scholarly journals On the Exact Analysis of an Idealized Quantum Switch

2021 ◽  
Vol 48 (3) ◽  
pp. 79-80
Author(s):  
Gayane Vardoyan ◽  
Saikat Guha ◽  
Philippe Nain ◽  
Don Towsley
Keyword(s):  
Communication Technology ◽  
Quantum Key Distribution ◽  
Quantum Limit ◽  
Secret Key ◽  
Standard Quantum ◽  
Standard Quantum Limit ◽  
Information Theoretic ◽  
Information Theoretic Security ◽  
Yield Information ◽  
Classical Means

Protocols that exploit quantum communication technology offer two advantages: they can either extend or render feasible the capabilities of their classical counterparts, or they exhibit functionality entirely unachievable through classical means alone. For an example of the former, quantum key distribution protocols such as E91 [2] and BBM92 [1] can in principle yield information-theoretic security by using entanglement to generate secure key bits. These raw secret key bits can then be distilled into a one-time pad to encode messages sent between two parties. For an example of the latter, distributed quantum sensing frameworks such as [3] and [11] employ entanglement to overcome the standard quantum limit [4].

scholarly journals The attack strategy for a quantum key distribution protocol based on Bell’s theorem

2021 ◽  
Vol 2056 (1) ◽  
pp. 012011
Author(s):  
Chan Myae Hein ◽  
T F Kamalov
Keyword(s):  
Quantum Key Distribution ◽  
Key Distribution ◽  
Bell’S Theorem ◽  
Bell's Theorem ◽  
Secret Key ◽  
Theoretical Concepts ◽  
Information Theoretic ◽  
Information Theoretic Security ◽  
Quantum Key Distribution Protocol ◽  
Attack Strategy

Abstract A new eavesdropping strategy is proposed for the Quantum Key Distribution (QKD) protocol. This scheme represents a new kind of intercept/resend strategy based on Bell’s theorem. Quantum key distribution (QKD) provides the foremost reliable form of secure key exchange, using only the input-output statistics of the devices to realize information-theoretic security. In this paper, we present an improved QKD protocol that can simultaneously distribute the quantum secret key. We are already using the QKD protocol with simulated results matched completely with the theoretical concepts.

scholarly journals Computing secure key rates for quantum cryptography with untrusted devices

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Ernest Y.-Z. Tan ◽  
René Schwonnek ◽  
Koon Tong Goh ◽  
Ignatius William Primaatmaja ◽  
Charles C.-W. Lim
Keyword(s):  
Probability Distribution ◽  
Quantum Key Distribution ◽  
Bell Inequality ◽  
Secret Key ◽  
Input Output ◽  
Information Theoretic ◽  
Technical Challenge ◽  
Information Theoretic Security ◽  
Chsh Inequality ◽  
Output Probability

AbstractDevice-independent quantum key distribution (DIQKD) provides the strongest form of secure key exchange, using only the input–output statistics of the devices to achieve information-theoretic security. Although the basic security principles of DIQKD are now well understood, it remains a technical challenge to derive reliable and robust security bounds for advanced DIQKD protocols that go beyond the previous results based on violations of the CHSH inequality. In this work, we present a framework based on semidefinite programming that gives reliable lower bounds on the asymptotic secret key rate of any QKD protocol using untrusted devices. In particular, our method can in principle be utilized to find achievable secret key rates for any DIQKD protocol, based on the full input–output probability distribution or any choice of Bell inequality. Our method also extends to other DI cryptographic tasks.

scholarly journals Device-independent quantum key distribution with random key basis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
René Schwonnek ◽  
Koon Tong Goh ◽  
Ignatius W. Primaatmaja ◽  
Ernest Y.-Z. Tan ◽  
Ramona Wolf ◽  
...  
Keyword(s):  
Quantum Key Distribution ◽  
Bell Inequality ◽  
Key Distribution ◽  
Theory And Practice ◽  
Information Theoretic ◽  
Information Theoretic Security ◽  
Experimental Parameters ◽  
Secret Keys ◽  
Simple Variant ◽  
First Time

AbstractDevice-independent quantum key distribution (DIQKD) is the art of using untrusted devices to distribute secret keys in an insecure network. It thus represents the ultimate form of cryptography, offering not only information-theoretic security against channel attacks, but also against attacks exploiting implementation loopholes. In recent years, much progress has been made towards realising the first DIQKD experiments, but current proposals are just out of reach of today’s loophole-free Bell experiments. Here, we significantly narrow the gap between the theory and practice of DIQKD with a simple variant of the original protocol based on the celebrated Clauser-Horne-Shimony-Holt (CHSH) Bell inequality. By using two randomly chosen key generating bases instead of one, we show that our protocol significantly improves over the original DIQKD protocol, enabling positive keys in the high noise regime for the first time. We also compute the finite-key security of the protocol for general attacks, showing that approximately 108–1010 measurement rounds are needed to achieve positive rates using state-of-the-art experimental parameters. Our proposed DIQKD protocol thus represents a highly promising path towards the first realisation of DIQKD in practice.

scholarly journals Physical-layer encryption on the public internet: A stochastic approach to the Kish-Sethuraman cipher

2014 ◽  
Vol 33 ◽  
pp. 1460361 ◽  
Author(s):  
Lachlan J. Gunn ◽  
James M. Chappell ◽  
Andrew Allison ◽  
Derek Abbott
Keyword(s):  
Quantum Key Distribution ◽  
Secure Communication ◽  
Key Distribution ◽  
Stochastic Approach ◽  
Physical Layer ◽  
Information Theoretic ◽  
The Public ◽  
Information Theoretic Security ◽  
Transit Times ◽  
The One

While information-theoretic security is often associated with the one-time pad and quantum key distribution, noisy transport media leave room for classical techniques and even covert operation. Transit times across the public internet exhibit a degree of randomness, and cannot be determined noiselessly by an eavesdropper. We demonstrate the use of these measurements for information-theoretically secure communication over the public internet.

scholarly journals Photonic quantum data locking

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 447
Author(s):  
Zixin Huang ◽  
Peter P. Rohde ◽  
Dominic W. Berry ◽  
Pieter Kok ◽  
Jonathan P. Dowling ◽  
...  
Keyword(s):  
Secret Key ◽  
Linear Optics ◽  
Information Theoretic ◽  
Information Theoretic Security ◽  
Quantum Phenomenon ◽  
Classical Information Theory ◽  
Photo Detection ◽  
Photon States ◽  
Multi Mode ◽  
Boson Sampling

Quantum data locking is a quantum phenomenon that allows us to encrypt a long message with a small secret key with information-theoretic security. This is in sharp contrast with classical information theory where, according to Shannon, the secret key needs to be at least as long as the message. Here we explore photonic architectures for quantum data locking, where information is encoded in multi-photon states and processed using multi-mode linear optics and photo-detection, with the goal of extending an initial secret key into a longer one. The secret key consumption depends on the number of modes and photons employed. In the no-collision limit, where the likelihood of photon bunching is suppressed, the key consumption is shown to be logarithmic in the dimensions of the system. Our protocol can be viewed as an application of the physics of Boson Sampling to quantum cryptography. Experimental realisations are challenging but feasible with state-of-the-art technology, as techniques recently used to demonstrate Boson Sampling can be adapted to our scheme (e.g., Phys. Rev. Lett. 123, 250503, 2019).

scholarly journals Entanglement-enhanced matter-wave interferometry in a high-finesse cavity

2021 ◽  
Author(s):  
James Thompson ◽  
Graham Greve ◽  
Chengyi Luo ◽  
Baochen Wu
Keyword(s):  
Cavity Qed ◽  
Degrees Of Freedom ◽  
Inertial Sensors ◽  
Mean Field ◽  
New Physics ◽  
Matter Wave ◽  
Quantum Limit ◽  
Entangled State ◽  
Standard Quantum ◽  
Standard Quantum Limit

Abstract Entanglement is a fundamental resource that allows quantum sensors to surpass the standard quantum limit set by the quantum collapse of independent atoms. Collective cavity-QED systems have succeeded in generating large amounts of directly observed entanglement involving the internal degrees of freedom of laser-cooled atomic ensembles. Here we demonstrate cavity-QED entanglement of external degrees of freedom to realize a matter-wave interferometer of 700 atoms in which each individual atom falls freely under gravity and simultaneously traverses two paths through space while also entangled with the other atoms. We demonstrate both quantum non-demolition measurements and cavity-mediated spin interactions for generating squeezed momentum states with directly observed metrological gain 3.4^{+1.1}_{-0.9} dB and 2.5^{+0.6}_{-0.6} dB below the standard quantum limit respectively. An entangled state is for the first time successfully injected into a Mach-Zehnder light-pulse interferometer with 1.7^{+0.5}_{-0.5} dB of directly observed metrological enhancement. These results open a new path for combining particle delocalization and entanglement for inertial sensors, searches for new physics, particles, and fields, future advanced gravitational wave detectors, and accessing beyond mean-field quantum many-body physics.

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