay
closer to the average evolution and fewer realisations are required to obtain the ensemble average. This is illustrated by
applying QSD to a driven two-level system using both randomly phased and adaptive noise. Applying QSD with adaptive noise
to an undriven two-level system enables us to derive a deterministic Schr?dinger equation that produces the exact evolution
of an arbitrary observable.
Received: 31 July 1997 / Received in final form: 12 February 1998 / Accepted: 13 March 1998 相似文献
8.
A. Casado T. Marshall R. Risco-Delgado E. Santos 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(1):109-119
We continue the study of parametric down conversion within the framework of the Wigner representation, by using a Maxwellian
approach developed in a recent paper [A. Casado et al., Eur. Phys. J. D 11, 465 (2000)]. This gives a mechanism, inside the crystal, for the production of the down-converted radiation. We obtain the
electric field to second order in the coupling constant by using the Green's function method, and compare our treatment with
the standard Hamiltonian approach. The spectrum of the down-converted radiation is calculated as a function of the parameters
of the nonlinear crystal (in particular the length) and the radius of the pumping beam.
Received 15 May 2000 相似文献
9.
S. Mancini A. Gatti L. Lugiato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(3):499-508
We study the noiseless amplification of an optical image by means of a confocal cavity containing a parametric medium. We
demonstrate, in the ideal situation, the possibility of preserving the signal-to-noise ratio while amplifying uniformly the
entire image. Some specific effects, which may degrade the performances of the scheme, are taken into account.
Received 23 March 2000 相似文献
10.
X. Luo S. Zhu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):111-117
A two-dimensional decoupling theory is developed when colored noise is included in a nonlinear dynamical system. By a functional
analysis, the colored noise is transformed to an effective noise that includes the noise correlation time, the mean dynamical
variable, and the original noise strength. When the two-dimensional decoupling theory is applied to single-mode and two-mode
dye laser systems, the mean, variance, and effective eigenvalue of laser intensity are calculated. Excellent agreement between
theoretical analysis, numerical simulations, and experimental measurements are obtained. It is seen that the increase of noise
correlation time can reduce the fluctuations in the laser system. It is also shown that there is relatively large fluctuation
in the phase when the laser undergoes from thermal light to coherent light when the theory is applied to a single mode dye
laser.
Received 20 August 2001 and Received in final form 4 December 2001 相似文献
11.
A. Lambrecht M.T. Jaekel S. Reynaud 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,3(1):95-104
We calculate the photon emission of a high finesse cavity moving in vacuum. The cavity is treated as an open system. The field
initially in the vacuum state accumulates a dephasing depending on the mirrors motion when bouncing back and forth inside
the cavity. The dephasing is not linearized in our calculation, so that qualitatively new effects like pulse shaping in the
time domain and frequency up-conversion in the spectrum are found. Furthermore we predict the existence of a threshold above
which the system should show self-sustained oscillations.
Received: 10 December 1997 / Received in final form: 27 March 1998 / Accepted: 27 March 1998 相似文献
12.
K. Mølmer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(2):301-305
We discuss the possibility of preparing an atomic sample of atoms with minimum fluctuations in the difference between populations
of two levels. A first scheme involves absorption of twin beams of light, and it presents a variant of a recent proposal for
atomic spin squeezing within an excited state manifold [Kuzmich et al., Phys. Rev. Lett. 79, 4782 (1997)]. A second scheme involves atoms with two stable states, and we suggest that by use of quantum non-demolition
detection and feed-back optical pumping, we may ensure a perfect agreement between the number of atoms in these two states.
Received: 14 May 1998 / Revised: 10 August 1998 / Accepted: 8 October 1998 相似文献
13.
A. Lambrecht S. Reynaud 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(3):309-318
We study the influence of finite conductivity of metals on the Casimir effect. We put the emphasis on explicit theoretical
evaluations which can help comparing experimental results with theory. The reduction of the Casimir force is evaluated for
plane metallic plates. The reduction of the Casimir energy in the same configuration is also calculated. It can be used to
infer the reduction of the force in the plane-sphere geometry through the “proximity theorem”. Frequency dependent dielectric
response functions of the metals are represented either by the simple plasma model or, more accurately, by using the optical
data known for the metals used in recent experiments, that is Al, Au and Cu. In the two latter cases, the results obtained
here differ significantly from those published recently.
Received 30 July 1999 相似文献
14.
15.
P. Grangier J.-P. Poizat 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(1):99-105
By generalizing recently obtained results we calculate the excess noise factor (Petermann factor) for a laser system with
non-orthogonal eigenmodes. The quantum consistency of the calculation is shown through the explicit conservation of input-output
commutation rules. As a result of the calculation, the excess noise in the lasing mode is shown to depend on the laser gain
below threshold, and on the noise analysis frequency below and above threshold.
Received: 27 October 1998 / Received in final form: 11 March 1999 相似文献
16.
C.-Q. Cao C.-G. Yu H. Cao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):279-284
The spontaneous emission of an excited atom is analyzed by quantum stochastic trajectory approach without both rotating-wave
approximation and Markovian approximation. The atom finite size effect is also taken into account. We show by an example that
the correction due to the counter-rotating wave term is rather small, even for the largest atomic number of real nuclei.
Received 10 July 2002 / Received in final form 12 November 2002 Published online 4 February 2003 相似文献
17.
T. Möller K. von Haeften T. Laarman R. von Pietrowski 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(1):5-9
We introduce a novel control method for a delayed dynamical system exhibiting high-dimensional chaos. The control is based
on a negative feedback loop with an adaptive filtering, consisting of a selective filter, centered at the frequency of the
orbit to be stabilized, with the addition of a time derivative correction. The validity of the method is also discussed in
the framework of a space-like representation adopted to study the analogies between delayed dynamical systems and spatially
extended systems.
Received: 12 April 1999 相似文献
18.
F. Grassia J. -M. Courty S. Reynaud P. Touboul 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(1):101-110
We present a quantum network approach to real high sensitivity measurements. Thermal and quantum fluctuations due to active
as well as passive elements are taken into account. The method is applied to the analysis of the capacitive accelerometer
using the cold damping technique, developed for fundamental physics in space by ONERA and the ultimate limits of this instrument
are discussed. It is confirmed in this quantum analysis that the cold damping technique allows one to control efficiently
the test mass motion without degrading the noise level.
Received 20 April 1999 and Received in final form 2 July 1999 相似文献
19.
E. Lantz F. Devaux 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):93-98
We study the properties of the spatial fluctuations in the far-field parametric fluorescence output of a type 1 degenerate
traveling-wave parametric amplifier. Results of a semi-classical simulation are compared with experiments in a LBO crystal.
This simulation is then used to predict amplified images of a continuous background, in a phase-sensitive as well as in a
phase-insensitive configuration.
Received 12 March 2001 相似文献
20.
X.-m. Hu J. Xiong J.-s. Peng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(3):401-413
A theoretical analysis of the spectral linewidth of V-type inversionless and Raman lasers is presented. First, we examine
the effects of the atomic coherence between dressed states and the Autler-Townes splitting on the linewidth. It is demonstrated
that near above threshold, the V inversionless laser has a narrower linewidth than that of the two-level laser. Instead of
the dressed coherence, it is the Autler-Townes splitting that is responsible for the linewidth reduction though the dressed
coherence determines the laser gain. Next, we explore the effects of the generated laser intensity on the linewidth. It is
shown that the linewidths of the V inversionless and Raman lasers follow the usual 1/I decrease for smaller laser intensity I, but a slower decrease than 1/I for larger laser intensity. For the V Raman laser, even more surprisingly, with the laser intensity increasing, the linewidth
appreciably increases as well. As a result, well above threshold, the V inversionless and Raman lasers may have a larger linewidth
than that of the two-level laser. Finally, a comparison is made between the V lasers and the Λ lasers. It is found that the
linewidth of the Λ inversionless laser shows a fast 1/I
2 decay under optimum conditions.
Received 25 October 1999 and Received in final form 10 March 2000 相似文献