Modification and realization of Brüschweiler’s search

The Brüschweiler quantum search [Phys. Rev. Lett. 85, 4815 (2000)] offers an exponential speedup over the corresponding classical search. In the Brüschweiler search, the data bits and measurement bit (the ancillary bit) are different bits. We propose a modified method, in which no ancillary bit is needed to reach exponential speedup. The modified Brüschweiler search can be easier to design and realize. We also demonstrate the modified search in a three-qubit molecular system using nuclear magnetic resonance.