Search for Quantum Coherence in Nanometer-scale targets

Transcription

1 08 August 010 Univ. Search for Quantum Coherence in Nanometer-scale targets Kyo Nakajima Okayama Univ.

2 Collaboration Okayama University A. Fukumi, K. Nakajima, I. Nakano, C. Ohae, S. Sato, T. Yamaguchi, M. Yoshimura, K. Yuasa N. Sasao, T. Taniguchi, S. Kuma K. Kawaguchi, J. Tang, Y. Miyamoto Kyoto University H. Nanjyo Kinki University T. Wakabayashi UBC T. Momose FPUA010

3 Contents Motivation Previous work of related topics - Matrix isolation, Interaction with environment - Superradiance, Dephasing time Current status of our experiments FPUA010 3

4 One of the final steps Neutrino Mass Spectroscopy Motivation M. Yoshimura, Phys. Rev. D75, (007) M. Yoshimura et al., Prog. Theor. Phys. 13, 53 (010) Neutrino pair emission from excited atoms Possibility of measuring the absolute magnitude and the nature of neutrino masses This process is based on Previous Macro-coherent two photon emission talk Two photon emission i f Radiative neutrino pair emission i f Macro-coherent excited atoms i f M. Yoshimura et al., arxiv: v1 [hep-ph] (008) i j i j Δ ( m i m j ) [ To obtain a large enhanced macro-coherent rate ] (1) Using atoms appropriate energy differences between atomic levels, i and f () Collection of atomic targets of O[Avogadro number] /cm 3 (3) Isolated among themselves and weakly interacting with environment Preparation of candidate atoms in nanometer-scale targets Study of the influence of dephasing processes FPUA010 4

5 Xenon atom as candidate targets Metastable state of Xenon atom Lowest excited state of R.G. atoms is metastable state and has high energy Population of 6s J= state 1.38, 1.51eV / 1.5, 1.37eV 5 p P 6 p 5 3/ 0.1 ev 5 p P3/ 6 3/ s P 6s 3/ 3/ 5 p P3/ 6 3/ s P 6s 3/ 3/ 8.4 ev i f i j 8.4 ev 4.91 evx / 4.84eVx 6 1 S0 6 1 S0 population of J= state is achieved by the relaxation from the higher state FPUA010 5

6 Pure Gas Solid Traps MOT Optical lattice. Xenon doped in materials Rate of macro-coherent emission depends on n N = n V [high density(nanometer-scale targets)] [large volume of targets] Implantations Matrix isolation Endohedral fullerene Nanotube Semiconductor. ph Xe /cm 3 (1atm) 10 /cm 3 parahydrogen ~cm /cm 3 (0.1%) Excited atoms interact with neighbor atoms Matrix isolation satisfies both conditions. First candidate possibility that other candidates are appropriate too FPUA010 6

7 Okayama Univ.: The tentative experiment is going on. FPUA010 7

8 Interaction with the ph molecules Shit / Width In the case of a B atom trapped in solid parahydrogen theoretical calculations agree with experimental spectrum B(s 3s S s p P) Potential curves B-pH distribution Absorption line 40040/cm (atomic) 46170/cm (in ph ) Width ~1000/cm Absorption spectrum Theory Experiment B(s 3s S s p P) B(s p D s p P) Xe in solid parahydrogen? FPUA010 8

9 Energy levels in matrices In the case of Xenon in Argon atomic states Blue shift Two photon excitation Transition between 6s J= state and 6p state was observed based on transient absorption experiments Energy levels in solid parahydrogen? search for E, ΔE experimentally FPUA010 9

10 I (w, w dw d (w) ) i ˆ t Optical superradiance Maxwell-Bloch approach (Semiclassical) Interaction with radiation field Hˆ dˆ ( r, 1 t ), ˆ 1 4 ( r, t) ( r, t) N 0 c t c t Atoms Tr( ˆ d w/o dephasing process ) Field Intensity of emission T R t (w) T R Super-radiant time scale Delay time 10 0 c 8 N d L N L T R T 1 4 D T R t (w) T R 0 ln N 0 : Number density d: dipole moment L: Sample length 1 0 FPUA N

11 Conditions necessary for SR Under the Influence of relaxation processes T R T 1, T T R : Time of correlation self-formation in the medium τ: Time of flight of photons through the sample T 1 : Time of energy irreversible relaxation * T R T T : Time of phase irreversible relaxation Homogeneous linewidth T T T1 T * : Inhomogeneous lifetime (in the case when the spectrum of the pumping pulse completely covers the relevant inhomogeneously broadened line) : Inversely proportional to the bandwidth of the pulse (in the case of selective excitation) In the solid state? FPUA010 11

12 Superradiance in Solid 1 3LaF 3 :Pr 3+ Diphenyl C 1 H 10 Pyrene C 16 H 10 T 1 = 91ns T = 100ps T *=30ps (4.K) R. Florian et al., Phys. Rev. A 9, 709 (1984). T 1 = 100ns T = 8ns T *=100ps T R ~10-100ps (4.K) P. V. Zinov ev et al., Sov. Phys. JETP. 58, 119 (1984). T 1 = 47μs T = 430ns Pumping bandwidth 3-4GHz Inhomogeneous >9-1GHz T R ~1ns (.K) V. A. Zuikov et al., Laser Phys. 9, 951 (1999). FPUA010 1

13 Homogenous dephasing time in matrices Under the large inhomogeneous broadening T is observed using photon echo (time domain spectroscopy) ex. W(CO) 6 in Ar Tungsten hexacarbonyl Vibrational transition /cm T = 400ps = 0.06/cm T 1 = 70ps Inhomogeneous line width.54/cm (8K) Dephasing time in cryogenic matrices obtained for the first time ~ ~ Electronic dephasing in solid parahydrogen ( much faster?) FPUA010 13

14 Xenon in solid parahydrogen - Experimental approach - Motivation Populating 6s J= states of xenon Toward [Number of excited atoms] [density] =nn ~ 10 5 /cm 3 Search for quantum coherence (for γsr) Procedures Preparation of parahydrogen crystals with xenon Confirmation of energy levels (6s J=1 state with VUV absorption) Two photon excitation to 6p 5 P3/ 6 p Measurement of characteristics of 5 6p 6s 6s transition P3/ 6 s 3/ 1 5 P3/ 6s 3/ Search for SR, γsr, 6 1 S0 FPUA010 14

15 Experimental Setup Arrangement of the crystal in the cryostat VUV absorption spectroscopy Laser-excited fluorescence spectroscopy FPUA010 15

16 log log (I (I 0 0 /I) /I) Xe in solid parahydrogen Absorption spectra of R.G. atom doped solid parahydrogen P. L. Raston and D. T. Anderson, Journal of Molecular Spectroscopy 44, 138 (007) ppm 150 ppm 50 ppm Other (No Xe) Perturbation by impurities vibrotational transition Wavenumber (/cm) Xe atoms are isolated Density of Xe atoms: ~10 16 /cm Experiments at UBC. FPUA010 16

17 -log 10 (I/I 0 ) VUV Absorption Spectroscopy - Preliminary results B 1 A A 1 P 1 A 1 Xe 10ppm / p-h Xe 100ppm / p-h Xe 100ppm / n-h Xe 1000ppm / Ar 3 Position of the resonant atomic line P 1 1 Position of the resonant atomic line P 1 (@UBC) A 1 A 11 3 P ev (Atomic) 0.1 ev (Atomic) 5 p P3/ 6 3/ s P 6s 3/ 3/ Energy (ev) A 1 P 3/ n=1 B 1 P 1/ n=1 E (ev) σ (ev) E (ev) σ ( ev) Gas ppm/H [Ref.] ppm ppm ppm ppm/H [Ref.] Chem. Phys. Lett., 14, 36 (197) 6 1 S0 Line width of Inhomogeneous broadening: σ~70mev Energy: E~9eV (7% blue shift) Not depend on the density. FPUA010 17

18 Intensity (a.u.) Intensity (a.u.) Excitation 5.3eV (3.5nm) run11 Ex3.5nm T d = 80ns Laser-excited Fluorescence Spectroscopy Background from substrate / ndf / 9 p p p p p p p e e Time distribution flu =600nm, E =1.1mJ ex ( =31.ns) flu =730nm, E =1.1mJ ex ( =17.4ns) flu =730nm, E =0.03mJ ex ( =14.6ns) Time ( s) Wavelength (nm) 730nm - Preliminary results - (@UBC) (@Okayama) 600nm 1.38, 1.51eV / , 1.37eV 70 (Atomic) run1 Ex3.5nm T d =30ns ev 0 (Atomic) 10 5 p P3/ 6 3/ s P 6s Density E (ev) σ (ev) 100ppm ppm atoms/pulse for 100ppm 10 6 atoms/pulse for 1000ppm (~1mJ/pulse, Gate700ns) FPUA / 5 p P 6 p 5 3/ 6 1 S0 3/ 4.91 evx / 4.84eVx (Atomic) There is a possibility that is the transition from 6p to 6s.

19 Current status and Plans Confirmation of electronic energy levels and lifetimes in solid parahydrogen 5 p P 6 p 5 3/ Understanding dephasing process 5 p P3/ 6 3/ s P 6s 3/ 3/ Also search for more appropriate systems 6 1 S0 FPUA010 19

20 Summary Quantum coherence in nanometer-scale targets is attractive to the macro-coherent two photon emission. - The preparation of the tentative experiment to measure basic characteristics is going on. It might be obviously challenging. However, there is a possibility of opening a new technique for exploring the neutrino properties. - Thank you for your attention - FPUA010 0