Fourier Transform Quantum State Tomography

TL;DR

This paper introduces a novel quantum state tomography method for photonic multi-qubit states using a single rotating wave plate and Fourier analysis, simplifying the process and scaling linearly with qubit number.

Contribution

It presents a new technique that reduces experimental complexity by using a single rotating wave plate and Fourier transform for quantum state reconstruction.

Findings

Method successfully reconstructs multi-qubit states.

Experimental complexity scales linearly with qubit number.

Uses Fourier coefficients to relate signals to quantum state parameters.

Abstract

We propose a technique for performing quantum state tomography of photonic polarization-encoded multi-qubit states. Our method uses a single rotating wave plate, a polarizing beam splitter and two photon-counting detectors per photon mode. As the wave plate rotates, the photon counters measure a pseudo-continuous signal which is then Fourier transformed. The density matrix of the state is reconstructed using the relationship between the Fourier coefficients of the signal and the Stokes' parameters that represent the state. The experimental complexity, i.e. different wave plate rotation frequencies, scales linearly with the number of qubits.