Due to the Heisemberg uncertainty principle, it is impossible to design a procedure which permits perfect cloning of an arbitrary, unknown "qubit" (the spin or polarization state of a single quantum system)1,2. However, it is believed that a perfect copying protocol can be achieved, at least in principle, if the qubit to be copied is destroyed in the original system. Quantum teleportation3,4 is supposed to allow for such a result. Here, this belief is shown to be invalidated by a fundamental uncertainty about the number of particles involved in any process, as predicted by Quantum Field Theory. As a result, teleportation cannot provide an infallible copying procedure for the single qubits, not even in the limit of perfect experimental sensitivities. The no-cloning theorem1,2 can then be generalized to the case of destroying the original. Teleportation remains an interesting statistical procedure, having an unavoidable theoretical error at the percent level or few orders of magnitude smaller, depending on the physical process that is used. Although it cannot be made arbitrarily small, such an error is small enough to remain hidden in present experiments.
Quantum teleportation allows the transmission of unknown quantum states over arbitrary distances. This paper studies quantum teleportation via two non-interacting qubits coupled to local fields and Ornstein Uhlenbeck noise. We consider two different qubit-noise configurations, i.e., common qubit-noise interactions and independent qubit-noise interactions. We introduce a Gaussian Ornstein Uhlenbeck process to take into account the noisy effects of the local external fields. Furthermore, we address the intrinsic behavior of classical fields toward single- and two-qubit quantum teleportation as a function of various parameters. Additionally, using a quantum estimation theory, we study single- and multi-parameter estimation of the teleported state output for single and two-qubit quantum teleportation scenarios. One important application of this work is obtaining more valuable information in quantum remote sensing.
Tele-conference systems are widely used as a form of communication media between remote sites. In order to overcome the limitations of video-based tele-conference systems with the continued technological innovations in mixed reality (MR), the use of a three-dimensional teleported avatar, in which a remote participant is teleported into a local environment, would be an effective future tele-conference system that would allow natural movement and interaction in the same location. However, technical difficulties must be resolved to enable control of the teleported avatar adapted to the environmental differences of the remote location and the user’s situation. This paper presents a novel method to adjust automatic gaze alignment of the teleported avatar with matching in the local site for MR collaborative environments. We ran comparative validation experiments to measure spatial accuracy of the gaze and evaluate the user’s communication efficiency using our method. In a quantitative experiment, the degree of gaze matching error in various environments was found to form a mirror-symmetrical U-shape, and the necessity of gaze matching gain was also recognized. Additionally, our experimental study showed that participants felt a greater co-presence during communication than in an idle situation without conversation.
Abstract With the continued technology innovation in object sensing and human motion tracking, the traditional two‐dimensional video‐based tele‐conference systems are projected to evolve into the three‐dimensional immersive and augmented reality (AR) based on which one can communicate with the teleported remote other as if present, moving and interacting naturally in the same location. One technical hurdle to this vision is the need to resolve the environmental differences and the resulting teleported avatar motion anomaly between the remote and local sites. This paper presents a novel method to first establish a spatial and object‐level match between the remote and local sites and adapts the position and motion of the teleported avatar into the local AR space according to the matched information. This results in a natural looking and spatially correct rendering of the remote user in the local augmented space and a significantly improved tele‐conference experience and communication performance. Copyright © 2015 John Wiley & Sons, Ltd.
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We show that, for the purpose of quantum communication via a quantum field, it is essential to view the field not only as a medium for transmission but also as a source of entanglement that can aid in the communication task. To this end, we consider the quantum communication scenario where Alice is initially entangled with an ancilla and intends to communicate with Bob through a quantum field, so as to make Bob entangled with the ancilla. We find that if Alice and Bob communicate by directly coupling to the quantum field, then they can generate negativity between Bob and the ancilla only at orders that are higher than second perturbative order. We then present a protocol based on quantum teleportation in which Alice and Bob consume entanglement that they obtained from the field via interaction or harvesting. We show that this protocol can transfer negativity already to second perturbative order.
We estimate the teleported and the gained parameters by means of Fisher information in a non-inertial frame. The sender and the receiver share an accelerated maximum or partial entangled state. The estimation degree of these parameters depends on Unruh acceleration, the used single mode approximation(within/ beyond), the structure of the initial teleported state, and the entanglement of the initial communication channel. The maximization and minimization estimation degree of the teleported parameters depend on the initial encoded information. The estimation degree of the parameters can be maximized if the partners teleport classical information.
We study the pairwise quantum correlations for teleported state via a symmetric multi-qubitsystem. In the other words, the proposed model is considered as a quantum channel. Using thequantum discord, super quantum discord and concurrence to quantify quantum correlations forteleported state, some analytical and numerical results are presented. Moreover, we compare thedynamical evolutions of quantum correlations and fidelity versus measurement strength and thenumber of qubit channel for teleported state via symmetric multi-qubit model. Our main goalnow is to study how we can increase the quantum correlations and the fidelity of the teleportedstate in the presence of decoherence. The results show that, measurement strength and thenumber of qubit can control the quantum information obtained through the quantum channel.Therefore, measurement strength can be a good option for measuring exchanged information inthe teleportation process. In addition to, quantum correlations can provide an effective role inquantum teleportation
One of the teleportation versions is applied to convey an entangled two-qubit system via a class of a two-qubit XYZ Heisenberg chain model. At thermal equilibrium, the exact solution of the XYZ model with an external magnetic field and the Kaplan-Shekhtman-Entin-Wohlman-Aharony interaction (KSEWA-interaction) is proposed in X, and Z direction. The teleported quantum Fisher information is studied, where we estimate the weight parameter θ, temperature and the strength parameter of KSEWA-interaction. It is found that, the strength of the KSEWA-interaction and the magnetic field be of benefit in the case of estimating the weight function. Meanwhile, the temperature decreases the teleported information.
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When sending a quantum state which originally has nonclassical properties such as various kinds of squeezing and photon antibunching effects according to the protocol for teleportation of continuous variables [S. L. Braunstein and H. J. Kimble, Phys. Rev. Lett. 80, 869 (1998)], we investigate to what extent those nonclassical properties can be preserved in the teleported field. Explicit conditions of the squeezing parameter for the second- and fourth-order quadrature-phase squeezings, the squared amplitude squeezing, and the photon antibunching effect to survive in the teleported field are obtained.
parameters, in the presence of the Unruh effect experienced by a mode of a free Dirac field. We investigate the effects of the partial measurement (PM) and partial measurement reversal (PMR) on the quantum resources and quantum Fisher information (QFI) of the teleported states. In particular, we discuss the optimal behaviour of the QFI, quantum coherence (QC) as well as fidelity with respect to the PM and PMR strength and examine the effect of the Unruh noise on optimal estimation. It is found that, in the single-qubit scenario, the PM (PMR) strength at which the optimal estimation of the phase parameter occurs is the same as the PM (PMR) strength with which the teleportation fidelity and the QC of the teleported single-qubit state reaches its maximum value. On the other hand, generalizing the results to two-qubit teleportation, we find that the encoded information in the weight parameter is better protected against the Unruh noise in two-qubit teleportation than in the one-qubit scenario. However, extraction of information encoded in the phase parameter is more efficient in single-qubit teleportation than in the two-qubit version.
(1990). A model of teleported texts (With reference to aboriginal television) Continuum: Vol. 3, Communication & Tradition, pp. 8-31.
We present a calculation of the fidelity of a cavity-field state teleported by means of a scheme that requires only two high-$Q$ cavities. Based on current experimental capabilities, we demonstrate the feasibility of our scheme if the mean photon number of the cavity field is on the order of unity, allowing a reasonably accurate teleportation.
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There are no “unknown quantum states.“ The phrase is self-contradictory. Moreover, Alice and Bob are only inanimate objects: They know nothing. What is teleported instantaneously from one system (Alice) to another system (Bob) is the applicability of the preparer's knowledge of the state of a particular qubit in the systems. The operation necessitates the use of dual classical and quantum channels. Other examples of dual transmission, including “unspeakable information,” are presented and discussed. This paper also includes a narrative of my recollections of how quantum teleportation was conceived.
When given an unknown quantum state which may be either a pure or a mixed state in the coherent state representation, we show that explicit expressions for the teleported state and its fidelity in the teleportation process (S. L. Braunstein and H. J. Kimble 1998 Phys. Rev. Lett. 80 869) can be obtained without explicit expansions for the two-mode squeezed vacuum state and the Bell basis in a specified representation.
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We propose a simplified scheme to teleport a superposition of coherent states from one mode to another of the same bimodal lossy cavity. Based on current experimental capabilities, we present a calculation of the fidelity that can be achieved, demonstrating accurate teleportation if the mean photon number of each mode is at most $1.5$. Our scheme applies as well for teleportation of coherent states from one mode of a cavity to another mode of a second cavity, when both cavities are embedded in a common reservoir.