共查询到20条相似文献,搜索用时 46 毫秒
1.
S. Spälter P. van Loock A. Sizmann G. Leuchs 《Applied physics. B, Lasers and optics》1997,64(2):213-218
The optical Kerr effect provides an ideal quantum non-demolition interaction. Experiments and proposals using this interaction
are reviewed with special emphasis on optical soliton pulses propagating in fibres. The performance of a quantum non-demolition
experiment using the optical Kerr effect may be reduced by self-phase modulation of the probe pulse. Proposals to overcome
this limitation are discussed.
Received: 15 April 1996 相似文献
2.
We show that a single-port optical cavity with a movable mirror can provide a quantum non-demolition measurement of the intensity
of a light beam. Due to radiation pressure, the cavity length is sensitive to the light intensity and can be measured with
a secondary light beam. Signal-meter correlations can be made very large even at non-zero temperature. We study these correlations
when the moving mirror is a plane–convex crystal resonator and we show the importance of spatial matching between light and
acoustic modes.
Received: 12 June 1996/Revised version: 3 September 1996 相似文献
3.
4.
We propose an alternative method for the quantum non-demolition measurement of photon numbers wherein weak cross-Kerr nonlinearities are to be used. The usual approach to quantum non-demolition measurements of quantum number involves encoding the photon number, through a cross-Kerr interaction, into a phase shift of a probe coherent state which is then detected through balanced homodyning. Weak nonlinearities produce small phase shifts which are difficult to detect and distinguish. In the method we propose, unbalanced homodyning acts as a displacement operator on the probe beam coherent state such that the cross-Kerr interaction encodes the photon number into the amplitude of a new coherent state. The value of the photon number can be determined by inefficient photon counting on the new coherent state. Our proposed method requires fewer resources than does the usual approach. 相似文献
5.
J. F. Roch G. Roger P. Grangier J.-M. Courty S. Reynaud 《Applied physics. B, Lasers and optics》1992,55(3):291-297
We review the schemes which have been implemented, in order to achieve quantum non-demolition (QND) measurements in the optical domain. The simplest schemes can be obtained using the optical Kerr effect, which yields a crossed-phase modulation coupling between two light beams. Other schemes use either independently generated squeezed light, or coupled-mode parametric amplifiers. These various schemes can be characterized using three criteria, which describe, respectively, the quality of the quantum measurement, the non-destruction of the signal, and the conditional variance of the output signal beam, given the output meter beam (quantum-state preparation criterion). We show that quantitative limits can be defined with respect to these criteria, delimiting classical and quantum domains of operation. Then we present in more detail a new experimental implementation of QND measurements, using three-level atoms inside a doubly-resonant optical cavity. 相似文献
6.
We describe, in detail, theoretical and experimental aspects related to our recently reported repeated back-action evading
measurements performed using two travelling-wave optical parametric amplifiers in series. The state of the observable being
measured is almost perfectly preserved after two successive measurements. The final signal, and the intermediate measurement
of the two successive setups are quantum correlated with conditional variances that lie in the quantum regime. Moreover, we
show that the two independent measurements are quantum correlated up to 30%.
Received: 11 April 1996/Revised version: 18 July 1996 相似文献
7.
The evolution of a two-level system subjected to stimulated transitions which is undergoing a sequence of measurements of
the level occupation probability is evaluated. Its time correlation function is compared to the one obtained through the pure
Schr?dinger evolution. Systems of this kind have been recently proposed for testing the quantum mechanical predictions against
those of macrorealistic theories, by means of temporal Bell inequalities. The classical requirement of noninvasivity, needed
to define correlation functions in the realistic case, finds a quantum counterpart in the quantum nondemolition condition.
The consequences on the observability of quantum mechanically predicted violations to temporal Bell inequalities are drawn
and compared to the already dealt case of the rf-SQUID dynamics.
Received: 28 March 1996 / Revised version: 13 August 1996 相似文献
8.
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
9.
We show that a Schr?dinger cat state can be generated using a crossed Kerr interaction between two optical modes and an appropriate
conditional measurement on one of the modes. The effect of damping on the generation process is analyzed in detail and two
possible detection schemes for the cat state are presented.
Received: 15 May 1996 相似文献
10.
We propose a scheme for quantum nondemolition (QND) measurement of the quadrature component of a traveling wave, which uses
the nonlinear ponderomotive interaction of electromagnetic waves reflected from a movable mirror. The influence of mechanical
and optical losses and of imbalance in the interferometer arms is analyzed.
Received: 27 March 1996 / Revised version: 25 September 1996 相似文献
11.
Yu. M. Ajvasjan V. V. Ivanov S. A. Kovalenko V. M. Baev E. A. Sviridenkov H. Atmanspacher H. Scheingraber 《Applied physics. B, Lasers and optics》1988,46(2):175-182
The dynamics of individual modes of a cw multimode dye laser in a 2-mirror configuration has been studied theoretically and experimentally. Numerical solutions of the laser rate equations including nonlinear mode coupling exhibit chaotic and stochastic behavior in the regime of high and low power, respectively. Chaotic behavior due to mode coupling has been observed in the operating regime well above threshold. The mode dynamics in this case is characterized by a chaotic attractor with low dimension between 2 and 3. With decreasing laser power the dimension increases, suggesting stochastic behavior due to quantum noise in the limit of the laser threshold.On leave at 1. Institut für Experimentalphysik, Universität Hamburg, Fed. Rep. Germany 相似文献
12.
Present schemes involving the quantum non-demolition interaction between atomic samples and off-resonant light pulses allow us to store quantum information corresponding to a single harmonic oscillator (mode) in one multi-atomic system. We discuss the possibility of involving several coherences of each atom so that the atomic sample can store information contained in several quantum modes. This is achieved by the coupling of different magnetic sublevels of the relevant hyperfine level by additional Raman pulses. This technique allows us to design not only the quantum non-demolition coupling, but also beam splitter-like and two-mode squeezer-like interactions between light and collective atomic spin. 相似文献
13.
The concept of a doubly resonant frequency doubler can be used for a variety of experiments concerning both classical phenomena like efficient frequency doubling at low power levels and quantum effects like squeezed states of light or Quantum Non Demolition (QND) measurements. In many of these experiments the strength of the nonlinear coupling of fundamental and second-harmonic modes is of crucial importance. First we treat the general theory for the calculation of the coupling parameter, which depends not only on properties of the nonlinear material but also on resonator geometry and some optical phases. On this basis we discuss in detail the situation for two different monolithic resonator geometries, namely a linear (standing-wave) and a ring (travelling-wave) cavity. Finally we compare theoretical predictions for these resonators to the experimentally achieved results. 相似文献
14.
We provide a general dynamical approach for the quantum Zeno and anti-Zeno efects in an open quantum system under repeated non-demolition measurements.In our approach the repeated measurements are described by a general dynamical model without the wave function collapse postulation.Based on that model,we further study both the short-time and long-time evolutions of the open quantum system under repeated non-demolition measurements,and derive the measurement-modified decay rates of the excited state.In the cases with frequent ideal measurements at zero-temperature,we re-obtain the same decay rate as that from the wave function collapse postulation(Nature,2000,405:546).The correction to the ideal decay rate is also obtained under the non-ideal measurements.Especially,we find that the quantum Zeno and anti-Zeno efects are possibly enhanced by the non-ideal natures of measurements.For the open system under measurements with arbitrary period,we generally derive the rate equation for the long-time evolution for the cases with arbitrary temperature and noise spectrum,and show that in the long-time evolution the noise spectrum is efectively tuned by the repeated measurements.Our approach is also able to describe the quantum Zeno and anti-Zeno efects given by the phase modulation pulses,as well as the relevant quantum control schemes. 相似文献
15.
G. Schrade P.J. Bardroff R.J. Glauber C. Leichtle V. Yakovlev W.P. Schleich 《Applied physics. B, Lasers and optics》1997,64(2):181-191
We show that three real-valued parameters govern the quantum motion of an ion stored in the Paul trap. These parameters are
two angles of rotation in phase space and a squeezing parameter. The time dependence of these parameters simplifies considerably
using Floquet solutions. This allows us to use the method of quantum state endoscopy to measure a pure state of the vibratory
motion of an ion taking into account the full time dependence of the trapping potential.
Received: 19 June 1996 相似文献
16.
We provide a general dynamical approach for the quantum Zeno and anti-Zeno efects in an open quantum system under repeated non-demolition measurements.In our approach the repeated measurements are described by a general dynamical model without the wave function collapse postulation.Based on that model,we further study both the short-time and long-time evolutions of the open quantum system under repeated non-demolition measurements,and derive the measurement-modified decay rates of the excited state.In the cases with frequent ideal measurements at zero-temperature,we re-obtain the same decay rate as that from the wave function collapse postulation(Nature,2000,405:546).The correction to the ideal decay rate is also obtained under the non-ideal measurements.Especially,we find that the quantum Zeno and anti-Zeno efects are possibly enhanced by the non-ideal natures of measurements.For the open system under measurements with arbitrary period,we generally derive the rate equation for the long-time evolution for the cases with arbitrary temperature and noise spectrum,and show that in the long-time evolution the noise spectrum is efectively tuned by the repeated measurements.Our approach is also able to describe the quantum Zeno and anti-Zeno efects given by the phase modulation pulses,as well as the relevant quantum control schemes. 相似文献
17.
The theory of unsharp quantum measurements is reviewed as a generalization of the von Neumann-Lüders measurement theory and applied to measurements of continuous quantities. A generalized notion of repeatability is proposed which is applicable even to intrinsically unsharp continuous observables. As an illustration a precise formulation of a quantum non-demolition (QND) measurement performed on a harmonic oscillator is given. 相似文献
18.
R. Bruckmeier K. Schneider H. Hansen M. Schalke S. Schiller J. Mlynek 《Applied physics. B, Lasers and optics》1997,64(2):203-212
QND measurements of the amplitude quadrature of continuous-wave light are performed with a monolithic dual-port degenerate
optical parametric amplifier (OPA). Operated with a vacuum meter input, both output beams are squeezed and 33% correlated,
demonstrating individually squeezed twin beams. The sum of the signal and meter transfer coefficients is 1.05, demonstrating
operation as a quantum optical tap. The device exhibits quantum state preparation ability for both signal and meter output,
reaching the conditional variances of dB and dB, respectively. An improved quantum measurement is realized by injecting 3.4 dB amplitude-squeezed light into the meter
input port of the OPA. This achieves increased correlation and squeezing of the output beams, and both improved operation
as a quantum optical tap and as a quantum state preparator. The all-solid-state system was operated for up to 5 hours with
high stability.
Received: 25 July 1996 相似文献
19.
Jun He Yong-Sheng Zhang Xiang-Fa Zhou Qun-Feng Chen Guang-Can Guo 《Optics Communications》2009,282(6):1167-1170
An method for adiabatic population transfer and the preparation of an arbitrary quantum superposition state using the oscillating dark states (ODS) in atomic system is presented. Quantum state of a three-level Λ configuration atomic system finally evolves into the same time-dependent state, and oscillates periodically between two ground levels under evolving adiabatic conditions when two pairs of classical detuning laser fields drive the system into the ODS forcedly, whatever the initial states of the system are. The decoherence of the ODS evolution is greatly suppressed and the oscillation is very stable, therefore adiabatic population transfer and the preparation of an arbitrary quantum superposition state of atomic system can be completed accurately and conveniently. 相似文献
20.
We derive a master equation describing the evolution of a quantum system subjected to a sequence of observations. These measurements occur randomly at a given rate and can be of a very general form. As an example, we analyse the effects of these measurements on the evolution of a two-level atom driven by an electromagnetic field. For the associated quantum trajectories we find Rabi oscillations, Zeno-effect type behaviour and random telegraph evolution spawned by mini quantum jumps as we change the rates and strengths of measurement. 相似文献