China
Africa
Explore chapters and articles related to this topic
Quantum Networks
Published in Jonathan P. Dowling, Schrödinger’s Web, 2020
What about entangling two mobile phones? That is a bit of a tall order. We can’t have everybody running around with long fibers attached to their phones. Once we make the quantum memories small, low-power, and cheap, everybody will have one on their phone. When you plug your phone into your charger, which you have to do every day or so, you get it recharged with electricity from the power grid. In the future, the charger will have a separate port to recharge your phone’s quantum memory from the quantum-entanglement-distribution grid. When you unplug it, the phone now is charged and has a trillion qubits that are entangled with some other nearby node in the quantum network. Let’s suppose Alice and Bob want to secure their text messages with QKD – the E91 protocol. First, their phones use their classical communication links to order the quantum network to allow them to share ebits. The network implements a series of swappers until it entangles all of Alice’s qubits with all of Bob’s. Once that step is completed, then Alice and Bob communicate directly over the classical phone link and execute the E91 protocol. They carry out measurements on their qubits, periodically interspersed with Bell tests, and communicate their measurement settings with each other. In a few milliseconds, Alice and Bob share a random key that is a trillion bits long. The quantum steps are now over, and then they implement a one-time pad to communicate securely with each other over the classical cell-phone towers.
Integrated nanophotonics for multi-user quantum key distribution networks
Published in Ching Eng Png, Yuriy Akimov, Nanophotonics and Plasmonics, 2017
The security of QKD has been proven theoretically. After more than two decades of research and development, QKD technology is now mature and ready for practical use. There are, however, challenges ahead with regard to its adoption in metropolitan area networks. For widespread adoption, QKD implementation must be compatible with the existing fiber-optic network infrastructure built for the Internet. Such networks typically consist of long-range backbone optical fiber links connecting a number of core nodes, and shorter-range optical fiber access networks that connect many remote users to these core nodes. Ad hoc installation of point-to-point QKD systems is unlikely to scale well in a metropolitan area network. In this review, we consider the implementation of multi-user QKD networks based on an approach called wavelength-multiplexed entanglement distribution, leveraging on integrated nanophotonics technology for scalability and cost reduction.
Elements of Quantum Electronics
Published in Michael Olorunfunmi Kolawole, Electronics, 2020
Quantum cryptography—another name for Quantum key distribution (QKD)—constitutes an approach for the distribution of cryptographic keys. In contrast to classical key distribution schemes, QKD security is based on the laws of quantum physics. In classical transmission system, the security of the information being transmitted is ensured by using cryptographic protocol: encrypting the information being sent from site A to site B and decrypting the encrypted information at the other end (site B), while preventing a malevolent third-party eavesdropping [26]. The classical cryptographic functions—encryption, decryption, and key distribution or management—have been discussed in detail in [26], Chapter 1.
Review of Security Methods Based on Classical Cryptography and Quantum Cryptography
Published in Cybernetics and Systems, 2023
Shalini Subramani, Selvi M, Kannan A, Santhosh Kumar Svn
In QKD protocols, the keys are shared from sender to receiver and are required to communicate through the transmission channel securely on which quantum carriers are transmitted. A system working for photons using BB84 polarized photons were demonstrated by Bennett in 1991. For explaining the further advancements theoretically, they presented an entangled particles states model for key distribution (Chou et al. 2011). The QKD protocols are proposed by Bennett, Brassard and Mermin in 1992. Now, Gracie is transmitting the plaintext message to Jack where they are sharing their keys with quantum bits. An eavesdropper is allowing them to share their key with authentication and transmitting through the public channel. This process involves public communication protocol between the Gracie and Jack in the public channel, along with specialized algorithm in QKD of cryptography. A shared key of encoding and decoding are only known by the sender Gracie and receiver Jack. According to the particles, a symmetric are secret key and asymmetric are pubic key transmitting in single-photon of polarization as shown in Figure 2.
Phase-encoded measurement device independent quantum key distribution without a shared reference frame
Published in Journal of Modern Optics, 2018
Zhu Zhuo-Dan, Zhao Shang-Hong, Dong Chen, Sun Ying
Quantum key distribution (QKD) allows two parties (typically called Alice and Bob) to generate a common string of secret bits, called secret key, even in the presence of an eavesdropper, Eve (1,2). However, there is a big gap between the theory and practice, before any security proofs can be applied to practical scenarios, various device imperfections should be carefully examined. For example, the detector efficiency mismatch can be exploited by eavesdroppers to implement the efficiency mismatch attack (3) or the time-shift attack (4,5). Lately, other imperfections, such as the detector’s after-gate pulses and the dead time, have also been exploited in hacking strategies (6,7). Currently, there are at least three main possible approaches to avoid the problem of quantum hacking and recover the security of QKD implementations. The first solution is called ‘precise mathematical models and patches’, which model all the devices, and include this information into the security proof (8,9) or find an appropriate countermeasure against the corresponding attack (10,11). This approach is unfortunately challenging and only known hacking strategies can be prevented. The second solution is named device-independent QKD (DI-QKD) (12). In this way, Alice and Bob can remove all side-channel loopholes from QKD implementations while pay no attention to how their devices operate. However, it needs a loophole-free Bell test which is beyond current technology. The third solution is called MDI-QKD (13), which can remove all (existing and yet to be discovered) detector side channels (14,15) while Bell state measurement (BSM) (16) is performed in untrusted third party. In summary, the first solution is very difficult to realize and can’t provide information theoretic security, DI-QKD is unfeasible to date, but MDI-QKD, already realized, is immune to all the detector attacks.
A MATLAB-based modelling and simulation package for DPS-QKD
Published in Journal of Modern Optics, 2022
Anuj Sethia, Anindita Banerjee
Inoue et al. introduced DPS QKD in 2002 [14–17]. It is a prepare-and-measure type of QKD protocol where, Alice (transmitter) generates heavily attenuated and phase encoded, train of pulses and transmits them over a quantum channel to Bob (receiver). The security is based on non-deterministic collapse of a wave function in a quantum measurement. The optical schematic of DPS QKD is presented in Figure 1.The protocol is executed as follows: Alice generates the state which is a train of N coherent pulses with θ as the initial phase and as an encoded phase which takes {}. This quantum state is represented as: She heavily attenuates the transmission power such that the mean photon number per pulse is less than unity.Bob receives the pulse train and passes it through a Delay Line Interferometer (DLI) with a delay that is inversely proportional to the repetition rate of pulse train. The interference between adjacent pulses results in selective detection between the two single-photon detectors D1(2) for a phase difference of 0(π).Bob tags each click and the corresponding detector. He shares the time information with Alice over a prior authenticated classical channel.Considering the time information shared by Bob and the phase encoding information already available with Alice, she can generate a raw data, partially correlated with Bob. This process is the beginning of key reconciliation. Synchronization mismatch with electronic noise and delay are the major sources of error causing irregularities in shared data.Bob performs the error estimation procedure with Alice. The discrepancies are due to imperfections at various levels in the communication system and contribute to the quantum bit error rate (QBER). QBER is defined as the ratio of incorrect bits to received bits. In conservative security analysis, all the errors are attributed to an eavesdropper. The amount of information exposed to Eve is estimated using the Shannon's noiseless coding theorem [18]. For an estimated QBER of e, the minimum information exposed is given by Thereafter, both the parties execute error-correction to generate correlated bit string on either end.Finally, Alice and Bob perform privacy amplification to obtain a final secure key. The error-corrected key is compressed to minimize the information leakage in the raw quantum transmission and during error correction. The extent of compression depends upon the amount of information leak and the eavesdropping strategy.