共查询到20条相似文献,搜索用时 15 毫秒
1.
We derive a general phase-matching condition(PMC) for enhancement of sensitivity in SU(1,1) interferometers. Under this condition, the quantum Fisher information(QFI) of two-mode SU(1,1) interferometry becomes maximal with respect to the relative phase of two modes, for the case of an arbitrary state in one input port and an even(odd) state in the other port, and the phase sensitivity is enhanced. We also find that optimal parameters can let the QFI in some areas achieve the Heisenberg limit for both pure and mixed initial states. As examples, we consider several input states: coherent and even coherent states, squeezed vacuum and even coherent states, squeezed thermal and even coherent states. Furthermore, in the realistic scenario of the photon loss channel, we investigate the effect of photon losses on QFI with numerical studies. We find the PMC remains unchanged and is not affected by the transmission coefficients for the above input states. Our results suggest that the PMC can exist in various kinds of interferometers and the phase-matching is robust to even strong photon losses. 相似文献
2.
We theoretically study the phase sensitivities of two different phase-shift configurations in an SU(1,1)interferometer with coherent ■ squeezed vacuum states.According to quantum Cramér-Rao theorem,we analytically obtain the ultimate phase sensitivities for two types of phase shift accumulating in one-and two-arm.Compared with the case of one-arm phase shift,the model with phase shift encoding in both arms may provide a better sensitivity when the strength of squeezed vacuum state is large enough.Furthermore,we discuss the achievable sensitivities with the homodyne measurement by invoking of error-propagation formula.In addition,we study the effect of internal and outernal photon losses on the phase sensitivity of the SU(1,1) interferometer and find that the unbalanced interferometer is helpful to improve precision even with high external losses. 相似文献
3.
Xiao-Yu Hu 《Frontiers of Physics》2016,11(3):114203
We study the phase sensitivity of an SU(1,1) interferometer with two input beams in the displaced squeezed vacuum state and the coherent state, respectively. We find that there exists an optimal squeezing fraction of the displaced squeezed vacuum state that optimizes the phase sensitivity. We also examine the effects of some factors, including the loss, mean photon number of the input beams and amplitude gain of the optical parameter amplifiers, on the optimal squeezing fraction so that we can choose the optimal values to enhance the phase sensitivity. 相似文献
4.
《中国物理 B》2019,(6)
Both the negativity of Wigner function and the phase sensitivity of an SU(1,1) interferometer are investigated in this paper. In the case that the even coherent state and squeezed vacuum state are input into the interferometer, the Heisenberg limit can be approached with parity detection. At the same time, the negativity volume of Wigner function of detection mode comes entirely from the input state and varies periodically with the encoding phase. In addition, the negativity volume of Wigner function is positively correlated with the phase sensitivity of the SU(1,1) interferometer. The positive correlation may mean that the non-classicality indicated by negative Wigner function is a kind of resource that can verify some related research results of phase estimation. 相似文献
5.
6.
Phase sensitivity of two nonlinear interferometers with inputting entangled coherent states 下载免费PDF全文
We investigate the phase sensitivity of the SU(1,1) interfereometer [SU(1,1)I] and the modified Mach–Zehnder interferometer(MMZI) with the entangled coherent states(ECS) as inputs. We consider the ideal case and the situations in which the photon losses are taken into account. We find that, under ideal conditions, the phase sensitivity of both the MMZI and the SU(1,1)I can beat the shot-noise limit(SNL) and approach the Heisenberg limit(HL). In the presence of photon losses, the ECS can beat the coherent and squeezed states as inputs in the SU(1,1)I, and the MMZI is more robust against internal photon losses than the SU(1,1)I. 相似文献
7.
The phase properties of the superposed squeezed states are studied. The superposed squeezed states are obtained by inserting
two squeezers in a Mach-Zehnder interferometer one for each arm. The visibility of the states as a measure of the coherence
of the generated photons in the nonlinear interferometer is analyzed. And the mean-square phase fluctuations are also considered
to analyze the phase properties of the superposed squeezed states. The quantities are obtained as a function of gain and the
input phase, when the amplified input is a coherent state, a number state, a thermal state, a displaced number state, or a
coherent thermal state. 相似文献
8.
H.-K. Zhao J. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(3):513-524
The time-dependent transport through an ultrasmall quantum dot coupling to two electron reservoirs is investigated. The quantum
dot is perturbed by a quantum microwave field (QMF) through gate. The tunneling current formulae are obtained by taking expectation
values over coherent state (CS), and SU(1,1) CS. We derive the transport formulae at low temperature by employing the nonequilibrium
Green function technique. The currents exhibit coherent behaviors which are strongly associated with the applied QMF. The
time-dependent currents appear compound effects of resonant tunneling and time-oscillating evolution. The time-averaged current
and differential conductance are calculated, which manifest photon-assisted behaviors. Numerical calculations reveal the similar
properties as those in classical microwave field (CMF) perturbed system for the situations concerning CS and squeezed vacuum
SU(1,1) CS. But for other squeezed SU(1,1) CS, the tunneling behavior is quite different from the system perturbed by a single
CMF through gate. Due to the quantum signal perturbation, the measurable quantities fluctuate fiercely.
Received 28 May 1998 相似文献
9.
利用低频光通信波段真空压缩态光场可实现基于光纤的量子精密测量.本文利用简并光学参量振荡器实验制备出1550 nm低频真空压缩态光场.在分析频段10—500 kHz范围内压缩态光场的压缩度均达3 dB.用实验制备的1550 nm真空压缩态光场填补光纤马赫-曾德尔干涉仪的真空通道,实现了量子增强型光纤马赫-曾德尔干涉仪,完成了突破标准量子极限的相位调制频率为500 kHz的低频信号测量.与光纤马赫-曾德尔干涉仪相比,测量信噪比提高了2 dB. 相似文献
10.
Jian-Dong Zhang 《中国物理 B》2023,32(1):10306-010306
SU(1,1) interferometers play an important role in quantum metrology. Previous studies focus on various inputs and detection strategies with symmetric gain. In this paper, we analyze a modified SU(1,1) interferometer using asymmetric gain. Two vacuum states are used as the input and on-off detection is performed at the output. In a lossless scenario, symmetric gain is the optimal selection and the corresponding phase sensitivity can achieve the Heisenberg limit as well as the quantum Cramer-Rao bound. In addition, we analyze the phase sensitivity with symmetric gain in the lossy scenario. The phase sensitivity is sensitive to internal losses but extremely robust against external losses. We address the optimal asymmetric gain and the results suggest that this method can improve the tolerance to internal losses. Our work may contribute to the practical development of quantum metrology. 相似文献
11.
We investigate a new superposition of two coherent states via conditional measurement on a Mach-Zehnder interferometer (MZI). The resulted output state is obtained by using the superposition of two opposite coherent states with the arbitrary relative phase factors for the a-mode and vacuum state in the b-mode. It is shown that the angle of the phase shifter between the two arms of the MZI is a very important parameter in this new state.
相似文献12.
We study a scheme for Mach-Zehnder(MZ) interferometer as a quantum linear device by injecting two-mode squeezed input states into two ports of interferometer.Two-mode squeezed states can be changed into two types of inputs for MZ interferometer:two squeezed states and Einstein-Podolsky-Rosen(EPR) entangled states.The interference patterns of the MZ interferometer vary periodically as the relative phase of the two arms of the interferometer is scanned,and are measured by the balanced homodyne detection system.Our experiments show that there are different interference patterns and periodicity of the output quantum states for two cases which depend on the relative phase of input optical fields.Since MZ interferometer can be used to realize some quantum operations,this work will have the important applications in quantum information and metrology. 相似文献
13.
利用量子技术增强Sagnac效应提高陀螺输出精度具有重要的研究意义, 是实现全自主导航的重要途径. 以相干态激光作为输入光源的光学陀螺因真空零点波动使其输出精度限制于散粒噪声极限而难以提高. 为减小真空波动的影响, 提出在激光输入的分束器的另一输入端输入压缩真空光并结合平衡零拍探测技术的方法增强Sagnac效应. 理论分析表明Sagnac效应性能得到有效提升: 干涉输出的灵敏度检测极限和动态范围均随着压缩程度的增加而呈指数级增长. 该方法只需对经典光学陀螺做少量改动就可实现, 是提高光学陀螺输出精度的一种新方法. 相似文献
14.
We discuss the unitary operator corresponding to the general two-mode coordinate-momentum mixed transformation(q2,p2)→(Aq1 Bq2,Cq1 Dp2),where A,B,C and Dare arbitrary real numbers,Suitably selecting the parameters A,B,Cand D,we obtain a new two-mode bosonic realization of the SU(1,1) Lie algebra.We also study the squeezing effects of the squeezed vacuum associated with the new two-mode bosonic realization of the SU(1,1) Lie algebra.The results show that the new squeezed vacuum does not possess second-order squeezing,but exhibits higher-order squeezing. 相似文献
15.
Quantum entanglement in the system of a moving V-type three-level atom interacting with the SU(1,1)-related coherent fields 下载免费PDF全文
In a system with a moving V-type three-level atom interacting with
the SU(1,1)-related coherent fields,
we investigate the entanglement between the moving three-level atom
and the SU(1,1)-related coherent fields by
using the quantum-reduced entropy, and that
between the SU(1,1)-related
coherent fields by using the quantum relative
entropy of entanglement. It is shown that the two kinds of entanglement
are dependent on the atomic motion and
exhibit the periodic evolution with a
period of 2π/p. The maximal atom--field qutrit entanglement
state can be prepared, and the entanglement preservation
of the SU(1,1)-related coherent fields
can be realized in the interacting process
via the appropriate selection of system
parameters and interaction time. 相似文献
16.
迈克耳孙干涉仪不仅可以用来研究物理学的基本问题,而且能够用于精密测量,比如引力波信号的测量.因此,构建高灵敏度的迈克耳孙干涉仪是实现微弱信号测量的关键.目前,人们利用压缩态可以降低迈克耳孙干涉仪的噪声;通过光学四波混频过程能够放大马赫·曾德尔干涉仪中的相位信号,从而提高干涉仪的信噪比和灵敏度.本文研究了一种用于高灵敏度相位测量的量子迈克耳孙干涉仪.在迈克耳孙干涉仪中,利用非简并光学参量放大器取代干涉仪中的线性光学分束器;并且将压缩态注入干涉仪的真空通道,可以得到高信噪比和高灵敏度的干涉仪.由于存在不可避免的光学损耗,分析了迈克耳孙干涉仪内部和外部的损耗对相位测量灵敏度的影响.通过理论计算研究了干涉仪的相位测量灵敏度随系统参数的变化关系,得到了高灵敏度的相位测量量子迈克耳孙干涉仪的实现条件,为用于精密测量的干涉仪的设计提供了直接参考. 相似文献
17.
A.-S. F. Obada G. M. Abd Al-Kader 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(1):189-198
The nonlinear extensions of the single-mode squeezed vacuum and
squeezed coherent states are studied. We have constructed the
nonlinear squeezed states (NLSS's) realization of
SU(1,1) Lie algebra. Two cases of this realization are
considered for unitary and non-unitary deformation operator
function. The nonlinear squeezed coherent states (NLSCS's)
are defined and special cases of these states are obtained.
Some nonclassical properties of these states are discussed. The
s-parameterized characteristic function and various moments are
calculated. The Glauber second-order coherence function is
calculated. The squeezing properties of the NLSCS's are studied.
Analytical and numerical results for the quadrature component
distributions for the NLSCS's are presented. A generation scheme for
NLSCS's using the trapped ions centre-of-mass motion approach is
proposed. 相似文献
18.
与双原子相互作用的双模关联场的相位性质 总被引:5,自引:0,他引:5
根据Pegg和Barnett相位理论研究了与双原子相互作用的双模SU(1,1)相干场的相位特性,证明了光场每个模的相位及两个模的相位差均保持随机分布,给出了光场两个模的相位和方差的表达式,揭示了在适当的初始条件下,系统呈现原子的相干捕获现象。 相似文献
19.
We study the photon counting noise in optical interferometers used for gravitational wave detection. In order to reduce quantum
noise a squeezed vacuum state is injected into the usually unused input port. Here, we specifically investigate the so-called
“dark port case,” when the beam splitter is oriented close to 90° to the incoming laser beam, such that nearly all photons
go to one output port of the interferometer, and only a small fraction of photons is seen in the other port (“dark port”).
For this case it had been suggested that signal amplification is possible without concurrent noise amplification [R. Barak
and Y. Ben-Aryeh, J. Opt. Soc. Am. B 25, 361 (2008)]. We show that by injection of a squeezed vacuum state into the second input port, counting noise is reduced
for large values of the squeezing factor, however the signal is not amplified. Signal strength only depends on the intensity
of the laser beam. 相似文献
20.
研究了强度差测量方案下,探测器量子效率对光子数态、关联数态、压缩真空态三种量子光源注入的马赫-曾德尔干涉仪相位测量灵敏度的影响.获得了相位测量灵敏度与效率的定量关系,比较了探测效率对不同量子态注入的干涉仪相位灵敏度的影响.研究表明:光子数态注入时,相位测量灵敏度始终不能超越标准量子极限;关联数态注入时,无论多大的光子数,要获得相位测量的量子增强,探测效率不得小于75%;对于压缩真空态,只要有压缩存在就可以获得一定的相位测量的量子增强;关联数态、压缩真空态的注入,相位灵敏度皆随探测效率的增大而不同程度的提高,且压缩真空态比关联数态具有更好的量子增强效果.给出了在量子增强的精密测量实验中对探测效率的要求,并结合实际应用说明了探测效率的提高有助于提高干涉仪探测的灵敏度. 相似文献