I "know" is mistyped in the same sentence as "snow", it is still likely that this error will be detected and corrected from the context, although "snow" is a valid word. Detection and correction may be harder or impossible if "know" is mistyped as "knew". As these examples show, redundancy is the key to recovery from errors.
Communication engineers have developed a variety of codes, such as LDPC and turbo codes, that achieve the efficiency limits set by Shannon theory. However, the field of error-correcting codes is still a vibrant research area, and is likely to remain so for many decades spurred by emerging applications.
Exploit wireless medium properties to generate secret keys:
Exploit properties of physical systems to design secure protocols for cyber-physical systems:
Exploit quantum mechanical properites to generate secret keys:
1 Qubit = Unit of quantum information stored in a single photon, electron, ion,...
One day we might use Qubits to communicate and compute in ways that defy our fantasy.
Measurements randomly project Qubits.
When observing from a certain point of view, two measurements can occur with random probabilities.
Pairs can be entangled
Quantum entanglement is a physical phenomenon that occurs when pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot be described independently - instead, a quantum state may be given for the system as a whole.
Quantum networks form an important element of quantum computing and quantum cryptography systems. Quantum networks allow for the transportation of quantum information between physically separate quantum systems. Secure communication can be implemented using quantum networks through quantum key distribution algorithms.Optical quantum networks using fiber optic links or free-space links play an important role transmitting quantum states in the form of photons across large distances. Optical cavities can be used to trap single atoms and can serve as storage and processing nodes in these networks.