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Coherence of Quantum Superpositions Through Coupling to Engineered Reservoirs



C J. Myatt, B E. King, Q A. Turchette, C A. Sackett, D Kielpinski, Wayne M. Itano, C Monroe, David J. Wineland


The theory of quantum mechanics applies to closed systems. In such ideal situations, a single atom can, for example, exist simultaneously in a superposition of two different spatial locations. In contrast, real systems always interact with their environment, with the consequence that macroscopic quantum superpositions (as illustrated by the Schrodinger's cat' thought-experiment) are not observed. Moreover, macroscopic superpositions decay so quickly that even the dynamics of decoherence cannot be observed. However, mesoscopic systems offer the possibility of observing the decoherence of such quantum superpositions. Here we present measurements of the decoherence of superposed motional states of a single trapped atom. Decoherence is induced by coupling the atom to engineered reservoirs, in which the coupling and state of the environment are controllable. We perform three experiments, finding that the decoherence rate scales with the square of a quantity dcescribing the amplitude of the superposition state.


decoherence, entangled states, laser cooling, quantum information, quantum measurement, trapped atoms


Myatt, C. , King, B. , Turchette, Q. , Sackett, C. , Kielpinski, D. , Itano, W. , Monroe, C. and Wineland, D. (2002), Coherence of Quantum Superpositions Through Coupling to Engineered Reservoirs, Nature (Accessed April 20, 2024)
Created December 31, 2001, Updated October 12, 2021