Developing a “Big Light” Proposal for submission in January 2005

1. Developing a “Big Light” Proposal for submission in January 2005 Proposal for IR-THz FEL is under development … …in collaboration with FELIX Jefferson Lab and UC Santa Barbara …to couple to the NHMFL’s suite of DC magnets Schematic of the relatively compact IR-THz source at Osaka University

2. High Magnetic FieldFree Electron Laser

3. Aim Combine a powerful FIR/IR radiation source with high magnetic fields to create a unique facility for physics, (bio)chemistry, and materials research. Electronic transitions Lattice vibrations Superconducting energy gap Pseudogaps in cuprates Collective modes in correlated systems optical industries Magnetic excitations J.L. Musfeldt

4. What is a Free-Electron Laser • Wavelength tuning: • Energy (g) • Wiggler (B)

5. Applications • Pulsed EPR • Spintronics • Quantum Information • Superconductivity • Phonon interactions • IR spectroscopy of ions • Time-resolved FT-IR • Magnetic excitation dynamics • Non-linear spectroscopy From Big Light Workshop

6. Pulsed EPR A spin echo seen in the rotating frame (From Chris Noble) • Relaxation • “hidden” Interactions (hyperfine, dipolar, etc.) • Spin manipulation Relaxation parameters T1 Spin-lattice relaxation time T2 Spin-memory time, spin-spin relaxation time

7. Why at High Field/Frequency ? • High absolute sensitivity (~1010 spins at 10 GHz, ~105 spins at 1000 GHz) (->smaller samples) • Some high-spin systems cannot be accessed at low frequencies • Higher Zeeman resolution (orientational selection) • High electron spin polarization (hν >> kT) • Faster timescale

8. Now and future

9. Applications • Biology • Distance measurements for protein structure (site-directed spin labeling) • Metalloproteins • Photosynthesis • DNA radicals • Etc… • Chemistry/Physics • Photo-excited states of fullerenes, nanotubes etc. • Semiconductors • Material research • Molecular magnets • Quantum Computing • Etc..

10. The dream • Frequency 300-1400 GHz (1mm-220 μm) • Power 1 kW • Pulselength variable 100 ps-2 ns • Phase-locked with frequency stability ~ 10-8 • Multiple pulses with variable distances • Repetition rate variable 1 µs – 10 s • Power stability < 1% • Second frequency

11. Qubits and schemes Pulsed EMR Pulsed EMR Pulsed EMR Pulsed EMR Pulsed EMR

12. This scheme is in the same spirit as proposals for multi-qubit devices based on quantum dots No H = 0 tunneling D. Loss and D.P. DiVincenzo, Phys. Rev. A 57, 120 (1998). To lowest order, the exchange generates a bias which each spin experiences due to the other spin within the dimer Method II: Exchange (dimer of S = 9/2 Mn4 SMMs) Wolfgang Wernsdorfer, George Christou, et al., Nature, 2002, 406-409 S. Hill

13. This scheme is in the same spirit as proposals for multi-qubit devices based on quantum dots D. Loss and D.P. DiVincenzo, Phys. Rev. A 57, 120 (1998). "off" Light "on" + - Control of exchange S. Hill

14. Detection • Direct FIR/IR detection (reflection/absorbtion) • Magnetization detection • Electrical/Current detection • Optical detection (pump/probe) • ICR detection

15. Probing the role of phonons in layered superconductors κ-(ET)2Cu(SCN)2 Hc2 Hc1 Tc Temperature (K) J.L Musfeldt

16. Field-dependent modes in (ET)2Cu[N(CN)2]Br J.L Musfeldt

17. Novel Spintronic Materials • Motivation • New class of materials for spintronic devices • A. Malajovich, J. J. Berry, N. Samarth and D. D. Awschalom, “Persistent sourcing of coherent spins for multifunctional semiconductor spintronics,” Nature 411, 770 (2001). • potential materials for fabricating logic gates for quantum computing • D. Loss and D. P. DiVincenzo, “Quantum computation with quantum dots,” Phys. Rev A 57, 120 (1998). D. D. Awschalom, “Manipulating and storing spin coherence in semiconductors,” Physica E 10, 1 (2001); A. Imamoglu, D. D. Awschalom, G. Burkard, D. P. DiVincenzo, D. Loss, M. Sherwin, and A. Small, “Quantum information processing using quantum dot spins and cavity QED,” Phys. Rev. Lett. 83, 4204 (1999). • Focus on Wide Gap Oxides • ZnO and (Zn,Mg)O • TiO2 D Reitze

18. The role of ultrafast lasers in studying spintronic materials Scott Crooker, Ph. D. thesis, 1997 • Spin relaxation in semiconductors • Non-magnetic semiconductors • Electron: Sze= ± ½; slow • D’yakanov-Perel’ • Hole: Szh= ± 3/2; faster • Exciton: Sze= ± ½ • Magnetic semiconductors • Ferromagnetic s-d exchange (allowed) • Anti-ferromagnetic p-d exchange (suppressed) • Time-resolved Faraday Rotation • ZnO  m* = 0.24 me ZnSe/ZnCdSe quantum wells D Reitze

19. The Dilute Sample Problem Conventional absorption spectroscopy Sample Photon detector Problem: Too little light absorbed by ions Action Spectroscopy (consequence spectroscopy) Fragmentmolecule detector Dunbar, Eyler et al.

20. Cr+/Anisole Mono-Complex vs DFT FELIX Mono-Complex Spectrum (O) DFT Ring-Bound (O) (O) (U) (M) DFT O-Bound (M) (O) (O) Dunbar, Eyler et al.

21. Jun Kono, Rice Solid State Spectroscopy • THz/FIR Dynamics in Semiconductors • Variety of low-energyexcitations (cyclotron resonance, electron spin resonance, intersubband transitions, donors, excitons, phonons, plasmons, etc.) • Variety of basicprocesses (carrier scattering, recombination, and tunneling processes) • Transition from classical to quantum, from AC fields to photons • FIR-FEL Provides THz Radiation with • Short pulsewidth (~ few ps)  Probing low-energy phenomena in the time domain • High peak intensities (up to ~0.5 MW)  Nonlinear optics in the THz range

22. Jun Kono, Rice TRCR Experimental Setup J. Kono et al., Appl. Phys. Lett. 75, 1119 (1999).

23. Jun Kono, Rice TRCR Example

24. Time-resolved study of superconducting MoGe thin films • Superconductivity: • electrons form pairs. • energy gap D in the electronic density of states (around eF). • Non-equilibrium state: • Electronic transitions across the full gap 2D breaks pairs, producing quasiparticle excitations. • Introducing excess quasiparticles (such as by photon absorption and pair breaking) leads to a non-equilibrium state. D How does the non-equilibrium system relax? H. Tashiro, L. Carr,D. B. Tanner, D. H. Reitze

25. high energy (E~EF) electronic excitations (quasiparticles) ~ femtoseconds low energy qp’s & EDebye phonons hn ~ picoseconds 1/tR excessDqp’s excess 2Dphonons 1/tB phonon escape(at rate1/tg ) bottleneck Relaxation processes in superconductors • Multi-step process, with a range of timescales. • Coupled system of excess quasiparticles and phonons, trapping and effective lifetime. • Rothwarf & Taylor paired electrons & thermal quasiparticles D Reitze et al.

26. Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U.S. Department of Energy Coherent Synchrotron Radiation Effect of Pulse Charge G Williams

27. Characteristics of THz Pulse Spectroscopy - minimum detectable fractional absorption better than 1 in 104 -transient FIR absorption with sub-picosecond temporal resolution ! ( ) ( ) ( ) w = w - w n n ik Þ $ - measures electric field, E(t), directly Transient Photoconductivity Binary Liquid Mixtures - semiconductors (ultrafast switches) - H2O & CH3OH, CH3CN, CH3COCH3 - Semiconductor nanocrystals - CH3OH & CH3CN, CH3COCH3 Solvation and Liquid Dynamics - nano -electronics, molecular electronics - electron transfer and solvation - OH librational dynamics - thermalization and relaxation processes - ionic solvation - reverse micelles - frequency dependent conductivity - neutral solvation - energy transfer - intermolecular and collective dynamics Intramolecular Electron Transfer THz Imaging - plastic and paper are transparent - accelerating charge generates pulse Overview 1 THz = 33.333 cm-1 = 4 meV = 300 micron l C. Schmuttenmaer

28. 2D Conductivity Grids

29. Selection of FELs Worldwide Van de Graaf Microtron / LINAC SC-LINAC Linac Linac Linac Linac Linac SC-LINAC SC-LINAC Linac Storage Ring SC-LINAC Van de Graaf

30. ~5 ms Pulse-shape Electrostatic With sufficient power and/or SC LINACs also CW or continuously pulsed lasers can be built RF Gun + Linac

31. Electrostatic FEL for the FIR UCSB Free Electron Laser • 10 ms coherent pulses. Optical pulse slicing and Cavity dumping  10 ps – 10 ns pulses • Injection locking at select frequencies • 10 kW peak power ( 5 MeV beam, 2 A current) • ~ 100 Hz Rep Rate • Frequency range 200 GHz – 4 THz ( 7 cm-1 – 130 cm-1, 1500 mm – 75 mm) Design goals

32. LINAC FEL for the MIR/IR • 0.5-4 ps micro-pulses • 20-50 MeV e-beam • 200 mm – 2 mm ( 1.5 THz – 150 THz, 50 cm-1 – 5000 cm-1, 6 meV – 600 meV) • Peak power 100 MW • Micropulse rep rate 1 ns to 50 ns • Macropulse 10 ms – CW FELIX, Rijnhuizen, Netherlands

33. Schematic Design

34. Budget and Personnel • This construction of the FEL should be funded separately from the NSF core grant. • Total costs ~ 15 – 20 M$ • Conceptual design : 1.5 year ( ~ 1.5 M$) • Construction 5 years ( ~ 15-20 M$) • Operation ( ~ 700k$ / year) • Personnel: • 2-3 students • 1 postdoc • 1 scholar scientist • 1 engineer • 1 technician

35. Infra-structure • Needed • Separate building. ( < 1G stray-fields of the swept magnets) • Estimated total floorplan 100x100 ft • Access to Magnets : • 50 T Hybrid • 36 T Series Connected Hybrid • 15 T Split coil magnet • 17 T Superconductor • ICR magnet

36. Cooperation with FEL expertsG. Williams, G. Neil - Jefferson Lab J. Allen, M Sherwin - UCSB A. van der Meer - FELIX G. Gallerano - ENEA-Frascati • Proposal to be submitted Jan 2005 • User input will be highly appreciated ! • For suggestions please contact: • J Singleton • LC Brunel • J van Tol

38. T2 and Electron spin polarization If T2 is determined by electron electron spin coupling, T2 is expected to get longer in the limit of hν>>kT, due to the decreasing probability of spin flip-flops. In coupled electron spin systems, the transverse relaxation is often prohibitively fast for pulsed EPR KUTTER C, MOLL HP, VANTOL J, ZUCKERMANN H, MAAN JC, WYDER PPRL 74 (1995)

39. What is currently available ? Sources (around 300-600 GHz) Gunn+Schottky diodes ~ 10-0.1 mW Array multipliers ~ 30 mW BWO ~ 10 mW Gyrotron amplifier ~ 1 – 100 W EIO (LF end) ~ 200 W FEL Amplifier table top ~ 10-100 W (big) office size ~ 10 kW FIR laser (CO2-pumped ~ 100 W molecular gas laser) • Multi-frequency quasi-optical techniques: • Low losses • Control and use of polarization • Fast detection (~600 ps)

40. Current high-field pulsed EPR instruments Kutter et al PRL 74 (1995), 2925 Commercial Instruments 95 GHz (3.4 T) 140 GHz (5 T) Home-built 180 GHz Frankfurt 275 GHz Leiden 604 GHz 21.6 T

41. Acknowledgements

42. FIR-laser set-up (Grenoble HMFL) Highest frequency pulsed EPR at 604 GHz • Time-scale limited by pulselength of the laser (100 ns) • Pulsed CO2 laser instable • Single frequency Moll et al. J. Magn. Reson 137, 46 (1999)

43. Quasi-optical techniquesand phase-coherent powerful pulsed source Sources (around 300-600 GHz) Gunn+Schottky diodes ~ 10-0.1 mW Array multipliers ~ 30 mW BWO ~ 10 mW Gyrotron amplifier ~ 1 – 10 W EIO (LF end) ~ 200 W FEL Amplifier table top ~ 10-100 W (big) office size ~ 10 kW • Multi-frequency quasi-optical techniques: • Low losses • Control and use of polarization • Fast detection (~600 ps)

44. 99.7 % recirculation Implementation 2 – 7 MV Rep rate 100 Hz Energy spread <10-5 NHMFL FEL3 041022 Van Der Graaf MM - FIR NHMFL FIR – MIR - IR RF LINAC Gun

45. High frequency – How high ? Kutter et al PRL 74 (1995), 2925 Commercial Instruments 95 GHz (3.4 T) 140 GHz (5 T) Home-built 180 GHz Frankfurt 275 GHz Leiden 604 GHz 21.6 T