20 QUANTUM COMMUNICATION
21 Protocols
21.10.+a	Quantum authentication / identification
21.20.-s	Quantum secret sharing / data hiding
21.20.Kl	Quantum key distillation
21.20.Kd	Quantum key distribution
21.20.Rp	Remote state preparation
21.20.Rc	Quantum remote control
21.20.Sc	Quantum bit-string commitment
21.30.+c	Quantum coding
21.40.+d	Quantum data compression
21.50.+t	Teleportation
21.60.+e	Entanglement based protocols
21.70.+q	Qudits
21.80.+c	Quantum cloning
22 Information security beyond quantum cryptography
22.10.+k	High key rates
22.20.+d	Continuous variables
22.30.+c	Quantum codes
22.40.+p	Privacy Amplification
22.50.+t	Teleportation as a cryptographical primitive
22.60.+e	Eavesdropping detection
22.65.+a	Eavesdropping attacks / strategies
22.70.+s	Security proofs
22.80.+p	Plug and play systems
22.90.+d	Distrustful cryptography
23 Long-distance quantum communication
23.05.+f	Fiber-based quantum communication
23.10.+l	Limits for shared entanglement
23.20.+f	Free-space entanglement
23.25.+c	Free-space quantum communication
23.30.+o	Outer-space quantum communication
23.40.+a	Adaptive optics
23.50.+s	Feasibility studies for satellite based quantum communication
23.60.+d	Study of decoherence
23.70.+s	Space qualified technologies
24 Sources
24.10.-s	Single photons
24.10.Od	Single photons on demand
24.10.Tw	Single photons at telecom wavelength
24.20.-e	Entangled photons
24.20.Od	Entangled photons on demand
24.20.Tw	Entangled photons at telecom wavelength
24.30.+s	Squeezed state sources
24.40.+h	High efficiency sources
24.50.+m	Multiphoton sources
24.60.+s	Generation of specific states of radiation
24.70.+c	Color center / quantum dot photon sources
25 Detectors
25.10.+e	Quantum efficiency of detection
25.20.+n	Number resolution
25.30.+c	Clock synchronization
25.40.+t	Automated state and process tomography
25.50.+m	Miniaturization
25.60.+a	Quantum state analyzers