Quantum correlations and violation of the Bell inequality induced by an external field in a two-photon radiative cascade

Journal Article · Wed Jun 15 00:00:00 EDT 2011 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.83.063819· OSTI ID:21550200

Luqi, Yuan; Das, Sumanta ^[1]

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1. Institute for Quantum Science and Engineering and Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843 (United States)

We study the polarization-dependent second-order correlation of a pair of photons emitted in a four-level radiative cascade driven by an external field. It is found that the quantum correlations of the emitted photons, degraded by the energy splitting of the intermediate levels in the radiative cascade, can be efficiently revived by a far-detuned external field. The physics of this revival is linked to an induced Stark shift and the formation of dressed states in the system by the nonresonant external field. Furthermore, we investigated the competition between the effect of the coherent external field and incoherent dephasing of the intermediate levels. We find that the degradation of quantum correlations due to the incoherent dephasing can be contained for small dephasing with the external field. We also studied the nonlocality of the correlations by evaluating the Bell inequality in the linear polarization basis for the radiative cascade. We find that the Bell parameter decreases rapidly with increase in the intermediate-level energy splitting or incoherent dephasing rate to the extent that there is no violation. However, the presence of an external field leads to control over the degrading mechanisms and preservation of nonlocal correlation among the photons. This in turn can induce a violation of Bell's inequality in the radiative cascade for arbitrary intermediate-level splitting and small incoherent dephasing.

• OSTI ID: 21550200
• Journal Information: Physical Review. A, Vol. 83, Issue 6; Other Information: DOI: 10.1103/PhysRevA.83.063819; (c) 2011 American Institute of Physics; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BELL THEOREM
CONTROL
CORRELATIONS
INVARIANCE PRINCIPLES
PAIR PRODUCTION
PHOTON EMISSION
PHOTONS
POLARIZATION
QUANTUM MECHANICS
RADIATIVE DECAY
BOSONS
DECAY
ELEMENTARY PARTICLES
EMISSION
INTERACTIONS
MASSLESS PARTICLES
MECHANICS
PARTICLE DECAY
PARTICLE PRODUCTION