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1.
We analyze the quantum measurement properties of dual non-degenerate parametric amplifers in the twin-beam configuration,
in the cascaded back-action-evasion configuration, and in Kerr-type photon-number quantum non-demolition measurements. It
is found that Einstein-Podolsky-Rosen correlations can be obtained between the quadrature components of an idler mode and
the sum of the readout of two signal modes. Furthermore, we discuss dual-mode quantum non-demolition measurements on the combination
of two light modes, and the generation of number-state entanglement.
Received: 12 April 1996/Revised version: 2 July 1996 相似文献
2.
QND measurement schemes often use Kerr nonlinearity to couple the intensity fluctuations of the signal beam to the phase
fluctuations of the probe beam by means of the cross-phase modulation effect. Such schemes use materials with intrinsic χ(3)nonlinearity. However, it has already been shown that Kerr-effect-like correlation between two light waves may be achieved
through cascaded χ(2): χ(2) processes. The value of the nonlinearity induced by cascading χ(2) can, in many cases, be much higher than fibre χ(3).
The authors point out the possibility of using the cascaded χ(2) nonlinearity instead of intrinsic χ(3) nonlinearity in the scheme which resembles the well-known photon number QND measurement scheme. The non-degenerate second-harmonic
generation (SHG) with a large phase mismatch is considered. The harmonic wave influence on the measurements is shown. High
QND measurement characteristics can be achieved with the use of an appropriate set of parameters.
Received: 6 April 1996 相似文献
3.
V. B. Braginsky M. L. Gorodetsky F. Y. Khalily 《Applied physics. B, Lasers and optics》1997,64(2):243-247
We propose a new scheme of QND measurement in microwave band. It is shown that with deflection of electron beam in the electric
field of a microwave resonator it is possible to measure quadrature amplitude of oscillations with the precision substantially
exceeding the standard quantum limit. Estimates for the parameters of the experimental setup are presented.
Received: 27 March 1996/Revised version: 5 August 1996 相似文献
4.
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
5.
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
6.
7.
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
8.
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
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.
Monitoring an arbitrary observable is analyzed in the framework of Restricted-Path-Integral (RPI) theory of continuous quantum
measurements. While in an usual (quantum-demolition) continuous measurement the measurement noise contains both classical
and quantum parts, only the classical noise is shown to be present in a quantum nondemolition (QND) continuous measurement.
As a result, no absolute restrictions exist on measurability of a QND observable and the measurement output satisfies the
classical equation of motion. Monitoring the energy gives an example of a discrete-spectrum observable.
Received: 7 April 1996 / Revised version: 7 August 1996 相似文献
11.
An investigation of the behaviour of amplitude and frequency noise of radiation of an active interferometer in the regime
of amplified optical bistability is presented. The phenomenon of non-amplification of external signal noise at sharp amplification
of the external signal is established. The impact of strong amplitude fluctuations is studied. Our results have shown that
the active interferometer allows an effective separation of the valid signal from the amplitude noise. The spectral density
of a fluctuation of the field frequency in the active interferometer is shown to fall sharply in comparison with the “quantum
limit”. The linewidth of radiation is determined by the spectral density at zero frequency and is equal to the natural linewidth
of the external signal. The influence of quantum noise of the amplifying and absorbing media of the active interferometer
is discussed.
Received: 26 January 1996 相似文献
12.
A. Apolonskii S. Baluschev U. Hinze E. Tiemann B. Wellegehausen 《Applied physics. B, Lasers and optics》1997,64(4):435-442
In a double-Λ level configuration of Na2 molecules, involving rotational–vibrational levels of the X, A and B bands, continuous resonant frequency mixing ω4=ω1−ω2+ω3 is demonstrated. A DCM dye laser at 661 nm (λ1) pumps a molecular Raman laser at 746 nm (λ2) in a sodium heatpipe, which is used to generate the molecular vapour. In the same heatpipe, both fields are mixed with the
radiation of an argon-ion laser at 514 nm (λ3) to generate up-converted laser radiation at 473 nm (λ4). For laser powers of 200 mW (λ1), 700 mW (λ2, internal power) and 140 mW (λ3), an output power of 120 μW (λ4) has been achieved. Dependences of the generated radiation on the pump fields (powers and detunings) and polarization features
are presented; influences of coherent coupling and population transfer mechanisms are discussed.
Received: 7 October 1996 相似文献
13.
Received: 11 March 1998/Revised version: 1 April 1998 相似文献
14.
A. Porzio C. Altucci M. Autiero A. Chiummo C. de Lisio S. Solimeno 《Applied physics. B, Lasers and optics》2001,73(7):763-766
We present a novel scheme to separate spatially twin beams generated by a type-I lithium niobate (LNB) optical parametric
oscillator near frequency degeneracy. The system is based on a holographic diffraction grating acting as a beam splitter in
a balanced detector. The fast and easy temperature tuning of LNB index of refraction allows an easy control of the twin-beam
wavelength distance in a range of the order of ∼100 nm. We report correlation spectra measured for different twin-beam wavelength
separations (15–60 nm) with a maximum noise reduction of 3.2 dB at 3.5 MHz. The described system exhibited a pump resonance
stability longer than 6 h with infrared output power fluctuations within 4% around an average value of ≃2 mW in each beam.
The measured oscillation threshold pump power was lower than 31 mW.
Received: 7 June 2001 / Revised version: 17 July 2001 / Published online: 10 October 2001 相似文献
15.
In this paper, we derived the Z-scan formula for a photorefractive crystal sample under an external applied electric field.
The far-field diffraction pattern of a Gaussian beam wavefront through a photorefractive crystal is calculated by considering
spatial-phase perturbation induced by the space-charge field. The photorefractive drift nonlinearities and correspondingly,
the electro-optic coefficients r
33, r
13, (r
23) and the characteristic ratio n
3
e
r
33/n
3
o
r
13 for a cerium-doped Sr0.61Ba0.39Nb2O6 crystal are determined from the Z-scan experiments. Z-scan with enhanced sensitivity is also realized by measuring the normalized
transmittance at the off-axis position in the far field. A deviation between the off-axis Z-scan experimental results and
the theoretical prediction is discussed too.
Received: 22 July 1996/Revised version: 7 October 1996 相似文献
16.
E. Majorana P. Puppo P. Rapagnani F. Ricci 《Applied physics. B, Lasers and optics》1997,64(2):145-151
The Back Action Evading technique is a particular kind of quantum non demolition measurement, first proposed by Caves et al.
in 1980 [3]. We present an experimental study to implement the Back Action Evading measurement scheme in monitoring the amplitude
of an harmonic oscillator excited by a classical force. Results showing the agreement of our theoretical model with the experimental
behaviour of our apparatus in the classical regime are presented. We discuss also the optimization of the performance of our
set-up, which should allow to monitor our oscillator in quantum regime even below the standard quantum limit level.
Received: 22 March 1996 相似文献
17.
Received: 12 June 1998 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.
A. Porzio C. Altucci P. Aniello C. de Lisio S. Solimeno 《Applied physics. B, Lasers and optics》2002,75(6-7):655-665
Twin-beam fluctuations are analyzed for detuned and mismatched OPO configurations. Resonances and frequency responses to the
quantum noise sources (quantum and pump amplitude/phase fluctuations) are examined as functions of cavity decay rates, excitation
parameters and detuning. The dependence of self- and mutual correlations of beam amplitudes and phases on detuning, mismatch
and damping parameters is discussed.
Received: 25 January 2002 / Revised version: 28 May 2002 / Published online: 15 November 2002
RID="*"
ID="*"Corresponding author. Fax: +39-81/676-346, E-mail: alberto.porzio@na.infn.it 相似文献
20.
We propose a QND-measurement of twin beams to improve the noise suppression achieved with squeezed states, which is currently
limited by the finite sensitivity of the photo detectors. The scheme can be implemented with existing fiber technology.
Received: 31 January 1996 / Revised version: 24 June 1996 相似文献