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We propose a rotationally-invariant quantum key distribution scheme that uses a pair of orthogonal qubit trines, realized as mixed states of three physical qubits. The measurement outcomes do not depend on how Alice and Bob choose their…
We present a flexible quantum-key-distribution-based protocol for quantum private queries. Similar to M. Jakobi et al's protocol [Phys. Rev. A 83, 022301 (2011)], it is loss tolerant, practical and robust against quantum memory attack.…
We obtain strict upper bounds on the bit transmission rate for communication of Classical bit codewords over Quantum channels. Albeit previous arguments in arXiv: 1804.01797 which have demonstrated that lower bounds can be shown to hold for…
An elementary derivation of best eavesdropping strategies for the 4 state BB84 quantum cryptography protocol is presented, for both incoherent and two--qubit coherent attacks. While coherent attacks do not help Eve to obtain more…
We present a new technique for proving the security of quantum key distribution (QKD) protocols. It is based on direct information-theoretic arguments and thus also applies if no equivalent entanglement purification scheme can be found.…
We propose a prepare-and-measure scheme for quantum key distribution with 2-bit quantum codes. The protocol is unconditionally secure under whatever type of intercept-and-resend attack. Given the symmetric and independent errors to the…
Quantum key distribution protocols typically make use of a one-way quantum channel to distribute a shared secret string to two distant users. However, protocols exploiting a two-way quantum channel have been proposed as an alternative route…
We suggest a quantum cryptographic scheme using continuous EPR-like correlations of bright optical beams. For binary key encoding, the continuous information is discretized in a novel way by associating a respective measurement, amplitude…
This paper presents noise analysis for the two-stage and the three-stage quantum cryptographic protocols based on random polarization rotations. The noise model used is that of uniform distribution of error over a certain small range that…
We revisit the practical implementation of high-dimensional quantum key distribution protocol using path entanglement reported in [Phys.Rev.Lett.~127,~110505,~2021]. Here we refine the noise robustness analysis performed there by simulating…
The safety of a quantum key distribution system relies on the fact that any eavesdropping attempt on the quantum channel creates errors in the transmission. For a given error rate, the amount of information that may have leaked to the…
We propose a bipartite quantum key distribution (QKD) protocol based on causal nonseparability: the presence of a resource -- a process matrix -- that does not correspond to any definite causal order between two parties. In our protocol,…
Semiquantum key distribution (SQKD) allows two parties (Alice and Bob) to create a shared secret key, even if one of these parties (say, Alice) is classical. However, most SQKD protocols suffer from severe practical security problems when…
In this comment, we present a frequency-shift attack on "quantum key distribution with classical Bob". This practical attack should also be considered in other two-way quantum key distribution protocols.
We have implemented an experimental set-up in order to demonstrate the feasibility of time-coding protocols for quantum key distribution. Alice produces coherent 20 ns faint pulses of light at 853 nm. They are sent to Bob with delay 0 ns…
Noise causes severe difficulties in implementing quantum computing and quantum cryptography. Several schemes have been suggested to reduce this problem, mainly focusing on quantum computation. Motivated by quantum cryptography, we suggest a…
Quantum key distribution (QKD) allows two distant parties to share encryption keys with security based on laws of quantum mechanics. In order to share the keys, the quantum bits have to be transmitted from the sender to the receiver over a…
The large-alphabet quantum cryptography protocol based on the two-mode coherently correlated multi-photon beams is proposed. The alphabet extension for the protocol is shown to result in the increase of the QKD effectiveness and security.
After carrying out a protocol for quantum key agreement over a noisy quantum channel, the parties Alice and Bob must process the raw key in order to end up with identical keys about which the adversary has virtually no information. In…
Quantum key distribution (QKD) offers a way for establishing information-theoretically secure communications. An important part of QKD technology is a high-quality random number generator (RNG) for quantum states preparation and for…