Download presentation

Presentation is loading. Please wait.

Published byDennis Surrell Modified over 4 years ago

1
QND measurement of photons Quantum Zeno Effect & Schrödingers Cat Julien BERNU YEP 2007

2
Historical Zeno Paradox

4
Quantum Zeno Effect TimePosition T P(right)

5
Quantum Zeno Effect TimeP(right)

6
R1R2 Classical source Our experimental setup QND measurement of the photon number

7
Coupling the cavity to a classical source Classical source The field gets a complex amplitude in phase space Complex phase space

8
Coupling the cavity to a classical source Time Mean photon number Quadratic start Zeno Effect ! Coherent field:

9
Experimental difficulties

10
Why 1 Hz precision? Effect of a frequency noise or sideband picks on the source or the cavity: random phase for injection pulses. Complex phase space

11
How? Source: Anritsu generator locked on a (very) good quartz locked on a commercial atomic clock Source: Anritsu generator locked on a (very) good quartz locked on a commercial atomic clock Cavity: position of the mirrors must be stable at the range of 10 -13 m (10 -3 atomic radius)! Cavity: position of the mirrors must be stable at the range of 10 -13 m (10 -3 atomic radius)! Sensitivity to accoustic vibrations, pressure, temperature, voltage, hudge field… Sensitivity to accoustic vibrations, pressure, temperature, voltage, hudge field… V 4 He Recycling 0.1 mbar @ 1 bar 0.2 Hz 0.1 mV @ ~100V = 0.2 Hz P Pump Thermal contractions: (1kg) 100 µK @ 0.8 K 0.2 Hz

12
Results Injection watched with QND measurements: time Injection pulses (Zeno Effect) Measurement

13
Results Injection watched with QND measurements: time

14
Results Then with continuous measurement: Injection watched with QND measurements: Perfect control! to be removed… Zeno Effect!

15
Results

16
Results Perfect agreement!

17
QND detection of atoms Re( ) Im( ) a single atom controls the phase of the field R1R2

18
QND detection of atoms Re( ) Im( ) /2 pulse R 1 The field phase "points" on the atomic state R1R2 a single atom controls the phase of the field

19
This is a "Schrödinger cat state" on off 0 +1 on off 0 +1 Schrödingers Cat

21
Production of Schrödingers Cat by a simple photon number parity measurement ( phase shift per photon): Schrödingers Cat

22
Wigner Function (Phase space)

23
Wigner Function (Phase space)

24
Wigner Function

25
Statistical mixture

26
Wigner Function Schrödinger Cat

27
Wigner Function

28
Simple parity measurement !

29
Size of the cat

30
Observing the decoherence 2 200

31
Size of the cat

32
Atom chip experiment

33
Conclusion Using our QND measurement procedure, we have been able to prevent the building up of a coherent field by Quantum Zeno Effect. We can also use it to produce big Schrödinger cats and study their decoherence by measuring their Wigner function.

34
Perspectives 2 cavities for non-local experiments: teleportation of atoms teleportation of atoms non-local Scrödingers cat non-local Scrödingers cat quantum corrector codes quantum corrector codes

35
Thank you! The team: J. B. Samuel Deléglise Christine Guerlin Clément Sayrin Igor Dotsenko Michel Brune Jean-Michel Raimond Serge Haroche Sebastien Gleyzes Stefan Kuhr Atom chip team

37
The origin of decoherence: entanglement with the environment Decay of a coherent field: the cavity field remains coherent the cavity field remains coherent the leaking field has the same phase as the leaking field has the same phase as Environment

38
Decay of a "cat" state: cavity-environment entanglement: cavity-environment entanglement: the leaking field "broadcasts" phase information trace over the environment trace over the environment decoherence (=diagonal field reduced density matrix) as soon as: decoherence (=diagonal field reduced density matrix) as soon as: Environment The origin of decoherence: entanglement with the environment

39
Wigner functions of Schrödingers cats

40
Residual problem Dephasing per photon / Number of photons 02004006008001000 1.0 0.8 0.6 0.4 0.2 0

41
No quantum Zeno effect for thermal photons and decays

42
Zeno Effect for quadratic growth Time

43
Results: injection Effect of a small frequency detuning between the source and the cavity: Complex phase space

45
Quantum Zeno Effect

46
Graphes de wigner

Similar presentations

OK

Фото MANIPULATING THE QUANTUM STATE OF SINGLE ATOMS AND PHOTONS works of Nobel Laureates in physics 2012 A.V.Masalov Lebedev Physics Institute, RAS, Moscow.

Фото MANIPULATING THE QUANTUM STATE OF SINGLE ATOMS AND PHOTONS works of Nobel Laureates in physics 2012 A.V.Masalov Lebedev Physics Institute, RAS, Moscow.

© 2018 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google

Ppt on disk formatting in windows Plasma panel display ppt online Ppt on limitation act 1963 Ppt on the rise of nationalism in europe class 10 Ppt on flexible exchange rate Ppt on conservation of environment for kids Ppt online open port Ppt on leadership styles Ppt on indian politics swami Ppt on prime numbers