This paper studies the cavity field generated by injecting atoms, one at a time, initially in the excited state and operating at a one-step two-photon transition. The interesting features of photon statistical distribution in the cavity are found and discussed, the conditions of generating photon number state are shown.
For an arbitrary initial photon probability distribution in a micromaser cavity, it is shown that photon-number eigenstates can be induced by passing excited atoms, one at a time, through the cavity. The photon number can be predicted for a given velocity of excited atoms. It is found that the total photon energy inside a lossless cavity becomes saturated once a photon number state is achieved. It is also possible to find more than one number states, each occurs with a certain probability under particular initial conditions. If the injected atoms have a small velocity distribution Av around v, then only a near-number state with the predicted photon number is possible. For Av/v - 0.1, the photon probability in the cavity can still maintain subpoisson distribution until sufficiently large number of excited atoms have passed. Other novel phenomena are also found in two-photon processes.
It is found that displacement and squeezing of arbitrary initial states of the field can be produced in the model of a lossless cavity when a large number of two-level atoms is injected, which are prepared in a superposition state coupled to the single mode via a multi-photon transition under the weak atom-field interaction. The dependence of the field density matrix elements on the number of injected atoms indicates that due to the same initial atomic coherence the emission of individual atoms is a co-operative process.
A simple scheme is presented for generating n atom W states with the two-photon resonant interaction between atoms and cavity field.In the proposed protocol,it is injected a two-level atom initially prepared in the excited state through the cavity prepared in the vacuum state.The other two-level atoms prepared in the ground state are injected into cavity.Because the interaction between the atoms and cavity field is resonant,the coupling strength can be relatively strong which will shorten the corresponding interaction time and thus reduce the effect of decoherence in experiment.
In this paper, we present a very simple approach to input-output relations in optical cavities, limiting ourselves to one- and two-photon states of the field. After field quantization, we derive the nonunitary transformation between inside and output annihilation and creation operators. Then we express the most general two-photon state generated by inside creation operators, through base states generated by output creation operators. After renormalization of coefficients of the inside two-photon state, we calculate the outside photon-number probability distribution in a general case; then we treat with some detail the single-mode and symmetrical cavity case. We found that the statistics of emitted photons may exhibit either quantum or classical behavior, depending both on source properties and on cavity characteristics.
A single two-level atom can be used to prepare an arbitrary photon number state (Fock state) in a high Q cavity . The atom undergoes a controlled succession of interactions with two cavity modes. One of them contains a coherent field. The atom transfers photons one by one from this field to the initially empty second mode. The scheme can be extended to prepare a quantum superposition of the vacuum with a Fock state, a highly non-classical situation. We discuss the feasibility of the experiment with our present Rydberg-atom cavity QED set-up.