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1.
We study the quantum memory protocol for spatially multimode light based on an atomic ensemble in the Λ-configuration. We
analytically solve a system of partial differential equations that describe the evolution of the medium and field for the
case where the interaction time considerably exceeds the lifetime of the excited state. This time ratio makes it possible
to apply the adiabatic approximation. Unlike problems aimed at storage the time profile of the signal field, we propose optimizing
the relation between the writing and reading times and the optical density of the medium, which ensures a high retrieval efficiency
of the quantum image. 相似文献
2.
3.
We presented a scheme to implement SWAP gate in a microwave cavity. In our scheme, two superconducting quantum interference
device (SQUID) qubits are coupled to a single-mode microwave cavity field by adiabatic passage method for their manipulation.
This process of implementing SWAP gate is in the range of present experiments. The scheme can be easily obtained only by three
steps, which does not require perform any operation. In the scheme, the operations only involve three lowest flux states of
the SQUIDs, and the excited states would not be excited; therefore, the decoherence due to spontaneous emission of the SQUIDs’
levels would not affect the operations. In addition, during the whole procedure the cavity field is not necessary to be excited
because it does not require transfer quantum information between the SQUID’s and the cavity field. Thus, the cavity decay
is suppressed. Therefore our scheme may be realized in superconducting systems. 相似文献
4.
Quantum control of stationary multi-color (MC) light fields in resonant medium with multi-Λ scheme of atomic transition is
proposed. We have found the general analytical solution in the adiabatic limit of quantum evolution resulting from the interaction
of the slow probe light with the new fields generated in the nondegenerate multi-wave mixing scheme. We have found a critical
condition for the stopping and quantum manipulation of the MC-light fields where the united light group velocity can be reduced
down to zero with optimal spectral parameters while preserving the delicate quantum correlations of the initial probe light
pulse. The manipulations, which provide the effective transference of quantum probe light to the new multifrequency light
fields have been analyzed.
The text was submitted by the authors in English. 相似文献
5.
6.
K. I. Osman S. S. Hassan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(3):537-544
The steady state bistable behaviour of a three-level Λ-shape is
examined in the presence of a control field
$({\rm \Omega} +\chi \left( t\right)
e^{i\varphi})$({\rm \Omega} +\chi \left( t\right)
e^{i\varphi})
: Ω is the strong Rabi component,
$\chi \left(
t\right) $\chi \left(
t\right)
is the stochastic part with relative phase ϕ; with
quantum interference between decay channels taken into account. One- and
two-way phase switching effect for the transmitted field against the phase
are predicted at fixed values for the incident input field. Also cooperative
switching effect shows multistable/bistable behaviour. Quantum interference
tends to diminish the dispersive effects responsible for multistable
behaviour (in the input-output relation and the cooperative switching
diagram) and asymmetry (in the phase switching diagram). Equivalence of the
role of the stochastic part of the control field with that of the
“classically” squeezed field is shown to occur only in the absence
of quantum interference. 相似文献
7.
X. Q. Jiang Y. L. Wang X. D. Sun 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,57(3):427-430
We study the spontaneous emission spectrum of a three-level Λ-type
atom in a damped cavity using the resolvent operator. The shape of the
spectrum is strongly influenced by the detuning and the coupling intensity
between the atom and the cavity mode. Especially, we find that the
splittings of the upper level of the three-level Λ-type atom are
different in strong coupling regime, intermediate coupling regime and weak
coupling regimes. 相似文献
8.
Tian L 《Physical review letters》2012,108(15):153604
Optomechanical systems with strong coupling can be a powerful medium for quantum state engineering of the cavity modes. Here, we show that quantum state conversion between cavity modes of distinctively different wavelengths can be realized with high fidelity by adiabatically varying the effective optomechanical couplings. The conversion fidelity for gaussian states is derived by solving the Langevin equation in the adiabatic limit. Meanwhile, we also show that traveling photon pulses can be transmitted between different input and output channels with high fidelity and the output pulse can be engineered via the optomechanical couplings. 相似文献
9.
X.-J. Liu H. Jing M.-L. Ge 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):297-303
We examine in detail the quantum memory technique for photons in a
double Λ atomic ensemble in this work. The novel
application of the present technique to create two different
quantum probe fields as well as entangled states of them is
proposed. A larger zero-degeneracy class besides dark-state
subspace is investigated and the adiabatic condition is confirmed
in the present model. We extend the single-mode quantum memory
technique to the case with multi-mode probe fields, and reveal the
exact pulse matching phenomenon between two quantized pulses in
the present system. 相似文献
10.
An exact quantum theory of nondegenerate parametric generation in a cavity is developed with allowance for quantum noise of
arbitrary intensity. Critical behavior of the second-order correlation functions which describe photon correlation effects
is found in the threshold region in the bistable generation regime.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 7, 502–506 (10 April 1996) 相似文献
11.
研究了量子态在一条均匀耦合的反铁磁自旋链中传输时, 信道中自旋激发数变化对其传输性质的影响. 利用信息流方法分析输出端粒子的算符演化动力学, 获得了量子态传输的平均保真度与信道自旋初态之间的关系. 结果表明, 平均保真度的大小只依赖于信道中自旋激发数的奇偶性. 通过比较在奇偶激发信道中获得的最大平均保真度, 构建了优化信道来提升量子态在自旋链中的传输质量. 进一步分析了纠缠在激发信道中的传输情况, 发现纠缠的传输质量不仅和信道中自旋激发的具体个数有关, 还取决于激发自旋的初始排列. 特别地, 当信道中自旋无激发或全部激发时, 纠缠传输的大小和持续时间都优于其他的激发信道. 上述研究结果有助于在实际系统中搭建适合量子态和纠缠传输的量子信道. 相似文献
12.
SONG Ming-Yu 《理论物理通讯》2011,56(5):837-844
We proposed an efficient scheme for constructing a quantum controlled phase-shift gate and generating the cluster states with rf superconducting quantum interference devices (SQUIDs) coupled to a microwave cavity through adiabatic evolution of dark eigenstates. During the operation, the spontaneous emission is suppressed since the rf SQUIDs are always in the three lowest flux states. Considering the influence from the cavity decay with achievable
experimental parameters, we numerically analyze the success probability and the fidelity for generating the two-SQUID maximally entangled state and the controlled phase-shift gate by adiabatic passage. 相似文献
13.
Chang-Yong Chen Shuai Kang Mang Feng 《International Journal of Theoretical Physics》2009,48(10):2928-2937
We improve the scheme of geometric quantum phase gate (Chen et al. in Phys. Rev. A 74:032328, 2006) by using double-Hamiltonian evolution technique to remove the photon fluctuation in the cavity mode during the gating. We
also shows that when the classical laser intensity is fixed, our gating time may be shorter than that in the ideal case due
to the introduction of the cavity mode decay, although the dissipation decreases the corresponding fidelity and the success
probability of the gate. 相似文献
14.
Jin-Xuan Han Jin-Lei Wu Zhong-Hui Yuan Yan Xia Yong-Yuan Jiang Jie Song 《Frontiers of Physics》2022,17(6):62504
Topological pumping of edge states in the finite lattice with nontrivial topological phases provides a powerful means for robust excitation transfer, requiring extremely slow evolution to follow an adiabatic transfer. Here, we propose fast topological pumping via edge channels to generate large-scale Greenberger−Horne−Zeilinger (GHZ) states in a topological superconducting circuit with a sped-up evolution process. The scheme indicates a conceptual way of designing fast topological pumping related to the instantaneous energy spectrum characteristics rather than relying on the shortcuts to adiabaticity. Based on fast topological pumping, large-scale GHZ states show greater robustness against on-site potential defects, the fluctuation of couplings and losses of the system in comparison with the conventional adiabatic topological pumping. With experimentally feasible qutrit-resonator coupling strengths and moderate decay rates of qutrits and resonators, fast topological pumping drastically improves the scalability of GHZ states with a high fidelity. Our work opens up prospects for the realization of large-scale GHZ states based on fast topological pumping in the superconducting quantum circuit system, which provides potential applications of topological matters in quantum information processing. 相似文献
15.
We report the use of broadband heterodyne spectroscopy to perform continuous measurement of the interaction energy Eint between one atom and a high-finesse optical cavity, during individual transit events of ≈250 μs duration. We achieve a fractional
sensitivity ≈4×10-4/ to variations in Eint/? within a measurement bandwidth that covers 2.5 decades of frequency (1–300 kHz). Our basic procedure is to drop cold cesium
atoms into the cavity from a magnetooptic trap while monitoring the cavity’s complex optical susceptibility with a weak probe
laser. The instantaneous value of the atom–cavity interaction energy, which in turn determines the coupled system’s optical
susceptibility, depends on both the atomic position and (Zeeman) internal state. Measurements over a wide range of atom–cavity
detunings reveal the transition from resonant to dispersive coupling, via the transfer of atom-induced signals from the amplitude
to the phase of light transmitted through the cavity. By suppressing all sources of excess technical noise, we approach a
measurement regime in which the broadband photocurrent may be interpreted as a classical record of conditional quantum evolution
in the sense of recently developed quantum trajectory theories.
Received: 2 June 1998 / Revised version: 4 December 1998 / Published online: 31 March 1999 相似文献
16.
M. L. Hu H. L. Lian 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(3):711-721
By analytically solving the master equation, we
investigate quantum state transfer, creation and distribution of
entanglement in the model of Milburn’s intrinsic decoherence. Our
results reveal that the ideal spin channels will be destroyed by the
intrinsic decoherence environment, and the detrimental effects
become severe as the decoherence rate γ and the spin chain
length N increase. For infinite evolution time, both the state
transfer fidelity and the concurrence of the created and distributed
entanglement approach steady state values, which are independent of
the decoherence rate γ and decrease as the spin chain length
N increases. Finally, we present two modified spin chains which
may serve as near perfect spin channels for long distance state
transfer even in the presence of intrinsic decoherence environments. 相似文献
17.
Ya-Xi Shen Long-Sheng Zeng Zhi-Guo Geng De-Gang Zhao Yu-Gui Peng Jie Zhu Xue-Feng Zhu 《中国科学:物理学 力学 天文学(英文版)》2021,(4)
Stimulated adiabatic passage has been extensively studied to achieve robust and selective population transfer in quantum systems. Recently, the quantum-classic analogy has been rapidly developing and can be considered responsible for the implementation of the adiabatic transfer of sound energy in cavity chain systems. In this article, we investigate the adiabatic transfer of sound energy between two topological end states in the Su-Schrieffer-Heeger(SSH) cavity chain, which can be considered to be the acoustic analog of the quantum chirped-pulse excitation. The topological adiabatic passage in SSH cavity chain has two categories. When the single-cavity resonance frequencies on the sublattices A and B in the SSH cavity chain do not switch their spectrum positions, the topologically protected adiabatic evolution results in the returning passage of the sound excited in one end cavity. When a level crossing with single-cavity resonance frequencies on the sublattices A and B exhibits switch in the frequency spectrum, acoustic energy is observed to be topologically pumped between the two end cavities of the SSH chain. 相似文献
18.
Multi-mode quantum memory is a basic element required for long-distance quantum communication,as well as scalable quantum computation.For on-demand readout and long storage times,control pulses are crucial in order to transfer atomic excitations back and forth into spin excitations.Here,we introduce noise-robust composite pulse sequences for high-fidelity excitation transfer in multi-mode quantum memory.These pulses are robust to the deviations in amplitude and the detuning parameters of realistic conditions.We show the efficiency of these composite pulses with a typical rare-earth ion-doped system.This approach could be applied to a variety of quantum memory schemes. 相似文献
19.
We propose and analyze a robust quantum state transfer protocol through a scalable quantum data bus that consists of a network of controlled dissipative modules. In particular, we first demonstrate the ability to achieve perfect state transfer between two distinct quantum sites which are adiabatically coupled to the data bus in non-dissipative situation. We then consider the role of dissipation in adiabatic quantum state transfer via using Born–Markov master equation in the standard Lindblad form. Numerical simulation shows that the dissipation effect on the quality of transmission can be suppressed by engineering the network couplings of data bus properly. 相似文献
20.
J. Ellis A. Kotzinian D. Naumov M. Sapozhnikov 《The European Physical Journal C - Particles and Fields》2007,52(2):283-294
We consider models for the spin transfers to Λ and Λ̄ hyperons produced in lepton–nucleon deep-inelastic scattering. We make
predictions for longitudinal Λ and Λ̄ spin transfers for the COMPASS experiment and for HERA, and for the spin transfer to
Λ hyperons produced at JLAB. We demonstrate that accurate measurements of the spin transfers to Λ and Λ̄ hyperons with COMPASS
kinematics have the potential to probe the intrinsic strangeness in the nucleon. We show that a measurement of Λ̄ polarisation
could provide a clean probe of the spin transfer from s̄ quarks and provides a new possibility to measure the antistrange
quark distribution function. COMPASS data in a domain of x that has not been studied previously will provide valuable extra
information to fix models for the nucleon spin structure. The spin transfer to Λ̄ hyperons, which could be measured by the
COMPASS experiment, would provide a new tool to distinguish between the SU(6) and Burkardt–Jaffe (BJ) models for baryon spin
structure. In the case of the HERA electron–proton collider experiments with longitudinally-polarised electrons, the separation
between the target and current fragmentation mechanisms is more clear. It provides a complementary probe of the strange quark
distribution and helps distinguish between the SU(6) and BJ models for the Λ and Λ̄ spin structure. Finally, we show that
the spin transfer to Λ hyperons measured in a JLAB experiment would be dominated by the spin transfer of the intrinsic polarised-strangeness
in the remnant nucleon, providing an independent way to check our model predictions.
PACS 13.60.Rj; 13.87.Fh; 13.88.+e; 14.40.Ev; 14.20.Jn 相似文献