Pub Date : 2005-09-01DOI: 10.1088/1464-4266/7/9/011
S. A. Podoshvedov
We propose to use multi-photon mode entangled states to beat the minimal period of an interference pattern. Using the multi-photon mode entangled states, we show that it is possible to observe an interference effect with a period of minimum size λ/2N in an N-photon absorbing substrate. In the framework of the method developed, we propose a simple scheme for a quantum encoder with a two-photon quantum channel for producing a desired N-photon mode entangled state on which to write an interference pattern with a smaller period, as compared with the one in the case of the use of classical light.
{"title":"Theoretical consideration of the use of mode entangled states to beat the minimal period of an interference pattern","authors":"S. A. Podoshvedov","doi":"10.1088/1464-4266/7/9/011","DOIUrl":"https://doi.org/10.1088/1464-4266/7/9/011","url":null,"abstract":"We propose to use multi-photon mode entangled states to beat the minimal period of an interference pattern. Using the multi-photon mode entangled states, we show that it is possible to observe an interference effect with a period of minimum size λ/2N in an N-photon absorbing substrate. In the framework of the method developed, we propose a simple scheme for a quantum encoder with a two-photon quantum channel for producing a desired N-photon mode entangled state on which to write an interference pattern with a smaller period, as compared with the one in the case of the use of classical light.","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":"2005-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/9/011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60920459","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 : 2005-09-01DOI: 10.1088/1464-4266/7/9/004
M. Guizar‐Sicairos, J. Gutiérrez-Vega
The dynamic coupled mode (DCM) method has been applied to study the transverse mode competition in optical resonators. In this work a differential equation for the homogeneously saturating dynamic gain is included in the original dynamic coupled mode method, thus increasing its physical resemblance and allowing the retrieval of gain temporal evolution at every point within the lasing medium. This new model provides a realistic temporal evolution of the mode competition and gain saturation within the resonator, which can give further information on spatial coherence properties. The new general formulation does not assume that lasing medium fills the optical cavity and is suitable for modelling the dependence of small-signal gain and power gain on the transverse and longitudinal coordinates. The application of the method to a typical CO2 unstable confocal resonator is fully described; results and their connection to relevant physical properties of gas lasers, such as spiking and relaxation oscillations, are discussed. Results of the numerical implementation of the DCM method with dynamic gain are in very good agreement with experimental measurements reported previously.
{"title":"Coupled mode competition in unstable resonators using the exact cavity equations of motion with dynamic gain","authors":"M. Guizar‐Sicairos, J. Gutiérrez-Vega","doi":"10.1088/1464-4266/7/9/004","DOIUrl":"https://doi.org/10.1088/1464-4266/7/9/004","url":null,"abstract":"The dynamic coupled mode (DCM) method has been applied to study the transverse mode competition in optical resonators. In this work a differential equation for the homogeneously saturating dynamic gain is included in the original dynamic coupled mode method, thus increasing its physical resemblance and allowing the retrieval of gain temporal evolution at every point within the lasing medium. This new model provides a realistic temporal evolution of the mode competition and gain saturation within the resonator, which can give further information on spatial coherence properties. The new general formulation does not assume that lasing medium fills the optical cavity and is suitable for modelling the dependence of small-signal gain and power gain on the transverse and longitudinal coordinates. The application of the method to a typical CO2 unstable confocal resonator is fully described; results and their connection to relevant physical properties of gas lasers, such as spiking and relaxation oscillations, are discussed. Results of the numerical implementation of the DCM method with dynamic gain are in very good agreement with experimental measurements reported previously.","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":"2005-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/9/004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60920487","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 : 2005-09-01DOI: 10.1088/1464-4266/7/9/007
D. Mogilevtsev
In this work it is demonstrated that the atom–field bound state created via interaction with bandgap field reservoirs is robust with respect to the atomic dephasing and losses of the reservoir's modes. Both the atomic excited state population and the degree of entanglement of the atom–field bound state tend to decay with rates much smaller than modal decay rates. Direct atomic damping leads to much quicker destruction of the atom–field bound state. Also in the work, conditions of the atom–field bound state formation in the presence of damping are derived.
{"title":"Robustness of the photon?atom bound state in bandgap reservoirs","authors":"D. Mogilevtsev","doi":"10.1088/1464-4266/7/9/007","DOIUrl":"https://doi.org/10.1088/1464-4266/7/9/007","url":null,"abstract":"In this work it is demonstrated that the atom–field bound state created via interaction with bandgap field reservoirs is robust with respect to the atomic dephasing and losses of the reservoir's modes. Both the atomic excited state population and the degree of entanglement of the atom–field bound state tend to decay with rates much smaller than modal decay rates. Direct atomic damping leads to much quicker destruction of the atom–field bound state. Also in the work, conditions of the atom–field bound state formation in the presence of damping are derived.","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":"2005-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/9/007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60920661","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 : 2005-09-01DOI: 10.1088/1464-4266/7/9/001
J. Torres, G. Molina-Terriza, L. Torner
We address the spatial shape of entangled photon states generated in spontaneous parametric downconversion in non-collinear geometries, when the interacting waves exhibit Poynting vector walk-off. We discuss how such shape depends on the interplay between the state ellipticity caused by the non-collinear geometry, and the Poynting vector walk-off. In particular, we study the impact of the new features exhibited by walking entangled photons on the implementation of quantum protocols based on the spiral spectra of the entangled photons.
{"title":"The spatial shape of entangled photon states generated in non-collinear, walking parametric downconversion","authors":"J. Torres, G. Molina-Terriza, L. Torner","doi":"10.1088/1464-4266/7/9/001","DOIUrl":"https://doi.org/10.1088/1464-4266/7/9/001","url":null,"abstract":"We address the spatial shape of entangled photon states generated in spontaneous parametric downconversion in non-collinear geometries, when the interacting waves exhibit Poynting vector walk-off. We discuss how such shape depends on the interplay between the state ellipticity caused by the non-collinear geometry, and the Poynting vector walk-off. In particular, we study the impact of the new features exhibited by walking entangled photons on the implementation of quantum protocols based on the spiral spectra of the entangled photons.","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":"2005-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/9/001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60919901","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 : 2005-09-01DOI: 10.1088/1464-4266/7/9/006
Xiao-Shu Liu, Wu Re-bing, Yang Liu, Jing Zhang, G. Long
In this paper, we study the suppression of adiabatic decoherence of a three-level atom with Λ configuration using the bang–bang control technique. We give the decoupling bang–bang operation group, and programme a sequence of periodic radio frequency twinborn pulses to realize the control process. Moreover, we study the process with practical conditions and establish the condition for efficient suppression of adiabatic decoherence.
{"title":"Dynamical control of adiabatic decoherence in the single three-level atom","authors":"Xiao-Shu Liu, Wu Re-bing, Yang Liu, Jing Zhang, G. Long","doi":"10.1088/1464-4266/7/9/006","DOIUrl":"https://doi.org/10.1088/1464-4266/7/9/006","url":null,"abstract":"In this paper, we study the suppression of adiabatic decoherence of a three-level atom with Λ configuration using the bang–bang control technique. We give the decoupling bang–bang operation group, and programme a sequence of periodic radio frequency twinborn pulses to realize the control process. Moreover, we study the process with practical conditions and establish the condition for efficient suppression of adiabatic decoherence.","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":"2005-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/9/006","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60920574","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 : 2005-08-23DOI: 10.1088/1464-4266/7/9/009
A N de Oliveira, S. Walborn, C. Monken
In this paper we implement a simple quantum algorithm using polarization and transverse spatial modes of the electromagnetic field as qubits. The transverse spatial modes used are the Laguerre–Gaussian and Hermite–Gaussian beams of order N = 1. With these two qubits carried by the same photon, we have implemented the Deutsch algorithm using a simple linear optical setup.
{"title":"Implementing the Deutsch algorithm with polarization and transverse spatial modes","authors":"A N de Oliveira, S. Walborn, C. Monken","doi":"10.1088/1464-4266/7/9/009","DOIUrl":"https://doi.org/10.1088/1464-4266/7/9/009","url":null,"abstract":"In this paper we implement a simple quantum algorithm using polarization and transverse spatial modes of the electromagnetic field as qubits. The transverse spatial modes used are the Laguerre–Gaussian and Hermite–Gaussian beams of order N = 1. With these two qubits carried by the same photon, we have implemented the Deutsch algorithm using a simple linear optical setup.","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":"2005-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/9/009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60920246","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 : 2005-08-19DOI: 10.1088/1464-4266/7/10/033
F. Benatti, F. Benatti, R. Floreanini, R. Floreanini
Two non-interacting two-level atoms immersed in a common bath can become mutually entangled when evolving with a Markovian, completely positive dynamics. For an environment made of external quantum fields, this phenomenon can be studied in detail: one finds that entanglement production can be controlled by varying the bath temperature and the distance between the atoms. Remarkably, in certain circumstances, the quantum correlations can persist in the asymptotic long-time regime.
{"title":"Controlling entanglement generation in external quantum fields","authors":"F. Benatti, F. Benatti, R. Floreanini, R. Floreanini","doi":"10.1088/1464-4266/7/10/033","DOIUrl":"https://doi.org/10.1088/1464-4266/7/10/033","url":null,"abstract":"Two non-interacting two-level atoms immersed in a common bath can become mutually entangled when evolving with a Markovian, completely positive dynamics. For an environment made of external quantum fields, this phenomenon can be studied in detail: one finds that entanglement production can be controlled by varying the bath temperature and the distance between the atoms. Remarkably, in certain circumstances, the quantum correlations can persist in the asymptotic long-time regime.","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":"2005-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/10/033","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60913214","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 : 2005-08-05DOI: 10.1088/1464-4266/7/12/031
A. Agliati, M. Bondani, A. Andreoni, G. D. Cillis, M. Paris
We address joint photodetection as a method for discriminating between the classical correlations of a thermal beam divided by a beam splitter and the quantum entanglement of a twin beam obtained by parametric down-conversion. We show that for intense beams of light the detection of the difference photocurrent may be used, in principle, in order to reveal entanglement, while the simple measurement of the correlation coefficient is not sufficient. We have experimentally measured the correlation coefficient and the variance of the difference photocurrent for several classical and quantum states. Results are in good agreement with theoretical predictions taking into account the extra noise in the generated fields that is due to the pump laser fluctuations.
{"title":"Quantum and classical correlations of intense beams of light investigated via joint photodetection","authors":"A. Agliati, M. Bondani, A. Andreoni, G. D. Cillis, M. Paris","doi":"10.1088/1464-4266/7/12/031","DOIUrl":"https://doi.org/10.1088/1464-4266/7/12/031","url":null,"abstract":"We address joint photodetection as a method for discriminating between the classical correlations of a thermal beam divided by a beam splitter and the quantum entanglement of a twin beam obtained by parametric down-conversion. We show that for intense beams of light the detection of the difference photocurrent may be used, in principle, in order to reveal entanglement, while the simple measurement of the correlation coefficient is not sufficient. We have experimentally measured the correlation coefficient and the variance of the difference photocurrent for several classical and quantum states. Results are in good agreement with theoretical predictions taking into account the extra noise in the generated fields that is due to the pump laser fluctuations.","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":"2005-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/12/031","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60914770","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 : 2005-08-02DOI: 10.1088/1464-4266/7/12/011
P. Aniello
A novel expansion of the evolution operator associated with an—in general, time-dependent—perturbed quantum Hamiltonian is presented. It is shown that it has a wide range of possible realizations that can be fitted according to computational convenience or to satisfy specific requirements. As a remarkable example, the quantum Hamiltonian describing a laser-driven trapped ion is studied in detail.
{"title":"A new perturbative expansion of the time evolution operator associated with a quantum system","authors":"P. Aniello","doi":"10.1088/1464-4266/7/12/011","DOIUrl":"https://doi.org/10.1088/1464-4266/7/12/011","url":null,"abstract":"A novel expansion of the evolution operator associated with an—in general, time-dependent—perturbed quantum Hamiltonian is presented. It is shown that it has a wide range of possible realizations that can be fitted according to computational convenience or to satisfy specific requirements. As a remarkable example, the quantum Hamiltonian describing a laser-driven trapped ion is studied in detail.","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":"2005-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/12/011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60913948","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 : 2005-08-02DOI: 10.1088/1464-4266/7/9/003
J. Peřina, J. Křepelka
We derive the multimode generating function, joint photon-number distribution and joint integrated-intensity distribution for spontaneous parametric down-conversion in relation to measured experimental data.
根据实测实验数据，导出了自发参量下转换的多模生成函数、联合光子数分布和联合积分强度分布。
{"title":"Multimode description of spontaneous parametric down-conversion","authors":"J. Peřina, J. Křepelka","doi":"10.1088/1464-4266/7/9/003","DOIUrl":"https://doi.org/10.1088/1464-4266/7/9/003","url":null,"abstract":"We derive the multimode generating function, joint photon-number distribution and joint integrated-intensity distribution for spontaneous parametric down-conversion in relation to measured experimental data.","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":"2005-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1464-4266/7/9/003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60920045","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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