addDecoherence

Implements a pure dephasing process via the Lindblad master equation in a specified subsystem

Contents

Syntax

Description

Detailed Description and Examples

Decoherence between different levels within one subsystem is realised by the Lindblad master equation. The Liouville von Neumann Equation is expanded by an additional term, resulting in:

$$\rho' = [H,\rho] +  \sum\limits_i \frac{1}{T_i} (R_i \rho R_i^{\dagger}  - \frac{1}{2} R_i^{\dagger} R_i \rho - \frac{1}{2} \rho R_i^{\dagger}  R_i)$$

where $R_i$ denotes the jumping Operator. If $R_i$ takes on a specific form, the Lindblad equation models a pure loss of phase information between the different levels of a subsystem. This loss progresses with a lifetime of $T_i$.

Example of a qbit coupled to a lightfield.

s = System;
s.addEntity(Nlevel(1),'qbit');
s.addEntity(Qoscillator(3,1),'lightfield');
s.addCoupling('qbit','lightfield',0.05);
s.addDecoherence('qbit',40);
s.addExternalField(Gausspulse(0.04,50,15,1),'qbit');
s.setTimestep(0.1);
s.simulate();

%plot the gained data
plot(s.time, s.getEnergy('qbit'));
hold on;
plot(s.time, s.getEnergy('lightfield'));
plot(s.time, s.getOpValue(s.H));
s.plotEfields;
xlabel('Time');
ylabel('Energy');
title('Qbit Coupled to a Lightfield');
thelegend = legend('qbit' ,'lightfield','total','laserpuls','Location','northeast');
set(thelegend,'FontSize',16);