Mary Cola - Academia.edu (original) (raw)
Papers by Mary Cola
Physical Review A, 2003
We present a quantum description of the interaction between a Bose-Einstein condensate and a sing... more We present a quantum description of the interaction between a Bose-Einstein condensate and a single-mode quantized radiation field in the presence of a strong far-off-resonant pump laser. In the linear regime, the atomic medium is described approximately by two momentum states coupled to the radiation mode. We calculate the evolution of the operators in the Heisenberg picture and their expectation values, such as average and variance of the occupation numbers, atom-atom and atom-field correlations, and two-mode squeezing parameters. Then, we disentangle the evolution operator and obtain the exact evolution of the state vector in the linear regime. This allows us to demostrate that the system can be atom-atom or atom-field thermally entangled. We define the quasiclassical and the quantum recoil limits, for which explicit expressions of the average population numbers are obtained.
Journal of Modern Optics, 2004
A collective atomic recoil laser (CARL) realized with a Bose-Einstein condensate offers the possi... more A collective atomic recoil laser (CARL) realized with a Bose-Einstein condensate offers the possibility to investigate new effects in the coherent interaction between optical and matter waves. This paper discusses some aspects of the nonlinear evolution of scattered radiation and the matterwave field in the high-Q cavity and superradiant CARL regimes.
International Journal of Modern Physics A, 2007
In this paper we optimize the experimental parameters to operate a Free Electron Laser with a las... more In this paper we optimize the experimental parameters to operate a Free Electron Laser with a laser wiggler in the Angstrom region. We show that the quantum regime of the Self Amplified Spontaneous Emission (Quantum SASE) may be reached with realistic parameters. The classical SASE regime is also discussed and compared with the quantum regime.
Recent experiments have demonstrated superradiant Raman scattering from a Bose-Einstein condensat... more Recent experiments have demonstrated superradiant Raman scattering from a Bose-Einstein condensate driven by a single off-resonant laser beam. We present a quantum theory describing this phenomenon, showing Raman amplification of matter wave due to collective atomic recoil from 3-level atoms in a Λ-configuration. When atoms are initially in a single lower internal state, a closed two-level system is realized between atoms with different internal states, and entangled atom-photon pairs can be generated. When atoms are initially prepared in both the lower internal states, a fraction of atoms recoiling in the backward direction can be generated.
Europhysics Letters (EPL), 2005
Free Electron Laser (FEL) and Collective Atomic Recoil Laser (CARL) are described by the same mod... more Free Electron Laser (FEL) and Collective Atomic Recoil Laser (CARL) are described by the same model of classical equations for properly defined scaled variables. These equations are extended to the quantum domain describing the particle's motion by a Schrödinger equation coupled to a selfconsistent radiation field. The model depends on a single collective parameterρ which represents the maximum number of photons emitted per particle. We demonstrate that the classical model is recovered in the limitρ ≫ 1, in which the Wigner function associated to the Schrödinger equation obeys to the classical Vlasov equation. On the contrary, forρ ≤ 1, a new quantum regime is obtained in which both FELs and CARLs behave as a two-state system coupled to the self-consistent radiation field and described by Maxwell-Bloch equations.
We address the interaction between a Bose-Einstein condensate and a singlemode quantized radiatio... more We address the interaction between a Bose-Einstein condensate and a singlemode quantized radiation field in the presence of a strong far off-resonant pump laser. The generation of atom-atom and atom-field entanglement is demonstrated in the linear regime. The effects of cavity losses are taken into account and an analytic solution of the corresponding master equation is given in terms of the Wigner function of the system.
We address the dynamics induced by collective atomic recoil in a Bose-Einstein condensate in pres... more We address the dynamics induced by collective atomic recoil in a Bose-Einstein condensate in presence of radiation losses and atomic decoherence. In particular, we focus on the linear regime of the lasing mechanism, and analyze the effects of losses and decoherence on the generation of entanglement. The dynamics is that of three bosons, two atomic modes interacting with a singlemode radiation field, coupled with a bath of oscillators. The resulting three-mode dissipative Master equation is solved analytically in terms of the Wigner function. We examine in details the two complementary limits of high-Q cavity and bad-cavity, the latter corresponding to the so-called superradiant regime, both in the quasi-classical and quantum regimes. We found that three-mode entanglement as well as two-mode atom-atom and atom-radiation entanglement is generally robust against losses and decoherence,thus making the present system a good candidate for the experimental observation of entanglement in condensate systems. In particular, steady-state entanglement may be obtained both between atoms with opposite momenta and between atoms and photons.
We propose an experiment to realize radiation to atom continuous variable quantum mapping, i.e. t... more We propose an experiment to realize radiation to atom continuous variable quantum mapping, i.e. to teleport the quantum state of a single mode radiation field onto the collective state of atoms with a given momentum out of a Bose-Einstein condensate. The atoms-radiation entanglement needed for the teleportation protocol is established through the interaction of a single mode with the condensate in presence of a strong far off-resonant pump laser, whereas the coherent atomic displacement is obtained by the same interaction with the radiation in a classical coherent field. In principle, verification of the protocol requires a joint measurement on the recoiling atoms and the condensate, however, a partial verification involving populations, i.e. diagonal matrix elements may be obtained through counting atoms experiments.
Journal of Modern Optics, 2004
We present the results of an experiment on superradiant Rayleigh scattering from a moving Bose-Ei... more We present the results of an experiment on superradiant Rayleigh scattering from a moving Bose-Einstein condensate, where a superposition of two atomic wavepackets is created by the interaction of a far-detuned laser beam with the condensate. The system is described by the CARL-BEC model which is a generalization of the Gross-Pitaevskii model to include the self-consistent evolution of the scattered
A Free Electron Laser (FEL) operating in the quantum regime can provide a compact and monochromat... more A Free Electron Laser (FEL) operating in the quantum regime can provide a compact and monochromatic X-ray source. Here we review the basic principles of a high-gain quantum FEL starting from noise, with special emphasis on the self-amplifled spontaneous emission (SASE) mode operation. In the flrst part, the full quantum theory of the N-particle and single-radiation-mode FEL Hamiltonian is presented.
Laser Physics, 2007
We investigate transverse effects in collective atomic recoil lasing (CARL), where a cold atomic ... more We investigate transverse effects in collective atomic recoil lasing (CARL), where a cold atomic sample is lightened by a far detuned laser beam resonant with the internal atomic transition. The gradient force of the scattered radiation field produces a collective self-focusing on the atoms, which could be observed in a Bose-Einstein condensate stored in a bidirectional optical ring cavity or
Physical Review A, 2005
We present the results of an experiment on light scattering from an elongated Bose-Einstein conde... more We present the results of an experiment on light scattering from an elongated Bose-Einstein condensate (BEC) interacting with a far-off-resonant pump laser. By collective atomic recoil lasing (CARL) a coherent superposition of two atomic wave packets with different momenta is created. Varying the intensity of a weak counterpropagating laser beam we observe the transition from the pure superradiant regime to
Optics Communications, 2004
We investigate the interaction of a moving BEC with a far detuned laser beam. Superradiant Raylei... more We investigate the interaction of a moving BEC with a far detuned laser beam. Superradiant Rayleigh scattering arises from the spontaneous formation of a matter-wave grating due to the interference of two wavepackets with different momenta. The system is described by the CARL-BEC model which is a generalization of the Gross–Pitaevskii model to include the self-consistent evolution of the scattered
Journal of Optics B-quantum and Semiclassical Optics, 2003
Continuous variable remote state preparation and teleportation are analysed using Wigner function... more Continuous variable remote state preparation and teleportation are analysed using Wigner functions in phase space. We suggest a remote squeezed state preparation scheme between two parties sharing an entangled twin beam, where homodyne detection on one beam is used as a conditional source of squeezing for the other beam. The scheme also works with noisy measurements, and provides squeezing if
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment - NUCL INSTRUM METH PHYS RES A, 2008
A compact tunable source of soft X-rays could be realized combining a state-of-the-art electron s... more A compact tunable source of soft X-rays could be realized combining a state-of-the-art electron source with an intense counter-propagating laser pulse. If the source is operated in the quantum regime, the theoretical model predicts high monochromaticity (single-spike) and unprecedented temporal coherence for the emitted radiation. Here we present numerical simulations of the complete quantum model for an Free Electron Laser (FEL) with a laser wiggler in three spatial dimensions, based on a discrete Wigner function formalism taking into account the longitudinal momentum quantization. The numerical model includes the complete spatial and temporal evolution of the electron and radiation beams, with an explicit description of diffraction, propagation, laser wiggler profile and emittance effects. The contribution of each interaction term is studied independently, and the 3D results are contrasted with the 1D quantum FEL model neglecting transverse effects. Finally the parameter space for...
Physics Letters A, 2005
A class of quantum protocols to teleport bipartite (entangled) states of two qubits is suggested.... more A class of quantum protocols to teleport bipartite (entangled) states of two qubits is suggested. Our schemes require a single entangled pair shared by the two parties and the transmission of three bits of classical information, as well as a two-qubit gate with an additional qubit at the receiver's location. Noisy quantum channels are considered and the effects on both the teleportation fidelity and the entanglement of the replica are evaluated.
Physical Review Letters, 2008
A free-electron laser (FEL) operating in the quantum regime can provide a compact and monochromat... more A free-electron laser (FEL) operating in the quantum regime can provide a compact and monochromatic x-ray source. Here we present the complete quantum model for a FEL with a laser wiggler in three spatial dimensions, based on a discrete Wigner-function formalism taking into account the longitudinal momentum quantization. The model describes the complete spatial and temporal evolution of the electron and radiation beams, including diffraction, propagation, laser wiggler profile and emittance effects. The transverse motion is described in a suitable classical limit, since the typical beam emittance values are much larger than the Compton wavelength quantum limit. In this approximation we derive an equation for the Wigner function which reduces to the three-dimensional Vlasov equation in the complete classical limit. Preliminary numerical results are presented together with parameters for a possible experiment.
Physical Review A, 2003
We suggest a general scheme for continuous variable quantum-state engineering based on conditiona... more We suggest a general scheme for continuous variable quantum-state engineering based on conditional measurements carried out on entangled twin beam of radiation. Realistic detection schemes such as on/off photodetection, homodyne detection, and joint measurement of two-mode quadratures are analyzed in detail. Imperfections of the apparatuses, such as nonunit quantum efficiency and finite resolution, are taken into account. We show that conditional on/off photodetection provides a reliable scheme to verify nonclassicality, whereas conditional homodyning represents a tunable and robust source of squeezed light. We also describe optical continuous variable teleportation as a conditional measurement, and evaluate the degrading effects of finite amount of entanglement, decoherence due to losses, and nonunit quantum efficiency.
Physical Review A, 2003
We present a quantum description of the interaction between a Bose-Einstein condensate and a sing... more We present a quantum description of the interaction between a Bose-Einstein condensate and a single-mode quantized radiation field in the presence of a strong far-off-resonant pump laser. In the linear regime, the atomic medium is described approximately by two momentum states coupled to the radiation mode. We calculate the evolution of the operators in the Heisenberg picture and their expectation values, such as average and variance of the occupation numbers, atom-atom and atom-field correlations, and two-mode squeezing parameters. Then, we disentangle the evolution operator and obtain the exact evolution of the state vector in the linear regime. This allows us to demostrate that the system can be atom-atom or atom-field thermally entangled. We define the quasiclassical and the quantum recoil limits, for which explicit expressions of the average population numbers are obtained.
Journal of Modern Optics, 2004
A collective atomic recoil laser (CARL) realized with a Bose-Einstein condensate offers the possi... more A collective atomic recoil laser (CARL) realized with a Bose-Einstein condensate offers the possibility to investigate new effects in the coherent interaction between optical and matter waves. This paper discusses some aspects of the nonlinear evolution of scattered radiation and the matterwave field in the high-Q cavity and superradiant CARL regimes.
International Journal of Modern Physics A, 2007
In this paper we optimize the experimental parameters to operate a Free Electron Laser with a las... more In this paper we optimize the experimental parameters to operate a Free Electron Laser with a laser wiggler in the Angstrom region. We show that the quantum regime of the Self Amplified Spontaneous Emission (Quantum SASE) may be reached with realistic parameters. The classical SASE regime is also discussed and compared with the quantum regime.
Recent experiments have demonstrated superradiant Raman scattering from a Bose-Einstein condensat... more Recent experiments have demonstrated superradiant Raman scattering from a Bose-Einstein condensate driven by a single off-resonant laser beam. We present a quantum theory describing this phenomenon, showing Raman amplification of matter wave due to collective atomic recoil from 3-level atoms in a Λ-configuration. When atoms are initially in a single lower internal state, a closed two-level system is realized between atoms with different internal states, and entangled atom-photon pairs can be generated. When atoms are initially prepared in both the lower internal states, a fraction of atoms recoiling in the backward direction can be generated.
Europhysics Letters (EPL), 2005
Free Electron Laser (FEL) and Collective Atomic Recoil Laser (CARL) are described by the same mod... more Free Electron Laser (FEL) and Collective Atomic Recoil Laser (CARL) are described by the same model of classical equations for properly defined scaled variables. These equations are extended to the quantum domain describing the particle's motion by a Schrödinger equation coupled to a selfconsistent radiation field. The model depends on a single collective parameterρ which represents the maximum number of photons emitted per particle. We demonstrate that the classical model is recovered in the limitρ ≫ 1, in which the Wigner function associated to the Schrödinger equation obeys to the classical Vlasov equation. On the contrary, forρ ≤ 1, a new quantum regime is obtained in which both FELs and CARLs behave as a two-state system coupled to the self-consistent radiation field and described by Maxwell-Bloch equations.
We address the interaction between a Bose-Einstein condensate and a singlemode quantized radiatio... more We address the interaction between a Bose-Einstein condensate and a singlemode quantized radiation field in the presence of a strong far off-resonant pump laser. The generation of atom-atom and atom-field entanglement is demonstrated in the linear regime. The effects of cavity losses are taken into account and an analytic solution of the corresponding master equation is given in terms of the Wigner function of the system.
We address the dynamics induced by collective atomic recoil in a Bose-Einstein condensate in pres... more We address the dynamics induced by collective atomic recoil in a Bose-Einstein condensate in presence of radiation losses and atomic decoherence. In particular, we focus on the linear regime of the lasing mechanism, and analyze the effects of losses and decoherence on the generation of entanglement. The dynamics is that of three bosons, two atomic modes interacting with a singlemode radiation field, coupled with a bath of oscillators. The resulting three-mode dissipative Master equation is solved analytically in terms of the Wigner function. We examine in details the two complementary limits of high-Q cavity and bad-cavity, the latter corresponding to the so-called superradiant regime, both in the quasi-classical and quantum regimes. We found that three-mode entanglement as well as two-mode atom-atom and atom-radiation entanglement is generally robust against losses and decoherence,thus making the present system a good candidate for the experimental observation of entanglement in condensate systems. In particular, steady-state entanglement may be obtained both between atoms with opposite momenta and between atoms and photons.
We propose an experiment to realize radiation to atom continuous variable quantum mapping, i.e. t... more We propose an experiment to realize radiation to atom continuous variable quantum mapping, i.e. to teleport the quantum state of a single mode radiation field onto the collective state of atoms with a given momentum out of a Bose-Einstein condensate. The atoms-radiation entanglement needed for the teleportation protocol is established through the interaction of a single mode with the condensate in presence of a strong far off-resonant pump laser, whereas the coherent atomic displacement is obtained by the same interaction with the radiation in a classical coherent field. In principle, verification of the protocol requires a joint measurement on the recoiling atoms and the condensate, however, a partial verification involving populations, i.e. diagonal matrix elements may be obtained through counting atoms experiments.
Journal of Modern Optics, 2004
We present the results of an experiment on superradiant Rayleigh scattering from a moving Bose-Ei... more We present the results of an experiment on superradiant Rayleigh scattering from a moving Bose-Einstein condensate, where a superposition of two atomic wavepackets is created by the interaction of a far-detuned laser beam with the condensate. The system is described by the CARL-BEC model which is a generalization of the Gross-Pitaevskii model to include the self-consistent evolution of the scattered
A Free Electron Laser (FEL) operating in the quantum regime can provide a compact and monochromat... more A Free Electron Laser (FEL) operating in the quantum regime can provide a compact and monochromatic X-ray source. Here we review the basic principles of a high-gain quantum FEL starting from noise, with special emphasis on the self-amplifled spontaneous emission (SASE) mode operation. In the flrst part, the full quantum theory of the N-particle and single-radiation-mode FEL Hamiltonian is presented.
Laser Physics, 2007
We investigate transverse effects in collective atomic recoil lasing (CARL), where a cold atomic ... more We investigate transverse effects in collective atomic recoil lasing (CARL), where a cold atomic sample is lightened by a far detuned laser beam resonant with the internal atomic transition. The gradient force of the scattered radiation field produces a collective self-focusing on the atoms, which could be observed in a Bose-Einstein condensate stored in a bidirectional optical ring cavity or
Physical Review A, 2005
We present the results of an experiment on light scattering from an elongated Bose-Einstein conde... more We present the results of an experiment on light scattering from an elongated Bose-Einstein condensate (BEC) interacting with a far-off-resonant pump laser. By collective atomic recoil lasing (CARL) a coherent superposition of two atomic wave packets with different momenta is created. Varying the intensity of a weak counterpropagating laser beam we observe the transition from the pure superradiant regime to
Optics Communications, 2004
We investigate the interaction of a moving BEC with a far detuned laser beam. Superradiant Raylei... more We investigate the interaction of a moving BEC with a far detuned laser beam. Superradiant Rayleigh scattering arises from the spontaneous formation of a matter-wave grating due to the interference of two wavepackets with different momenta. The system is described by the CARL-BEC model which is a generalization of the Gross–Pitaevskii model to include the self-consistent evolution of the scattered
Journal of Optics B-quantum and Semiclassical Optics, 2003
Continuous variable remote state preparation and teleportation are analysed using Wigner function... more Continuous variable remote state preparation and teleportation are analysed using Wigner functions in phase space. We suggest a remote squeezed state preparation scheme between two parties sharing an entangled twin beam, where homodyne detection on one beam is used as a conditional source of squeezing for the other beam. The scheme also works with noisy measurements, and provides squeezing if
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment - NUCL INSTRUM METH PHYS RES A, 2008
A compact tunable source of soft X-rays could be realized combining a state-of-the-art electron s... more A compact tunable source of soft X-rays could be realized combining a state-of-the-art electron source with an intense counter-propagating laser pulse. If the source is operated in the quantum regime, the theoretical model predicts high monochromaticity (single-spike) and unprecedented temporal coherence for the emitted radiation. Here we present numerical simulations of the complete quantum model for an Free Electron Laser (FEL) with a laser wiggler in three spatial dimensions, based on a discrete Wigner function formalism taking into account the longitudinal momentum quantization. The numerical model includes the complete spatial and temporal evolution of the electron and radiation beams, with an explicit description of diffraction, propagation, laser wiggler profile and emittance effects. The contribution of each interaction term is studied independently, and the 3D results are contrasted with the 1D quantum FEL model neglecting transverse effects. Finally the parameter space for...
Physics Letters A, 2005
A class of quantum protocols to teleport bipartite (entangled) states of two qubits is suggested.... more A class of quantum protocols to teleport bipartite (entangled) states of two qubits is suggested. Our schemes require a single entangled pair shared by the two parties and the transmission of three bits of classical information, as well as a two-qubit gate with an additional qubit at the receiver's location. Noisy quantum channels are considered and the effects on both the teleportation fidelity and the entanglement of the replica are evaluated.
Physical Review Letters, 2008
A free-electron laser (FEL) operating in the quantum regime can provide a compact and monochromat... more A free-electron laser (FEL) operating in the quantum regime can provide a compact and monochromatic x-ray source. Here we present the complete quantum model for a FEL with a laser wiggler in three spatial dimensions, based on a discrete Wigner-function formalism taking into account the longitudinal momentum quantization. The model describes the complete spatial and temporal evolution of the electron and radiation beams, including diffraction, propagation, laser wiggler profile and emittance effects. The transverse motion is described in a suitable classical limit, since the typical beam emittance values are much larger than the Compton wavelength quantum limit. In this approximation we derive an equation for the Wigner function which reduces to the three-dimensional Vlasov equation in the complete classical limit. Preliminary numerical results are presented together with parameters for a possible experiment.
Physical Review A, 2003
We suggest a general scheme for continuous variable quantum-state engineering based on conditiona... more We suggest a general scheme for continuous variable quantum-state engineering based on conditional measurements carried out on entangled twin beam of radiation. Realistic detection schemes such as on/off photodetection, homodyne detection, and joint measurement of two-mode quadratures are analyzed in detail. Imperfections of the apparatuses, such as nonunit quantum efficiency and finite resolution, are taken into account. We show that conditional on/off photodetection provides a reliable scheme to verify nonclassicality, whereas conditional homodyning represents a tunable and robust source of squeezed light. We also describe optical continuous variable teleportation as a conditional measurement, and evaluate the degrading effects of finite amount of entanglement, decoherence due to losses, and nonunit quantum efficiency.