Quantum Control in Semiconductor Quantum Dots YanTen Lu
- Slides: 26
Quantum Control in Semiconductor Quantum Dots Yan-Ten Lu Physics, NCKU
Basic Requirements 1. Representation of qubits 2. Controllable unitary evolution 3. Preparation of initial qubit states 4. Measurement of final qubit states
Representation of qubits Single photon Cavity QED Trapped ions Nuclear spins Solid state devices
C 11 H 5 F 5 O 2 Fe 15 = 3 x 5 -- Realization of Shor Algorithm (1994) by I. Chuang (2001), IBM Almaden
Time Constants (Nielsen & Chuang p. 278) system nuclear spin electron spin ion trap (In+) electron (Au) electron (Ga. As) Quantum dot Optical cavity Microwave cavity Coh. T 10+2 10 -3 10 -1 10 -8 10 -10 10 -6 10 -5 1 Op. T 10 -3 10 -7 10 -14 10 -13 10 -9 10 -14 10 -4 No Op 10+5 10+4 10+13 10+6 10+3 10+9 10+4
Quantum Dots Charge (current) Spin Exciton
What is a quantum dot? In a semiconductor quantum dot, the electronic levels have a density of states characteristic of a single atom. Yet, the dots is a mesoscopic system, the quantization of electronic levels is realized within a system of 105 – 106 atoms.
In. As/Ga. As, S. P. Gua, et. al. APL 1997
C. Pryor, PRL 1998
Charged quantum dots, Nielson & Chuang, p. 344
Spin of a quantum dot Loss & Di. Vinceenzo, PRA, 1998
Exciton in Semiconductor E k Eb = 6 me. V
Exciton in Q-dot Eb = 20 me. V
Energy levels of multiple excitons, A. Barenco, PRB, 1995
L. Sham, PRL 2001, PRB 2002
Ee - Eh = 1. 6926 Eex = 1. 6724 Tcoh = 30 ps H. Ando, PRL 2001
Time Scale Consideration Pusle duration of operation laser beam must be less than coherence time Pulse duration of laser beam must be long enough to ensure Combined laser pulses
Excited by a left polarized beam
Two-pulse combination
Fidelity Test
What We can do ? More detail study of fidelity dependence on the shape of laser pulse. Applied to system of coupled quantum dots (1 -d and 2 -d)
M. Bayer, Science 2001
K. R. Brown, et. al. PRA 2001
- Yan ten
- History of quantum dots
- Evident technologies
- Classical physics
- Quantum physics vs quantum mechanics
- __-____--__ __-__ morse code
- Mcl ucl audiology
- Schuffner dots malaria
- Which artist utilized benday dots in his artwork
- Dot wall
- Malaria means bad air
- Fixing into thermalite blocks
- Trantas dots
- Tbnow
- Think dots differentiated instruction
- Think dots differentiated instruction
- O with 2 dots
- Darko hunter
- Dippin' dots franquicia precio
- Exploding dots subtraction
- Lesson 31 connect the dots lewis
- Connect all dots without crossing the lines
- Clear the blue dots
- Connect 9 dots with 4 straight lines
- Valence bond picture
- Pop art benday dots
- Gold standard for diagnosis of malaria