Creation of two-photon states via interactions between Rydberg atoms during light storage

Abstract

We propose a new method to create two-photon states in a controllable way using interaction between the Rydberg atoms during the storage and retrieval of slow light. A distinctive feature of the suggested procedure is that the slow light is stored into a superposition of two atomic coherences under conditions of electromagnetically induced transparency (EIT). Interaction between the atoms during the storage period creates entangled pairs of atoms in a superposition state that is orthogonal to the initially stored state. Restoring the slow light from this new atomic state one can produce a two photon state with a second-order correlation function determined by the atom-atom interaction and the storage time. Therefore the measurement of the restored light allows one to probe the atom-atom coupling by optical means with a sensitivity that can be increased by extending the storage time. As a realization of this idea we consider a many-body Ramsey-type technique which involves π/2 pulses creating a superposition of Rydberg states at the beginning and the end of the storage period. In that case the regenerated light is due to the resonance dipole-dipole interaction between the atoms in the Rydberg states.

Mean field theory of weakly-interacting Rydberg polaritons in the EIT system based on the nearest-neighbor distribution

“…Thus, the combination of the strong DDI of Rydberg atoms and the high optical nonlinearity of EIT can efficiently mediate the interaction between photons via Rydberg polaritons in the dipole blockade regime, where the Rydberg polariton is the collective excitation involving the light and the atomic coherence between the ground and Rydberg states [15,16]. The Rydberg-EIT mechanism can lead to the applications of quantum optics and quantum information processing [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32].…”

“…In Ref. [28], J. Ruseckas et al proposed a method to create two-photon states by making pairs of Rydberg atoms entangled during the storage.…”

Quantum delocalization in photon-pair generation

“…This effect, if the nonlocal mechanism had not been identified, might indeed be interpreted as simply manifesting a position-momentum quantum uncertainty with respect to directions perpendicular to the down-converted photon propagation. It is also interesting to conjecture whether effects of a similar kind might play a role in the creation of two-photon states through interactions between Rydberg atoms [100]. It remains to be seen what other forms of photon-pair nonlocality might prove amenable to experimental determination; the possible implications for quantum entanglement between emitted photons is a subject now under further active investigation.…”

Nonclassical storage and retrieval of a multiphoton pulse in cold Rydberg atoms

“…Quite recently, important experimental progress has been achieved on light storage and retrieval in EIT media of cold [33][34][35] or thermal [36] Rydberg atoms. It is found that a multiphoton pulse can be engineered to exhibit such peculiar properties as Rydberg-mediated interactions [33] and two-photon states [37]. However, a satisfactory theoretical method to reproduce relevant experimental results is still lacking, although several * jhwu@nenu.edu.cn methods [38][39][40][41][42] have been proposed to deal with the dynamic propagation of single-photon or few-photon pulses in Rydberg-EIT media.…”