München 2004 – scientific programme

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Q: Quantenoptik und Photonik

Q 22: Poster Quanteninformation, -kommunikation und -computer

Q 22.6: Poster

Tuesday, March 23, 2004, 14:00–16:00, Schellingstr. 3

Time-bin entangled single photons from a cavity-QED source — •T. Wilk, T. Legero, M. Hennrich, A. Kuhn, and G. Rempe — Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching, Germany

Entangled photons are an indispensable ingredient of many quantum information schemes. Most applications use polarisation entangled photons, while others employ time-bin entanglement [1]: a single-photon wave-packet is distributed over two distinct intervals which are separated in time. In contrast to former experiments, where the time-bin entanglement is realised by sending a single photon through a Mach-Zehnder interferometer with unbalanced arms, we here present a single-photon generation scheme that directly delivers such photons.

The photons emerge from a cavity-QED source, where a single atom undergoes an adiabatic passage, driven by the ambient cavity and pumping laser pulses [2]. Any variation of the amplitude of the laser pulses affects the emission probability and has a direct impact on the shape of the single-photon wave-packets. Therefore arbitrary shaping of time-bin entangled photons seems possible. We investigate whether the relative phase between the two time bins can be controlled by appropriately changing the phase of the driving laser. The degree and lifetime of a possible entanglement, can be determined by time-resolved two-photon interference [3].

[1] Brendel et al. Phys. Rev. Lett. 82, 2594 (1999)

[2] Kuhn et al. Phys. Rev. Lett. 89, 67901 (2002)

[3] Legero et al. Appl. Phys. B 77, 797 (2003)