Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [no-cloning-theorem]

In physics, the no-cloning theorem states that it is impossible to create an identical copy of an arbitrary unknown quantum state. (Wikipedia)

3
votes
0answers
42 views

What role do Hecke operators and ideal classes perform in “Quantum Money from Modular Forms?”

Cross-posted on MO The original ideas from the 70's/80's - that begat the [BB84] quantum key distribution - concerned quantum money that is unforgeable by virtue of the no-cloning theorem. A ...
1
vote
1answer
34 views

What does it mean that copying a state is impossible but creating a copy of by entangling is possible?

Why is it that copying an unknown qubit is impossible but creating a copy of the standard computational basis is possible by entangling it to existing qubits? And why one is possible and the other isn'...
1
vote
3answers
194 views

How to prove teleportation does not violate no-cloning theorem?

For a given teleportation process as depicted in the figure, how one can say that teleporting the qubit state $|q\rangle$ has not cloned at the end of Bob's measurement?
1
vote
1answer
65 views

Proof of no-cloning

I was reading a proof of No-cloning theorem, there are a couple of steps that are not clear to me, but the book does not give explanation for them. So here it is: Theorem: It is impossible to create ...
7
votes
3answers
340 views

What do they mean by “qubit can't be copied”?

What does it mean by ''qubit can't be copied'' ? In a note, it is saying that: Copying a qubit means $$U|\psi\rangle_A|0\rangle_B=|\psi\rangle_A|\psi\rangle_B$$ i.e; applying a unitary ...
6
votes
1answer
335 views

No-cloning theorem and distinguishing between two non-orthogonal quantum states

I'm currently reading Quantum Computation and Quantum Information and I'm not sure if I correctly understand this exercise (on page 57) : Exercise 1.2: Explain how a device which, upon input of one ...