The utility of a five-qubit entangled state for quantum teleportation, quantum state sharing and superdense coding is investigated. The state can be utilized for perfect teleportation and quantum state sharing of an a...
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The utility of a five-qubit entangled state for quantum teleportation, quantum state sharing and superdense coding is investigated. The state can be utilized for perfect teleportation and quantum state sharing of an arbitrary single- and two-qubit state. The capacity of superdense coding of the state reaches the "Holevo bound", which means that five classical bits can be transmitted by sending three qubits. The preparation of the five-qubit state and detection of the multipartite states in cavity QED are discussed. The distinct advantage of the feasible cavity QED technology that we use is insensitive to the thermal field and the cavity decay.
In this paper, we present a one-shot method for preparing pure entangled states between a sender and a receiver at a minimal cost of entanglement and quantum communication. In the case of preparing unentangled states,...
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In this paper, we present a one-shot method for preparing pure entangled states between a sender and a receiver at a minimal cost of entanglement and quantum communication. In the case of preparing unentangled states, an earlier paper showed that a 2l-qubit quantum state could be communicated to a receiver by physically transmitting only l + o(l) qubits in addition to consuming l ebits of entanglement and some shared randomness. When the states to be prepared are entangled, we find that there is a reduction in the number of qubits that need to be transmitted, interpolating between no communication at all for maximally entangled states and the earlier two-for-one result of the unentangled case, all without the use of any shared randomness. We also present two applications of our result: a direct proof of the achievability of the optimal superdense coding protocol for entangled states produced by a memoryless source, and a demonstration that the quantum identification capacity of an ebit is two qubits.
作者：
Chen, JianxinYing, MingshengTsinghua Univ
State Key Lab Intelligent Technol & Syst Dept Comp Sci & Technol Beijing 100084 Peoples R China Univ Technol Sydney
Fac Engn & Informat Technol Ctr Quantum Computat & Intelligent Syst Sydney NSW 2007 Australia
The intrinsic idea of superdense coding is to find as many gates as possible such that they can be perfectly discriminated. In this paper, we consider a basic scheme of discrimination of quantum gates, called ancilla-...
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The intrinsic idea of superdense coding is to find as many gates as possible such that they can be perfectly discriminated. In this paper, we consider a basic scheme of discrimination of quantum gates, called ancilla-assisted discrimination, in which a set of quantum gates on a dimensional system are perfectly discriminated with assistance from an r-dimensional ancilla system. The main contribution of the present paper is two-fold: (1) The number of quantum gates that can be discriminated in this scheme is evaluated. We prove that any rd + 1 quantum gates cannot be perfectly discriminated with assistance from the ancilla, and there exist rd quantum gates which can be perfectly discriminated with assistance from the ancilla. (2) The dimensionality of the minimal ancilla, system is estimated. We prove that there exists a constant positive number c such that, for any k <= cr quantum gates, if they are d-assisted discriminable, then they are also r-assisted discriminable, and there are c'r (c' > c) different quantum gates which can be discriminated with a r-dimensional ancilla, but, they cannot be discriminated if the ancilla is reduced to an r-dimensional system. Thus, the order O(r) of the number of quantum gates that, can be discriminated with assistance from an r-dimensional ancilla is optimal. The results reported in this paper represent a preliminary step toward understanding the role ancilla system plays in discrimination of quantum gates as well as the power kind limit of superdense coding.
Simple schemes are proposed for implementing deterministic teleportation, superdense coding, and quantum information splitting with W-type entangled states. The physical realization of these schemes should be much sim...
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Simple schemes are proposed for implementing deterministic teleportation, superdense coding, and quantum information splitting with W-type entangled states. The physical realization of these schemes should be much simpler than previous ones due to the assistance of an auxiliary particle. We illustrate the ideas in cavity quantum electrodynamics. The important features of our schemes can also be demonstrated in other systems.
superdense coding plays an important role in quantum information and can be performed with trapped ions. By confining the ions in a linear trap or a trap-cavity setup, we propose schemes to implement a reliable superd...
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superdense coding plays an important role in quantum information and can be performed with trapped ions. By confining the ions in a linear trap or a trap-cavity setup, we propose schemes to implement a reliable superdense coding by means of bichromatic radiation method. Experimental feasibility and reliability for achieving our schemes is discussed in detail.
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, an...
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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.
Quantum entanglement is the most striking feature of quantum mechanics and is considered an important and valuable resource in quantum information processing. Intensive challenges to harness the power of the quantum e...
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Quantum entanglement is the most striking feature of quantum mechanics and is considered an important and valuable resource in quantum information processing. Intensive challenges to harness the power of the quantum entanglement are going on. In this paper, some of the fundamental concepts and applications of the quantum entanglement are reviewed.
We derive the general formula for the capacity of a noiseless quantum channel assisted by an arbitrary amount of noisy entanglement. In this capacity formula, the ratio of the quantum mutual information and the von Ne...
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We derive the general formula for the capacity of a noiseless quantum channel assisted by an arbitrary amount of noisy entanglement. In this capacity formula, the ratio of the quantum mutual information and the von Neumann entropy of the sender's share of the noisy entanglement plays the role of mutual information in the completely classical case. A consequence of our results is that bound entangled states cannot increase the capacity of a noiseless quantum channel.
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