Superradiant and Subradiant Behavior of the Overdamped Many-Atom Micromaser (original) (raw)

Quantum theory of a micromaser operating on the atomic scattering from a resonant standing wave

Physical Review A, 2001

We study the amplification of a resonant standing-wave light field due to the interaction with a beam of monovelocity two-level atoms moving in the Raman-Nath regime and in the Bragg regime. The atomic density is low so that, at most, one atom is inside the cavity at a time. This system is very similar to the well-known micromaser but it is operating in the optical region of the field frequencies. Therefore, the situation corresponds to a microlaser. Unlike the micromaser system, the momentum transfer between the atoms and photons in the microlaser essentially effects the center-of-mass motion of the atoms and the evolution of the field.

Collective two-atom effects and trapping states in the micromaser

Physical Review A, 2006

We investigate signals of trapping states in the micromaser system in terms of the average number ⟨n⟩ of cavity photons as well as a suitably defined correlation length of atoms leaving the cavity. In the description of collective two-atom effects we allow the mean number, γ , of pump atoms inside the cavity during the characteristic atomic cavity transit time to be as large as of order one. The master equation we consider, which describes the micromaser including collective two-atom effects, still exhibits trapping states for γ≠0 , even for a mean number of atoms inside the cavity close to one. We, however, argue more importantly that the trapping states are more pronounced in terms of the correlation length as compared to ⟨n⟩ , i.e., we suggest that trapping states can be more clearly revealed experimentally in terms of the atom correlation length. For axion detection in the micromaser this observable may, therefore, be an essential ingredient.

Hierarchy of time scales and quasitrapping in the N-atom micromaser

2000

We study the dynamics of the reduced density matrix(RDM) of the field in the micromaser. The resonator is pumped by N-atomic clusters of two-level atoms. At each given instant there is only one cluster in the cavity. We find the conditions of the independent evolution of the matrix elements of RDM belonging to a (sub)diagonal of the RDM, i.e. conditions

Role of spatial mode function in the presence of two-atom events in a micromaser

Optics Communications, 2007

In this paper, we discuss the effects of spatial mode function in an one-photon micromaser in the presence of two-atom events. It is shown that two-atom events allow us a possibility to study the effects of different cavity eigenmodes in a micromaser. We find that squeezing properties of the radiation field depend upon the parity (odd or even) and order (lower or higher) of cavity eigenmodes. For example, squeezing can be obtained for odd-order cavity eigenmodes which completely vanishes for even-order modes. Our results also show that effects similar to self-induced transparency are never obtained in the presence of two-atom events. Finally, we consider the effect of pump fluctuations and cavity losses in our system.

Dynamics, correlations, and phases of the micromaser

Physical Review A, 1996

The micromaser possesses a variety of dynamical phase transitions parametrized by the flux of atoms and the time of flight of the atom within the cavity. We discuss how these phases may be revealed to an observer outside the cavity using the long-time correlation length in the atomic beam. Some of the phase transitions are not reflected in the average excitation level of the outgoing atom, which is the commonly used observable. The correlation length is directly related to the leading eigenvalue of the time evolution operator, which we study in order to elucidate the phase structure. We find that as a function of the time of flight the transition from the thermal to the maser phase is characterized by a sharp peak in the correlation length. For longer times of flight there is a transition to a phase where the correlation length grows exponentially with the flux. We present a detailed numerical and analytical treatment of the different phases and discuss the physics behind them.

Superradiant Effects in Systems of Two-Level Atoms

Physical Review A, 1972

The problem of the evolution in time of a system of two-level atoms that are coupled through their electromagnetic fields, is studied and solved in the framework of semiclassical radiation theory. The atoms may be in any initial states and the radiation reaction is fully taken into account. Both superradiance and time-dependent frequency shift or chirping effects are found. The assumption that all the atoms see the same field is shown to place severe constraints on the evolution of the system, in the form of constants of the motion. These constraints are most easily pictured in terms of the Bloch-vector representation of the atomic system, and they lead to explicit solutions for the time development of each atom. It is shown that the evolution of the complex system is describable by means of a collective super Bloch vector, whose behavior is similar to the behavior of the Bloch vector for a single isolated atom. The constraints on the motion also imply that the system cannot radiate all its energy coherently; some of it remains trapped, to be dissipated ultimately by incoherent processes. Somecurves are presented to illustrate the behavior of the system in special cases.

Trapping and photon number states in a two-photon micromaser

Journal of Luminescence, 1998

We present a theoretical analysis of a two-photon micromaser and investigate the statistical properties of the radiation. We analyze both vacuum as well as non-vacuum trapped states that follow from the theory. Non-vaccum trapped states have not been found in previous theories of the two-photon micromaser. We explore how photon number states can be generated in the limit of large flux of atoms in the cavity.

Correlated-emission laser: Theory of the quantum-beat micromaser

Physical Review A, 1988

We show that if we inject three-level atoms, at a low rate, through a double cavity, with the two upper levels strongly coupled, and if, in the theoretical analysis, one makes the rotating-wave approximation, this problem is formally equivalent to the ordinary two-level micromaser. We also obtain the relevant master equation and the photon statistics.

Quantum Micro-Mechanics with Ultracold Atoms

Pushing the Frontiers of Atomic Physics - Proceedings of the XXI International Conference on Atomic Physics, 2009

In many experiments isolated atoms and ions have been inserted into highfinesse optical resonators for the study of fundamental quantum optics and quantum information. Here, we introduce another application of such a system, as the realization of cavity optomechanics where the collective motion of an atomic ensemble serves the role of a moveable optical element in an optical resonator. Compared with other optomechanical systems, such as those incorporating nanofabricated cantilevers or the large cavity mirrors of gravitational observatories, our cold-atom realization offers direct access to the quantum regime. We describe experimental investigations of optomechanical effects, such as the bistability of collective atomic motion and the first quantification of measurement backaction for a macroscopic object, and discuss future directions for this nascent field.