Download presentation

Presentation is loading. Please wait.

Published byCatalina Simson Modified over 3 years ago

1
Quantum trajectories for the laboratory: modeling engineered quantum systems Andrew Doherty University of Sydney

2
Goal of this lecture will be to develop a model of the most important aspects of this experiment using the theory of quantum trajectories I hope the discussion will be somewhat tutorial and interactive.

5
Single photon source Modes of the light approach atom and are scattered off Every so often a photon is emitted into the light field, spontaneous emission

6
Single photon source Modes of the light approach atom and are scattered off Every so often a photon is emitted into the light field, spontaneous emission Detector counts photons in scattered field

7
Single photon source Modes of the light approach atom and are scattered off Every so often a photon is emitted into the light field, spontaneous emission Count rate

8
Concept of a quantum trajectory Harmonic oscillators representing input field approach system Interact one at a time undergo projective measurement

9
Single photon source Evolution for no photon emission This happens most of the time Photon emission Happens some of the time

10
No photon emission Probability of no photon emission up to time t

11
Photon emission at t Photon emission at time t Probability of photon emission between t and t+dt Total probability of photon emission

12
Distant Detector Photon emission at time t Probability of photon emission between t and t+dt Total probability of photon emission

13
Detector Efficiency Photon detection at time t+t p Probability of photon detection between t+t p and t+t p +dt Total probability of photon detection

14
Beam Splitter

15
Quantum Interference

16
Two single photon sources Evolution for no photon emission Photon detection at c Photon detection at d

17
Two single photon sources Evolution for no photon emission Photon detection at c Photon detection at d

18
Detection at c Photon detection at c Free evolution with no photon emission

19
Detection at d Photon detection at d Free evolution with no photon emission

20
Detection at d Photon detection at d Free evolution with no photon emission

21
Coincidence Probability Hong-Ou-Mandel Dip

22
State Preparation Free evolution Microwave pi/2-pulses v v State preparation (shelving) v v Optical pi-pulses v v

23
Detection at c

24
Wait Wait for any subsequent photon emission

25
Microwave pi-pulses Microwave pi-pulses swap spin states

26
Optical pi-pulses Optical pi-pulses prepare for second single photon emission

27
Free evolution Free evolution up to second emission

28
Detection at c Detection at c and wait

29
Remote Entanglement We have a state roughly equal to With the probability we would have guessed And output state given by: (could be improved by tightening co-incidence window)

30
Coincidence Probability Hong-Ou-Mandel Dip

31
Notes on this calculation Fidelity of entangled state has same dependence on physical parameters as for HOM experiment. Need propagation phases to be constant over interval between photons Easy to see that other factors like detector efficiency and path length difference after the beam splitter factor out also Timing error hasn’t been included here, could be done easily by modeling the pulse that prepares the state e. This is another kind of mode-match error and would look much like the dependence on the decay rates. Note that difference in the delay time for the two paths factors out. This is because we have modeled the propagation of the single photon pulse as if the beam were perfectly monochromatic. This approximation is valid because we are in the Markov regime but if the delays are too large, this needs to be corrected

Similar presentations

OK

Chapter 40 Serway & Jewett 6 th Ed.. Approximate Total Absorption Cavity.

Chapter 40 Serway & Jewett 6 th Ed.. Approximate Total Absorption Cavity.

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on value education for students Ppt on principles of peace building institute Ppt on atmospheric refraction for class 10 Ppt on obesity diets Ppt on ms excel 2010 Ppt on oxygen cycle for class 9 Ppt on motivation in organisational behaviour Ppt on 4g lte Best ppt on water cycle Mems display ppt on tv