共查询到20条相似文献,搜索用时 15 毫秒
1.
A. Trifonov G. Björk J. Söderholm T. Tsegaye 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(2):251-258
In an interferometer, path information and interference visibility are incompatible quantities. Complete determination of
the path will exclude any possibility of interference, rendering zero visibility. However, it is, under certain conditions,
possible to trade the path information for improved (conditioned) visibility. This procedure is called quantum erasure. We
have performed such experiments with polarization-entangled photon pairs. Using a partial polarizer, we could vary the degree
of entanglement between the object and the probe. We could also vary the interferometer splitting ratio and thereby vary the
a priori path predictability. This allowed us to test quantum erasure under a number of different experimental conditions. All experiments
were in good agreement with theory.
Received 15 July 2001 and Received in final form 30 November 2001 相似文献
2.
Xun-Li Feng Zhao-Yang Chen Zhi-Zhan Xu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(1):117-121
The nondegenerate two-photon interaction of a two-level atom with a broadband multimode squeezed vacuum is investigated. We
find that in the two-photon process the squeezed vacuum has a driving effect on the atom which can lead to an ac Stark effect
when the average photon number of the squeezed vacuum is larger than a critical value.
Received: 2 February 1999 / Received in final form: 20 April 1999 相似文献
3.
C.P. Sun X.F. Liu D.L. Zhou S.X. Yu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):85-92
To account for the phenomenon of quantum decoherence of a macroscopic object, such as the localization and disappearance of
interference, we invoke the adiabatic quantum entanglement between its collective states (such as that of the center-of-mass
(CM)) and its inner states based on our recent investigation. Under the adiabatic limit where motion of the CM does not excite
the transition of inner states, it is shown that the wave function of the macroscopic object can be written as an entangled
state with correlation between adiabatic inner states and quasi-classical motion configurations of the CM. Since the adiabatic
inner states are factorized with respect to each component of the macroscopic object, this adiabatic separation can induce
the quantum decoherence. This observation thus provides us with a possible solution to the Schr?dinger cat paradox.
Received 24 October 2000 and Received in final form 8 March 2001 相似文献
4.
5.
Hong-yi Fan J. Chen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):437-442
Based on the newly constructed Einstein, Podolsky and Rosen (EPR) entangled state representation we introduce macroscopic
classical functions associated with atomic coherent state τ with angular momentum value j. These functions are proportional to the ordinary one-variable Hermite polynomials of order 2j. The corresponding Wigner quasiprobability function for τ in phase space is also derived which turns out to be a two-variable Hermite polynomial H
2j, 2j. In so doing, a new classical-quantum correspondence scheme for angular momentum system is established.
Received 7 August 2002 / Received in final form 14 December 2002 Published online 24 April 2003
RID="a"
ID="a"Work supported by the National Natural Science Foundation of China under grant 10175057.
RID="b"
ID="b"e-mail: fhym@sjtu.edu.en 相似文献
6.
M. Konôpka V. Bužek 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(2):285-293
We propose a method for entangling a system of two-level atoms in photonic crystals. The atoms are assumed to move in void
regions of a photonic crystal. The interaction between the atoms is mediated either via a defect mode or via a resonant dipole-dipole interaction. We show that these interactions can produce pure entangled atomic states. We analyze the problem with parameters typical
for currently existing photonic crystals and Rydberg atoms and we show that the atoms can emerge from photonic crystals in
entangled states. Depending on the linear dimensions of the crystal we estimate that a pair of atoms entangled in a photonic
crystal can be separated by tens of centimeters.
Receive 11 June 1999 and Received in final form 4 October 1999 相似文献
7.
V.S. Malinovsky J.L. Krause 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(2):147-155
We present a general theory of adiabatic rapid passage (ARP) with intense, linearly chirped laser pulses. For pulses with
a Gaussian profile and a fixed bandwidth, we derive a rigorous formula for the maximum temporal chirp rate that can be sustained
by the pulse. A modified Landau-Zener formula displays clearly the relationships among the pulse parameters. This formula
is used to derive the optimal conditions for efficient, robust population transfer. As illustrations of the theory, we present
results for two- and four-level systems, and selective vibronic excitation in the I2 molecule. We demonstrate that population transfer with chirped pulses is more robust and more selective than population transfer
with transform-limited pulses.
Received 6 September 2000 and Received in final form 25 September 2000 相似文献
8.
J. Zou B. Shao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(3):329-334
Aharonov-Bohm-type electron interference in the presence of the two-mode SU(1,1) coherent state(CS) field is investigated.
The visibility of the time-averaged interference pattern is discussed for this state, and a comparison with classical cases
is made. It is shown that the time evolution of the intensity of electron interference exhibits collapse and revival (CR)
phenomenon for this state. The fluctuation in electron interference, and its relation to CR phenomenon are also discussed.
Received: 22 August 1997 / Accepted: 15 January 1998 相似文献
9.
R. Jung S. Gerlach R. Schumann G. von Oppen U. Eichmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):415-419
We report on the first successful loading of a magneto-optical trap (MOT) with metastable He atoms from a Stark-slower. Thereby,
deceleration of the atoms relies on laser-atom interaction in an inhomogeneous electric field. We show that the results obtained
are comparable with early results from other groups achieved with a Zeeman slower. The Stark slower, which is able to fully
control the final velocity of the atomic He beam, is the first step in achieving complete spin independent kinematic control
based solely on electric fields.
Received 2 October 2002 / Received in final form 20 January 2003 Published online 29 April 2003
RID="a"
ID="a"e-mail: eichmann@mbi-berlin.de 相似文献
10.
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
11.
D.A. Trifonov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):349-353
A survey on the generalizations of Heisenberg uncertainty relation and a general scheme for their entangled extensions to
several states and observables is presented. The scheme is illustrated on the examples of one and two states and canonical
quantum observables, and spin and quasi-spin components. Several new uncertainty relations are displayed.
Received 10 October 2001 / Received in final form 6 March 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: dtrif@inrne.bas.bg 相似文献
12.
R.K. Varma 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(2):211-218
It has been shown earlier [3,6] that matter waves which are known to lie typically in the range of a few angstrom, can also
manifest in the macrodomain with a wave length of a few centimeters, for electrons propagating along a magnetic field. This
followed from the predictions of a probability amplitude theory by the author [1,2] in the classical macrodomain of the dynamics
of charged particles in a magnetic field. It is shown in this paper that this case constitutes only a special case of a generic
situation whereby composite systems such as atoms and molecules in their highly excited internal states, can exhibit matter
wave manifestation in macro and mesodomains, in one-dimensional scattering. The wave length of these waves is determined,
not by the mass of the particle as in the case of the de Broglie wave, but by the frequency ω, of the classical orbital motion
of the internal state in the correspondence limit, and is given by a nonquantal expression, λ = 2πv/ω, v being the velocity of the particle. For the electrons in a magnetic field the frequency corresponds to the gyrofrequency,
Ω and the nonquantal wave length is given by λ = 2πv
|| /Ω; v
|| being the velocity of electrons along the magnetic field.
Received 29 September 2001 / Received in final form 23 May 2002 Published online 19 July 2002 相似文献
13.
T. Krüger 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):299-307
Suppose that a pair of entities which have been generated jointly from a common source are separated by an experimental device
so that they cannot interact any more. Then, strictly formulating within the framework of traditional quantum mechanics, the
ensemble of all pairs may be represented by either a separable or a non-separable statistical operator. The former stands for the independence of the sub-ensembles whereas the latter admits correlations
(EPR correlations) due to the presence of interference or cross terms. The second-order correlation function Δ, which is also
amenable by experiment, adopts different values depending on the choice of the statistical operator. So, by performing an
experiment of this kind with molecules, the question could be decided whether EPR correlations appear in the molecular domain
too. A detailed elaboration of the following idea is presented: let an achiral precursor molecule M2 dissociate so that two chiral fragments of different handedness are obtained. After separation R-M (L-M) interacts in a region
of space A (B) with a photon I (II) in an already known linear polarization state. The enantiomeric correlation between the
fragments is thereby conferred to the photons, and the corresponding changes of the polarization state are detected for different
polarizer settings to finally yield Δ.
Received 10 May 2000 and Received in final form 25 August 2000 相似文献
14.
G. Duchateau E. Cormier R. Gayet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):191-196
A simple theoretical approach based on Coulomb-Volkov states is introduced to predict ionisation of atoms by intense laser
pulses in cases where the effective interaction time does not exceed one or two optical cycles [M. Nisoli et al., Opt. Lett. 22, 522 (1997)]. Under these conditions, the energy distributions of ejected electrons predicted by this non-perturbative approach
are in very good agreement with “exact" results obtained by a full numerical treatment. The agreement is all the better that
the principal quantum number of the initial state is high. For very strong fields, most electrons are ejected at an energy
which is close to the classical kinetic energy that would be transferred to free electrons by the electromagnetic field during
the pulse. The power of the present approach appears when keV. In this region, full numerical treatments become very lengthy and finally do not converge. However, the present Coulomb-Volkov
theory still makes reliable predictions in very short computer times.
Received 19 November 1999 and Received in final form 19 January 2000 相似文献
15.
P.E. Toschek Ch. Wunderlich 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):387-396
The evolution of a quantum system under observation becomes retarded or even impeded. We review this “quantum Zeno effect”
in the light of the criticism that has been raised upon a previous attempt to demonstrate it, of later reexaminations of both
the projection postulate and the significance of the observations, and of the results of a recent experiment on an individual cold atom. Here, the micro-state of the quantum system gets unveiled with the observation, and the effect of measurement
is no longer mixed up with dephasing the object's wave function by the reactive effect of the detection. A procedure is outlined
that promises to provide, by observation, an upper limit for the delay of even an exponential decay.
Received 11 January 2001 and Received in final form 28 February 2001 相似文献
16.
17.
Preparation of Fock states and quantum entanglement via stimulated Raman adiabatic passage using a four-level atom 总被引:3,自引:0,他引:3
S.-Q. Gong R. Unanyan K. Bergmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(2):257-262
We study the behaviour of an atom-cavity system exposed to a stimulated Raman adiabatic passage (STIRAP) process in a four-level
system, with a coupling scheme which generate two degenerate dark states. We find that the non-adiabatic interaction of the
two dark states guarantees that the cavity Fock states can always be generated by both intuitively and counterintuitively
ordered pulses. Furthermore, we propose a method to entangle two atoms. Depending on the ordering of the pulses two orthogonal
entangled states can be prepared. Since these entangled states do not have component of the excited states included, the technique
is robust against the detrimental consequences of spontaneous emission.
Received 20 March 2001 相似文献
18.
G. Brida M. Genovese F. Piacentini 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(3):577-580
Following the theoretical suggestion of [E. Santos, Phys. Lett. A 327, 33 (2004);
E. Santos, Eur. Phys. J. D 42, 501 (2007)], we present experimental results addressed to
test restricted families of local realistic models, but without
relying on the fair sampling assumption. 相似文献
19.
D.V. Rao R. Cesareo A. Brunetti G.E. Gigante 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):43-49
Total Compton, individual shell and Compton energy-absorption scattering cross-sections are evaluated in the energy region
0.005 to 10 MeV for H, C, N, O, P and Ca. Compton energy absorption cross-sections deviate numerically with available values.
The cause of the numerical discrepancies are not fully understood but can be attributed to Doppler broadening of the Compton
scattered photons through a given angle.
Received 25 June 2002 / Received in final form 27 September 2002 Published online 3rd April 2003
RID="a"
ID="a"e-mail: dvrao@ssmain.uniss.it 相似文献
20.
A. S. Sanz F. Borondo 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):319-326
A complete theoretical treatment in many problems relevant to
physics, chemistry, and biology requires considering the action
of the environment over the system of interest.
Usually the environment involves a relatively large number of degrees
of freedom, this making the problem numerically intractable from a
purely quantum-mechanical point of view.
To overcome this drawback, a new class of quantum trajectories is
proposed.
These trajectories, based on the same grounds as Bohmian ones, are
solely associated to the system reduced density matrix, since the
evolution of the environment degrees of freedom is not considered
explicitly.
Within this approach, environment effects come into play through a
time-dependent damping factor that appears in the system equations
of motion.
Apart from their evident computational advantage, this type of
trajectories also results very insightful to understand the system
decoherence.
In particular, here we show the usefulness of these trajectories
analyzing decoherence effects in interference phenomena, taking as
a working model the well-known double-slit experiment. 相似文献