Bad Qubits — Learn Quantum by Doing

Multiple choice

The fermionic anticommutation relations include {a_p-dagger, a_q-dagger} = 0. Setting p = q gives a_p-dagger a_p-dagger = 0. Which physical principle does this encode?

The Born–Oppenheimer approximation
The Heisenberg uncertainty principle
Conservation of total spin
The Pauli exclusion principle — you cannot create two electrons in the same spin-orbital