# Implementing a distance-based classifier with a quantum interference circuit

## TL;DR

This paper presents a simple quantum interference circuit for distance-based classification, demonstrating effective pattern recognition with minimal quantum resources on IBM Quantum hardware.

## Contribution

It introduces a novel, resource-efficient quantum classifier using interference circuits, contrasting with complex classical models on large quantum computers.

## Key findings

- Classifies benchmark tasks effectively with simple quantum circuits
- Demonstrates feasibility on IBM Quantum hardware
- Shows promising performance with numerical simulations

## Abstract

Lately, much attention has been given to quantum algorithms that solve pattern recognition tasks in machine learning. Many of these quantum machine learning algorithms try to implement classical models on large-scale universal quantum computers that have access to non-trivial subroutines such as Hamiltonian simulation, amplitude amplification and phase estimation. We approach the problem from the opposite direction and analyse a distance-based classifier that is realised by a simple quantum interference circuit. After state preparation, the circuit only consists of a Hadamard gate as well as two single-qubit measurements, and computes the distance between data points in quantum parallel. We demonstrate the proof-of-principle using the IBM Quantum Experience and analyse the performance of the classifier with numerical simulations, showing that it classifies surprisingly well for simple benchmark tasks.