Two-mode Squeezed State Research Articles

Photocount distribution of two-mode squeezed states.

We derive a closed-form expression for the number probability distribution of a ``generic'' two-mode field in a two-mode squeezed state. We discuss its dependence on the average particle number in the two modes and on the amount of squeezing. We show that the distribution exhibits oscillations for particle numbers appropriately greater than the average, similar to the one-mode case, although the conditions under which such an oscillatory behavior occurs are different. These results are directed to the investigation of nonclassical properties in the radiation field produced by a parametric amplifier operated in a two-mode regime.

Characteristics of Rabi oscillations in the two-mode squeezed state of the field.

The phenomenon of collapses and revivals of Rabi oscillations is studied for a two-level atom undergoing either one- or two-photon transitions in the two-mode squeezed state field inside a lossless cavity. The qualitative behavior of this phenomenon is found to be different as compared with corresponding coherent-state fields. Analytic expressions for excitation probabilities are obtained. Also, the statistical aspect of the field in terms of intensity-intensity correlations is discussed.

Nonclassical photon statistics of two-mode squeezed states.

The concept of photon antibunching as a manifestation of nonclassical character in single-mode radiation is extended to two-mode radiation. A simple criterion for the existence of nonclassical effects in two-mode radiation is established. It implies that the intermode photon bunching, rather than antibunching, can play a key role in rendering two-mode radiation nonclassical. The two-mode squeezed vacuum states are used as simple examples to illustrate the essential point of the criterion. The criterion is then used to study the nonclassical properties of two types of two-mode squeezed states. A state generated by applying the squeeze operator to the two-mode vacuum first, followed by the displacement operator, is called a two-mode coherent squeezed state. If the order of the two operators is reversed, a two-mode squeezed coherent state is obtained. It is found that the latter has a much stronger tendency to become a nonclassical state than the former, assuming that the parameters involved are all the same. A measure of nonclassical depth of radiation is adopted. It is found that, according to this measure, the effect of squeezing in making two-mode coherent squeezed states nonclassical is not monotonic. Such phenomena do not occur in squeezed coherent states.

Correlated photons in parametric frequency conversion with initial two-mode squeezed states

We consider the joint photon counting statistics for a parametric frequency converter driven by a two-mode squeezed state. Significant anti-correlations are found analogous to those recently observed for two-photon states incident at a beam splitter.

Entropy as a measure of quantum optical correlation.

Previous work on quantum correlations has focused attention on the influence of the correlation on observables. In this paper we introduce an observable-independent index of correlation based on the information content, or entropy, of that correlation. We analyze a pair of spins and verify that they are maximally correlated when the index of correlation is maximized. The index of correlation suggests that two optical-field modes are most strongly correlated when prepared in a two-mode squeezed state.

Simple approach to the wave functions of one- and two-mode squeezed states.

With use of the coordinate representation of the one-mode squeeze operator, the coordinate representation wave function of the one-mode squeezed state is simply rederived. A parallel treatment for the two-mode squeeze operator yields the two-mode squeezed state wave function.