Brun, Devetak, and Hsieh [Science 314, 436 (2006)] demonstrated that preshared entanglement between the sender receiver enables quantum communication protocols have better parameters than schemes without assistance of entanglement. Subsequently, same authors derived a version so-called Singleton bound relates entanglement-assisted quantum-error-correcting codes proposed by them. We present an s...

We study the communication complexity of a number of graph properties where the edges of the graph G are distributed between Alice and Bob (i.e., each receives some of the edges as input). Our main results are: An Ω(n) lower bound on the quantum communication complexity of deciding whether an nvertex graph G is connected, nearly matching the trivial classical upper bound of O(n logn) bits of co...

We prove an infinite separation between quantum information complexity and quantum communication complexity by considering the exclusion game, first introduced by Perry, Jain and Oppenheim [1], who showed that for appropriately chosen parameters of the game, the quantum information cost vanishes as the size of the problem n increases. We extend their result by showing that for those parameters,...

This paper studies privacy and secure function evaluation in communication complexity. The focus is on quantum versions of the model and on protocols with only approximate privacy against honest players. We show that the privacy loss (the minimum divulged information) in computing a function can be decreased exponentially by using quantum protocols, while the class of privately computable funct...

Quantum Key Distribution (QKD) is a key exchange protocol which is implemented over free space optical links and optical fiber cable. When direct communication is not possible, QKD is performed over fiber cables, but the imperfections in detectors used at receiver side and also the material properties of fiber cables limit the long distance communication. Free space based quantum key distributi...

A possible mechanism of nonlinear quantum evolution is introduced and its implications for quantum communication are investigated. First, it is argued that an appropriate combination of wavefunction collapse and the consciousness of observer may permit the observer to distinguish nonorthogonal quantum states in principle, and thus consciousness will introduce certain nonlinearity into quantum d...

Secure transmission of messages has been a major goal since ages, for which cryptography is used. Cryptography is a mathematical techniques used for secure communication. Classical cryptography is traditional means that comprises mathematical functions to restrict eavesdropping problem in communication. Quantum cryptography is a new approach towards secure communication which uses phenomenon of...