Quantum Computing Basics Flashcards
What are the differences between unitary & measurement gates?
- Unitary: Are reversible, includes all operations on a quantum circuit. It can act on any basis
- Measurement: Are irrevserible, so must be specified statically (cannot depend dynamically on the state). It projects the state onto a basis with probabilities predicted by QM.
What does the following operator do?
What is a CNOT (or C-X) gate?
Given this defined space, what projection operators for the first qubit?
What is the Bell’s basis?
How does superdense coding let you send bits of information with 1 qubit?
How does quantum teleportation work?
What is a Toffoli gate?
A CC-X gate.
How do Toffoli gates create NAND and FANOUT gates, and what implication does this have?
This means that quantum computing can subsume all of classical computing.
Explain what ancilla and garbage qubits are. What is the method for eliminating garbage quibits?
Reconstructing classical algorithms on quantum circuits requires more qubits than the number of classical bits. We require ancilla qubits as a workspace for our calculation, and some garbage qubits than need to be elminated & returned to |0>.
How would you use Toffoli C-U gates to emulate a (C^n)-U gate?
Note: solution is not unique. (C^n)-U gates will work provided you have a function V such that V^2 = U.
How would you turn the following (C^n)-U circuit into a Toffoli gate?
