CQT Talk by Paolo Villoresi, University of Padova
Date/Time: Friday, 07 Nov at 11:00 am
Venue: CQT Level 3 Conference Room, S15-03-18
Title: Space Quantum Communications exploiting Satellite Links
Quantum Communications on planetary scale require complementary channels including ground and satellite links [1-5]. The former have progressed up to commercial stage using fiber-cables, while for satellite links, the absence of terminals in orbit has impaired theirs development.
Nowadays, the demonstration of the feasibility of such links is crucial for designing space payloads and to eventually enable the realization of protocols such as quantum keydistribution (QKD) and quantum teleportation along satellite-toground or intersatellite links . Here we report the faithful transmission of qubits from space to ground by exploiting satellite corner cube retroreflectors acting as transmitter in orbit, as already
exploited in the first single photon exchange  obtaining a low error rate suitable for QKD. The scheme of the experiment is illustrated in the Figure on the right . Finally, on the base of the findings, we envisage a two-way QKD protocol exploiting modulated retroreflectors that necessitates a minimal payload on satellite, thus facilitating the
expansion of Space Quantum Communications .
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arXiv:1406.4051v1 [quant-ph] 16 Jun 2014
CQT Colloquium by William D. Phillips, National Institute of Standards and Technology, University of Maryland
Date/Time: Friday, 07 Nov at 4:00 pm
Venue: CQT Seminar Room, S15-03-15
Title: An atomic superfluid Bose-Einstein condensate in a ring
Abstract: We create an atomic-gas Bose-Einstein condensate in a ring-shaped trap and interrupt the circulation in the ring with a repulsive barrier. This system can exhibit behavior similar to that of a superconducting loop interrupted by a weak link or Josephson junction. We observe controllable, discrete phase slips (jumps in the phase winding number around the ring) and hysteretic behavior in such a system. A novel interference measurement can detect the presence, direction, and winding number of the circulation in the ring as well as provide a determination of the current-phase relationship of the weak link.