Note on Needle in a Haystack

TL;DR

This paper presents a quantum database method that leverages superposition of true and false states in qubits for efficient retrieval and creation of large data sets, utilizing Grover's algorithm for nondestructive readout.

Contribution

It introduces a novel quantum database structure and a method for nondestructive data retrieval using Grover's algorithm, enabling larger data storage than classical systems.

Findings

Allows storage of up to 2^{2n} words in n qubits

Enables nondestructive retrieval of stored data

Uses multiple copies for high-probability word determination

Abstract

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.