Preserving Quantum States : A Super-Zeno Effect

Dhar, Deepak; Grover, Lov K.; Roy, Shasanka M.

Preserving Quantum States : A Super-Zeno Effect

Authors

Dhar, Deepak

Grover, Lov K.

Roy, Shasanka M.

Description

We construct an algorithm for suppressing the transitions of a quantum mechanical system, initially prepared in a subspace P of the full Hilbert space of the system, to outside this subspace by subjecting it to a sequence of unequally spaced short-duration pulses. Each pulse multiplies the amplitude of the vectors in the subspace by -1. The number of pulses required by the algorithm to limit the leakage probability to $ε$ in time $T$ increases as $T \exp[ \sqrt{\log(T^2/ε)}]$, compared to $T^2 ε^{-1}$ in the standard quantum Zeno effect.
4 pages, 1 figure, rewritten for clarity