Reduced density matrix

[HAMIDEH GHARIB MASOULEH]

Hi, 

I'm new to SymPy, and I'm in the middle of a calculation where I use the groundstates of a Heisenberg model hamiltonian to write my density matrix. I found the function Density() which rewrites the matrix as a superposition of qubits, but then I am stuck.

Is there any function to calculate the reduced density matrix?

Or any function for partial trace?

Or any way to decompose, let's say, |000> to |0>|0>|0>?

Any help is appreciated

Hamideh

[Oscar]

Hi Hamideh,

Most SymPy users do not use the quantum module and probably don't know anything about quantum mechanics. Your question probably does not have enough detail for anyone to be able to answer it. It would be better to be more explicit:

1. What system are you considering?

2. What would the "reduced density matrix" look like?

3. How would you calculate it by hand?

4. What code have you already tried?

Oscar

[Chris Smith]

A search of SymPy *.py files for "reduced density" gives a hit in method `_reduced_density` which is called from the private method `Qubit._eval_trace` which is called by `Trace(qubit).doit()`. Does that get you any closer to a solution?

Chris

/c