scholarly journals Mutually unbiased bases and symmetric informationally complete measurements in Bell experiments

2021 ◽  
Vol 7 (7) ◽  
pp. eabc3847
Author(s):  
Armin Tavakoli ◽  
Máté Farkas ◽  
Denis Rosset ◽  
Jean-Daniel Bancal ◽  
Jedrzej Kaniewski
Keyword(s):  
Quantum Key Distribution ◽  
Random Number ◽  
Random Number Generation ◽  
Bell Inequalities ◽  
Extremal Point ◽  
Optimal Rate ◽  
Quantum Nonlocality ◽  
Space Structures ◽  
Mutually Unbiased Bases ◽  
Practical Relevance

Mutually unbiased bases (MUBs) and symmetric informationally complete projectors (SICs) are crucial to many conceptual and practical aspects of quantum theory. Here, we develop their role in quantum nonlocality by (i) introducing families of Bell inequalities that are maximally violated by d-dimensional MUBs and SICs, respectively, (ii) proving device-independent certification of natural operational notions of MUBs and SICs, and (iii) using MUBs and SICs to develop optimal-rate and nearly optimal-rate protocols for device-independent quantum key distribution and device-independent quantum random number generation, respectively. Moreover, we also present the first example of an extremal point of the quantum set of correlations that admits physically inequivalent quantum realizations. Our results elaborately demonstrate the foundational and practical relevance of the two most important discrete Hilbert space structures to the field of quantum nonlocality.

scholarly journals Optimal Strategy to Certify Quantum Nonlocality

2021 ◽  
Author(s):  
S. Gómez ◽  
D. Uzcátegui ◽  
I. Machuca ◽  
E. S. Gómez ◽  
S. P. Walborn ◽  
...  
Keyword(s):  
Experimental Data ◽  
Random Number ◽  
Bell Inequality ◽  
Random Number Generation ◽  
Quantum Nonlocality ◽  
Entangled Photons ◽  
Challenging Problem ◽  
Practical Applications ◽  
Variable Limit ◽  
The One

Abstract Certification of quantum nonlocality plays a central role in practical applications like device-independent quantum cryptography and random number generation protocols. These applications entail the challenging problem of certifying quantum nonlocality, something that is hard to achieve when the target quantum state is only weakly entangled, or when the source of errors is high, e.g. when photons propagate through the atmosphere or a long optical fiber. Here we introduce a technique to find a Bell inequality with the largest possible gap between the quantum prediction and the classical local hidden variable limit for a given set of measurement frequencies. Our method represent an efficient strategy to certify quantum nonlocal correlations from experimental data without requiring extra measurements, in the sense that there is no Bell inequality with a larger gap than the one provided. Furthermore, we also reduce the photodetector efficiency required to close the detection loophole. We illustrate our technique by improving the detection of quantum nonlocality from experimental data obtained with weakly entangled photons.

scholarly journals Practical random number generation protocol for entanglement-based quantum key distribution

2009 ◽  
Vol 9 (7&8) ◽  
pp. 683-692
Author(s):  
G.B. Xavier ◽  
T. Ferreira da Silva ◽  
G. Vilela de Faria ◽  
G.P. Temporao ◽  
J.P. von der Weid
Keyword(s):  
Quantum Key Distribution ◽  
Random Number ◽  
Single Photon ◽  
Photon Counting ◽  
Random Number Generation ◽  
Key Distribution ◽  
Photon Detectors ◽  
Random Number Generators ◽  
Single Photon Counting ◽  
Simple Protocol

A simple protocol which takes advantage of the inherent random times of detections in single photon counting modules is presented for random active basis choices when using entanglement-based protocols for Quantum Key Distribution (QKD). It may also be applicable to the BB84 protocol in certain cases. The scheme presented uses the single photon detectors already present on a QKD setup, working on the same rate as the system is capable of detecting, and is, therefore, not limited by the output rates of quantum random number generators. This protocol only requires small hardware modifications making it an attractive solution. We perform a proof-of-principle experiment employing a spontaneous parametric down-conversion process in a $\chi^{(2)}$ non-linear crystal to demonstrate the feasibility of our scheme, and show that the generated sequence passes randomness tests.

scholarly journals Quantum Bounds on Detector Efficiencies for Violating Bell Inequalities Using Semidefinite Programming

Cryptography ◽  
2020 ◽  
Vol 4 (1) ◽  
pp. 2
Author(s):  
Alexander Sauer ◽  
Gernot Alber
Keyword(s):  
Quantum Information ◽  
Quantum Key Distribution ◽  
Quantum Information Processing ◽  
Bell Inequalities ◽  
Quantum Correlations ◽  
Quantum Nonlocality ◽  
Semidefinite Programs ◽  
Dark Counts ◽  
Optimal Inequality ◽  
Detector Model

Loophole-free violations of Bell inequalities are crucial for fundamental tests of quantum nonlocality. They are also important for future applications in quantum information processing, such as device-independent quantum key distribution. Based on a detector model which includes detector inefficiencies and dark counts, we estimate the minimal requirements on detectors needed for performing loophole-free bipartite and tripartite Bell tests. Our numerical investigation is based on a hierarchy of semidefinite programs for characterizing possible quantum correlations. We find that for bipartite setups with two measurement choices and our detector model, the optimal inequality for a Bell test is equivalent to the Clauser–Horne inequality.

scholarly journals Optimal strategy to certify quantum nonlocality

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Gómez ◽  
D. Uzcátegui ◽  
I. Machuca ◽  
E. S. Gómez ◽  
S. P. Walborn ◽  
...  
Keyword(s):  
Experimental Data ◽  
Random Number ◽  
Bell Inequality ◽  
Random Number Generation ◽  
Quantum Nonlocality ◽  
Entangled Photons ◽  
Challenging Problem ◽  
Practical Applications ◽  
Variable Limit ◽  
The One

AbstractCertification of quantum nonlocality plays a central role in practical applications like device-independent quantum cryptography and random number generation protocols. These applications entail the challenging problem of certifying quantum nonlocality, something that is hard to achieve when the target quantum state is only weakly entangled, or when the source of errors is high, e.g. when photons propagate through the atmosphere or a long optical fiber. Here we introduce a technique to find a Bell inequality with the largest possible gap between the quantum prediction and the classical local hidden variable limit for a given set of measurement frequencies. Our method represents an efficient strategy to certify quantum nonlocal correlations from experimental data without requiring extra measurements, in the sense that there is no Bell inequality with a larger gap than the one provided. Furthermore, we also reduce the photodetector efficiency required to close the detection loophole. We illustrate our technique by improving the detection of quantum nonlocality from experimental data obtained with weakly entangled photons.

scholarly journals Quantum Random Number Generation for 1.25-GHz Quantum Key Distribution Systems

2015 ◽  
Vol 33 (13) ◽  
pp. 2855-2859 ◽  
Author(s):  
Anthony Martin ◽  
Bruno Sanguinetti ◽  
Charles Ci Wen Lim ◽  
Raphael Houlmann ◽  
Hugo Zbinden
Keyword(s):  
Quantum Key Distribution ◽  
Distribution Systems ◽  
Random Number ◽  
Random Number Generation ◽  
Key Distribution ◽  
Number Generation

Random Number Generation Based on the Rossler Attractor

2014 ◽  
Vol 1 ◽  
pp. 272-275 ◽  
Author(s):  
Vincent Canals ◽  
Antoni Morro ◽  
Josep L. Rosselló
Keyword(s):  
Random Number ◽  
Random Number Generation ◽  
Number Generation
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