Jonathan Oppenheim, Robert W. Spekkens, Andreas Winter
备注:
7 pages revtex4, v2 has corrections in response to referee's comments. Accepted in Phys Rev Lett. Acceptance revoked due to a disagreement over our use of a Creative Commons license. See http://www.damtp.cam.ac.uk/user/jono/item/toc.html
Recently, it was discovered that the `quantum partial information' needed to merge one party's state with another party's state is given by the conditional entropy, which can be negative [Horodecki, Oppenheim, and Winter, Nature 436, 673 (2005)]. Here we find a classical analogue of this, based on a long known relationship between entanglement and shared private correlations: namely, we consider a private distribution held between two parties, and correlated to a reference system, and ask how much secret communication is needed for one party to send her distribution to the other. We give optimal protocols for this task, and find that private information can be negative - the sender's distribution can be transferred and the potential to send future distributions in secret is gained through the distillation of a secret key. An analogue of `quantum state exchange' is also discussed and one finds cases where exchanging a distribution costs less than for one party to send it. The results give new classical protocols, and also clarify the various relationships between entanglement and privacy.
A system of interacting classical oscillators is discussed, similar to a quantum mechanical system of a discrete energy level, interacting with the energy quasi-continuum of states considered Fano. The limit of a continuous spectrum is analyzed together with the possible connection of the problem under study with the generation of coherent phonons.
In this paper we consider the use of certain classical analogues to quantum tunneling behavior to improve the performance of simulated annealing on a discrete spin system of the general Ising form. Specifically, we consider the use of multiple simultaneous spin flips at each annealing step as an analogue to quantum spin coherence as well as modifications of the Boltzmann acceptance probability to mimic quantum tunneling. We find that the use of multiple spin flips can indeed be advantageous under certain annealing schedules, but only for long anneal times.