Pub Date : 2005-06-01DOI: 10.1088/1464-4266/7/6/002
H. Tajalli, M. Sahrai
This paper investigates the group velocity of a probe field in a four-level atomic system. It is shown that switching from positive to negative dispersion can be achieved just by the intensity of the coupling field. Superluminal light propagation in the system at stake is accompanied by reduced absorption to make sure that the probe field is not attenuated as it passes through the medium.
{"title":"Switching from normal to anomalous dispersion via coherent field","authors":"H. Tajalli, M. Sahrai","doi":"10.1088/1464-4266/7/6/002","DOIUrl":"https://doi.org/10.1088/1464-4266/7/6/002","url":null,"abstract":"This paper investigates the group velocity of a probe field in a four-level atomic system. It is shown that switching from positive to negative dispersion can be achieved just by the intensity of the coupling field. Superluminal light propagation in the system at stake is accompanied by reduced absorption to make sure that the probe field is not attenuated as it passes through the medium.","PeriodicalId":87441,"journal":{"name":"Journal of optics. B, Quantum and semiclassical optics : journal of the European Optical Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/6/002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60918080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-06-01DOI: 10.1088/1464-4266/7/6/R02
H. Fan, A. Wünsche
Two-mode entangled-state wavefunctions and with complex variables z and y are introduced and investigated. They are direct analogues of the wavefunctions and in the single-mode case or are linearly related to each other by two-dimensional Fourier transformation. The states and are eigenstates of two pairs of commuting operators (Z,Z†) (or (Q+,P−)) and (Y,Y†) (or (P+,Q−)) to eigenvalues (z,z*) and (y,y*), respectively, and are normalized by means of the two-dimensional delta function. The entangled states and are represented as two limiting cases of two-mode squeezed coherent states. Different representations of these states, in particular, the analogue of the Agarwal–Simon representation of squeezed vacuum states, are derived and the properties of these states are discussed. The transition from the single-mode to the two-mode case is made using the common property of the squeezing operators to belong to different realizations of the abstract SU(1,1) group. The Wigner quasiprobability in representation of the states and is discussed and is explicitly calculated for two-mode squeezed vacuum (and squeezed coherent) states.
{"title":"REVIEW ARTICLE: Wavefunctions of two-mode states in entangled-state representation","authors":"H. Fan, A. Wünsche","doi":"10.1088/1464-4266/7/6/R02","DOIUrl":"https://doi.org/10.1088/1464-4266/7/6/R02","url":null,"abstract":"Two-mode entangled-state wavefunctions and with complex variables z and y are introduced and investigated. They are direct analogues of the wavefunctions and in the single-mode case or are linearly related to each other by two-dimensional Fourier transformation. The states and are eigenstates of two pairs of commuting operators (Z,Z†) (or (Q+,P−)) and (Y,Y†) (or (P+,Q−)) to eigenvalues (z,z*) and (y,y*), respectively, and are normalized by means of the two-dimensional delta function. The entangled states and are represented as two limiting cases of two-mode squeezed coherent states. Different representations of these states, in particular, the analogue of the Agarwal–Simon representation of squeezed vacuum states, are derived and the properties of these states are discussed. The transition from the single-mode to the two-mode case is made using the common property of the squeezing operators to belong to different realizations of the abstract SU(1,1) group. The Wigner quasiprobability in representation of the states and is discussed and is explicitly calculated for two-mode squeezed vacuum (and squeezed coherent) states.","PeriodicalId":87441,"journal":{"name":"Journal of optics. B, Quantum and semiclassical optics : journal of the European Optical Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/6/R02","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60918500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-06-01DOI: 10.1088/1464-4266/7/6/007
A. T. Avelar, B. Baseia
Inspired by a previous work (Zheng and Guo 1998 Phys. Lett. A 244 512) we propose a scheme for creating Fock states of the quantized radiation field using atoms driven by a classical field. This scheme is an alternative to another published one (Maia et al 2004 J. Opt. B: Quantum Semiclass. Opt. 6 351). Comparisons between them and others are discussed.
受前人研究的启发(Zheng and Guo 1998 Phys.)。列托人。我们提出了一种利用经典场驱动原子产生量子化辐射场的Fock态的方案。该方案是另一种已发表方案(Maia et al . 2004 J. Opt. B: Quantum半类)的替代方案。选择6 351)。讨论了它们与其他方法的比较。
{"title":"Preparing highly excited Fock states of a cavity field using driven atoms","authors":"A. T. Avelar, B. Baseia","doi":"10.1088/1464-4266/7/6/007","DOIUrl":"https://doi.org/10.1088/1464-4266/7/6/007","url":null,"abstract":"Inspired by a previous work (Zheng and Guo 1998 Phys. Lett. A 244 512) we propose a scheme for creating Fock states of the quantized radiation field using atoms driven by a classical field. This scheme is an alternative to another published one (Maia et al 2004 J. Opt. B: Quantum Semiclass. Opt. 6 351). Comparisons between them and others are discussed.","PeriodicalId":87441,"journal":{"name":"Journal of optics. B, Quantum and semiclassical optics : journal of the European Optical Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/6/007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60918389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-06-01DOI: 10.1088/1464-4266/7/10/003
H. Hofmann
Since quantum feedback is based on classically accessible measurement results, it can provide fundamental insights into the dynamics of quantum systems by making available classical information on the evolution of system properties and on the conditional forces acting on the system. In this paper, the feedback induced interaction dynamics between a pair of quantum systems is analysed. It is pointed out that any interaction Hamiltonian can be simulated by local feedback if the levels of decoherence are sufficiently high. The boundary between genuine entanglement generating quantum interactions and non-entangling classical interactions is identified and the nature of the information exchange between two quantum systems during an interaction is discussed.
{"title":"Simulation of interaction Hamiltonians by quantum feedback: a comment on the dynamics of information exchange between coupled systems","authors":"H. Hofmann","doi":"10.1088/1464-4266/7/10/003","DOIUrl":"https://doi.org/10.1088/1464-4266/7/10/003","url":null,"abstract":"Since quantum feedback is based on classically accessible measurement results, it can provide fundamental insights into the dynamics of quantum systems by making available classical information on the evolution of system properties and on the conditional forces acting on the system. In this paper, the feedback induced interaction dynamics between a pair of quantum systems is analysed. It is pointed out that any interaction Hamiltonian can be simulated by local feedback if the levels of decoherence are sufficiently high. The boundary between genuine entanglement generating quantum interactions and non-entangling classical interactions is identified and the nature of the information exchange between two quantum systems during an interaction is discussed.","PeriodicalId":87441,"journal":{"name":"Journal of optics. B, Quantum and semiclassical optics : journal of the European Optical Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/10/003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60911225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-23DOI: 10.1088/1464-4266/7/11/007
L.Zhang, G.J.Yang, L.X.Xia
Self-organization effects related to light amplification in the collective atomic recoil laser system with the driven atoms confined in a harmonic trap are investigated further. In the dispersive parametric region, our study reveals that the spontaneously formed structures in the phase space contributes an important role to the light amplification of the probe field under the atomic motion being modified by the trap.
{"title":"Self-organization effects and light amplification of collective atomic recoil motion in a harmonic trap","authors":"L.Zhang, G.J.Yang, L.X.Xia","doi":"10.1088/1464-4266/7/11/007","DOIUrl":"https://doi.org/10.1088/1464-4266/7/11/007","url":null,"abstract":"Self-organization effects related to light amplification in the collective atomic recoil laser system with the driven atoms confined in a harmonic trap are investigated further. In the dispersive parametric region, our study reveals that the spontaneously formed structures in the phase space contributes an important role to the light amplification of the probe field under the atomic motion being modified by the trap.","PeriodicalId":87441,"journal":{"name":"Journal of optics. B, Quantum and semiclassical optics : journal of the European Optical Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/11/007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60913422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-22DOI: 10.1088/1464-4266/7/10/032
K. McKenzie, E. Mikhailov, K. Goda, P. Lam, N. Grosse, M. Gray, N. Mavalvala, D. McClelland
Quantum optical states which have no coherent amplitude, such as squeezed vacuum states, cannot rely on standard readout techniques to generate error signals for control of the quadrature phase. Here we investigate the use of asymmetry in the quadrature variances to obtain a phase-sensitive readout and to lock the phase of a squeezed vacuum state, a technique which we call noise locking (NL). We carry out a theoretical derivation of the NL error signal and the associated stability of the squeezed and anti-squeezed lock points. Experimental data for the NL technique both in the presence and absence of coherent fields are shown, including a comparison with coherent locking techniques. Finally, we use NL to enable a stable readout of the squeezed vacuum state on a homodyne detector.
{"title":"Quantum noise locking","authors":"K. McKenzie, E. Mikhailov, K. Goda, P. Lam, N. Grosse, M. Gray, N. Mavalvala, D. McClelland","doi":"10.1088/1464-4266/7/10/032","DOIUrl":"https://doi.org/10.1088/1464-4266/7/10/032","url":null,"abstract":"Quantum optical states which have no coherent amplitude, such as squeezed vacuum states, cannot rely on standard readout techniques to generate error signals for control of the quadrature phase. Here we investigate the use of asymmetry in the quadrature variances to obtain a phase-sensitive readout and to lock the phase of a squeezed vacuum state, a technique which we call noise locking (NL). We carry out a theoretical derivation of the NL error signal and the associated stability of the squeezed and anti-squeezed lock points. Experimental data for the NL technique both in the presence and absence of coherent fields are shown, including a comparison with coherent locking techniques. Finally, we use NL to enable a stable readout of the squeezed vacuum state on a homodyne detector.","PeriodicalId":87441,"journal":{"name":"Journal of optics. B, Quantum and semiclassical optics : journal of the European Optical Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/10/032","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60913169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-19DOI: 10.1088/1464-4266/7/10/017
J. Gea-Banacloche, M. Ozawa
We explore the connections between the constraints on the precision of quantum logical operations that arise from a conservation law, and those arising from quantum field fluctuations. We show that the conservation-law-based constraints apply in a number of situations of experimental interest, such as Raman excitations, and atoms in free space interacting with the multimode vacuum. We also show that, for these systems, and for states with a sufficiently large photon number, the conservation-law-based constraint represents an ultimate limit closely related to the fluctuations in the quantum field phase.
{"title":"Constraints for quantum logic arising from conservation laws and field fluctuations","authors":"J. Gea-Banacloche, M. Ozawa","doi":"10.1088/1464-4266/7/10/017","DOIUrl":"https://doi.org/10.1088/1464-4266/7/10/017","url":null,"abstract":"We explore the connections between the constraints on the precision of quantum logical operations that arise from a conservation law, and those arising from quantum field fluctuations. We show that the conservation-law-based constraints apply in a number of situations of experimental interest, such as Raman excitations, and atoms in free space interacting with the multimode vacuum. We also show that, for these systems, and for states with a sufficiently large photon number, the conservation-law-based constraint represents an ultimate limit closely related to the fluctuations in the quantum field phase.","PeriodicalId":87441,"journal":{"name":"Journal of optics. B, Quantum and semiclassical optics : journal of the European Optical Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/10/017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60911777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-17DOI: 10.1088/1464-4266/7/6/005
X. Jia, Xiaolong Su, Q. Pan, C. Xie, K. Peng
The influence of mode mismatch on the quantum correlation measurement of phase quadratures of entangled state light beams in a Bell state direct detector is quantitatively discussed. The experimental measurements and theoretical calculation are in good agreement.
{"title":"The influence of mode mismatch on correlation measurement in a Bell state direct detector","authors":"X. Jia, Xiaolong Su, Q. Pan, C. Xie, K. Peng","doi":"10.1088/1464-4266/7/6/005","DOIUrl":"https://doi.org/10.1088/1464-4266/7/6/005","url":null,"abstract":"The influence of mode mismatch on the quantum correlation measurement of phase quadratures of entangled state light beams in a Bell state direct detector is quantitatively discussed. The experimental measurements and theoretical calculation are in good agreement.","PeriodicalId":87441,"journal":{"name":"Journal of optics. B, Quantum and semiclassical optics : journal of the European Optical Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/6/005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60918298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-17DOI: 10.1088/1464-4266/7/6/006
H. Fan, Xu-bing Tang, Wei-jun Gui
By means of the 'invariant eigenoperator' method which originates from the Heisenberg equation of motion, we derive the energy-level gap of some dynamic Hamiltonians in quantum optics, including a generalized Jaynes–Cummings model.
{"title":"Deriving the energy-level gap of some dynamic Hamiltonians in quantum optics by means of the invariant eigenoperator method","authors":"H. Fan, Xu-bing Tang, Wei-jun Gui","doi":"10.1088/1464-4266/7/6/006","DOIUrl":"https://doi.org/10.1088/1464-4266/7/6/006","url":null,"abstract":"By means of the 'invariant eigenoperator' method which originates from the Heisenberg equation of motion, we derive the energy-level gap of some dynamic Hamiltonians in quantum optics, including a generalized Jaynes–Cummings model.","PeriodicalId":87441,"journal":{"name":"Journal of optics. B, Quantum and semiclassical optics : journal of the European Optical Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/6/006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60918364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-05-17DOI: 10.1088/1464-4266/7/6/004
A. Klimov, P. Espinoza
It is shown that the quantum dynamics of spin coherent states governed by quadratic spin-like Hamiltonians, in the large spin limit, is well described in terms of evolution along classical trajectories on the two-dimensional sphere. Two non-linear effects: (a) spin squeezing and (b) spin entanglement are analysed using the Wigner function approach in the quasiclassical limit and numerically compared with the exact solution.
{"title":"Classical evolution of quantum fluctuations in spin-like systems : squeezing and entanglement","authors":"A. Klimov, P. Espinoza","doi":"10.1088/1464-4266/7/6/004","DOIUrl":"https://doi.org/10.1088/1464-4266/7/6/004","url":null,"abstract":"It is shown that the quantum dynamics of spin coherent states governed by quadratic spin-like Hamiltonians, in the large spin limit, is well described in terms of evolution along classical trajectories on the two-dimensional sphere. Two non-linear effects: (a) spin squeezing and (b) spin entanglement are analysed using the Wigner function approach in the quasiclassical limit and numerically compared with the exact solution.","PeriodicalId":87441,"journal":{"name":"Journal of optics. B, Quantum and semiclassical optics : journal of the European Optical Society","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2005-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/6/004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60918668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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