We present a family of protocols for flipping a coin over a telephone in a quantum mechanical setting. The family contains protocols with n + 2 messages for all n > 1, and asymptotically achieves a bias of 0.192. The case n = 2 is equivalent to the protocol of Spekkens and Rudolph with bias 0.207, which was the best known protocol. The case n = 3 achieves a bias of 0.199, and n = 8 achieves a bias of 0.193. The analysis of the protocols uses Kitaev's description of coin-flipping as a semidefinite program. We construct an analytical solution to the dual problem which provides an upper bound on the amount that a party can cheat.

This paper reports on the design and use of tactile user interfaces embedded within or wrapped around the devices that they control. We discuss three different interaction prototypes that we built These interfaces were embedded onto two handheld devices of dramatically different form factors. We describe the design and implementation challenges, and user feedback and reactions to these prototypes. Implications for future design in the area of manipulative or haptic user interfaces are highlighted.