3 votes
Accepted

Misunderstanding of QKD BB84 protocol

This looks like a mistake in the image to me (or a reflection of Alice and Bob using faulty procedures to convert bits to qubits and vice versa, which seems much less likely). Under ideal conditions, ...
Mariia Mykhailova's user avatar
3 votes
Accepted

Doubt in understanding the use of Uhlmann's Theorem in BB84 security proof

The relation in 1. is essentially a statement of Uhlmann's theorem. Ulmann's theorem states: Given two density matrices $\rho$ and $\sigma$, we have that the fidelity $F(\rho, \sigma)$ is given by $$F(...
xzkxyz's user avatar
  • 396
3 votes
Accepted

How to correctly describe state preparation?

For applications such as BB84, it really doesn't matter which of the two descriptions you use, because from everybody's perspective apart from Alice, they do not have access to the first system, and ...
DaftWullie's user avatar
  • 57.5k
2 votes

Is there any programming project that implements one QKD protocol or demonstrates it?

Yes, there are such projects! The codes are on GitHub, alongside an explanation of the protocols, which makes understanding the protocols like a walk in the park! Here's the link: https://github.com/...
Milap's user avatar
  • 21
1 vote

How can entanglement deal with individual attack in QKD?

This is indeed a problem that can't be ignored when stepping from theory to implementation. Physical realisations for photon scattering should provide a rate as close as possible to exact single ...
Daniele Cuomo's user avatar
1 vote
Accepted

Why is applying a Hadamard transform useful in the entanglement-based version of BB84

Eve can wait until Alice makes the announcement, but the announcement only happens once Bob has received the qubit, so in the simplest attack (where Eve just measures the qubit and then sends it on to ...
GotCarter's user avatar
  • 401
1 vote

What authentication protocol to use for BB84 and other QKD protocols?

In classical cryptography, the Diffie-Hellman key exchange is also susceptible to a man-in-the-middle attack, and to get around that, we use a digital signature algorithm, like RSA or ECDSA. You can ...
amihart's user avatar
  • 41

Only top scored, non community-wiki answers of a minimum length are eligible