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SS2026/Quantum Computing/4. Observing and measuring/Observing probabilistic and measuring quantum systems.md

@@ -6,3 +6,18 @@ Because after observing all possibilities collapse to one.
 
 Example:
 
+![[Pasted image 20260729093827.png]]
+![[Pasted image 20260729093834.png]]
+
+The point here is that the result doesn't change if we observe at any point in the process!
+
+##  Measuring a quantum system
+
+Given a quantum state $\psi \in \mathbb{C}^n$ we will
+![[Pasted image 20260729094624.png]]
+
+BUT!!!
+Measuring a quantum state CHANGES THE SYSTEM!!!
+
+![[Pasted image 20260729094710.png]]
+![[Pasted image 20260729094718.png]]