# Questions tagged [master-equation]

The tag has no usage guidance.

14 questions
Filter by
Sorted by
Tagged with
1 vote
39 views

### Density matrix and State vector give different result in mesolve in QuTiP

qutip mesolve gives me different population evolve depending on that initial state is state vector or density matrix. And, in some situation, it gives me negative population. It doesn't make sense... ...
• 11
63 views

### QuTip for time-dependent driven harmonic oscillator without damping?

Is it possible to find the dynamics of a time-dependent system? For example, a harmonic oscillator that is driven by an external time-dependent drive? Does QuTip have a way to solve the Schrodinger ...
107 views

In QuTiP, it is possible to solve Lindblad master equations describing the time evolution of an open quantum system $\rho$: \dot{\rho}(t)=-\frac{i}{\hbar}[H(t), \rho(t)]+\sum_n \frac{1}{2}\left[2 ... 1 vote 1 answer 39 views ### Can superoperators work in Monte Carlo solver in QuTip? The Monte Carlo solver works with kets instead of density matrices. And it doesn't allow a superoperator (which acts on density matrices or superkets) as a collapse operator. Since my master equation ... • 153 2 votes 1 answer 97 views ### Notation for Lindblad operators I was reading the paper Quantum computation, quantum state engineering, and quantum phase transitions driven by dissipation . The claim is that universal quantum computation can be achieved using the ... • 2,339 4 votes 0 answers 50 views ### Distribution of density operators under Stochastic Master Equation Stochastic master equations (SME) are used in studies of open quantum systems. The general form of an SME is: \begin{align} \tag{1} d\tilde{\sigma}(t) = - i [H, \tilde{\sigma}(t) ]dt + \frac{1}{2}\... • 2,339 2 votes 1 answer 253 views ### Nielsen and Chuang: Solving equation of motion for amplitude damping I would like to know how to obtain a solution to the equation of motion given in Section 8.4.1 Master equations of Nielsen and Chuang, 10th edition. The equation of motion that allows getting the ... • 2,339 1 vote 0 answers 128 views ### Qutip: Mesolve gives different and weird results with different fock state numbers I have been trying to simulate the average number of particles at 3 sites of coupled harmonic oscillators. I have used the code from the below tutorial: https://notebook.community/ajgpitch/qutip-... 1 vote 0 answers 189 views ### QuTiP VS RK45: Which one gives the correct results for time-dependent systems? I am writing a code for a quantum thermal machine which includes both coherent and dissipative time evolutions in its different stages of operation. However, evolving the system with "mesolve&... • 111 3 votes 1 answer 88 views ### Show that if the Lindblad satisfy \sum_\mu L_\mu L_\mu^\dagger=\sum_\mu L_\mu^\dagger L_\mu then \rho\propto I is a fixed point of an evolution How can we show that the Lindblad condition:\sum_{\mu}L_{\mu} L_{\mu}^{\dagger} = \sum_{\mu} L_{\mu}^{\dagger}L_{\mu},\tag{1}$$implies that \rho \propto I is the fixed point of the evolution ... 2 votes 1 answer 108 views ### How to solve non-"cross-damping off" Linblad equation in QuTiP? As I understand from the official QuTiP guidlines, it is only capable of solving "cross-damping off" Master Equation in form: \dot{\rho(t)} = -\dfrac{i}{\hbar}[H(t),\rho(t)] + \sum\limits_n\... • 21 5 votes 1 answer 163 views ### What does "generator" mean in the master equation? I seem to read a lot of times that some materials called this \mathcal{L} in the equation(Lindblad master equation) below as the generator:$$ \mathcal{L} \rho=-i[H, \rho]+\sum_{\alpha}\left(V_{\...
• 613
I have a three composite system of the form $H_{\text{tot}}=H_{ab}\otimes H_c$ where the system $C$ is behaving as the dissipator or the environment (I can model it as a thermal bath). And it is ...