A team of researchers from various educational institutions has made a breakthrough in the field of quantum cryptography after creating an ultra-secure network.
In a research paper published in Science Advances, the team led by Siddarth Koduru Joshi of the University of Bristol has established a quantum network protocol that allows multiple parties to directly communicate without actively switching or trusting nodes.
Prior to the team’s breakthrough, quantum communication networks were mostly limited to two users. Scaling used to be a tough nut to crack as it presented a number of problems.
“In most practical networks, it is rare to be able to trust every connected node. Furthermore, such networks tend to use multiple copies of both the sender and receiver hardware at each node, thereby increasing the cost prohibitively. The second category is actively switched or ‘access networks’ where only certain pairs of users are allowed to exchange a key at a time.”
Joshi’s team has circumvented the issues of trust and node switching by creating a network architecture that enables the secure transmission of entangled photons to all the connected nodes.
“Here, we present a city-wide quantum communication network, with eight users, that forms a fully connected graph/network (where each user simultaneously exchanges a secure key with every other user) while requiring only eight wavelength channel pairs, minimal user hardware [i.e., two detectors and a polarization analysis module (PAM)], and no trusted nodes… Just one source of polarization-entangled photon pairs is shared passively between all users and requires neither trust in the service provider nor adaptations to add or remove users.”
The researchers say the novel solution is highly scalable while keeping the infrastructure and hardware required to build the ultra-secure quantum communication network at a minimum.
