5 Analyze quantum operations
This chapter covers
- Getting information about quantum operations
- Finding the matrix that describes the given quantum gate
- Estimating the eigenvalues of quantum gates
- Using Q# and Qiskit to analyze operations
In chapter 4, we learned to use measurements to analyze quantum states in different situations. In this chapter, we’ll consider several new types of tasks that involve analyzing unitary transformations. Of course, these tasks will build on top of our learnings from the earlier chapters, since you can only learn things about operations by preparing certain states, applying these operations to those states, and then extracting information about the resulting states using measurements.
Quantum states are the most common kind of input data for quantum algorithms, but they are not the only ones. While typically unitary operations appear in algorithms as their building blocks, they can also be used as input data. In fact, algorithms that take a unitary as an input and aim to learn something about it can be just as important as the ones that learn something about a quantum state.