Dresden 2011 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 28: Quantum Information: Quantum Communication 1

Q 28.5: Talk

Wednesday, March 16, 2011, 11:30–11:45, SCH A01

The excitation of a two-level atom by a propagating light pulse — •Yimin Wang, Lana Sheridan, and Valerio Scarani — Centre for Quantum Technologies, Singapore

State mapping between atoms and photons, and photon-photon interactions play an important role in scalable quantum information processing. We consider the interaction of a two-level atom with a quantized propagating pulse in free space and study the probability P_e(t) of finding the atom in the excited state at any time t. This probability is expected to depend on (i) the quantum state of the pulse field and (ii) the overlap between the pulse and the dipole pattern of the atomic spontaneous emission. In the full three-dimensional vector model for the field, we show that the second effect is captured by a single parameter Λ∈[0,8π/3], obtained by weighing the numerical aperture with the dipole pattern. Then P_e(t) can be obtained by solving time-dependent Heisenberg-Langevin equations. We provide detailed solutions for both single-photon states and coherent states and for various shapes of the pulse. By optimizing the pulse bandwidth of each kind of pulse with specific shapes, the maximum excitation probability is shown respectively. The effect of mean photon numbers for coherent state pulse is also analyzed.

Reference

[1] G. Zumofen et al., Phys. Rev. Lett. 101, 180404 (2008).

[2] M. Stobińska et al., Euro. Phys. Lett., 86, 14007 (2009).

[3] M. K. Tey et al., Nature Physics 4, 924 (2008).

[4] Y. M. Wang et al., arXiv: 1010.4661v1, (2010).