initial implementation of quantum state as list of amplitudes

quantum.py

@@ -0,0 +1,10 @@
+class Psi:
+    def __init__(self, n_qubits):
+        """
+        set up a quantum system with the given number of qubits
+        initialized to the "zero" qubit.
+        """
+        self.n_qubits = n_qubits
+        # in this classical simulation, we use 2^n_qubits complex numbers
+        self.amplitudes = [0] * (1 << n_qubits)
+        self.amplitudes[0] = 1