Abstract ........................................................ i
Zusammenfassung ................................................. v
1 Introduction: Quantum information technologies ............... 1
1.1 Quantum information ..................................... 2
1.2 Quantum communication ................................... 4
1.3 Quantum teleportation ................................... 4
1.4 Quantum networks ........................................ 7
1.5 The scope of this thesis ................................ 9
2 Fundamental properties of semiconductor quantum dots ........ 11
2.1 Low-dimensional semiconductor nanostructures ........... 13
2.2 Heteroepitaxial growth ................................. 14
2.3 Quantum dot sample design .............................. 18
2.4 Stuctural properties of self-assembled quantum dots .... 19
2.5 Quantum dot electronic structure ....................... 21
2.6 Optical properties of self-assembled quantum dots ...... 23
2.6.1 Inhomogeneously broadened emission from
quantum dot ensembles ........................... 24
2.6.2 Towards low density quantum dot material ........ 25
2.6.3 Probing few particle states in individual
quantum dots .................................... 27
2.6.4 Spontaneous emission dynamics of InGaAs
quantum dots .................................... 30
2.6.5 Non-classical light emission from a single
quantum dot ..................................... 38
2.7 Summary and conclusions ................................ 48
3 Two-dimensional photonic band gap materials ................. 51
3.1 Basics of photonic crystals ............................ 51
3.2 Optical properties of photonic crystals ................ 58
3.2.1 Two-dimensional photonic band gap ............... 58
3.2.2 Inhibition of spontaneous emission in two-
dimensional photonic crystals ................... 61
3.2.3 Spatial redistribution of light in
two-dimensional photonic crystals ............... 63
3.3 Efficient single photon generation ..................... 66
3.3.1 Enhanced extraction efficiency for single
quantum dots in photonic crystals .............. 69
3.3.2 Absolute photon extraction efficiency ........... 72
3.3.3 Single photon generation ........................ 74
3.3.4 Photon antibunching up to T=77 К ................ 76
3.4 Summary and conclusions ................................ 79
4 Individual quantum dot-cavity systems ....................... 81
4.1 Basic properties of optical microcavities .............. 82
4.2 Photonic crystal cavities .............................. 86
4.3 Quantum dot-cavity coupling ............................ 90
4.3.1 The weak coupling regime ........................ 92
4.3.2 The strong coupling regime ..................... 101
4.3.3 Tuning the cavity mode via nitrogen
deposition ..................................... 105
4.4 Efficient and selective cavity resonant excitation .... 108
4.4.1 The idea of cavity resonant excitation ......... 109
4.4.2 Cavity resonant excitation of a single
quantum dot .................................... 112
4.4.3 Efficiently pumped single photon source ........ 115
4.4.4 Selective excitation of spatially coupled
quantum dots ................................... 117
4.5 Realisation of an efficient, cavity enhanced source
of single photons ..................................... 121
4.5.1 Purcell enhanced single photon generation ...... 121
4.5.2 Degraded single photon emission purity ......... 124
4.6 Non-resonant quantum dot-cavity coupling .............. 128
4.6.1 Quantum dot lifetime dependence of coupled
dot-cavity system .............................. 128
4.6.2 Phonon mediated scattering ..................... 131
4.6.3 Off-resonant quantum dot-cavity cross-talk ..... 134
4.7 Summary and conclusions ............................... 142
5 Outlook .................................................... 145
5.1 Entangled photon pair generation ...................... 145
5.2 Lateral electric fields ............................... 146
5.3 Electrically tunable dot-cavity system ................ 150
5.4 Individual quantum dot coupling in complex photonic
nanostructures ........................................ 151
List of publications .......................................... 155
Bibliography .................................................. 157
Acknowledgment ................................................ 175
|
