Title :
Quasi-order of clocks and their synchronism and quantum bounds for copying timing information
Author :
Janzing, Dominik ; Beth, Thomas
Author_Institution :
Comput. Sci. Dept., Univ. of Karlsruhe, Germany
fDate :
1/1/2003 12:00:00 AM
Abstract :
The statistical state of any (classical or quantum) system with nontrivial time evolution can be interpreted as the pointer of a clock. The quality of such a clock is given by the statistical distinguishability of its states at different times. If a clock is used as a resource for producing another one the latter can at most have the quality of the resource. We show that this principle, formalized by a quasi-order, implies constraints on many physical processes. Similarly, the degree to which two (quantum or classical) clocks are synchronized can be formalized by a quasi-order of synchronism. Copying timing information is restricted by quantum no-cloning and no-broadcasting theorems since classical clocks can only exist in the limit of infinite energy. We show this quantitatively by comparing the Fisher timing information of two output systems to the input´s timing information. For classical signal processing in the quantum regime our results imply that a signal looses its localization in time if it is amplified and distributed to many devices.
Keywords :
clocks; information theory; optical information processing; quantum communication; signal processing; synchronisation; timing; Fisher timing information; classical clocks; input timing information; no-broadcasting theorem; nontrivial time evolution; output systems; quantum bounds; quantum clocks; quantum no-cloning theorem; quantum system; quasi-order; quasi-order of synchronism; signal processing; statistical state; timing information copying; Application software; Circuits; Clocks; Cloning; Context; Pulse amplifiers; Quantum mechanics; Signal processing; Synchronization; Timing;
Journal_Title :
Information Theory, IEEE Transactions on
DOI :
10.1109/TIT.2002.806162