It is known that a macroscopic quantum superposition (MQS), when it is exposed to an environment, decoheres at a rate scaling with the separation of its component states in phase space. This is more or less consistent with the well-known proposition that a more macroscopic quantum state is reduced more quickly to a classical state in general. Effects of initial mixedness, however, on the subsequent decoherence of MQSs have been less known. We study the evolution of a highly mixed MQS interacting with an environment and compare it with that of a pure MQS having the same size as the central distance between its component states. Although the decoherence develops more rapidly for the mixed MQS in short times, its rate can be significantly suppressed after a certain time and becomes smaller than the decoherence rate of its corresponding pure MQS. In an optics experiment to generate a MQS, our result has the practical implication that nonclassicality of a MQS can still be observable in moderate times, even though a large amount of noise is added to the initial state.
© 2008 Optical Society of America
Original Manuscript: February 5, 2008
Revised Manuscript: March 30, 2008
Manuscript Accepted: April 16, 2008
Published: May 23, 2008
Hyunseok Jeong, Jinhyoung Lee, and Hyunchul Nha, "Decoherence of highly mixed macroscopic quantum superpositions," J. Opt. Soc. Am. B 25, 1025-1030 (2008)