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研究了准二维谐振势阱中粒子数有限的非理想玻色气体的热力学性质。利用巨正则系综的求和方法与平均场理论,给出了有限粒子数与原子间相互作用对系统势力学性质的共同修正;并将所得结果与三维时的情况进行了比较。结果表明:降低维数不能提高系统的临界温度;在准二维谐振系统中,有限粒子数对系统的影响随着粒子数的增大而减小直至消失,而相互作用的影响与粒子数无关,因此可以通过增大粒子数来提高准二维谐振系统的临界温度。 相似文献
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提出一种理论方案,利用量子纠缠特性,实现对量子态的远程操作.采用两粒子非最大纠缠态作为资源,借助于辅助量子位,实现态算子的制备,并利用态算子特性,我们能够以一定的概率实现对量子态的远程操作.这种非局域的操作是量子世界特有的现象,这方面的研究有助于对量子力学基本问题的探讨. 相似文献
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在单向循环腔中,研究了一个被耦合场和探测场来驱动的准Λ型原子系统的光学双稳态和多稳态行为.考察了耦合场强和频率失谐量对光学双稳态和多稳态行为的影响.发现光学双稳态到多稳态的转换或逆转换可以通过改变耦合场的强度或改变耦合场的频率就可以实现.原子合作参数对光学多稳态的影响也得到了讨论. 相似文献
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One- and two-photon absorption-amplification response in a four-level atomic system with vacuum-induced coherence 下载免费PDF全文
This paper theoretically studies the effects of the vacuum-induced coherence
on one- and two-photon absorption in a four-level atomic medium.
It finds that the one- and two-photon absorption and amplification
properties are quite sensitive to the vacuum-induced coherence. It
is also shown that the one- and two-photon absorption spectra can
be dramatically affected by modulating the relative phase of the
applied fields. With the proper choice of the relative phase, the
amplification without inversion for the probe field can be
realized. 相似文献
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Optical bistability and multistability in a three-level Δ-type atomic system under the nonresonant condition 下载免费PDF全文
Under a nonresonant condition, we theoretically investigate hybrid
absorptive-dispersive optical bistability and multistability
behaviours in a three-level Δ-type system by using a microwave
field to drive a hyperfine transition between two upper excited
states inside a unidirectional ring cavity. We find that the optical
bistability and multistability behaviours can be controlled by
adjusting the intensity of the microwave field or the intensity of
the coherent coupling field. Furthermore, our studies show an
interesting phenomenon of the transition from the optical
bistability to the optical multistability only by changing the
negative detuning of the coupling field into the positive detuning
of the coupling field. 相似文献
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Entanglement swapping between atom and cavity and generation of entangled state of cavity fields 下载免费PDF全文
This paper proposes a scheme where entanglement swapping between atom and cavity can
be realized. \Lambda -type three-level atoms interacting resonantly with
cavity field are considered. By detecting atom and cavity field, it
realizes entanglement swapping between atom and cavity. It uses the technique
of entanglement swapping to generate an entangled state of two cavity fields
by measuring on atoms. It discusses the experimental feasibility of
the proposed scheme
and application of entangled state of cavity fields. 相似文献
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Monolayer MnTe2 stabilized as 1T structure has been theoretically predicted to be a two-dimensional (2D) ferromagnetic metal and can be tuned via strain engineering. There is no naturally van der Waals (vdW) layered MnTe2 bulk, leaving mechanical exfoliation impossible to prepare monolayer MnTe2. Herein, by means of molecular beam epitaxy (MBE), we successfully prepared monolayer hexagonal MnTe2 on Si(111) under Te rich condition. Sharp reflection high-energy electron diffraction (RHEED) and low-energy electron diffraction (LEED) patterns suggest the monolayer is atomically flat without surface reconstruction. The valence state of Mn4+ and the atom ratio of ([Te]:[Mn]) further confirm the MnTe2 compound. Scanning tunneling spectroscopy (STS) shows the hexagonal MnTe2 monolayer is a semiconductor with a large bandgap of ~2.78 eV. The valence-band maximum (VBM) locates at the Γ point, as illustrated by angle-resolved photoemission spectroscopy (ARPES), below which three hole-type bands with parabolic dispersion can be identified. The successful synthesis of monolayer MnTe2 film provides a new platform to investigate the 2D magnetism. 相似文献
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磁共振成像(MRI)技术因其可以无损伤、无电离辐射、多参数多模态、高分辨率成像特点备受科学家关注,目前MRI技术广泛应用于医学临床,辅助诊断多种疾病[1-2]。灰度不均匀性或者偏差场作为MRT技术的主要缺点表现在对视觉检查和医疗诊断方面存在一定的误差,并且对图像的定量分析有很大的影响。为提高磁共振图像分析可靠性和疾病诊断精度,针对磁共振图像中由于非均匀场产生的灰度不均匀性,提出了同态滤波校正方法。该方法首先对图像的背景区域去除,然后对背景区域做高斯滤波得到非均匀场估计,最后对结果做指数运算即可得到校正后的图像。定性和定量分析实验结果表明,同态滤波方法能够有效校正磁共振图像非均匀场,改善图像质量。 相似文献
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Without need of another control light, this paper analyses in a time-dependent way a new scheme to achieve ultraslow propagation of the input probe field through a medium composed of two-level atoms where their upper level is split into two hyperfine sub-levels via some applied static field such as a DC magnetic or a DC electric field or whatever other static field.[第一段] 相似文献