Optimized methods for inserting and deleting records and data retrieving in quantum database

Abstract

In this paper, we show how a quantum CNOT-based relational database is built, then we show how to query its quantum tables using the most used SQL-like queries, e.g. INSERT, UPDATE, DELETE and SELECT. We specify each time the evolution of the probability amplitude corresponding to the records before and after the query has been executed and we propose corresponding circuits implementation.

From Digital to Quantum Epidemiology: The Quantum Data Lake concept for Big Data related to viral infectious diseases

“…Grover's algorithm searches through the database using parallelism, it acts on the register in a superposition of states of each element at one time. Grover's algorithm applies to the Hadamard gate (Hadamard transformation) which performs rotation of every qubit and is setting up an equal superposition of each of the database elements (Younes 2007;Gueddana et al 2010;Hamouda et al 2016). On the whole Grover's algorithm has four stages: initialization (Hadamard transformation creates an equal superposition of all states), quantum oracle (oracle O marks the solutions by ipping the sign of that state's amplitude), ampli cation (increasing the amplitude of the marked state), and measurement (Bender et al 1999).…”

“…UPDATE statement (updating a set of records) can be done using CNOT gate by permutation with unitary operator U or replacing the qubit states (Younes 2007;Hamouda et al 2016). INSERT statement (inserting one or more records into the database) can be implemented using a controlled Hadamard gate (Younes 2007;Gueddana et al 2010;Hamouda et al 2016). DELETE statement (deleting records from the database) can be made by Grover operator G (Gueddana et al 2010;Hamouda et al 2016).…”

“…INSERT statement (inserting one or more records into the database) can be implemented using a controlled Hadamard gate (Younes 2007;Gueddana et al 2010;Hamouda et al 2016). DELETE statement (deleting records from the database) can be made by Grover operator G (Gueddana et al 2010;Hamouda et al 2016). BACKUP (backing up a required portion of a database) and RESTORE (restoring a backup) require key qubit, oracle, and partial diffusion operator Dp (Younes 2007).…”

“…;Younes 2007;Younes et al 2008;Gueddana et al 2010;Hamouda et al 2016;Figgatt et al 2017;Luongo 2022) and sources: Microsoft (https://docs.microsoft.com/en-us/azure/quantum/); IBM (https://quantumcomputing.ibm.com/composer/docs/iqx/); Qiskit (https://qiskit.org/textbook/chstates/introduction.html/). The most important property of a quantum database is the capability to be in more than one state at the same time.…”