Showing papers on "No-teleportation theorem published in 2006"
TL;DR: In this article, it is shown that there is a class of $W$ states that can be used for perfect teleportation and super-dense coding, and that these states can be classified into two categories: GHZ states and W$ states.
Abstract: True tripartite entanglement of the state of a system of three qubits can be classified on the basis of stochastic local operations and classical communications. Such states can be classified into two categories: GHZ states and $W$ states. It is known that GHZ states can be used for teleportation and superdense coding, but the prototype $W$ state cannot be. However, we show that there is a class of $W$ states that can be used for perfect teleportation and superdense coding.
432 citations
TL;DR: The results show that the presence of redundancy divides information about the system into three parts: classical ( redundant); purely quantum; and the borderline, undifferentiated or "nonredundant," information.
Abstract: We lay a comprehensive foundation for the study of redundant information storage in decoherence processes. Redundancy has been proposed as a prerequisite for objectivity, the defining property of classical objects. We consider two ensembles of states for a model universe consisting of one system and many environments: the first consisting of arbitrary states, and the second consisting of "singly branching" states consistent with a simple decoherence model. Typical states from the random ensemble do not store information about the system redundantly, but information stored in branching states has a redundancy proportional to the environment's size. We compute the specific redundancy for a wide range of model universes, and fit the results to a simple first-principles theory. Our results show that the presence of redundancy divides information about the system into three parts: classical (redundant); purely quantum; and the borderline, undifferentiated or "nonredundant," information.
202 citations
TL;DR: In this paper, a six-photon interferometer was used to teleport an arbitrary polarization state of two photons, and the observed teleportation fidelities for different initial states are all well beyond the state estimation limit of 0.40 for a two-qubit system.
Abstract: Quantum teleportation1, a way to transfer the state of a quantum system from one location to another, is central to quantum communication2 and plays an important role in a number of quantum computation protocols3,4,5. Previous experimental demonstrations have been implemented with single photonic6,7,8,9,10,11 or ionic qubits12,13. However, teleportation of single qubits is insufficient for a large-scale realization of quantum communication and computation2,3,4,5. Here, we present the experimental realization of quantum teleportation of a two-qubit composite system. In the experiment, we develop and exploit a six-photon interferometer to teleport an arbitrary polarization state of two photons. The observed teleportation fidelities for different initial states are all well beyond the state estimation limit of 0.40 for a two-qubit system14. Not only does our six-photon interferometer provide an important step towards teleportation of a complex system, it will also enable future experimental investigations on a number of fundamental quantum communication and computation protocols3,15,16,17,18.
185 citations
TL;DR: In this article, Deng et al. proposed a scheme which allows an arbitrary 2-qubit quantum state teleportation between two remote parties with control of many agents in a network, and then they generalize the scheme to teleport an arbitrary n-quit quantum state.
115 citations
TL;DR: In this paper, the authors generalize Yeo and Chua's results to teleporting an arbitrary $N$-qubit state via a genuine four qubit entanglement channel.
Abstract: Recently Yeo and Chua [Phys. Rev. Lett. 96, 060502 (2006)] presented an explicit protocol for faithfully teleporting an arbitrary two-qubit state via a genuine four-qubit entanglement channel. Here we generalize completely their results to teleporting an arbitrary $N$-qubit state via genuine $N$-qubit entanglement channels. And we present the general form of the genuine multipartite entanglement channels, namely, the sufficient and necessary condition the genuine $N$-qubit entanglement channels must satisfy to teleport an arbitrary $N$-qubit state.
111 citations
TL;DR: The concepts of quantum entanglement and teleportation in the CV framework are developed by analogy with the qubit-based approach by addressing the study of CV quantum teleportation networks where more users share a multipartite state and an arbitrary pair of them performs quantum teleportation.
Abstract: Very recently, we took part in a new development of quantum information, the so-called continuous variable (CV) quantum information theory. Such a further development is mainly due to the experimental and theoretical advantages offered by CV systems, i.e., quantum systems described by a set of observables, like position and momentum, which have a continuous spectrum of eigenvalues. According to this novel trend, quantum information protocols like quantum teleportation have been suitably extended to the CV framework. Here, we briefly review some mathematical tools relative to CV systems, and we consequently develop the concepts of quantum entanglement and teleportation in the CV framework by analogy with the qubit-based approach. Some connections between teleportation fidelity and entanglement properties of the underlying quantum channel are inspected. Next, we address the study of CV quantum teleportation networks where more users share a multipartite state and an arbitrary pair of them performs quantum teleportation. In this context, we show alternative protocols, and we investigate the optimal strategy that maximizes the performance of the network.
89 citations
TL;DR: This protocol is modified for multiparty quantum state sharing of an arbitrary m-particle entangled state based on quantum teleportation with only Bell state measurements and local unitary operations which make this protocol more convenient in a practical application than others.
73 citations
TL;DR: This work revisits the problem of conveying classical messages by transmitting quantum states, and derive new, optimal bounds on the number of quantum bits required for this task, using a simple linear algebraic technique.
Abstract: We revisit the problem of conveying classical messages by transmitting quantum states, and derive new, optimal bounds on the number of quantum bits required for this task. Much of the previous work on this problem, and on other communication tasks in the setting of bounded error entanglement-assisted communication, is based on sophisticated information theoretic arguments. Our results are derived from first principles, using a simple linear algebraic technique. A direct consequence is a tight lower bound for the Inner Product function that has found applications to privacy amplification in quantum key distribution protocols.
45 citations
TL;DR: This Letter introduces a framework of quantum schemes where Alice commits a string of n bits to Bob, in such a way that she can only cheat on a bits and Bob can learn at most b bits of information before the reveal phase.
Abstract: Unconditionally secure nonrelativistic bit commitment is known to be impossible in both the classical and the quantum world. However, when committing to a string of $n$ bits at once, how far can we stretch the quantum limits? In this Letter, we introduce a framework of quantum schemes where Alice commits a string of $n$ bits to Bob, in such a way that she can only cheat on $a$ bits and Bob can learn at most $b$ bits of information before the reveal phase. Our results are twofold: we show by an explicit construction that in the traditional approach, where the reveal and guess probabilities form the security criteria, no good schemes can exist: $a+b$ is at least $n$. If, however, we use a more liberal criterion of security, the accessible information, we construct schemes where $a=4{log }_{2}n+O(1)$ and $b=4$, which is impossible classically. Our findings significantly extend known no-go results for quantum bit commitment.
40 citations
TL;DR: An exact expression for teleportation fidelity is obtained that depends solely on the dimension and singlet fraction for the entanglement channel andEntanglement (measures by I concurrence) for the state.
Abstract: We analyze quantum teleportation for composite systems, specifically for concatenated teleporation (decomposing a large composite state into smaller states of dimension commensurate with the channel) and partial teleportation (teleporting one component of a larger quantum state) We obtain an exact expression for teleportation fidelity that depends solely on the dimension and singlet fraction for the entanglement channel and entanglement (measures by $I$ concurrence) for the state; in fact quantum teleportation for composite systems provides an operational interpretation for $I$ concurrence In addition we obtain tight bounds on teleportation fidelity and prove that the average fidelity approaches the lower bound of teleportation fidelity in the high-dimension limit
31 citations
TL;DR: The no-splitting theorem as discussed by the authors states that an unknown quantum bit (qubit) cannot be split into two complementary qubits (i.e., a qubit state is a single entity which cannot be cloned or split).
TL;DR: In this paper, the authors proposed a method to realize the teleportation of an unknown entangled state that consists of many qudits through a partially entangled-qudit quantum channel with the help of 2log2d-bit classical communication.
Abstract: We propose a method to realize the teleportation of an unknown entangled state that consists of many qudits through a partially entangled-qudit quantum channel with the help of 2log2d-bit classical communication. The operations used in the teleportation process include a generalized Bell-state measurement and a series of single-qudit π-measurements performed by Alice, a series of generalized qudit-Pauli gates and two-level unitary gates, as well as a qubit measurement performed by Bob. For a maximally entangled quantum channel, the successful probability of the teleportation becomes unit.
TL;DR: This paper provides the optimal trade-off between the approximation measure ϵ and the amount of classical entropy used in the encryption of single quantum bits and considers n-qubit encryption schemes which are a composition of independent single-qu bit ones and provide the optimal schemes both in the 2- and the ∞-norm.
Abstract: It is well known that n bits of entropy are necessary and sufficient to perfectly encrypt n bits (one-time pad). Even if we allow the encryption to be approximate, the amount of entropy needed does not asymptotically change. However, this is not the case when we are encrypting quantum bits. For the perfect encryption of n quantum bits, 2n bits of entropy are necessary and sufficient (quantum one-time pad), but for approximate encryption one asymptotically needs only n bits of entropy. In this paper, we provide the optimal trade-off between the approximation measure ϵ and the amount of classical entropy used in the encryption of single quantum bits. Then, we consider n-qubit encryption schemes which are a composition of independent single-qubit ones and provide the optimal schemes both in the 2- and the ∞-norm. Moreover, we provide a counterexample to show that the encryption scheme of Ambainis-Smith [Proceedings of RANDOM ’04, pp. 249–260] based on small-bias sets does not work in the ∞-norm.
TL;DR: In this paper, the authors investigated the lower bound of the amount of entanglement required for faithfully teleporting a quantum state belonging to a subset of the whole Hilbert space and presented a probabilistic teleportation scheme using a non-maximally entangled state as the quantum channel.
TL;DR: This paper proposes a scheme for teleporting a kind of essential three-particle non-symmetric entangled state, which is much more valuable than a GHZ and W state for some applications in quantum information processing and shows that there exists a class of transformations which ensure the success of this scheme.
Abstract: This paper proposes a scheme for teleporting a kind of essential three-particle non-symmetric entangled state, which is much more valuable than a GHZ and W state for some applications in quantum information processing. In comparison with previous proposal of teleportation, the resources of entangled states as quantum channel and the number of classical messages required by our scheme can be cut down. Moreover, it is shown that there exists a class of transformations which ensure the success of this scheme, because the two-particle transformation performed by the receiver in the course of teleportation may be a generic two-particle operation instead of a control-NOT (CNOT) operation. In addition, all kinds of transformations performed by sender and receiver are given in detail.
TL;DR: In this article, the existence of incomparable states which are not interconvertible deterministically by local operations and classical communications was shown to be a physical impossibility of quantum information processing.
Abstract: We present here a scheme that relates seemingly two different kinds of physical impossibilities of quantum information processing. We derive, exact flipping of three arbitrary states not lying in one great circle is not possible with certainty, by using the existence of incomparable states which are not interconvertible deterministically by local operations and classical communications. In contrast, considering the non-existence of exact universal flipper, the incomparability of a pair of bipartite pure entangled states can be established. PACS number(s): 03.67.Hk, 03.65.Ud.
TL;DR: This work shows that this trade-off between the teleportation fidelity and the fidelity of estimation of the teleported state from the results of the Bell measurement can be improved by up to 2.77% if the authors use a suitable non-Gaussian operation.
Abstract: In standard coherent state teleportation with a shared two-mode squeezed vacuum (TMSV) state there is a trade-off between the teleportation fidelity and the fidelity of estimation of the teleported state from the results of the Bell measurement. Within the class of Gaussian operations this trade-off is optimal, i.e., there is not a Gaussian operation that would give a larger estimation fidelity for a given output fidelity. We show that this trade-off can be improved by up to 2.77% if we use a suitable non-Gaussian operation. This operation can be implemented by the standard teleportation protocol in which the shared TMSV state is replaced with a suitable non-Gaussian entangled state. We also demonstrate that this operation can be used to enhance the transmission fidelity of a certain noisy channel.
TL;DR: The effectiveness of decoherence suppression schemes is explored using quantum bits (qubits) stored in Li np Rydberg states using pulsed electric fields to control the electronic spin-orbit coupling, facilitating qubit creation, manipulation, and measurement.
Abstract: The effectiveness of decoherence suppression schemes is explored using quantum bits (qubits) stored in Li np Rydberg states. Following laser excitation, pulsed electric fields coherently control the electronic spin-orbit coupling, facilitating qubit creation, manipulation, and measurement. Spin-orbit coupling creates an approximate decoherence-free subspace for extending qubit storage times. However, sequences of fast NOT operations are found to be substantially more effective for preserving coherence.
TL;DR: In this paper, the authors proposed a classical analogue of the Hughston-Jozsa-Wootters (HJW) quantum non-locality, called classical remote steering.
Abstract: An interesting protocol for classical teleportation of an unknown classical state was recently suggested by Cohen, and by Gour and Meyer. In that protocol, Bob can sample from a probability distribution that is given to Alice, even if Alice has absolutely no knowledge about . Pursuing a similar line of thought, we suggest here a limited form of non-locality — "classical non-locality." Our non-locality is the (somewhat limited) classical analogue of the Hughston–Jozsa–Wootters (HJW) quantum non-locality. The HJW non-locality (also known as "quantum remote steering") tells us how, for a given density matrix ρ, Alice can generate any ρ-ensemble on the North Star. This is done using surprisingly few resources — one shared entangled state (prepared in advance), one generalized quantum measurement, and no communication. Similarly, our classical non-locality (which we call "classical remote steering") presents how, for a given probability distribution , Alice can generate any -ensemble on the North Star, using only one correlated state (prepared in advance), one (generalized) classical measurement, and no communication. It is important to clarify that while the classical teleportation and the classical non-locality protocols are probably rather insignificant from a classical information processing point of view, they significantly contribute to our understanding of what exactly is quantum in their well established and highly famous quantum analogues.
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TL;DR: The characterization of invertible quantum operations implies that one-way schemes for encrypting quantum states using a classical key may be slightly more general than the ``private quantum channels'' studied by Ambainis, Mosca, Tapp and de Wolf (FOCS 2000), and their results extend in a straightforward manner to the general case.
Abstract: In this note, we characterize the form of an invertible quantum operation, i.e., a completely positive trace preserving linear transformation (a CPTP map) whose inverse is also a CPTP map. The precise form of such maps becomes important in contexts such as self-testing and encryption. We show that these maps correspond to applying a unitary transformation to the state along with an ancilla initialized to a fixed state, which may be mixed.
The characterization of invertible quantum operations implies that one-way schemes for encrypting quantum states using a classical key may be slightly more general than the ``private quantum channels'' studied by Ambainis, Mosca, Tapp and de Wolf (FOCS 2000). Nonetheless, we show that their results, most notably a lower bound of 2n bits of key to encrypt n quantum bits, extend in a straightforward manner to the general case.
TL;DR: In this article, the standard quantum teleportation scheme is deconstructed and those aspects of it that appear remarkable and "non-classical" are identified, and an alternative teleportation scheme, involving only classical states and classical information, is then formulated, and it is shown that the classical scheme reproduces all of these remarkable aspects, despite the fact that they had seemed nonclassical.
Abstract: The standard quantum teleportation scheme is deconstructed, and those aspects of it that appear remarkable and "non-classical" are identified. An alternative teleportation scheme, involving only classical states and classical information, is then formulated, and it is shown that the classical scheme reproduces all of these remarkable aspects, despite the fact that they had seemed non-classical. This leads to a re-examination of quantum teleportation, which suggests that its significance depends on the interpretation of quantum states.
TL;DR: In this article, the authors investigated quantum teleportation of even and odd coherent states in terms of the EPR entanglement states for continuous variables and showed that the quality of teleporting quantum states also depends on the characteristics of the states themselves.
Abstract: This paper has investigated quantum teleportation of even and odd coherent states in terms of the EPR entanglement states for continuous variables. It discusses the relationship between the fidelity and the entanglement of EPR states, which is characterized by the degree of squeezing and the gain of classical channels. It shows that the quality of teleporting quantum states also depends on the characteristics of the states themselves. The properties of teleporting even and odd coherent states at different intensities are investigated. The difference of teleporting two such kinds of quantum states are analysed based on the quantum distance function.
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TL;DR: The extended Temperley--Lieb category is proposed as a mathematical framework to describe quantum information and computation involving maximally entangled states and local unitary transformations.
Abstract: In this paper, we explore algebraic structures and low dimensional topology underlying quantum information and computation. We revisit quantum teleportation from the perspective of the braid group, the symmetric group and the virtual braid group, and propose the braid teleportation, the teleportation swapping and the virtual braid teleportation, respectively. Besides, we present a physical interpretation for the braid teleportation and explain it as a sort of crossed measurement. On the other hand, we propose the extended Temperley--Lieb diagrammatical approach to various topics including quantum teleportation, entanglement swapping, universal quantum computation, quantum information flow, and etc. The extended Temperley--Lieb diagrammatical rules are devised to present a diagrammatical representation for the extended Temperley--Lieb category which is the collection of all the Temperley--Lieb algebras with local unitary transformations. In this approach, various descriptions of quantum teleportation are unified in a diagrammatical sense, universal quantum computation is performed with the help of topological-like features, and quantum information flow is recast in a correct formulation. In other words, we propose the extended Temperley--Lieb category as a mathematical framework to describe quantum information and computation involving maximally entangled states and local unitary transformations.
TL;DR: A scheme in which any given qubit could be remotely prepared by using minimum classical bits and the previously shared non-maximally entangled state with a high fidelity, under the condition that the receiver holds the knowledge of θ is presented.
Abstract: In a process of remote state preparation, the universality of quantum channel is an essential ingredient. That is, one quantum channel should be feasible to remotely prepare any given qubit state. This problem appears in a process where one uses non-maximally entangled state as the passage. We present a scheme in which any given qubit | = cos θ|0+sin θei|1 could be remotely prepared by using minimum classical bits and the previously shared non-maximally entangled state with a high fidelity, under the condition that the receiver holds the knowledge of θ. This condition is helpful to reduce the necessary amount of quantum channels, which is proven to be a low quantity to realize the universality. We also give several methods to investigate the trade-off between this amount and the achievable fidelity of the protocol.
TL;DR: The Braunstein–Kimble method for teleportation of light is analyzed in the language of quantum wave functions and a pictorial example of continuous variable teleportation is presented using computer simulation.
Abstract: A dialog with Asher Peres regarding the meaning of quantum teleportation is briefly reviewed. The Braunstein–Kimble method for teleportation of light is analyzed in the language of quantum wave functions. A pictorial example of continuous variable teleportation is presented using computer simulation.
TL;DR: Two simple schemes for probabilistic teleportation of an arbitrary unknown two-particle state using a non-maximally entangled EPR pair and a non -maximalally entangled GHZ state as quantum channels are proposed.
Abstract: Two simple schemes for probabilistic teleportation of an arbitrary unknown two-particle state using a non-maximally entangled EPR pair and a non-maximally entangled GHZ state as quantum channels are proposed. After receiving Alice's Bell state measurement results, Bob performs a collective unitary transformation on his inherent particles without introducing the auxiliary qubit. The original state can be probabilistically teleported. Meanwhile, quantum circuits for realization of successful teleportation are also presented.
TL;DR: In this article, an expression for the accessible information in mirror-symmetric ensembles of real qubit states was formulated and an optimal quantum measurement strategy was proposed for extracting accessible information.
Abstract: We formulate an expression for the accessible information in mirror-symmetric ensembles of real qubit states This expression is used to make a detailed study of optimum quantum measurements for extracting the accessible information in three-state, mirror-symmetric ensembles Distinct measurement regimes are identified for these ensembles with optimal measurement strategies involving different numbers of measurement operators, similar to results found for minimum error discrimination Our results generalize known results for the accessible information in two pure states and in the trine ensemble
03 Jan 2006
TL;DR: In this paper, the authors showed that the complete teleportation is possible even in the case of non-maximal entangled states, where the entangled state between Alice and Bob is not maximal.
Abstract: The quantum teleportation has been discussed by several articles by several different schemes. In most of models, complete teleportation can be occurred if the entangled state between Alice and Bob is maximal. In [1], we reformulated the teleportation and showed in our scheme that the complete teleportation is possible even in the case for non‐maximal entangled state.
01 Jan 2006
TL;DR: In this paper, anti-linear maps governing EPR tasks in the absence of distinguished reference bases are presented. But they do not cover the problem of perfect quantum teleportation and its composition rule, nor of EPR with an arbitrary mixed state.
Abstract: The topics of the paper are: a) Anti-linear maps governing EPR tasks in the absence of distinguished reference bases b) Imperfect quantum teleportation and its composition rule c) Quantum teleportation by distributed measurements d) Remarks on EPR with an arbitrary mixed state, and triggered by a Luders measurement
TL;DR: In this paper, the authors present additional considerations to elucidate the nature of Cohen's classical teleportation of classical bits and show that the teleportation is a classical teleportation in the classical sense.
Abstract: We present additional considerations to elucidate the nature of Cohen's classical teleportation of classical bits.