### Abstract

A quantum electrodynamic calculation of the interaction of an excited-state atom with a ground-state atom is performed. For an excited reference state and a lower-lying virtual state, the contribution to the interaction energy naturally splits into a pole term and a Wick-rotated term. The pole term is shown to dominate in the long-range limit, altering the functional form of the interaction from the retarded 1/R7 Casimir-Polder form to a long-range tail - provided by the Wick-rotated term - proportional to cos[2(Em-En)R/(c)]/R2, where Em<En is the energy of a virtual state, lower than the reference-state energy En, and R is the interatomic separation. General expressions are obtained which can be applied to atomic reference states of arbitrary angular symmetry. Careful treatment of the pole terms in the Feynman prescription for the atomic polarizability is found to be crucial in obtaining correct results.

Original language | English |
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Article number | 042506 |

Journal | Physical Review A |

Volume | 95 |

Issue number | 4 |

DOIs | |

Publication status | Published - Apr 12 2017 |

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### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

### Cite this

*Physical Review A*,

*95*(4), [042506]. https://doi.org/10.1103/PhysRevA.95.042506

**Long-range tails in van der Waals interactions of excited-state and ground-state atoms.** / Jentschura, U.; Debierre, V.

Research output: Contribution to journal › Article

*Physical Review A*, vol. 95, no. 4, 042506. https://doi.org/10.1103/PhysRevA.95.042506

}

TY - JOUR

T1 - Long-range tails in van der Waals interactions of excited-state and ground-state atoms

AU - Jentschura, U.

AU - Debierre, V.

PY - 2017/4/12

Y1 - 2017/4/12

N2 - A quantum electrodynamic calculation of the interaction of an excited-state atom with a ground-state atom is performed. For an excited reference state and a lower-lying virtual state, the contribution to the interaction energy naturally splits into a pole term and a Wick-rotated term. The pole term is shown to dominate in the long-range limit, altering the functional form of the interaction from the retarded 1/R7 Casimir-Polder form to a long-range tail - provided by the Wick-rotated term - proportional to cos[2(Em-En)R/(c)]/R2, where Em<En is the energy of a virtual state, lower than the reference-state energy En, and R is the interatomic separation. General expressions are obtained which can be applied to atomic reference states of arbitrary angular symmetry. Careful treatment of the pole terms in the Feynman prescription for the atomic polarizability is found to be crucial in obtaining correct results.

AB - A quantum electrodynamic calculation of the interaction of an excited-state atom with a ground-state atom is performed. For an excited reference state and a lower-lying virtual state, the contribution to the interaction energy naturally splits into a pole term and a Wick-rotated term. The pole term is shown to dominate in the long-range limit, altering the functional form of the interaction from the retarded 1/R7 Casimir-Polder form to a long-range tail - provided by the Wick-rotated term - proportional to cos[2(Em-En)R/(c)]/R2, where Em<En is the energy of a virtual state, lower than the reference-state energy En, and R is the interatomic separation. General expressions are obtained which can be applied to atomic reference states of arbitrary angular symmetry. Careful treatment of the pole terms in the Feynman prescription for the atomic polarizability is found to be crucial in obtaining correct results.

UR - http://www.scopus.com/inward/record.url?scp=85017513833&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85017513833&partnerID=8YFLogxK

U2 - 10.1103/PhysRevA.95.042506

DO - 10.1103/PhysRevA.95.042506

M3 - Article

AN - SCOPUS:85017513833

VL - 95

JO - Physical Review A

JF - Physical Review A

SN - 2469-9926

IS - 4

M1 - 042506

ER -