1

I was trying to write a program that performs various operation on qubits with qiskit, and one of such operations is to perform the following:

"Qubit observation is simulated, modeling the wave function collapse as follows:

 r <= |a^2|, x = 0 (basisstate |0>
 r > |a^2|, x = 1 (basisstate |1>

where r is a random number in the range [0,1), and a is the qubit that should be observed."

I noticed that the measure() method in qiskit will collapse the quantum system - which is something that I want to prevent. How can I project quantum vector (or qubit) into binary vector in qiskit (without collapsing the quantum system)? Or is there a quantum programming SDK that allows me to do so? Thanks in advance.

Update: 24/9/2019 Mariia Mykhailova, thank you for the info. That's exactly what I needed! For others, the Qiskit api has been updated, use result.data() instead of result.get_data(circuit).

Ming
  • 55
  • 4

1 Answers1

1

If you are modeling a quantum computing system in accordance to the postulates of quantum mechanics, observing a qubit without collapsing the system state is impossible. This is one of the fundamental principles of quantum systems, and you can not work around it without sacrificing the realism of your model.

That being said, you can model such an observation by accessing the wavefunction directly and calculating the probabilities of the qubit collapsing to one or another basis state manually, without actually performing a measurement. It's just not something you'll be able to do on an actual quantum device!

I'm not closely familiar with the tools Qiskit has for accessing wavefunction, this link seems to provide some starting points.

Mariia Mykhailova
  • 1,987
  • 1
  • 9
  • 18