Pub Date : 1994-08-01DOI: 10.1088/0954-8998/6/4/009
S. Wilkinson, A. Smith
We present results of a numerical calculation of gain without inversion in the transient regime. We show that atomic coherence and gain without population inversion can be induced on time scales short compared to atomic radiative lifetimes. We also describe the process in terms of transient dressed states.
{"title":"Gain without inversion in four level atoms using pulsed lasers","authors":"S. Wilkinson, A. Smith","doi":"10.1088/0954-8998/6/4/009","DOIUrl":"https://doi.org/10.1088/0954-8998/6/4/009","url":null,"abstract":"We present results of a numerical calculation of gain without inversion in the transient regime. We show that atomic coherence and gain without population inversion can be induced on time scales short compared to atomic radiative lifetimes. We also describe the process in terms of transient dressed states.","PeriodicalId":130003,"journal":{"name":"Quantum Optics: Journal of The European Optical Society Part B","volume":"330 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122742737","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 : 1994-08-01DOI: 10.1088/0954-8998/6/4/010
Yang Zhao, Danhong Huang, Cunkai Wu
In the presence of a coherent coupling between two electron conduction sub-bands within doped quantum wells, both the Coulomb and light induced electronic renormalizations on electron and hole eigenenergies and eigenstates are studied by employing a generalized density functional approach. The dynamic properties of interband absorption of a probing laser are investigated. Electromagnetically induced transparency in interband transitions and optical switching is shown. The effects on the absorption coefficient due to pump field amplitude, electron area density, inhomogeneous level broadening, and delta -doping layer position are investigated and explained.
{"title":"Electromagnetically induced transparency of interband transitions in quantum wells","authors":"Yang Zhao, Danhong Huang, Cunkai Wu","doi":"10.1088/0954-8998/6/4/010","DOIUrl":"https://doi.org/10.1088/0954-8998/6/4/010","url":null,"abstract":"In the presence of a coherent coupling between two electron conduction sub-bands within doped quantum wells, both the Coulomb and light induced electronic renormalizations on electron and hole eigenenergies and eigenstates are studied by employing a generalized density functional approach. The dynamic properties of interband absorption of a probing laser are investigated. Electromagnetically induced transparency in interband transitions and optical switching is shown. The effects on the absorption coefficient due to pump field amplitude, electron area density, inhomogeneous level broadening, and delta -doping layer position are investigated and explained.","PeriodicalId":130003,"journal":{"name":"Quantum Optics: Journal of The European Optical Society Part B","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127807546","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 : 1994-08-01DOI: 10.1088/0954-8998/6/4/008
G. Vemuri
We explore the possibility of enhancing the gain in lasing without inversion schemes by replacing the usual incoherent pump with a finite bandwidth (spectrally coloured) pump. Three level atoms in the ladder and lambda configuration are modelled and we find that replacing the incoherent pump with a partially coherent pump amplifies the gain by as much as a factor of 4. The results are obtained via Monte-Carlo simulations of the density matrix equations, which, for a coloured pump, have the form of Langevin equations. We find that for a given set of atom-field parameters, the gain for coherent pumping is larger than for incoherent pumping, and that maximum gain is obtained for a partially coherent pump. The frequency of the coloured pump plays an important role in determining the optimum gain that can be obtained.
{"title":"Enhancement of gain in inversionless atomic media using finite bandwidth driving fields","authors":"G. Vemuri","doi":"10.1088/0954-8998/6/4/008","DOIUrl":"https://doi.org/10.1088/0954-8998/6/4/008","url":null,"abstract":"We explore the possibility of enhancing the gain in lasing without inversion schemes by replacing the usual incoherent pump with a finite bandwidth (spectrally coloured) pump. Three level atoms in the ladder and lambda configuration are modelled and we find that replacing the incoherent pump with a partially coherent pump amplifies the gain by as much as a factor of 4. The results are obtained via Monte-Carlo simulations of the density matrix equations, which, for a coloured pump, have the form of Langevin equations. We find that for a given set of atom-field parameters, the gain for coherent pumping is larger than for incoherent pumping, and that maximum gain is obtained for a partially coherent pump. The frequency of the coloured pump plays an important role in determining the optimum gain that can be obtained.","PeriodicalId":130003,"journal":{"name":"Quantum Optics: Journal of The European Optical Society Part B","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128424021","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 : 1994-08-01DOI: 10.1088/0954-8998/6/4/006
W. Lange, A. Nottelmann, C. Peters
An experiment is presented which demonstrates 'amplification without inversion' (AWI) and 'inversion without amplification' of a picosecond pulse in a generalized lambda-type system. The phenomena are based on Zeeman coherence in the J=1-level of the ground state multiplet in samarium, induced by a picosecond pulse train. The experiment and its relation to other AWI proposals and to previous experiments in atomic spectroscopy are discussed in detail.
{"title":"Observation of inversionless amplification in Sm vapour and related experiments","authors":"W. Lange, A. Nottelmann, C. Peters","doi":"10.1088/0954-8998/6/4/006","DOIUrl":"https://doi.org/10.1088/0954-8998/6/4/006","url":null,"abstract":"An experiment is presented which demonstrates 'amplification without inversion' (AWI) and 'inversion without amplification' of a picosecond pulse in a generalized lambda-type system. The phenomena are based on Zeeman coherence in the J=1-level of the ground state multiplet in samarium, induced by a picosecond pulse train. The experiment and its relation to other AWI proposals and to previous experiments in atomic spectroscopy are discussed in detail.","PeriodicalId":130003,"journal":{"name":"Quantum Optics: Journal of The European Optical Society Part B","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121363332","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 : 1994-08-01DOI: 10.1088/0954-8998/6/4/014
A. Manka, J. Dowling, C. Bowden, M. Fleischhauer
We review the effects of density dependent near dipole-dipole, or local field, interactions on lasing without inversion. In particular, we consider the nonlinear behaviour of the macroscopic electric susceptibility of a dense, coherently prepared, three-level Lambda system. For certain values of the atomic density, we observe enhancement of the absorptionless index of refraction and inversionless gain by more than two orders of magnitude. We also predict a piezophotonic switching effect whereby a small change in density induces the system to flip from a strong absorber into a local field enhanced inversionless amplifier.
{"title":"A review of local field effects in lasing without inversion","authors":"A. Manka, J. Dowling, C. Bowden, M. Fleischhauer","doi":"10.1088/0954-8998/6/4/014","DOIUrl":"https://doi.org/10.1088/0954-8998/6/4/014","url":null,"abstract":"We review the effects of density dependent near dipole-dipole, or local field, interactions on lasing without inversion. In particular, we consider the nonlinear behaviour of the macroscopic electric susceptibility of a dense, coherently prepared, three-level Lambda system. For certain values of the atomic density, we observe enhancement of the absorptionless index of refraction and inversionless gain by more than two orders of magnitude. We also predict a piezophotonic switching effect whereby a small change in density induces the system to flip from a strong absorber into a local field enhanced inversionless amplifier.","PeriodicalId":130003,"journal":{"name":"Quantum Optics: Journal of The European Optical Society Part B","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126999523","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 : 1994-06-01DOI: 10.1088/0954-8998/6/3/005
P. Domokos, J. Janszky, P. Adam, T. Larsen
Approximating a continuous superposition by a discrete one leads to an understanding of the role of quantum interference in generating squeezed coherent states, and in its quantum properties. It was shown that discrete superposition with a large enough number of coherent states with appropriate coefficients can have practically the same features as the squeezed coherent state. Dependent on the parameters W, r and 8, different numbers of coherent states are required for the interference fringe to form a Wigner function resembling that of the squeezed vacuum state and to reduce the deviation below a certain value. For the case of rotating the direction of squeezing, about 20 states were required to lower the deviation to 0.05%, while 640 states would be necessary when a unit displacement along the imaginary axis is included. When only a few coherent states are superimposed, the resulting state changes chaotically. In the case when the approximated squeezed coherent state was displaced along the imaginary axis an interesting Schrodinger cat-like state was found with about 20 coherent states on the real axis. At this point a significant peak occurs in the variances of the quadratures. It turned out that non-classical states can be effectively produced by a discrete superposition of coherent states with the coefficients derived from the one-dimensional representation of the given state.
{"title":"Role of quantum interference in producing non-classical states","authors":"P. Domokos, J. Janszky, P. Adam, T. Larsen","doi":"10.1088/0954-8998/6/3/005","DOIUrl":"https://doi.org/10.1088/0954-8998/6/3/005","url":null,"abstract":"Approximating a continuous superposition by a discrete one leads to an understanding of the role of quantum interference in generating squeezed coherent states, and in its quantum properties. It was shown that discrete superposition with a large enough number of coherent states with appropriate coefficients can have practically the same features as the squeezed coherent state. Dependent on the parameters W, r and 8, different numbers of coherent states are required for the interference fringe to form a Wigner function resembling that of the squeezed vacuum state and to reduce the deviation below a certain value. For the case of rotating the direction of squeezing, about 20 states were required to lower the deviation to 0.05%, while 640 states would be necessary when a unit displacement along the imaginary axis is included. When only a few coherent states are superimposed, the resulting state changes chaotically. In the case when the approximated squeezed coherent state was displaced along the imaginary axis an interesting Schrodinger cat-like state was found with about 20 coherent states on the real axis. At this point a significant peak occurs in the variances of the quadratures. It turned out that non-classical states can be effectively produced by a discrete superposition of coherent states with the coefficients derived from the one-dimensional representation of the given state.","PeriodicalId":130003,"journal":{"name":"Quantum Optics: Journal of The European Optical Society Part B","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123640335","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 : 1994-06-01DOI: 10.1088/0954-8998/6/3/002
L. Vaidman
A possible realistic implementation of a method for interaction-free measurements, due to Elitzur and Vaidman, is proposed and discussed. It is argued that the effect can be observed in an optical laboratory.
{"title":"On the realization of interaction-free measurements","authors":"L. Vaidman","doi":"10.1088/0954-8998/6/3/002","DOIUrl":"https://doi.org/10.1088/0954-8998/6/3/002","url":null,"abstract":"A possible realistic implementation of a method for interaction-free measurements, due to Elitzur and Vaidman, is proposed and discussed. It is argued that the effect can be observed in an optical laboratory.","PeriodicalId":130003,"journal":{"name":"Quantum Optics: Journal of The European Optical Society Part B","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129844494","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 : 1994-06-01DOI: 10.1088/0954-8998/6/3/003
A. Luks, V. Peřinová
A combination of less frequent criticism with positive investigations has resulted in the substitution of group theoretic considerations by a simpler quantum mechanical model, has taken into account homodyne and heterodyne detection schemes, and proceeded by an analysis of phase data processing. Limiting procedures in s-phase formalisms have been provided concentrating on the Wigner function for number and ideal phase. The Wigner function for number and realistic phase has been expressed by closed formulae along with the antinormal phase distributions.
{"title":"Presumable solutions of quantum phase problem and their flaws","authors":"A. Luks, V. Peřinová","doi":"10.1088/0954-8998/6/3/003","DOIUrl":"https://doi.org/10.1088/0954-8998/6/3/003","url":null,"abstract":"A combination of less frequent criticism with positive investigations has resulted in the substitution of group theoretic considerations by a simpler quantum mechanical model, has taken into account homodyne and heterodyne detection schemes, and proceeded by an analysis of phase data processing. Limiting procedures in s-phase formalisms have been provided concentrating on the Wigner function for number and ideal phase. The Wigner function for number and realistic phase has been expressed by closed formulae along with the antinormal phase distributions.","PeriodicalId":130003,"journal":{"name":"Quantum Optics: Journal of The European Optical Society Part B","volume":"135 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126912815","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 : 1994-06-01DOI: 10.1088/0954-8998/6/3/004
V. Belavkin, C. Bendjaballah
The question of phase measurement for a quantum oscillator using the quantum non-demolition principle (NDP), which does not need the use of the wave packet reduction postulate, is studied. It is shown that this approach is appropriate to introduce in a proper way the relevant observables for unlocalized (unsharp) measurement of quantum phase. Our analysis suggests that in contrast to other quantum-mechanical problems (e.g. The position and the momentum of a particle), the operator to represent the phase of a quantum field cannot be separated from the measurement process. Thus, the quantum phase operator must be defined for a corresponding measurement scheme. Moreover, it allows us to describe the time continuous process of quantum phase observations and also to study the stochastic dynamics of the oscillator under such measurement.
{"title":"Continuous measurements of quantum phase","authors":"V. Belavkin, C. Bendjaballah","doi":"10.1088/0954-8998/6/3/004","DOIUrl":"https://doi.org/10.1088/0954-8998/6/3/004","url":null,"abstract":"The question of phase measurement for a quantum oscillator using the quantum non-demolition principle (NDP), which does not need the use of the wave packet reduction postulate, is studied. It is shown that this approach is appropriate to introduce in a proper way the relevant observables for unlocalized (unsharp) measurement of quantum phase. Our analysis suggests that in contrast to other quantum-mechanical problems (e.g. The position and the momentum of a particle), the operator to represent the phase of a quantum field cannot be separated from the measurement process. Thus, the quantum phase operator must be defined for a corresponding measurement scheme. Moreover, it allows us to describe the time continuous process of quantum phase observations and also to study the stochastic dynamics of the oscillator under such measurement.","PeriodicalId":130003,"journal":{"name":"Quantum Optics: Journal of The European Optical Society Part B","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128310599","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 : 1994-06-01DOI: 10.1088/0954-8998/6/3/001
B. Crosignani, P. Porto
We describe a thought experiment in which the decay rate of an ensemble of excited atoms turns out to depend on both the efficiency and geometry of the counters used to detect the emitted photons. This quantum mechanical effect, of intrinsically non-local nature, implies an enhancing of the atomic decay rate and is present under experimental conditions completely different from those giving rise to the freezing of atomic decay corresponding to quantum Zeno effect.
{"title":"Spontaneous emission and non-locality in quantum mechanics","authors":"B. Crosignani, P. Porto","doi":"10.1088/0954-8998/6/3/001","DOIUrl":"https://doi.org/10.1088/0954-8998/6/3/001","url":null,"abstract":"We describe a thought experiment in which the decay rate of an ensemble of excited atoms turns out to depend on both the efficiency and geometry of the counters used to detect the emitted photons. This quantum mechanical effect, of intrinsically non-local nature, implies an enhancing of the atomic decay rate and is present under experimental conditions completely different from those giving rise to the freezing of atomic decay corresponding to quantum Zeno effect.","PeriodicalId":130003,"journal":{"name":"Quantum Optics: Journal of The European Optical Society Part B","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126774308","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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