A convenient method to prepare the effective pure state in a quantum ensemble

TL;DR

This paper introduces a simple, systematic method for preparing the effective pure state in quantum ensembles using temporal averaging, suitable for implementation on NMR quantum computers.

Contribution

It presents a unified quantum circuit design for efficiently preparing the effective pure state in multi-qubit systems, decomposed into basic quantum gates.

Findings

The method simplifies the preparation process for effective pure states.

The quantum circuit is explicitly decomposed into one-qubit and two-qubit gates.

The approach is practical for implementation on NMR quantum computers.

Abstract

A simple method is proposed to prepare conveniently the effective pure state |00...0><0...00| with any number of qubits in a quantum ensemble. The preparation is based on the temporal averaging (Knill, Chuang, and Laflamme, Phys.Rev.A 57, 3348(1998)). The quantum circuit to prepare the effective pure state is designed in a unified and systematical form and is explicitly decomposed completely into a product of a series of one-qubit quantum gates and the two-qubit diagonal quantum gates. The preparation could be programmed and implemented conveniently on an NMR quantum computer.