Contents
How are qubits encoded?
Qubit to be encoded is marked by red dot. Qubits in green and blue regions are initialised in states |0〉 and |+〉, respectively.
What is a cubit in quantum computing?
A qubit (or quantum bit) is the quantum mechanical analogue of a classical bit. In classical computing the information is encoded in bits, where each bit can have the value zero or one.
How do you check if a qubit is entangled?
A two-qubit state |ψ⟩∈C4 is an entangled state if and only if there not exist two one-qubit states |a⟩=α|0⟩+β|1⟩∈C2 and |b⟩=γ|0⟩+λ|1⟩∈C2 such that |a⟩⊗|b⟩=|ψ⟩, where ⊗ denotes the tensor product and α,β,γ,λ∈C.
How many basis states does a single qubit have?
A single-qubit has two computational basis states. In the z-basis these are \\vert 1 angle ∣1⟩. A two-qubit system has 4 computational basis states denoted as
What happens when you measure only a subset of qubits?
Where you have to be a little more careful is if you’re measuring only a subset of qubits. Then, the probability is still p x = ⟨ ψ | P x | ψ ⟩, but the output state is P x | ψ ⟩ / p x, which could still be a superposition of multiple basis states (all those for which the measured qubits correspond to x ).
How to create a circuit with multiple qubits?
Create a quantum circuit that produces the Bell state: 1 √2 (|01⟩+|10⟩) 1 2 ( | 01 ⟩ + | 10 ⟩) . Use the statevector simulator to verify your result. The circuit you created in question 1 transforms the state |00⟩ | 00 ⟩ to 1 √2 (|01⟩+|10⟩) 1 2 ( | 01 ⟩ + | 10 ⟩), calculate the unitary of this circuit using Qiskit’s simulator.
How to calculate single qubit unitary in Qiskit?
We can see Qiskit has performed the tensor product: X⊗I = [0 I I 0] = ⎡ ⎢ ⎢ ⎢⎣0 0 1 0 0 0 0 1 1 0 0 0 0 1 0 0⎤ ⎥ ⎥ ⎥⎦ X ⊗ I = [ 0 I I 0] = [ 0 0 1 0 0 0 0 1 1 0 0 0 0 1 0 0] Calculate the single qubit unitary ( U U) created by the sequence of gates: U = XZH U = X Z H. Use Qiskit’s unitary simulator to check your results.