Optimal 2N qubit entangled channels for quantum communication

S. Muralidharan, S. Karumanchi, S. Jain +2 more

Shohini Ghose, A. Kumar, Angèle M. Hamel

We propose a 2N qubit entangled channel that can be used to teleport N qubits in a network to a single receiver. We describe the structure of this channel and explicitly demonstrate how the protocol works. The channel can be used to implement a scheme in which all parties have to participate in order for the teleportation to be successful. This can be advantageous in various scenarios and we discuss the potential application of this protocol to voting.

Binayak Samadder Choudhury

Liping Cao, Hai-Jing, Chen +3 more

Mei-Yu Wang, Fengli Yan

In this paper, we investigate perfect quantum teleportation and dense coding by using an 2 N -qubit W state channel. In the quantum teleportation scheme, an unknown N -qubit entangled state can be perfectly teleported. One ebit of entanglement and two bits of classical communication are consumed in the teleportation process, just like when using the Bell state channel. While N + 1 bits of classical information can be transmitted by only sending N particles in the dense coding protocol.

Harry Buhrman, Matthias Christandl, Christopher Perry +1 more

By how much must the communication complexity of a function increase if we demand that the parties not only correctly compute the function but also return all registers (other than the one containing the answer) to their initial states at the end of the communication protocol? Protocols that achieve this are referred to as clean and the associated cost as the clean communication complexity. Here we present clean protocols for calculating the inner product of two n-bit strings, showing that (in the absence of preshared entanglement) at most n+3 qubits or n+O(sqrt[n]) bits of communication are required. The quantum protocol provides inspiration for obtaining the optimal method to implement distributed cnot gates in parallel while minimizing the amount of quantum communication. For more general functions, we show that nearly all Boolean functions require close to 2n bits of classical communication to compute and close to n qubits if the parties have access to preshared entanglement. Both of these values are maximal for their respective paradigms.