scholarly journals Quantum Bit Commitment and the Reality of the Quantum State

2018 ◽  
Vol 48 (1) ◽  
pp. 92-109 ◽  
Author(s):  
R. Srikanth
Keyword(s):  
Quantum State ◽  
Quantum Bit ◽  
Bit Commitment

Optimization of coherent attacks in generalizations of the BB84 quantum bit commitment protocol

2002 ◽  
Vol 2 (1) ◽  
pp. 66-96
Author(s):  
R.W. Spekkens ◽  
T. Rudolph
Keyword(s):  
State Estimation ◽  
Quantum State ◽  
Upper Bound ◽  
Upper Bounds ◽  
Entangled State ◽  
Quantum State Estimation ◽  
Quantum Bit ◽  
Bit Commitment ◽  
Single Qubit ◽  
Qubit States

It is well known that no quantum bit commitment protocol is unconditionally secure. Nonetheless, there can be non-trivial upper bounds on both Bob's probability of correctly estimating Alice's commitment and Alice's probability of successfully unveiling whatever bit she desires. In this paper, we seek to determine these bounds for generalizations of the BB84 bit commitment protocol. In such protocols, an honest Alice commits to a bit by randomly choosing a state from a specified set and submitting this to Bob, and later unveils the bit to Bob by announcing the chosen state, at which point Bob measures the projector onto the state. Bob's optimal cheating strategy can be easily deduced from well known results in the theory of quantum state estimation. We show how to understand Alice's most general cheating strategy, (which involves her submitting to Bob one half of an entangled state) in terms of a theorem of Hughston, Jozsa and Wootters. We also show how the problem of optimizing Alice's cheating strategy for a fixed submitted state can be mapped onto a problem of state estimation. Finally, using the Bloch ball representation of qubit states, we identify the optimal coherent attack for a class of protocols that can be implemented with just a single qubit. These results provide a tight upper bound on Alice's probability of successfully unveiling whatever bit she desires in the protocol proposed by Aharonov et al., and lead us to identify a qubit protocol with even greater security.

scholarly journals Zero-knowledge convincing protocol on quantum bit is impossible

Quantum ◽  
2017 ◽  
Vol 1 ◽  
pp. 41 ◽  
Author(s):  
Pawel Horodecki ◽  
Michal Horodecki ◽  
Ryszard Horodecki
Keyword(s):  
Information Processing ◽  
Quantum State ◽  
Qubit State ◽  
Third Party ◽  
Zero Knowledge ◽  
Quantum Bit ◽  
Qubit System ◽  
Nonzero Probability

Consider two parties: Alice and Bob and suppose that Bob is given a qubit system in a quantum state ϕ, unknown to him. Alice knows ϕ and she is supposed to convince Bob that she knows ϕ sending some test message. Is it possible for her to convince Bob providing him "zero knowledge" i. e. no information about ϕ he has? We prove that there is no "zero knowledge" protocol of that kind. In fact it turns out that basing on Alice message, Bob (or third party - Eve - who can intercept the message) can synthetize a copy of the unknown qubit state ϕ with nonzero probability. This "no-go" result puts general constrains on information processing where information about quantum state is involved.

scholarly journals Strong no-go theorem for Gaussian quantum bit commitment

2010 ◽  
Vol 81 (1) ◽  
Author(s):  
Loïck Magnin ◽  
Frédéric Magniez ◽  
Anthony Leverrier ◽  
Nicolas J. Cerf
Keyword(s):  
Quantum Bit ◽  
Bit Commitment

scholarly journals Quantum-inspired learning vector quantizers for prototype-based classification

2020 ◽  
Author(s):  
Thomas Villmann ◽  
Alexander Engelsberger ◽  
Jensun Ravichandran ◽  
Andrea Villmann ◽  
Marika Kaden
Keyword(s):  
State Space ◽  
Quantum State ◽  
Inner Product ◽  
Mathematical Framework ◽  
Feature Mapping ◽  
Quantum Bit ◽  
Vector Quantizers ◽  
New Ideas ◽  
Learning Scenarios ◽  
Bit Vector

AbstractPrototype-based models like the Generalized Learning Vector Quantization (GLVQ) belong to the class of interpretable classifiers. Moreover, quantum-inspired methods get more and more into focus in machine learning due to its potential efficient computing. Further, its interesting mathematical perspectives offer new ideas for alternative learning scenarios. This paper proposes a quantum computing-inspired variant of the prototype-based GLVQ for classification learning. We start considering kernelized GLVQ with real- and complex-valued kernels and their respective feature mapping. Thereafter, we explain how quantum space ideas could be integrated into a GLVQ using quantum bit vector space in the quantum state space $${\mathcal {H}}^{n}$$ H n and show the relations to kernelized GLVQ. In particular, we explain the related feature mapping of data into the quantum state space $${\mathcal {H}}^{n}$$ H n . A key feature for this approach is that $${\mathcal {H}}^{n}$$ H n is an Hilbert space with particular inner product properties, which finally restrict the prototype adaptations to be unitary transformations. The resulting approach is denoted as Qu-GLVQ. We provide the mathematical framework and give exemplary numerical results.

scholarly journals Measurement-Device-Independent Two-Party Cryptography with Error Estimation

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6351
Author(s):  
Zishuai Zhou ◽  
Qisheng Guang ◽  
Chaohui Gao ◽  
Dong Jiang ◽  
Lijun Chen
Keyword(s):  
Error Estimation ◽  
Bit Error Rate ◽  
Error Rate ◽  
Cryptographic Protocols ◽  
Measurement Device ◽  
Joint Measurement ◽  
Quantum Bit ◽  
Bit Commitment ◽  
Innovative Method ◽  
Limited Power

We present an innovative method for quantum two-party cryptography. Our protocol introduces joint measurement and error estimation to improve the security of two-party cryptographic protocols. Our protocol removes the assumption of the attacker’s limited power and catches the attacking actions through highly estimated bit error rate. Our protocol is formally proved to be secure against both eavesdroppers and dishonest communication parties. We also utilize our designed protocol to construct two specific two-party cryptographic applications: Quantum bit commitment and quantum password identification.

Quantum bit commitment in a channel with noise

JETP Letters ◽  
2001 ◽  
Vol 73 (2) ◽  
pp. 107-113
Author(s):  
S. N. Molotkov ◽  
S. S. Nazin
Keyword(s):  
Quantum Bit ◽  
Bit Commitment
Sign in / Sign up

Export Citation Format

Share Document