Degradation of a quantum directional reference frame as a random walk
Stephen D. Bartlett, Terry Rudolph, Barry C. Sanders, Peter S. Turner
备注：
5 pages, no figures. Comments are welcome. v2: several changes to clarify the key results. v3: journal reference added, acknowledgements and references updated
We investigate if the degradation of a quantum directional reference frame through repeated use can be modeled as a classical direction undergoing a random walk on a sphere. We demonstrate that the behaviour of the fidelity for a degrading quantum directional reference frame, defined as the average probability of correctly determining the orientation of a test system, can be fit precisely using such a model. Physically, the mechanism for the random walk is the uncontrollable back-action on the reference frame due to its use in a measurement of the direction of another system. However, we find that the magnitude of the step size of this random walk is not given by our classical model and must be determined from the full quantum description.
From Qubits to Rhythm: Exploring Quantum Random Walks in Rhythmspaces
Interdisciplinary Centre for Computer Music Research, University of Plymouth（跨学科计算机音乐研究中心，普利茅斯大学）；Centre for Quantum Technologies and Applications, Deutsches Elektronen-Synchrotron DESY（量子技术与应用中心，德意志电子同步辐射研究中心）；Universidad Icesi（伊赛尼大学）；Music Technology Group, Pompeu Fabra University（音乐技术小组，庞培法布拉大学）
