Frascati 2007 Beatrix C Hiesmayr Testing Quantum Mechanics

Frascati 2007, Beatrix C. Hiesmayr Testing Quantum Mechanics with neutral kaons by Beatrix C. Hiesmayr Institute for Theoretical Physics University of Vienna Austria

Frascati 2007, Beatrix C. Hiesmayr The kaonic quantum eraser “Erasing the Past and Impacting the Future” Aharanov & Zubairy: Science 307: 875, 2005 Bramon, Garbarino, Hiesmayr, Phys. Rev. Lett. 92 (2004) 020405 Bramon, Garbarino, Hiesmayr, Phys. Rev. A 68 (2004) 062111 many experiments with photons, neutrons or atoms Why, kaons? just another quantum system? • because the working principle can be Is this demonstrated in A NEW all? WAY, !!only!! possible with kaons • and it can be performed at KLOE 2 • and allows for a clear conceptual simplification

Frascati 2007, Beatrix C. Hiesmayr “Erasing the past and impacting the future” 1801 Thomas Young: Photons interfere! Interference lost because photon watched (gain which way info)! 1982 Drühl & Scully: Erasing the which way info brings interference back! No wonder Einstein would be confused!

Frascati 2007, Beatrix C. Hiesmayr Experiment: Zeilinger et al.

Frascati 2007, Beatrix C. Hiesmayr Experiment: Zeilinger et al. second passage first passage

Frascati 2007, Beatrix C. Hiesmayr Experiment: Zeilinger et al. H/V or +45°/-45° normalized to surviving kaon pairs

Frascati 2007, Beatrix C. Hiesmayr Experiment: Kim et al. choice to show which way info or not is partially active !

Frascati 2007, Beatrix C. Hiesmayr All photon experiments have in common: • kind of double slit device • used entanglement This we have also for kaons! Bramon, Garbarino, Hiesmayr, Phys. Rev. A 69 (2004) 022112. „A kaon is a kind of double slit, automatically marked in time“ Kaon in time: short-lived state long-lived state

Frascati 2007, Beatrix C. Hiesmayr Measurements: active & passive Strangeness basis: “Active” measurement: Strong interactions: 0 K +p L+p+ K 0+n K-+p, L+p 0 K 0+p K++n “Passive” measurement: Semileptonic decay modes DQ=DS: K 0(sd) p-(ud)+l++nl K 0(sd) p+(ud)+l-+nl Lifetime basis: K+ L+p+ K K“Active” measurement: L+p 0 “Passive” measurement: Free propagation: Sensitive to the decay modes: any decay mode observed before t+4. 8 t. S are identified as KS at time t Misidentification: few parts in 10 -3! 2 p’s are identified as KS 3 p’s are identified as KL

Frascati 2007, Beatrix C. Hiesmayr (A) Active Eraser with active measurements T, tr 0 object system source S, tl 1. Setup 2. Setup meter system S, tr 0 left (object) right (meter) active S active T active S (matter block remove): (matter block inserted):

Frascati 2007, Beatrix C. Hiesmayr (B) Partially active eraser with active measurements object system T source S, tl meter system left (object) active S S, tr 0 right (meter) active T, active S partially active choice due to instability of kaon

Frascati 2007, Beatrix C. Hiesmayr (C) Passive eraser with passive measurements object system S source S, tl T T meter system left (object) active S right (meter) passive T, passive S

Frascati 2007, Beatrix C. Hiesmayr (D) Passive eraser with passive measurements T S left (? ? object? ? ) passive T, passive S right (? ? meter? ? ) passive T, passive S

Frascati 2007, Beatrix C. Hiesmayr (A) + (B) + (C) A cut-off cylinder (3 mm Be, radius=2. 5 cm), placed off-center: Region II (meter) Region I (object) Beam pipe (1 cm radius) 1 cm 4 cm Region II (object) 2 cm 10 o Region I (meter) 3 mm Be (r=4. 2 x 10 -3) by A. Go by A. Di. Domenico

Frascati 2007, Beatrix C. Hiesmayr (A) Active eraser with active measurements Toy MC for 2/fb with 50% detection efficiency: l ~ 500 events in strangeness vs strangeness: l ~ 450 events in strangeness vs lifetime: by A. Go

Frascati 2007, Beatrix C. Hiesmayr (D) Passive eraser with passive measurements Asymmetry: object meter Toy MC simulation with L=50 fb-1 Dt >0 A Dt/t. S A by Di. Domenico Dt/t. S

Frascati 2007, Beatrix C. Hiesmayr Summary of “kaonic” eraser • remarkably all these QE options lead to the same probabilities! • this is even true regardless the temporal ordering • demonstrates nicely the very nature of QE: sorting events according to acessible information Hopefully DAFNE will be the first to show that!