High dimensional quantum communication

Information and Communication

Project Description

The field of quantum communication has evolved from the earliest studies on quantum cryptography- quantum key distribution (QKD). Since the first protocol proposed by Bennett and Brassard in 1984, many interesting protocols for quantum cryptography have been proposed. The idea behind these protocols is: a key is exchanged between the sender and the receiver on a public channel and the existence of an eavesdropper can be traced with certainty. This apparently impossible task is achieved through the quantum features of microscopic objects such as the polarization of a single-photon or electronic spin. Basically one exploits the property of the quantum systems that a measurement irreversibly changes the state of the system. In parallel to the QKD protocols, a number of schemes have been proposed for the direct quantum communication without the need of a key.

In an optical quantum communication set-up, single photons are carriers of information. Usually they can carry only one bit of information, a logic 0 or a logic 1. Recently there has been an interest in the question: is it possible for a single photon to carry more than one-bit of information? If it becomes possible to send more information on a single photon, it would lead to high dimension QKD protocols and potentially a faster communication. A major thrust of this project will be to develop an approach of high dimensional quantum communication that is highly efficient and practically realizable.

The present protocols for QKD or direct communication are typically based on a point to point communication. In a communication network this requires direct communication between any two communicators. This approach may be highly inefficient if the data is exchanged between a group of users such as a sender and multiple receivers. In this case, one would require a large number of one to one channels. A protocol that involves communication from a group of users to another group of users simultaneously via a “group to group communication” may help resolve this issue.  This type of quantum communication protocols pose new challenges. It is the objective of this proposal to study the possibilities of the group to group communication so that all users can share the same information.

In this project, the expertise in the two areas discussed above, namely, high dimension quantum communication between two users and the protocols for a group to group communication will be combined and ultimately develop a high dimension network for quantum cryptography for group to group communication. Such a network may potentially lead to highly efficient exchange of data between multiple users and point in the direction of the elusive quantum internet.

Team Members