What are the key theoretical problems?

1. Security proof of BB84 and E91, etc., protocols for bare QKD system:
   What's the measure of security and so what's the absolute secure case (criterion)?
   How to prove the absolute security of BB84 and E91 protocol using a general approach?
   What are the equivalence between BB84 and E91 protocol?
   How about some other extended protocols?
   
2. Security proof of post-processing protocols for total QKD system:
   Error correction: Direct xxx, Reverse xxx;
   Privacy amplification
   
3. Relations among: secure key rate vs. secure transmission distance vs
   
4. General (if possible and necessary) analysis on the ways of attacks:
   Individual attack: general model and detailed analysis?
   Collective attack: general model and detailed analysis?
   Coherent attack: general model and detailed analysis? Moreover, Gaussian attack.
   BTW, what is PNS attack?
   
5. Summary of several important protocols: BB84, Ekert91, SARG, Decoy state, etc. (if any)
   
6. Summarize several VERY important literatures on this, e.g.: GLLP, etc.
   
7. All the above discussions, analysis and calculations, etc., should be restricted to discrete cases (polarization or phase or energy, etc. state of the photons even when entangled photon pairs are considered) with only the qubit is considered. That is to say, anything related to qutrit, qudit, etc. should be ignored.
   
8. Several keywords: secure key rate; secure transmission distance; entropy (Shannon; von Neumann); inter-information; measure; measurement; degree of security; xxx
   
9. Photon statistics theory:
   Photon statistics of the light field emitted by diode lasers: quantum open system theory for lasers;
   Several important photon distributions: Poissonian; Gaussian; Fock; thermal;
   Random number generation theory and implementation of random number generator.
   
10. Stochastic process theory:
    General theory of stochastic process and the basic concepts therein;
    Stochastic Schroedinger equation, Langevin equation and master equations for quantum open system;
    General theory of quantum noise and quantum detection;
    Several quantum detections: homodyne detection; heterdyne detection; QND detection, etc.

What are the key technical problems?

1. Laser source generation:
   DFB pulsed lasers: gain-switching and gain-switched;
   Attenuation and attenuator;
   
   
2. Optics:
   Phase modulation and phase modulator;
   Farady rotation and Farady rotator;
   MZ interference and MZ interferometer;
   Michelson interference and interferometer, and several other interference and interferometer;
   Sagnac related stuff;
   Polarization maintainer (controller);
   Beam coupler (BC, c.f. BS) and polarization beam coupler (PBC c.f. PBS );
   
   
3. Quantum detection of signals:
   Single photon detection and detector using APD: Si for < 1000nm and InGaAs/InP for communication wavelength;
   Single photon detection and detector using PMT;
   Homodyne detection using PIN;
   Heterdyne detection using PIN.
   
4. Post-processing software and hardware implementation:
   Error correction algorithms and software;
   Privacy amplification algorithm and software;
   LDPC coding algorithm and software