Josephson dynamics for coupled polariton modes under the atom–field interaction in the cavity

Abstract

We consider a new approach to the problem of Bose-Einstein condensation (BEC) of polaritons for atom-field interaction under the strong coupling regime in the cavity. We investigate the dynamics of two macroscopically populated polariton modes corresponding to the upper and lower branch energy states coupled via Kerr-like nonlinearity of atomic medium. We found out the dispersion relations for new type of collective excitations in the system under consideration. Various temporal regimes like linear (nonlinear) Josephson transition and/or Rabi oscillations, macroscopic quantum selftrapping (MQST) dynamics for population imbalance of polariton modes are predicted. We also examine the switching properties for time-averaged population imbalance depending on initial conditions, effective nonlinear parameter of atomic medium and kinetic energy of lowbranch polaritons.

High-temperature phase transition in the coupled atom-light system in the presence of optical collisions

“…Such an interaction arises due to nonlinear effects in atom-field interaction, described by second terms in expressions (16) for S − and S † − , cf. [31]. We expect, that in the future it will be possible to examine superfluid properties of such polaritons by using very thin-walled (up to 60 nm) waveguides for the experiment with Josephson junctions at high enough temperatures.…”

Quantum cloning in coupled states of an optical field and an atomic ensemble by means of quasi-condensation of polaritons

“…In some sense such a technique is similar to the method proposed earlier to achieve a good QND-measurement for light quadrature component and/or photon number -see e.g. [10]. The problem of retrieval procedure for the scheme proposed by us in Fig.1 requires detailed analysis that is not the subject of study in the paper.…”

“…In particular, in Ref. [9] we propose a new quantum non-demolition (QND) technique to store the quantum information which is very closed to the QND measurement procedure in quantum and atomic optics [10]. We have shown that atomic system under the BEC condition satisfies formulated criteria for reasonable efficiency of quantum information storage and transmission simultaneously, and therefore is perspective for creating a long lived memory.…”

Excitation of coherent polaritons in a two-dimensional atomic lattice

“…We will consider it in the low atomic excitation density limit, where all the atoms predominantly occupy the lower level |a [11]. The boson annihilation (φ k ) and creation (φ + k ) operators for collective excitations in a two-level atomic system can then be defined in the k-space representation:…”

“…Note that the phase transition in question may take place at sufficiently high (room) temperatures because of the low-branch polariton effective mass [9]. Kasprzak et al [10] demonstrated a macroscopical population of ground state (inplane wave number k ) of a 2D gas of exciton-polaritons in semiconductor nanostructures (Cd-Te) at 5 K. The superfluid properties and Josephson dynamics of such polaritons were studied by Alodjants et al [11] and observed experimentally by Lai et al [12]. In addition, as shown by Alodjants et al [13] certain conditions enable optical cloning and quantum memory based on the cavity polaritons in question.…”