AsianScientist (Dec. 18, 2017) – In a study published in the journal Science Advances, a team of researchers in Singapore has developed efficient ‘toolboxes’ for enhancing the security of high-speed quantum communication.
Quantum computers are powerful machines that can break today’s most prevalent encryption technologies in minutes. If successfully implemented, these computers could be exploited to decrypt any organization’s trade secrets, confidential communication and sensitive data, retrospectively or remotely.
Quantum key distribution (QKD) is an emerging quantum technology that enables the establishment of secret keys between two or more parties in an untrusted network. Importantly, unlike conventional encryption techniques, the security of QKD is mathematically unbreakable—it is based solely on the established laws of nature. As such, messages and data encrypted using QKD keys are completely secure against any attacks on the communication channel.
However, despite these major developments and advances, practical QKD systems still face some inherent limitations. One major limitation is the secret key throughput—current QKD systems are only able to transmit 10,000 to 100,000 secret bits per second.
In this study, a research team led by Assistant Professor Charles Lim of the Department of Electrical and Computer Engineering at the National University of Singapore overcame the above problem with a QKD system based on time and phase bases. Encoding quantum information in the time and phase bases is a promising approach that is highly robust against typical optical channel disturbances and yet scalable in the information dimension.
Using this method, secret bits are encoded in the arrival time of single photons, while the complementary phase states—for measuring information leakages—are encoded in the relative phases of the time states. This encoding technique, in principle, could allow one to pack arbitrarily many bits into a single photon and generate extremely high secret key rates for QKD. The team managed to pack two secret bits in a single photon, with a secret key rate of 26.2 megabits per second.
The security proof techniques used in this study were developed by Lim and an interferometry technique by Professor Daniel Gauthier’s research group from Duke University and Ohio State University. Lim was involved in the protocol design of the QKD system as well as proving the security of the protocol using quantum information theory.
“Our newly developed theoretical and experimental techniques have resolved some of the major challenges for high-dimensional QKD systems based on time-bin encoding, and can potentially be used for image and video encryption, as well as data transfer involving large encrypted databases. This will help pave the way for high-dimensional quantum information processing,” said Lim.
Moving forward, the team will be exploring ways to generate more bits in a single photon using time-bin encoding. This will help advance the development of commercially viable QKD systems for ultra-high rate quantum secure communication.
The article can be found at: Islam et al. (2017) Provably Secure and High-rate Quantum Key Distribution with Time-bin Qudits.
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Source: National University of Singapore; Photo: Shutterstock.
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