Quantum Capacity Theorems and Their Proofs
The main quantum capacity theorems and how they are proved: coding theorems, entanglement-assisted capacity, additivity and superadditivity.
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The Quantum Source Coding Theorem and Compression
Schumacher’s quantum source coding theorem shows quantum data can be compressed down to its von Neumann entropy. History, concepts and uses.
The Quantum Channel Coding Theorem, Explained
The quantum channel coding theorem sets how much information noisy quantum channels can carry reliably. Foundations, codes and implications.
Quantum Bit Error Rate (QBER)
The quantum bit error rate measures errors in the sifted key of a QKD system. How it is calculated, what causes it and why it signals eavesdropping.
The Quantum Chernoff Bound for State Discrimination
The quantum Chernoff bound gives the best error exponent for telling two quantum states apart with many copies. Definition and applications.
Quantum Fisher Information and Measurement Precision
Quantum Fisher information sets the best possible precision for estimating a parameter. Its definition, the Cramér-Rao bound and metrology uses.
The Quantum Hamming Bound on Code Parameters
The quantum Hamming bound limits the parameters of non-degenerate quantum codes. Its derivation, examples and implications for code design.
Quantum Error Correction: The Information View
Quantum error correction from an information theory perspective: codes, detection and correction, limits and the road to fault tolerance.
Superdense Coding: Two Bits From One Qubit
Superdense coding, proposed by Bennett and Wiesner in 1992, sends two classical bits with one qubit using a shared entangled pair. How it works.
Entanglement of Formation and the Cost of Correlation
The entanglement of formation is the minimum entanglement needed to create a given state. Its definition, formulas for two qubits and uses.
Entanglement Entropy: Measuring Shared Information
Entanglement entropy measures how entangled one part of a system is with the rest. Definition, calculation and meaning in physics.
Quantum Discord: Correlation Without Entanglement
Quantum discord captures non-classical correlations that can exist even without entanglement. Its definition, measurement and possible uses.