共查询到20条相似文献,搜索用时 10 毫秒
1.
M. D. Martín L. Via J. K. Son R. Ruf E. E. Mendez 《Physica E: Low-dimensional Systems and Nanostructures》2000,6(1-4)
We have used time-resolved photoluminescence spectroscopy to study the light emission dynamics in a semiconductor microcavity as a function of excitation density and exciton-cavity detuning. We paid special attention to polariton spin relaxation by using circularly polarized excitation. We have found a striking behavior of the photoluminescence degree of polarization, which reaches its maximum value at a finite time. As the excitation density is increased and the system enters the stimulated emission regime, this maximum is followed by a negative dip, whose depth strongly depends on exciton-cavity detuning. 相似文献
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We describe an optical system that allows for a direct experimental observation of the quantum magnetic correlated dynamics of polarized light. By adjusting the Zeeman and the Raman fields, we could realize a ferromagnetic phase, super-counter-fluidity phase, and antiferromagnetic phase of polarized light, that are of interest for studying spin-dependent photon-photon interactions. We also design an experimental protocol for the observation of these phases. Moreover, the technique of controlling photospin correlation may be used for building quantum information devices. 相似文献
4.
Microcavity exciton-polaritons within GaN-based structures are the object of the present work. The impact of the structural imperfections on the properties of the two-dimensional polariton gas is investigated through the calculation of its phase diagram. We demonstrate that the presence of disorder first induces a quasi-phase transition of the polariton system towards a Bose-glass phase before it becomes superfluid as its density increases. Calculations of the density of states as well as the condensate wavefunction and the related spectrum of elementary excitations in the framework of the Gross-Pitaevskii theory provide further insight into the properties of exciton-polaritons in GaN-based microcavities. 相似文献
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Deng H Press D Götzinger S Solomon GS Hey R Ploog KH Yamamoto Y 《Physical review letters》2006,97(14):146402
We study the momentum distribution and relaxation dynamics of semiconductor microcavity polaritons by angle-resolved and time-resolved spectroscopy. Above a critical pump level, the thermalization time of polaritons at positive detunings becomes shorter than their lifetime, and the polaritons form a quantum degenerate Bose-Einstein distribution in thermal equilibrium with the lattice. 相似文献
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Effective spin systems in coupled microcavities 总被引:1,自引:0,他引:1
We show that atoms trapped in microcavities that interact via the exchange of virtual photons can model an anisotropic Heisenberg spin-1/2 lattice in an external magnetic field. All parameters of the effective Hamiltonian can individually be tuned via external lasers. Since the occupations of excited atomic levels and photonic states are strongly suppressed, the effective model is robust against decoherence mechanisms, has a long lifetime, and its implementation is feasible with current experimental technology. The model provides a feasible way to create cluster states in these devices. 相似文献
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We consider the dynamics of a quantum coherence of two chosen spins in systems of dipolar coupled nuclear spins s=1/2 in solid. With the purpose to study this coherence we suggest two different methods. One of them uses the partial trace technique and reduced density matrix. The second method is based on the calculation the intensity of multiple quantum coherences using two-spin operator and the density matrix of the whole spin system. Results of calculations of the multiple-quantum dynamics in spin clusters of various dimensionalities are presented. It is shown that the whole density matrix method is more informative than the method based on the reduced density matrix. 相似文献
9.
《Comptes Rendus Physique》2002,3(1):41-52
Investigations of quantum effects in semiconductor quantum-well microcavities interacting with laser light in the strong-coupling regime are presented. Modifications of quantum fluctuations of the outgoing light are expected due to the non-linearity originating from coherent exciton–exciton scattering. In the strong-coupling regime, this scattering translates into a four-wave mixing interaction between the mixed exciton–photon states, the polaritons. Squeezing and giant amplification of the polariton field and of the outgoing light field fluctuations are predicted. However, polariton–phonon scattering is shown to yield excess noise in the output field, which may destroy the non-classical effects. Experiments demonstrate evidence for giant amplification due to coherent four-wave mixing of polaritons. Noise reduction below the thermal noise level was also observed. To cite this article: E. Giacobino et al., C. R. Physique 3 (2002) 41–52 相似文献
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H. Nagao K. Kinugawa Y. Shigeta K. Ohta K. Yamaguchi 《Journal of Molecular Liquids》2001,90(1-3):63-68
We investigate quantum spin dynamics of spin network systems in a liquid and in a molecular cluster with external magnetic field and discuss the importance of topological spin structures in relation to the quantum computing and quantum mechanical dimensions of the nuclear and the electron spins. 相似文献
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Adrados C Liew TC Amo A Martín MD Sanvitto D Antón C Giacobino E Kavokin A Bramati A Viña L 《Physical review letters》2011,107(14):146402
The dynamics of optical switching in semiconductor microcavities in the strong coupling regime is studied by using time- and spatially resolved spectroscopy. The switching is triggered by polarized short pulses which create spin bullets of high polariton density. The spin packets travel with speeds of the order of 10(6) m/s due to the ballistic propagation and drift of exciton polaritons from high to low density areas. The speed is controlled by the angle of incidence of the excitation beams, which changes the polariton group velocity. 相似文献
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D. Scalbert M. Vladimirova A. Brunetti S. Cronenberger M. Nawrocki J. Bloch A.V. Kavokin I.A. Shelykh R. Andr D. Solnyshkov G. Malpuech 《Superlattices and Microstructures》2008,43(5-6):417
Time-resolved Kerr (Faraday) rotation experiments allow for the observation of polariton spin beats in both InGaAs and CdMnTe quantum well (QW) microcavities. The existence of these beats is an unambiguous manifestation of the coherent energy exchange between exciton and photon components of polariton states created by a circularly polarized and spectrally wide femtosecond laser pulse. The polariton states are also shown to be split into a linearly polarized doublet. This splitting is responsible for the polarization transfer between linearly and circularly polarized states. In a highest-quality sample, the resulting spin dynamics could be detected. 相似文献
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G. Müller 《Zeitschrift für Physik B Condensed Matter》1987,68(2-3):149-159
The present study highlights some of the complexities observed in the dynamical properties of one-dimensional quantum spin systems. Exact results for zero-temperature dynamic correlation functions are presented for two contrasting situations:
- a system with a fully ordered ferromagnetic ground state;
- a system at aT c=0 critical point.
15.
J. L. Guo Y. J. Mi H. S. Song 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2012,66(1):24
We study the dynamics of quantum discord of two-qubit system in a quantum spin
environment at finite temperature in the thermodynamics limit. Special attention is paid
to the difference between the entanglement and quantum discord when considering the
influences of the environment temperature and the initial system states. We show that in
the same range of the physical parameters, when the system states behave no entanglement
or entanglement sudden death, the quantum discord keeps nonzero. So the quantum discord is
more robust than entanglement under this decoherence environment. Furthermore, we also
illustrate that we can tune the parameters related to the system and the environment to
suppress the decay of quantum discord. 相似文献
16.
Widera A Trotzky S Cheinet P Fölling S Gerbier F Bloch I Gritsev V Lukin MD Demler E 《Physical review letters》2008,100(14):140401
We report on the observation of many-body spin dynamics of interacting, one-dimensional (1D) ultracold bosonic gases with two spin states. By controlling the nonlinear atomic interactions close to a Feshbach resonance we are able to induce a phase diffusive many-body spin dynamics of the relative phase between the two components. We monitor this dynamical evolution by Ramsey interferometry, supplemented by a novel, many-body echo technique, which unveils the role of quantum fluctuations in 1D. We find that the time evolution of the system is well described by a Luttinger liquid initially prepared in a multimode squeezed state. Our approach allows us to probe the nonequilibrium evolution of one-dimensional many-body quantum systems. 相似文献
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Quantum spin dynamics as a model for quantum computer operation 总被引:1,自引:0,他引:1
H. De Raedt K. Michielsen A. Hams S. Miyashita K. Saito 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(1):15-28
We study effects of the physical realization of quantum computers on their logical operation. Through simulation of physical
models of quantum computer hardware, we analyze the difficulties that are encountered in programming physical realizations
of quantum computers. Examples of logically identical implementations of the controlled-NOT operation and Grover's database
search algorithm are used to demonstrate that the results of a quantum computation are unstable with respect to the physical
realization of the quantum computer. We discuss the origin of these instabilities and discuss possibilities to overcome this,
for practical purposes, fundamental limitation of quantum computers.
Received 5 November 2001 and Received in final form 8 February 2002 相似文献
19.
The quantum entanglement,discord,and coherence dynamics of two spins in the model of a spin coupled to a spin bath through an intermediate spin are studied.The effects of the important physical parameters including the coupling strength of two spins,the interaction strength between the intermediate spin and the spin bath,the number of bath spins and the temperature of the system on quantum coherence and correlation dynamics are discussed in different cases.The frozen quantum discord can be observed whereas coherence does not when the initial state is the Bell-diagonal state.At finite temperature,we find that coherence is more robust than quantum discord,which is better than entanglement,in terms of resisting the influence of environment.Therefore,quantum coherence is more tenacious than quantum correlation as an important resource. 相似文献
20.
Ell C Brick P Hübner M Lee ES Lyngnes O Prineas JP Khitrova G Gibbs HM Kira M Jahnke F Koch SW Deppe DG Huffaker DL 《Physical review letters》2000,85(25):5392-5395
The nonlinear optical response of semiconductor microcavities in the nonpertubative regime is studied in resonant single-beam-transmission and pump-probe experiments. In both cases a pronounced third transmission peak lying spectrally between the two normal modes is observed. A fully quantized theory is essential for the agreement with the experimental observations, demonstrating that quantum fluctuations leading to intraband polarizations are responsible for this effect. 相似文献