Loading Classical Data into a Quantum Computer

TL;DR

This paper introduces efficient quantum circuits for loading classical data into quantum states with logarithmic qubit and gate depth, discusses limitations, and explores improvements through classical compression techniques.

Contribution

It presents a family of quantum circuits that load classical data efficiently into quantum states with logarithmic resource requirements.

Findings

Quantum data loading circuits have logarithmic depth and qubit count.

Simulations verify the behavior of the proposed circuits.

Discussion of limitations and potential improvements in data loading methods.

Abstract

This document describes a family of quantum circuits which load classical data into a quantum state. When loading $N$ classical bits, the result quantum state is of order $\log_2(N)$ qubits. Furthermore the gate depth of the data loading circuit is of order $\log_2(N)$. Limitations to the efficiency of the data loading process such as the Holevo bound are discussed. Methods to improve the efficiency of the data loading procedure such as combining classical compression techniques with quantum decompression circuitry, are also discussed. Simulations using the Quipper language were conducted to verify the circuits behavior.