From the course: Quantum Computing Fundamentals

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Phase shift gates

Phase shift gates

From the course: Quantum Computing Fundamentals

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Phase shift gates

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- So far, we've taken our qubits to one of four quantum states. Our two computational basis states, zero and one, and we've used the Hadamard gate to transform those into superposition states at both sides of the x-axis. But there's a lot more surface area on this Bloch sphere, so how do we move our qubits into some of those other possible superpositions? - Well, one way to play with the quantum state is to apply a phase shift, rotating a qubit around the z-axis. We've already seen one type of phase shift gate, the Pauli Z gate, which rotates our qubit 180 degrees around the z-axis. That can transition our qubit from the positive x state to the negative x state. And if we apply it a second time, that brings us back to the positive x. - Both of those rotations passed over the y-axis so how can we transition to a state there? - For that, we'll use a new gate called the S gate, which applies a phase shift of pi over two…

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