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Time evolution and squeezing of the field amplitude in cavity QED

Joseph E. Reiner, Wade P. Smith, L. A. Orozco +2 more

We present the conditional time evolution of the electromagnetic field produced by a cavity QED system in the strongly coupled regime. We obtain the conditional evolution through an intensity–amplitude correlation function that measures the time evolution of the field after the detection of a photon. A connection exists between this correlation function and the spectrum of squeezing, which permits the study of squeezed states in the time domain. We calculate the spectrum of squeezing from the master equation for the reduced density matrix using both the quantum-regression theorem and quantum trajectories. Our calculations not only show that spontaneous emission degrades the squeezing signal, they also point to the dynamical processes that cause this degradation.We present the conditional time evolution of the electromagnetic field produced by a cavity QED system in the strongly coupled regime. We obtain the conditional evolution through an intensity–amplitude correlation function that measures the time evolution of the field after the detection of a photon. A connection exists between this correlation function and the spectrum of squeezing, which permits the study of squeezed states in the time domain. We calculate the spectrum of squeezing from the master equation for the reduced density matrix using both the quantum-regression theorem and quantum trajectories. Our calculations not only show that spontaneous emission degrades the squeezing signal, they also point to the dynamical processes that cause this degradation.

arXiv:quant-ph/0012096Journal of the Optical Society of America BDec 1, 200125 citations

On the Squeezing Properties in Cavity QED

Rui‐Hua Xie

Chinese Journal of PhysicsFeb 1, 19960 citations

Phase-dependent squeezing and entanglement in a cavity QED

J.J. Mu, Bang‐Pin Hou

OptikJun 3, 20130 citations

Quantum State Reduction and Conditional Time Evolution of Wave-Particle Correlations in Cavity QED

G. T. Foster, Luis A. Orozco, H. M. Castro-Beltrán +1 more

We report measurements in cavity QED of a wave-particle correlation function which records the conditional time evolution of the field of a fraction of a photon. Detection of a photon prepares a state of well-defined phase that evolves back to equilibrium via a damped vacuum Rabi oscillation. We record the regression of the field amplitude. The recorded correlation function is nonclassical and provides an efficiency independent path to the spectrum of squeezing. Nonclassicality is observed even when the intensity fluctuations are classical.We report measurements in cavity QED of a wave-particle correlation function which records the conditional time evolution of the field of a fraction of a photon. Detection of a photon prepares a state of well-defined phase that evolves back to equilibrium via a damped vacuum Rabi oscillation. We record the regression of the field amplitude. The recorded correlation function is nonclassical and provides an efficiency independent path to the spectrum of squeezing. Nonclassicality is observed even when the intensity fluctuations are classical.

Physical Review LettersOct 9, 2000141 citations

Temperature-enhanced squeezing in cavity QED

Dominique Spehner, Miguel Orszag

We study the time evolution of the quantum field inside a cavity coupled to a beam of two-level atoms of temperature T , given that each atom, after having crossed the cavity, interacts with a classical field and finally with a detector measuring its state. It is found that, if the coupling between the atoms and the quantum field is weak and is not too small, for any given realization of the measurements, an arbitrary initial state of the field localizes after some time into squeezed states. The centre α of the squeezed state moves randomly in time in the complex plane, but the squeezing amplitude r and phase ϕ show very small fluctuations. Their mean values and are independent of the random results of the measurements, of the initial state and of the atom–field coupling constant λ. The time evolution of r and ϕ is determined analytically by deriving and solving the quantum state diffusion equation describing the field dynamics in the limit of small λ, keeping finite. It is shown that increases with T , i.e., the squeezing is enhanced by increasing the temperature of the atomic beam.We study the time evolution of the quantum field inside a cavity coupled to a beam of two-level atoms of temperature T , given that each atom, after having crossed the cavity, interacts with a classical field and finally with a detector measuring its state. It is found that, if the coupling between the atoms and the quantum field is weak and is not too small, for any given realization of the measurements, an arbitrary initial state of the field localizes after some time into squeezed states. The centre α of the squeezed state moves randomly in time in the complex plane, but the squeezing amplitude r and phase ϕ show very small fluctuations. Their mean values and are independent of the random results of the measurements, of the initial state and of the atom–field coupling constant λ. The time evolution of r and ϕ is determined analytically by deriving and solving the quantum state diffusion equation describing the field dynamics in the limit of small λ, keeping finite. It is shown that increases with T , i.e., the squeezing is enhanced by increasing the temperature of the atomic beam.

Journal of Optics B Quantum and Semiclassical OpticsAug 30, 20022 citations

CLASSICAL VERSUS QUANTUM EFFECTS IN CAVITY QED

Jonathan P. Dowling

Foundations of Quantum MechanicsApr 1, 19920 citations

Time evolution and squeezing of the field amplitude in cavity QED

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