Can quantum state tomography break bb84?
I am currently reading through this paper and read some of the wikipedia pages on weak measurement and quantum tomography and I am curious if weak measurement could be used to break BB84 quantum key...
View ArticleWhat is the probability of detecting Eve's tampering, in BB84?
Alice sends a 0 in computational basisI understand that theres a $\frac12$ probability that eve guesses the basis wrong, and can go with Hadamard. So it's $\frac12$ chance Eve will pick computational...
View ArticleCounting channel uses of the lossy bosonic channel or definition of channel uses
The PLOB-bound ("Fundamental Limits of Repeaterless Quantum Communications") gives an asymptotic upper bound on the secret-key rate per used lossy bosonic channel.However, I'm not sure how to count the...
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Show when $a_k$ and $b_k$ are correlated when measuring in different bases,...
I'm trying to answer the following question about the BB84 protocol from Nielsen and Chuang's Introduction to Quantum Information.As I understand it, the string $b$ is determining whether we are...
View ArticleHow are eavesdroppers detected when using BB84 in the presence of noise?
I would like to expand upon this question: What is the probability of detecting Eve's tampering, in BB84?Let's say that when the receiver (colloquially referred to as Bob) receives a qubit and measures...
View ArticleDoubt in Simple proof of Security of the BB84 QKD
I am not able to understand an argument from Simple proof of Security of the BB84 QKD; I need your help. In page 2 it is mentioned that "Alice can measure her half of the encoded EPR pairs before or...
View ArticleDoubt in CSS error correction step
At the end of page 3 in Simple proof of security of the BB84 QKD, the following equation (equation 4) is given :$$\begin{array}{r}\frac{1}{2^{n}\left|C_{2}\right|} \sum_{z}\left[\sum_{w_{1}, w_{2} \in...
View ArticleShow That an Intercept and Resend Attack on all qubits reduces mutual...
Exercise 5.3.3 With no eavesdropping the mutual information $H(A:B)$ between the substring of $\mathcal R$ held by Alice and $\mathcal R'$ held by Bob is $1$ bit. Show that if Eve is performing an...
View ArticleComprehension questions on quantum cryptography especially BB84
I have recently read a lot about the BB84 protocol, I have used three primary sources, the original work, a QK book, and a diploma thesis.My questions refer to the photons sent by Alice, the base of...
View ArticleBB84 Protocol doubt
I was studying BB84 protocol from lecture notes by John Watrous. I had some doubts which i thought of asking. Here is the protocol.Alice prepares strings $x=(01110100)$ and $y=(11010001)$. based on the...
View ArticleHeisenberg Uncertainty Principle for BB84 Protocol using Paulis Spin Matrices
I am doing a term project on the BB84 Protocol and it makes use of the Heisenberg Uncertainty Principle. I think I understand the principle in theory. If we have two non-commuting observables, then we...
View ArticleEavesdropping in case of the BB84 Protocol
I try to understand eavesdropping in case of the BB84 protocol (lets assume we have single photons, no noise etc.). Alice and Bob generate a classical random bit $a_i'$ and $b_i'$. Alice generates an...
View ArticleWhere can I find a detailled exposition of the Information theoretic part of...
I understand the general idea of information reconciliation and advantage distillation, but I can't find any exposition of the algorithm used, unlike the quantum part of the protocol which is well...
View ArticleFormal measurement of the probability of an outcome of a Qubit in the...
I am fairly new to Quantum Computing and have a question which might be trivial for all of you, but I am really struggling with it.From Quantum Computation and Quantum Information I have learned, that...
View ArticleIs there a BB84 "man"-in-the-middle attack forcing the same keys on Alice and...
Consider the following scenario:Alice and Bob run BB84 to each other.Eavesdropper Eve is present in the middle. Here we assume that she has access to all channels: the quantum channel, in the classical...
View ArticleProbability of error in BB84 if Eve is using Breidbart's basis
I'm taking a course on quantum cryptography and I have a homework to calculate probability of error in BB84.The task says to assume that Eve uses the Breidbart basis with eigenvectors $$|φ_0⟩ =...
View ArticleWhy is applying a Hadamard transform useful in the entanglement-based version...
In Simple Proof of Security of the BB84 Quantum Key Distribution Protocol, the description of the entanglement-based version of BB84 indicates that Alice and Bob perform a Hadamard transform on their...
View ArticleWhat do we mean by family of CSS codes?
In proving the security of BB84 in Nielsen and Chuang (10th anniversary edition - Section 12.6.5), they argue that a codeword in $\text{CSS}(C_1, C_2)$ is represented by$$\frac{1}{\sqrt{|C_2|}}...
View ArticleDerivations of Equations (12.205 - 12.207) in Nielsen Chuang
While proving the security of the BB84 protocol, Nielsen and Chuang demonstrate that it is possible to reduce the CSS protocol to the secure BB84 protocol without requiring Alice to reveal the value of...
View ArticleHow does a rectilinear filter used for QKD-BB84 detect both horizontal and...
When using the BB84 algorithm for QKD, you arbitrarily choose which of two filters (bases) to use when detecting a photon: rectilinear or diagonal. If you choose rectilinear, you can detect...
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