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Quantum computation offers unique properties that cannot be paralleled by conventional computers. In particular, reading qubits may change their state and thus signal the presence of an intruder. This paper develops a proof-of-concept for a quantum honeypot that allows the detection of intruders on reading. The idea is to place quantum sentinels within all resources offered within the honeypot. Additional to classical honeypots, honeypots with quantum sentinels can trace the reading activity of the intruder within any resource. Sentinels can be set to be either visible and accessible to the intruder or hidden and unknown to intruders. Catching the intruder using quantum sentinels has a low theoretical probability per sentinel, but the probability can be increased arbitrarily higher by adding more sentinels. The main contributions of this paper are that the monitoring of the intruder can be carried out at the level of the information unit, such as the bit, and quantum monitoring activity is fully hidden from the intruder. Practical experiments, as performed in this research, show that the error rate of quantum computers has to be considerably reduced before implementations of this concept are feasible. [ABSTRACT FROM AUTHOR]

This paper proposes a perimeter detection scheme based on the quantum physical properties of photons. Existing perimeter intrusion detection schemes, if using light, rely on the classical properties of light only. Our quantum sensor network uses the quantum property of spatial superposition of photons, meaning that a photon can simultaneously follow two different paths after going through a beam splitter. Using multiple Mach–Zehnder interferometers, an entire web of paths can be generated, such that one single photon occupies them all. If an intruder violates this web in some arbitrary point, the entire photon superposition is destroyed, the photon does not self-interfere any more and this event is detected by measurements. For one single photon, the intruder detection probability is limited theoretically but can be increased arbitrarily with the usage of a sequence of photons. We show both theoretical bounds as well as practical results of the proposed schemes. The practical results are obtained by simulation experiments on IBM Quantum platforms. The benefits of our quantum approach are: low power, invisibility to potential intruders, scalability and easy practical implementation. [ABSTRACT FROM AUTHOR]

This paper studies the effect of quantum computers on Bitcoin mining. The shift in computational paradigm towards quantum computation allows the entire search space of the golden nonce to be queried at once by exploiting quantum superpositions and entanglement. Using Grover's algorithm, a solution can be extracted in time O ( 2 256 / t) , where t is the target value for the nonce. This is better using a square root over the classical search algorithm that requires O (2 256 / t) tries. If sufficiently large quantum computers are available for the public, mining activity in the classical sense becomes obsolete, as quantum computers always win. Without considering quantum noise, the size of the quantum computer needs to be ≈ 10 4 qubits. [ABSTRACT FROM AUTHOR]

Quantum bit commitment (QBC) is a quantum version of the classical bit commitment security primitive. As other quantum security primitives and protocols, QBC improves on cheating detection over its classical counterpart. The implementation of the QBC protocol below relies on the use of common quantum gates: the Hadamard gate used for orthonormal bases and the CNOT gate used to swap qubits. The protocol was run and tested on IBM quantum experience (IBM QX). IBM QX offers two different quantum environments: as a simulator and as a real quantum machine. In our implementation, honest and dishonest participants were considered. Results of both the simulation and the quantum execution were compared against the theoretical expectations. The IBM QX simulator gives results that match the theoretical model. The IBM QX real computer deviates from the expected behavior by a measurable amount. Using the standard deviation and the Hamming distance, the conclusion is that the quantum computer is usable as the difference to the simulator is within an acceptable margin of error. The QBC protocol of choice is fully secure against cheating by Bob. The only way Alice can cheat is using multi-dimensional entanglement. The cost for Alice to cheat is exponential in the number of qubits used, namely O (2 6 n + 3 k + 1) . [ABSTRACT FROM AUTHOR]

Byline: Marius Nagy, Selim G. Akl In this paper we show how the tree contraction method can be applied to compute the cardinality of the minimum vertex cover of a two-terminal series-parallel graph. We then construct a real-time paradigm for this problem and show that in the new computational environment, a parallel algorithm is superior to the best possible sequential algorithm, in terms of the accuracy of the solution computed. Specifically, there are cases in which the solution produced by a parallel algorithm that uses p processors is better than the output of any sequential algorithm for the same problem, by a factor superlinear in p.

This paper proposes a different approach to pinpoint the causes for which an unconditionally secure quantum bit commitment protocol cannot be realized, beyond the technical details on which the proof of Mayers' no-go theoremis constructed. We have adopted the tools of quantum entropy analysis to investigate the conditions under which the security properties of quantum bit commitment can be circumvented. Our study has revealed that cheating the binding property requires the quantum system acting as the safe to harbor the same amount of uncertainty with respect to both observers (Alice and Bob) as well as the use of entanglement. Our analysis also suggests that the ability to cheat one of the two fundamental properties of bit commitment by any of the two participants depends on how much information is leaked from one side of the system to the other and how much remains hidden from the other participant. [ABSTRACT FROM AUTHOR]

Quantum bit commitment (QBC) is a fundamental cryptographic primitive that can be used as a building block for a whole set of applications like remote coin tossing, zero-knowledge proofs or secure two-party computation. Unconditionally secure QBC, that is a protocol which is both fully binding and fully concealing, is deemed impossible due to the use of entanglement by a dishonest participant [10, 14]. In this paper, we describe a protocol that implements QBC using quantum memories, meaning that a qubit can be stored for as long as needed. We prove that, in the absence of entanglement, our protocol exhibits both properties: it is both binding and concealing. Its security exploits the algebraic properties of an equivalence class with two types of operators: permutation and the Hadamard transform. The only theoretical attack that can be mounted concerns the binding property through the use of entanglement and the Schmidt decomposition. However, for all practical purposes, such an attack can be made arbitrarily difficult, by increasing the value of a security parameter, namely the number of qubits used in the protocol. [ABSTRACT FROM AUTHOR]

This paper explores parallels between concepts defined in cryptography and concepts of biology at different levels of organization. Cryptographic settings, including the presence of an eavesdropper are extensive in the realm of plants and animals. It also turns out that principles of information protection show strong similarities between the two disciplines: computer science and molecular biology. Biological information, as held by the DNA molecule, and digital information, as used in digital communication systems, are subject to analogous procedures of protection and repair when damaged. [ABSTRACT FROM AUTHOR]

Rank-varying computational complexity describes those computations in which the complexity of executing each step is not a constant, but evolves throughout the computation as a function of the order of execution of each step [2]. This paper identifies practical instances of this computational paradigm in the procedures for computing the quantum Fourier transform and its inverse. It is shown herein that under the constraints imposed by quantum decoherence, only a parallel approach can guarantee a reliable solution or, alternatively, improve scalability. [ABSTRACT FROM AUTHOR]

We develop an entanglement verification method not based on Bell inequalities, that achieves a higher reliability per number of qubits tested than existing procedures of this kind. Used in a quantum cryptographic context, the method gives rise to a new protocol for distributing classical keys through insecure quantum channels. The cost of quantum and classical communication is significantly reduced in the new protocol, while its security is increased with respect to other entanglement-based protocols exchanging the same number of qubits. To achieve this performance, our scheme relies on a simple quantum circuit and the ability to store qubits. [ABSTRACT FROM AUTHOR]

It has been said that quantum cryptography in general offers a secure solution to the problem of key enhancement. This means that two parties who already share a small secret key, can use quantum protocols to establish a new large secret key. This large secret key can be arbitrarily long and is unbreakable. Thus, to date, the main contribution of quantum cryptography has been believed to be quantum key enhancement. This paper shows that quantum cryptography can do significantly more. The quantum protocol described here distributes an unbreakable secret key to the two parties by relying on public information only. This is the first time that quantum cryptography is shown to be able to produce secret information using only public information. This contribution is also unique for cryptography in general, classical and quantum. [ABSTRACT FROM AUTHOR]

The identity theft problem, an ever growing threat to safety and security in today's society, is very difficult to tackle using classical means, due to the fact that classical information can be easily read and copied. In this paper, we show that we can do more than it is possible classically through the use of specific tools and techniques from quantum information processing and quantum cryptography. Specifically, we devise a quantum security scheme that completely eliminates the problem of identity theft in sensor networks, although our scheme may be of interest in more general situations involving secrecy and authentication. The hypercomputational aspect of this result pertains to the unprecedented level of security achieved, a level that is beyond the reach of classical information processing. [ABSTRACT FROM AUTHOR]

Determining the optimal location of a switching center in a tree network of users is accurately modeled by the median problem. A real-time approach is used in this paper to investigate the dynamics of such a communication network in two cases: (1) a growing tree of nodes associated with equal demand rates, and (2) a stream of corrections that arbitrarily change the demand rates at the nodes. The worst-case analysis performed in both situations clearly demonstrates the importance of parallelism in such real-time paradigms. It is shown that the error generated by the best sequential algorithm in the first case can be arbitrarily large. A synergistic behavior is revealed when the quality-up is investigated in the second case. [ABSTRACT FROM AUTHOR]

This paper is structured around the idea that a finite Universal Computer cannot be realized and presents in detail a series of unconventional computing paradigms supporting this idea from a quantum mechanical perspective. [ABSTRACT FROM AUTHOR]

The quantum model of computation not only offers entirely new ways to manipulate information, but also allows information processing tasks to be formulated in unconventional, genuine quantum mechanical terms. We show that the task of distinguishing among entangled quantum states combines entanglement and non-determinism in a way that makes the quantum solution impossible to simulate on any classical machine (even one equipped with the same measurement capabilities as the quantum computational device). A new class of information processing tasks is thus uncovered whose members are readily carried out by a quantum computer, yet are impossible to perform on any classical machine (whether deterministic or probabilistic). In the broad, unconventional context created by quantum mechanics, the computational power of a quantum computer is therefore strictly greater than that of a classical computer. [ABSTRACT FROM AUTHOR]

The paper is intended to be a survey of all the important aspects and results that have shaped the field of quantum computation and quantum information. The reader is first familiarized with those features and principles of quantum mechanics providing a more efficient and secure information processing. Their applications to the general theory of information, cryptography, algorithms, computational complexity and error-correction are then discussed. Prospects for building a practical quantum computer are also analyzed. [ABSTRACT FROM AUTHOR]

The authors reflect on the selected researched materials from the workshop on Unconventional Computational Problems held on August 13, 2007 in Kingston, Ontario. The authors briefly state that unconventional computation is committed to discovering new computing ideas that can solve problems that are difficult for ordinary computers. The authors add that the discussions from the researched materials will provide the reader insights about the theory of computing.