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Quantum Illusions: Exploring Time and Superpositions in Photons and Particles

Delve into the realm of quantum states, superpositions, and the mysteries of time through experiments with photons, atoms, and more. Explore the Copenhagen Interpretation, Schrödinger's Cat thought experiment, and the Many Worlds theory.

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Quantum Illusions: Exploring Time and Superpositions in Photons and Particles

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  1. Quantum Illusions and Time Joan Vaccaro K K

  2. y E x z y x E z Quantum States Photons(particles of light) • polarisation of E (electric field):two orthogonal directions

  3. E y x z y E x z E y x y x z E z • arbitrary polarisation • superpositionsplacement of “one thing on topof another” • measurement 50% PBS 50%

  4. y y E E x x z z • superposition of two positions opaque absorber with 2 slits upper d lower • verifying the superposition photons pile up here one at a time interference pattern but NOT here need many photons for verification

  5. Experiments Young photons 1802 Young electrons 1926 Davisson, Germer & Thomson atoms 1930 Estermann & Stern neutrons 1945 Wollan & Shull bucky balls 2002 Zeilinger virus? bacteria? flea? cat? people? Thomson Shull Zeilinger

  6. Tr(1), Pa(1) Tr(2), Pa(2) Tr(3), Pa(3) Tr(4), Pa(4) Many Worlds …first a bit of history… • 1920’s: treatment of radioactive decay radioactive atom possible tracks Tr() & paths Pa() of single particle cloud chamber but only one track per particle is seen

  7. Tr(3), Pa(3) Tr(4), Pa(4) Tr(1), Pa(1) Tr(2), Pa(2) Copenhagen Interpretation: • 1927: Bohr and Heisenberg in Copenhagen when experimenter looks at cloud chamber its state collapses see only one track

  8. 00:00 12 9 3 6 Schrödinger’s Cat radioactive atom + Geiger detector

  9. 09:30 12 9 6 Schrödinger’s Cat radioactive atom + Geiger detector hammer trips and breaks vial of poison cat dies

  10. 00:15 12 9 3 6 Schrödinger’s Cat radioactive atom + Geiger detector hammer trips and breaks vial of poison cat dies Partial decay leads to superposition state until experimenter looks inside box and state collapses hi kitty oh no… 50% chance 50% chance OR

  11. I don’t like it and I’m sorry I ever had anything to do with it. collapse is not described by any dynamical process(with forces, potentials etc.) Schrödinger hi kitty oh no… 50% chance 50% chance OR

  12. Everett 1957 (50th anniversary year) • applying quantum mechanics to universe (cosmology) • no external observers (experimenters) to collapse state • We need new toy example • don’t know how to treat“no life process”(dead) and “life process” (alive) as physical states

  13. 00:00 12 9 3 6 The cat that may (or may not) be fed

  14. 09:30 12 9 6 The cat that may (or may not) be fed 3

  15. 00:15 12 9 3 6 The cat that may (or may not) be fed Why don’t we see this superposition?

  16. This is what happens when we look… here kitty-kitty…

  17. This is what happens when we look… there you are you’ve over eaten you’re so hungry …so how do we see superpositions

  18. The dropped cat experiment (with catchers) - how to “see” a superposition interference probability

  19. The dropped cat experiment (with catchers) - how to “see” a superposition interference probability

  20. Parameters d = 0.1m x = 1m m = 10 kg L = 1067 m t = 1026 y The dropped cat experiment (with catchers) - how to “see” a superposition interference d L probability x

  21. we never even try to do this kind of experiment - need control (& disentangle atom… from cat etc.) - but, importantly, need to repeat it many times to build up interference pattern separate “worlds” evolve… you’ve fat! here’s food $ $$$ the poor but happy world the rich but sad world the perception of “one single world” is an illusion

  22. Many Times David Pegg’s quantum theory of time • canonical approach to quantising gravity • Wheeler-deWitt - equation: - universe is in a stationary state - no motion – frozen dynamics - energy is well known (zero) Pegg, J.Phys. A 24, 3031 (1991). prob. prob. X P • Heisenberg uncertainty principleif you know positionX well, momentumP is uncertain “ “ energyE “ timeT “ “time in the universe must be uncertain X P

  23. use new set of axes – each axis represents a different time 3 state of the universe axes chosen to make projections all equal 2 1 1 2 3 4 5 History vector – totality of reality – state at all times

  24. divide universe into 2 parts: Clock + Restclock must have equally spaced energy levels R C orthogonal clock states 1 M M+1 P find interval where Clock and Rest are separate and non-interacting • rewrite interval in terms of orthogonal clock states

  25. Rn+1 Rn Rn t  Rn Rn t M M+1 P R1 R2 R3 RP C R • the dynamics of Rest can be written in terms of the time parameter t defined by Clock: t =  Schrödinger’s equation for dynamics

  26. R1 R2 R3 RP C R we live at these different times the perception of “one present” is an illusion this illusion is on par with the single world illusion

  27. Puzzle: how does our perception of travelling in time arise? R1 R2 R3 RP these states of Rest are non-orthogonal so can’t be sure which one we are in Rm-1 Rm R Rm+1 • this gives a connection between different states of Rest • but the connection is the same in both directions!

  28. Puzzle: why do we travel in one direction in time? • anti-particles are the time reversed versions of particles time gamma ray photons electron e anti- electron e+ electron e anti- electron e+ electron e space • all anti-particle and particle pairs are time symmetric except for Kaons (K mesons)

  29. K0 K0 K0 antimatter  e+  K0 matter   + antimatter e K0 matter Neutral kaons K0 have a lifetime of less than 106 s. Decay paths: K0 e+ +  +   e + ++ positron pion neutrino (more likely) electron pion antineutrino • equal number of K0 and are found to yield different numbers of e+and e • violation of CP &  T symmetry (CERN 1998) R1 R2 R3 RP t K0 short lifetime long lifetime time asymmetric

  30. K0 R1 R2 R3 RP t K0 short lifetime long lifetime only unsure of which state in the “future” we are in Rm Rm-1 Rm+1 Kaons appear to be responsible for us travelling through time!!!

  31. RIP Conclusion Many worlds: we exist in many worlds but havethe illusion (and pleasures) of only one- but somewhere we are having a really good time Many times:we exist at many times but have the illusion of only onepresent whichmarchessteadily toward to our demise! - but consoled by knowingwe still exist at earlier times Free will: even our perception of free will is an illusion – we cant change the future because we already exist there (hopefully)- but we can enjoy the illusion

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