Today I read a paper titled “Note on Needle in a Haystack”
The abstract is:
Introduced below is a quantum database method, not only for retrieval but also for creation.
It uses a particular structure of true’s and false’s in a state vector of n qubits, permitting up to 2**2**n words, vastly more than for classical bits.
Several copies are produced so that later they can be destructively observed and a word determined with high probability.
Grover’s algorithm is proposed below to read out, nondestructively the unknown contents of a given stored state vector using only one state vector.