Author
Won-Young Hwang
Other affiliations: Northwestern University, KAIST, Seoul National University
Bio: Won-Young Hwang is an academic researcher from Chonnam National University. The author has contributed to research in topics: Quantum key distribution & Quantum state. The author has an hindex of 13, co-authored 51 publications receiving 1768 citations. Previous affiliations of Won-Young Hwang include Northwestern University & KAIST.
Papers published on a yearly basis
Papers
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TL;DR: A decoy-pulse method to overcome the photon-number-splitting attack for Bennett-Brassard 1984 quantum key distribution protocol in the presence of high loss by intentionally and randomly replacing signal pulses by multiphoton pulses (decoy pulses).
Abstract: We propose a decoy-pulse method to overcome the photon-number-splitting attack for Bennett-Brassard 1984 quantum key distribution protocol in the presence of high loss: A legitimate user intentionally and randomly replaces signal pulses by multiphoton pulses (decoy pulses). Then they check the loss of the decoy pulses. If the loss of the decoy pulses is abnormally less than that of signal pulses, the whole protocol is aborted. Otherwise, to continue the protocol, they estimate the loss of signal multiphoton pulses based on that of decoy pulses. This estimation can be done with an assumption that the two losses have similar values. We justify that assumption.
1,575 citations
TL;DR: In this paper, a simple variation of the basic ideas of the BB84 quantum cryptographic scheme leading to a method of key expansion was given, where a secure random sequence (the bases sequence) determines the encoding bases in a proposed scheme.
77 citations
TL;DR: In this paper, a geometric formulation for minimum error discrimination of qubit states with equal a priori probabilities is presented. But the geometric formulation does not depend on detailed relations among the given states, such as the angles between them, but on a property assigned by the set of given states itself.
Abstract: We show a geometric formulation for minimum-error discrimination of qubit states that can be applied to arbitrary sets of qubit states given with arbitrary a priori probabilities. In particular, when qubit states are given with equal a priori probabilities, we provide a systematic way of finding optimal discrimination and the complete solution in a closed form. This generally gives a bound to cases when prior probabilities are unequal. Then it is shown that the guessing probability does not depend on detailed relations among the given states, such as the angles between them, but on a property that can be assigned by the set of given states itself. This also shows how a set of quantum states can be modified such that the guessing probability remains the same. Optimal measurements are also characterized accordingly, and a general method of finding them is provided.
46 citations
TL;DR: It is shown that, remarkably, the guessing probability can be determined by the no-signaling principle, and it is shown by proving that, in the semidefinite programing for the discrimination, the optimality condition corresponds to the constraint that quantum theory cannot be used for a superluminal communication.
Abstract: We provide a general framework of utilizing the no-signaling principle in derivation of the guessing probability in the minimum-error quantum state discrimination. We show that, remarkably, the guessing probability can be determined by the no-signaling principle. This is shown by proving that, in the semidefinite programing for the discrimination, the optimality condition corresponds to the constraint that quantum theory cannot be used for a superluminal communication. Finally, a general bound to the guessing probability is presented in a closed form.
37 citations
TL;DR: In this paper, a special case of the Helstrom theorem was proved by using the no-signaling condition in the special theory of relativity that faster-than-light communication is impossible.
Abstract: We prove a special case of the Helstrom theorem by using the no-signaling condition in the special theory of relativity that faster-than-light communication is impossible.
25 citations
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TL;DR: Essential theoretical tools that have been developed to assess the security of the main experimental platforms are presented (discrete- variable, continuous-variable, and distributed-phase-reference protocols).
Abstract: Quantum key distribution (QKD) is the first quantum information task to reach the level of mature technology, already fit for commercialization. It aims at the creation of a secret key between authorized partners connected by a quantum channel and a classical authenticated channel. The security of the key can in principle be guaranteed without putting any restriction on an eavesdropper's power. This article provides a concise up-to-date review of QKD, biased toward the practical side. Essential theoretical tools that have been developed to assess the security of the main experimental platforms are presented (discrete-variable, continuous-variable, and distributed-phase-reference protocols).
2,926 citations
TL;DR: A protocol for quantum secure direct communication using blocks of Einstein-Podolsky-Rosen (EPR) pairs is proposed, and a set of ordered N EPR pairs is used as a data block for sending secret message directly.
Abstract: A protocol for quantum secure direct communication using blocks of Einstein-Podolsky-Rosen (EPR) pairs is proposed. A set of ordered N EPR pairs is used as a data block for sending secret message directly. The ordered N EPR set is divided into two particle sequences, a checking sequence and a message-coding sequence. After transmitting the checking sequence, the two parties of communication check eavesdropping by measuring a fraction of particles randomly chosen, with random choice of two sets of measuring bases. After insuring the security of the quantum channel, the sender Alice encodes the secret message directly on the message-coding sequence and sends them to Bob. By combining the checking and message-coding sequences together, Bob is able to read out the encoded messages directly. The scheme is secure because an eavesdropper cannot get both sequences simultaneously. We also discuss issues in a noisy channel.
1,580 citations
TL;DR: The current state of research and future directions in quantum key distribution and quantum networks are reviewed in this paper, with a special emphasis on quantum key distributions and quantum key sharing in quantum networks.
Abstract: Quantum communication, and indeed quantum information in general, has changed the way we think about quantum physics In 1984 and 1991, the first protocol for quantum cryptography and the first application of quantum non-locality, respectively, attracted a diverse field of researchers in theoretical and experimental physics, mathematics and computer science Since then we have seen a fundamental shift in how we understand information when it is encoded in quantum systems We review the current state of research and future directions in this new field of science with special emphasis on quantum key distribution and quantum networks
1,420 citations
TL;DR: The current status of single-photon-source and single-Photon-detector technologies operating at wavelengths from the ultraviolet to the infrared are reviewed and applications of these technologies to quantum communication are discussed.
Abstract: We review the current status of single-photon-source and single-photon-detector technologies operating at wavelengths from the ultraviolet to the infrared. We discuss applications of these technologies to quantum communication, a field currently driving much of the development of single-photon sources and detectors.
1,280 citations
TL;DR: A review of the progress in photonic quantum information processing can be found in this article, where the emphasis is given to the creation of photonic entanglement of various forms, tests of the completeness of quantum mechanics (in particular, violations of local realism), quantum information protocols for quantum communication, and quantum computation with linear optics.
Abstract: Multiphoton interference reveals strictly nonclassical phenomena. Its applications range from fundamental tests of quantum mechanics to photonic quantum information processing, where a significant fraction of key experiments achieved so far comes from multiphoton state manipulation. The progress, both theoretical and experimental, of this rapidly advancing research is reviewed. The emphasis is given to the creation of photonic entanglement of various forms, tests of the completeness of quantum mechanics (in particular, violations of local realism), quantum information protocols for quantum communication (e.g., quantum teleportation, entanglement purification, and quantum repeater), and quantum computation with linear optics. The scope of the review is limited to ``few-photon'' phenomena involving measurements of discrete observables.
1,156 citations