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Anton Zeilinger - One of the best experts on this subject based on the ideXlab platform.
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Quantum Communication with photons
Optics in Our Time, 2016Co-Authors: Mario Krenn, Thomas Scheidl, Rupert Ursin, Mehul Malik, Anton ZeilingerAbstract:The secure Communication of information plays an ever increasing role in our society today. Classical methods of encryption inherently rely on the difficulty of solving a problem such as finding prime factors of large numbers and can, in principle, be cracked by a fast enough machine. The burgeoning field of Quantum Communication relies on the fundamental laws of physics to offer unconditional information security. Here we introduce the key concepts of Quantum superposition and entanglement as well as the no-cloning theorem that form the basis of this field. Then, we review basic Quantum Communication schemes with single and entangled photons and discuss recent experimental progress in ground and space-based Quantum Communication. Finally, we discuss the emerging field of high-dimensional Quantum Communication, which promises increased data rates and higher levels of security than ever before. We discuss recent experiments that use the orbital angular momentum of photons for sharing large amounts of information in a secure fashion.
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Course 9 - Entangled Photons and Quantum Communication
Quantum Entanglement and Information Processing École d' été de Physique des Houches Session LXXIX, 2004Co-Authors: Markus Aspelmeyer, Časlav Brukner, Anton ZeilingerAbstract:This chapter discusses the concept of entangled photons and their application in Quantum Communication. Quantum entanglement offers unique insights into the fundamental principles of our physical world and provides the basis of novel Communication protocols, which allow efficient Communication and computation. Prominent examples are Quantum cryptography, the simultaneous distribution of a cryptographic key that is ultimately secured by the laws of Quantum physics, Quantum dense coding, a protocol to double the classically allowed capacity of a Communication channel by encoding 2 bits of information per bit sent, or Quantum teleportation, the remote transfer of an arbitrary Quantum state between distant locations. Further examples include entanglement-assisted classical Communication to enhance the Communication capacity in a noisy environment or methods to exploit the computational advantages provided by Quantum entanglement for Communication complexity problems. These Quantum Communication protocols utilize entanglement as a resource and form the basis for a new emerging Quantum information technology. To achieve Quantum Communication within a network it is a central task to be able to distribute and manipulate Quantum entanglement, in principle up to a global scale. At present, the only suitable system for transmitting information in long-distance Quantum Communication are photons.
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Entanglement purification for Quantum Communication
Nature, 2001Co-Authors: Jian-wei Pan, Časlav Brukner, Christoph Simon, Anton ZeilingerAbstract:The distribution of entangled states between distant locations will be essential for the future large-scale realization of Quantum Communication schemes such as Quantum cryptography^ 1 , 2 and Quantum teleportation^ 3 . Because of unavoidable noise in the Quantum Communication channel, the entanglement between two particles is more and more degraded the further they propagate. Entanglement purification^ 4 , 5 , 6 , 7 is thus essential to distil highly entangled states from less entangled ones. Existing general purification protocols^ 4 , 5 , 6 are based on the Quantum controlled-NOT (CNOT) or similar Quantum logic operations, which are very difficult to implement experimentally. Present realizations of CNOT gates are much too imperfect to be useful for long-distance Quantum Communication^ 8 . Here we present a scheme for the entanglement purification of general mixed entangled states, which achieves 50 per cent of the success probability of schemes based on the CNOT operation, but requires only simple linear optical elements. Because the perfection of such elements is very high, the local operations necessary for purification can be performed with the required precision. Our procedure is within the reach of current technology, and should significantly simplify the implementation of long-distance Quantum Communication.
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Feasible Entanglement Purification for Quantum Communication
Nature, 2001Co-Authors: Jian-wei Pan, Časlav Brukner, Christoph Simon, Anton ZeilingerAbstract:The distribution of entangled states between distant locations will be essential for the future large scale realization of Quantum Communication schemes such as Quantum cryptography and Quantum teleportation. Because of the unavoidable noise in the Quantum Communication channel, the entanglement between two particles is more and more degraded the further they propagate. Entanglement purification is thus essential to distill highly entangled states from less entangled ones. Existing general purification protocols are based on the Quantum controlled-NOT (CNOT) or similar Quantum logic operations, which are very difficult to implement experimentally. Present realizations of CNOT gates are much too imperfect to be useful for long-distance Quantum Communication. Here we present a feasible scheme for the entanglement purification of general mixed entangled states, which does not require any CNOT operations, but only simple linear optical elements. Since the perfection of such elements is very high, the local operations necessary for purification can be performed with the required precision. Our procedure is within the reach of current technology and should significantly simplify the implementation of long-distance Quantum Communication.
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Quantum Communication
Quantum Information, 2001Co-Authors: Harald Weinfurter, Anton ZeilingerAbstract:Quantum entanglement lies at the heart of the new field of Quantum Communication and computation. For a long time, entanglement was seen just as one of those fancy features which make Quantum mechanics so counterintuitive. But recently, Quantum information theory has shown the tremendous importance of Quantum correlations for the formulation of new methods of information transfer and for algorithms exploiting the capabilities of Quantum computers. While the latter needs entanglement between a large number of Quantum systems, the basic Quantum Communication schemes rely only on entanglement between the members of a pair of particles, directly pointing to a possible realization of such schemes by means of correlated photon pairs such as those produced by parametric down-conversion.
Falk Unger - One of the best experts on this subject based on the ideXlab platform.
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Noisy Interactive Quantum Communication
SIAM Journal on Computing, 2019Co-Authors: Gilles Brassard, Ashwin Nayak, Alain Tapp, Dave Touchette, Falk UngerAbstract:We study the problem of simulating protocols in a Quantum Communication setting over noisy channels. This problem falls at the intersection of Quantum information theory and Quantum Communication c...
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FOCS - Noisy Interactive Quantum Communication
2014 IEEE 55th Annual Symposium on Foundations of Computer Science, 2014Co-Authors: Gilles Brassard, Ashwin Nayak, Alain Tapp, Dave Touchette, Falk UngerAbstract:We study the problem of simulating protocols in a Quantum Communication setting over noisy channels. This problem falls at the intersection of Quantum information theory and Quantum Communication complexity, and will be of importance for eventual real-world applications of interactive Quantum protocols, which can be proved to have exponentially lower Communication costs than their classical counterparts for some problems. These are the first results concerning the Quantum version of this problem, originally studied by Schulman in a classical setting (FOCS '92, STOC '93). We simulate a length N Quantum Communication protocol by a length O(N) protocol with arbitrarily small error. Our simulation strategy has a far higher Communication rate than a naive one that encodes separately each particular round of Communication to achieve comparable success. Such a strategy would have a Communication rate going to 0 in the worst interaction case as the length of the protocols increases, in contrast to our strategy, which has a Communication rate proportional to the capacity of the channel used. Under adversarial noise, our strategy can withstand, for arbitrarily small aepsi; > 0, error rates as high as 1/2 -- aepsi; when parties preshare perfect entanglement, but the classical channel is noisy. We show that this is optimal. Note that in this model, the naive strategy would not work for any constant fraction of errors. We provide extension of these results in several other models of Communication, including when also the entanglement is noisy, and when there is no pre-shared entanglement but Communication is Quantum and noisy. We also study the case of random noise, for which we provide simulation protocols with positive Communication rates and no pre-shared entanglement over some Quantum channels with Quantum capacity Q = 0, proving that Q is in general not the right characterization of a channel's capacity for interactive Quantum Communication. Our results are stated for a general Quantum Communication protocol in which Alice and Bob collaborate, and hold in particular in the Quantum Communication complexity settings of the Yao and Cleve-Buhrman models.
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Noisy Interactive Quantum Communication
arXiv: Quantum Physics, 2013Co-Authors: Gilles Brassard, Ashwin Nayak, Alain Tapp, Dave Touchette, Falk UngerAbstract:We study the problem of simulating protocols in a Quantum Communication setting over noisy channels. This problem falls at the intersection of Quantum information theory and Quantum Communication complexity, and it will be of importance for eventual real-world applications of interactive Quantum protocols, which can be proved to have exponentially lower Communication costs than their classical counterparts for some problems. These are the first results concerning the Quantum version of this problem, originally studied by Schulman in a classical setting (FOCS '92, STOC '93). We simulate a length $N$ Quantum Communication protocol by a length $O(N)$ protocol with arbitrarily small error. Under adversarial noise, our strategy can withstand, for arbitrarily small $\epsilon > 0$, error rates as high as $1/2 -\epsilon$ when parties pre-share perfect entanglement, but the classical channel is noisy. We show that this is optimal. We provide extension of these results in several other models of Communication, including when also the entanglement is noisy, and when there is no pre-shared entanglement but Communication is Quantum and noisy. We also study the case of random noise, for which we provide simulation protocols with positive Communication rates and no pre-shared entanglement over some Quantum channels with Quantum capacity $C_Q=0$, proving that $C_Q$ is in general not the right characterization of a channel's capacity for interactive Quantum Communication. Our results are stated for a general Quantum Communication protocol in which Alice and Bob collaborate, and these results hold in particular in the Quantum Communication complexity settings of the Yao and Cleve--Buhrman models.
Hartmut Klauck - One of the best experts on this subject based on the ideXlab platform.
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Lower Bounds for Quantum Communication Complexity
SIAM Journal on Computing, 2007Co-Authors: Hartmut KlauckAbstract:We prove lower bounds on the bounded error Quantum Communication complexity. Our methods are based on the Fourier transform of the considered functions. First we generalize a method for proving classical Communication complexity lower bounds developed by Raz [Comput. Complexity, 5 (1995), pp. 205-221] to the Quantum case. Applying this method, we give an exponential separation between bounded error Quantum Communication complexity and nondeterministic Quantum Communication complexity. We develop several other lower bound methods based on the Fourier transform, notably showing that $\sqrt{\bar{s}(f)/\log n}$, for the average sensitivity $\bar{s}(f)$ of a function $f$, yields a lower bound on the bounded error Quantum Communication complexity of $f((x \wedge y)\oplus z)$, where $x$ is a Boolean word held by Alice and $y,z$ are Boolean words held by Bob. We then prove the first large lower bounds on the bounded error Quantum Communication complexity of functions, for which a polynomial Quantum speedup is possible. For all the functions we investigate, the only previously applied general lower bound method based on discrepancy yields bounds that are $O(\log n)$.
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Interaction in Quantum Communication
IEEE Transactions on Information Theory, 2007Co-Authors: Hartmut Klauck, Ashwin Nayak, Amnon Ta-shma, David ZuckermanAbstract:In some scenarios there are ways of conveying information with many fewer, even exponentially fewer, qubits than possible classically. Moreover, some of these methods have a very simple structure-they involve only few message exchanges between the communicating parties. It is therefore natural to ask whether every classical protocol may be transformed to a "simpler" Quantum protocol-one that has similar efficiency, but uses fewer message exchanges. We show that for any constant k, there is a problem such that its k+1 message classical Communication complexity is exponentially smaller than its k message Quantum Communication complexity. This, in particular, proves a round hierarchy theorem for Quantum Communication complexity, and implies, via a simple reduction, an Omega(N1k/) lower bound for k message Quantum protocols for Set Disjointness for constant k. Enroute, we prove information-theoretic lemmas, and define a related measure of correlation, the informational distance, that we believe may be of significance in other contexts as well
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Lower bounds for Quantum Communication complexity
arXiv: Quantum Physics, 2001Co-Authors: Hartmut KlauckAbstract:We prove new lower bounds for bounded error Quantum Communication complexity. Our methods are based on the Fourier transform of the considered functions. First we generalize a method for proving classical Communication complexity lower bounds developed by Raz to the Quantum case. Applying this method we give an exponential separation between bounded error Quantum Communication complexity and nondeterministic Quantum Communication complexity. We develop several other lower bound methods based on the Fourier transform, notably showing that \sqrt{\bar{s}(f)/\log n}, for the average sensitivity \bar{s}(f) of a function f, yields a lower bound on the bounded error Quantum Communication complexity of f(x AND y XOR z), where x is a Boolean word held by Alice and y,z are Boolean words held by Bob. We then prove the first large lower bounds on the bounded error Quantum Communication complexity of functions, for which a polynomial Quantum speedup is possible. For all the functions we investigate, the only previously applied general lower bound method based on discrepancy yields bounds that are O(\log n).
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FOCS - Lower bounds for Quantum Communication complexity
Proceedings 42nd IEEE Symposium on Foundations of Computer Science, 2001Co-Authors: Hartmut KlauckAbstract:We prove new lower bounds for bounded error Quantum Communication complexity. Our methods are based on the Fourier transform of the considered functions. First we generalize a method for proving classical Communication complexity lower bounds developed by R. Raz (1995) to the Quantum case. Applying this method we give an exponential separation between bounded error Quantum Communication complexity and nondeterministic Quantum Communication complexity. We develop several other Fourier based lower bound methods, notably showing that /spl radic/(s~(f)/log n) n, for the average sensitivity s~(f) of a function f, yields a lower bound on the bounded error Quantum Communication complexity of f (x/spl and/y/spl oplus/yz), where x is a Boolean word held by Alice and y, z are Boolean words held by Bob. We then prove the first large lower bounds on the bounded error Quantum Communication complexity of functions, for which a polynomial Quantum speedup is possible. For all the functions we investigate, only the previously applied general lower bound method based on discrepancy yields bounds that are O(log n).
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Quantum Communication Complexity
arXiv: Quantum Physics, 2000Co-Authors: Hartmut KlauckAbstract:This paper surveys the field of Quantum Communication complexity. Some interesting recent results are collected concerning relations to classical Communication, lower bound methods, one-way Communication, and applications of Quantum Communication complexity.
Jian-wei Pan - One of the best experts on this subject based on the ideXlab platform.
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Entangled photons and Quantum Communication
Physics Reports, 2010Co-Authors: Zhen-sheng Yuan, Xiao-hui Bao, Chao Yang Lu, Cheng-zhi Peng, Jun Zhang, Jian-wei PanAbstract:This article reviews the progress of Quantum Communication that utilizes photonic entanglement. We start with a survey of various methods for generating entangled photons, followed by an introduction of the theoretical principles and the experimental implementations of Quantum key distribution. We then move on to a discussion of more involved Quantum Communication protocols including Quantum dense coding, teleportation and Quantum Communication complexity. After that, we review the progress in free-space Quantum Communication, decoherence-free subspace, and Quantum repeater protocols which are essential ingredients for long-distance Quantum Communication. Practical realizations of Quantum repeaters, which require an interface between photons and Quantum memories, are discussed briefly. Finally, we draw concluding remarks considering the technical challenges, and put forward an outlook on further developments of this field.
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Advanced Quantum Communication based on multi-photon entanglement
2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006Co-Authors: Jian-wei Pan, Yu-ao Chen, Qiang ZhangAbstract:We present several experimental progresses for advanced Quantum Communication based on multi-photon entanglement. Quantum secret sharing (QSS) and third-man Quantum cryptograph (TQC) shows the advancement in multi-party Quantum Communication. Quantum error rejection (QER) holds the promise for error-free transfer in long-distance Quantum Communication. Fault-tolerant Quantum cryptography in a decoherence-free subspace (DFS) and Quantum-relay-assisted key distribution respectively overcome the difficulties caused by decoherence and photon loss, the two main crucial problems in long-distance Quantum Communication.
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Entanglement purification for Quantum Communication
Nature, 2001Co-Authors: Jian-wei Pan, Časlav Brukner, Christoph Simon, Anton ZeilingerAbstract:The distribution of entangled states between distant locations will be essential for the future large-scale realization of Quantum Communication schemes such as Quantum cryptography^ 1 , 2 and Quantum teleportation^ 3 . Because of unavoidable noise in the Quantum Communication channel, the entanglement between two particles is more and more degraded the further they propagate. Entanglement purification^ 4 , 5 , 6 , 7 is thus essential to distil highly entangled states from less entangled ones. Existing general purification protocols^ 4 , 5 , 6 are based on the Quantum controlled-NOT (CNOT) or similar Quantum logic operations, which are very difficult to implement experimentally. Present realizations of CNOT gates are much too imperfect to be useful for long-distance Quantum Communication^ 8 . Here we present a scheme for the entanglement purification of general mixed entangled states, which achieves 50 per cent of the success probability of schemes based on the CNOT operation, but requires only simple linear optical elements. Because the perfection of such elements is very high, the local operations necessary for purification can be performed with the required precision. Our procedure is within the reach of current technology, and should significantly simplify the implementation of long-distance Quantum Communication.
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Feasible Entanglement Purification for Quantum Communication
Nature, 2001Co-Authors: Jian-wei Pan, Časlav Brukner, Christoph Simon, Anton ZeilingerAbstract:The distribution of entangled states between distant locations will be essential for the future large scale realization of Quantum Communication schemes such as Quantum cryptography and Quantum teleportation. Because of the unavoidable noise in the Quantum Communication channel, the entanglement between two particles is more and more degraded the further they propagate. Entanglement purification is thus essential to distill highly entangled states from less entangled ones. Existing general purification protocols are based on the Quantum controlled-NOT (CNOT) or similar Quantum logic operations, which are very difficult to implement experimentally. Present realizations of CNOT gates are much too imperfect to be useful for long-distance Quantum Communication. Here we present a feasible scheme for the entanglement purification of general mixed entangled states, which does not require any CNOT operations, but only simple linear optical elements. Since the perfection of such elements is very high, the local operations necessary for purification can be performed with the required precision. Our procedure is within the reach of current technology and should significantly simplify the implementation of long-distance Quantum Communication.
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ISCAS - Quantum Communication and entanglement
2000 IEEE International Symposium on Circuits and Systems. Emerging Technologies for the 21st Century. Proceedings (IEEE Cat No.00CH36353), 1Co-Authors: Harald Weinfurter, Jian-wei Pan, Christoph Simon, Dirk Bouwmeester, Matthew Daniell, Thomas Jennewein, Gregor Weihs, Anton ZeilingerAbstract:Quantum entanglement lies at the heart of new proposals for Quantum Communication and computation, like Quantum cryptography and Quantum teleportation. Here we describe the experimental realizations of Quantum Communication schemes, which improve existing classical methods or add new features to the world of Communication.
Gilles Brassard - One of the best experts on this subject based on the ideXlab platform.
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Noisy Interactive Quantum Communication
SIAM Journal on Computing, 2019Co-Authors: Gilles Brassard, Ashwin Nayak, Alain Tapp, Dave Touchette, Falk UngerAbstract:We study the problem of simulating protocols in a Quantum Communication setting over noisy channels. This problem falls at the intersection of Quantum information theory and Quantum Communication c...
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FOCS - Noisy Interactive Quantum Communication
2014 IEEE 55th Annual Symposium on Foundations of Computer Science, 2014Co-Authors: Gilles Brassard, Ashwin Nayak, Alain Tapp, Dave Touchette, Falk UngerAbstract:We study the problem of simulating protocols in a Quantum Communication setting over noisy channels. This problem falls at the intersection of Quantum information theory and Quantum Communication complexity, and will be of importance for eventual real-world applications of interactive Quantum protocols, which can be proved to have exponentially lower Communication costs than their classical counterparts for some problems. These are the first results concerning the Quantum version of this problem, originally studied by Schulman in a classical setting (FOCS '92, STOC '93). We simulate a length N Quantum Communication protocol by a length O(N) protocol with arbitrarily small error. Our simulation strategy has a far higher Communication rate than a naive one that encodes separately each particular round of Communication to achieve comparable success. Such a strategy would have a Communication rate going to 0 in the worst interaction case as the length of the protocols increases, in contrast to our strategy, which has a Communication rate proportional to the capacity of the channel used. Under adversarial noise, our strategy can withstand, for arbitrarily small aepsi; > 0, error rates as high as 1/2 -- aepsi; when parties preshare perfect entanglement, but the classical channel is noisy. We show that this is optimal. Note that in this model, the naive strategy would not work for any constant fraction of errors. We provide extension of these results in several other models of Communication, including when also the entanglement is noisy, and when there is no pre-shared entanglement but Communication is Quantum and noisy. We also study the case of random noise, for which we provide simulation protocols with positive Communication rates and no pre-shared entanglement over some Quantum channels with Quantum capacity Q = 0, proving that Q is in general not the right characterization of a channel's capacity for interactive Quantum Communication. Our results are stated for a general Quantum Communication protocol in which Alice and Bob collaborate, and hold in particular in the Quantum Communication complexity settings of the Yao and Cleve-Buhrman models.
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Noisy Interactive Quantum Communication
arXiv: Quantum Physics, 2013Co-Authors: Gilles Brassard, Ashwin Nayak, Alain Tapp, Dave Touchette, Falk UngerAbstract:We study the problem of simulating protocols in a Quantum Communication setting over noisy channels. This problem falls at the intersection of Quantum information theory and Quantum Communication complexity, and it will be of importance for eventual real-world applications of interactive Quantum protocols, which can be proved to have exponentially lower Communication costs than their classical counterparts for some problems. These are the first results concerning the Quantum version of this problem, originally studied by Schulman in a classical setting (FOCS '92, STOC '93). We simulate a length $N$ Quantum Communication protocol by a length $O(N)$ protocol with arbitrarily small error. Under adversarial noise, our strategy can withstand, for arbitrarily small $\epsilon > 0$, error rates as high as $1/2 -\epsilon$ when parties pre-share perfect entanglement, but the classical channel is noisy. We show that this is optimal. We provide extension of these results in several other models of Communication, including when also the entanglement is noisy, and when there is no pre-shared entanglement but Communication is Quantum and noisy. We also study the case of random noise, for which we provide simulation protocols with positive Communication rates and no pre-shared entanglement over some Quantum channels with Quantum capacity $C_Q=0$, proving that $C_Q$ is in general not the right characterization of a channel's capacity for interactive Quantum Communication. Our results are stated for a general Quantum Communication protocol in which Alice and Bob collaborate, and these results hold in particular in the Quantum Communication complexity settings of the Yao and Cleve--Buhrman models.
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Quantum Communication complexity
Foundations of Physics, 2003Co-Authors: Gilles BrassardAbstract:Can Quantum Communication be more efficient than its classical counterpart? Holevo’s theorem rules out the possibility of communicating more than n bits of classical information by the transmission of n Quantum bits—unless the two parties are entangled, in which case twice as many classical bits can be communicated but no more. In apparent contradiction, there are distributed computational tasks for which Quantum Communication cannot be simulated efficiently by classical means. In some cases, the effect of transmitting Quantum bits cannot be achieved classically short of transmitting an exponentially larger number of bits. In a similar vein, can entanglement be used to save on classical Communication? It is well known that entanglement on its own is useless for the transmission of information. Yet, there are distributed tasks that cannot be accomplished at all in a classical world when Communication is not allowed, but that become possible if the non-communicating parties share prior entanglement. This leads to the question of how expensive it is, in terms of classical Communication, to provide an exact simulation of the spooky power of entanglement.
