# getPolarisation

returns the polarisation of a subsystem

## Contents

- Syntax
- Description
- Example: Qbit in a cavity

## Syntax

- getPolarisation(name)

## Description

getPolarisation(name) returns a vector containing the polarisation of the subystem name over time. If the subsystem is a Nlevel system the dipole matrix is used to calculate this value.

If the subystem is a quantum oscillator the lowering and raising operators are used

## Example: Qbit in a cavity

    clear; close all;
    s = System;
    a = Nlevel(1);
    s.addEntity(a,'qbit');
    s.addEntity(Qoscillator(3,1),'cavity');
    s.addCoupling('qbit','cavity',0.05);
    s.addDissipation('qbit',200);
    s.addExternalField(Gausspulse(0.04,100,30,1),'qbit');
    s.setTmax(400);
    s.setTimestep(0.1);
    s.simulate;

    h =plot(s.time,s.getPolarisation('qbit'));
    xlabel('Time in au');
    ylabel('Energy');
    legend('qbit');